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Friday, October 19, 2018: After many years, the Nautilus Minisub restoration is high on the priorities list again. I've posted a page (Refurbishing4) documenting my progress, but nothing detailing the process; so today I've started this blog.
BACKGROUND: We emptied the shop and laid down an epoxy floor; no cement dust in there anymore. Got all the tools and equipment set up for the car, motorcycle, diving helmet, and submarine projects.
LEMONS TO LEMONADE: Having to order parts and special tools by mail is slow but that also gives me time to refine the design. This week I came up with a way to locate the motor in a better part of the hull and do away with the 36" interconnecting shaft, pillow block bearings, and couplers.
THE PLAN: (1) bench-test the motor; (2) watertank test some propellers; (3) remove most of the sheet metal and framing from the sub's superstructure; (4) remove the top of the cabin; (5) make an access hatch in the roof of the pressure hull aft of the passenger compartment; (6) install the drivetrain, dive plane / rudder actuators, and aft ballast valve actuators, et al; (7) install all other pilot controls and systems; (8) make and install an improved pilot access hatch with a 1/10th scale wheelhouse structure attached; (9) reinstall all original exterior framing, sheet metal, and viewports to the hull and superstructure; (10) check weight and balance; (11) proceed to Float Test #10.
Once she's operational again, we'll experiment to find the right propeller; then do the scale exterior detailing to replicate what's seen in the movie.
At 48 volts, the ME1117 motor cruises at 6hp and sprints at 19hp. I've chosen two nine-inch propellers; a 7" and a 10" pitch. The 7" will be quicker off the line but the 10" will be faster at WOT. If we only spin the 7" at 2500 rpm, with a 30% slip that's a boat speed of 11.6 mph; 16.6 mph with the 10" pitch. She'd cruise between 4.6 and 6.6 mph turning 1,000 rpm.
Those are calculated estimates of potential, but (1) the unloaded motor is capable of 4000 rpm; and (2) a submarine is not limited by the bow wave which restricts top speed in displacement hulls; so we're optimistic. Optimal performance with minimal cavitation is the goal.
A more radical prop and/or more powerful motor would be an easy swap; but anything close to those speeds would be fast enough for our purposes.
Tuesday, November 06, 2018: As of today we have the four propellers we want to test. A 9 X 7, 9 X 10, 10-1/4 X 10, and a four-bladed 12 X 12. This will show us how the motor performs with props designed for its horsepower rating, and also how it handles larger, more radical propellers.
For submarines, the name of the game is maximum thrust for minimal cavitation. That means large, big-bite props turning slowly. The four blade bronze 12 X 12 will show us how she handles a big load with direct-drive; should punch out of the hole nicely but that won't have the highest top speed.
Eventually I'll want a five-bladed hammerhead prop as seen on the Disney Nautilus. I actually went against my nature and looked into a 3D printed prop but the price was a ripoff and after I thought about it a "Polaroid part" on my handmade submarine would really suck. So I'll cut it out of steel, bend the blades to the desired pitch and stress relieve them, do some contouring, and adapt it with a hub. Simple. I will have a substantial pitch angle per blade so I'll need to gear that one down 2 to 1. Fortunately, ready-made gearboxes for this motor are available.
Sunday, December 02, 2018: Ordered a 2:1 GEAR REDUCTION for the drivetrain. Also, hand-fabricated an adapter bushing to mate the metric prop shaft to our SAE 12X12 propeller. Ready to assemble for bench testing.
Monday, December 03, 2018: I've been planning to run the driveshaft through-hull bearing box from a Kawasaki JS-550 jetski in the submarine because (1) it's watertight, (2) can turn at 6,000 rpm, and (3) I have one. But it's uncertain what the box's depth capability might be and it's probably not more than one additional atmosphere.
So last night I designed an improvement to the mount so that now when the shaft leaves the pressure hull it enters a watertight pressure-compensated chamber before reaching the propeller. With two watertight bearings fore and aft in that secondary chamber; no water should reach the JS-550 box and no additional (depth compensating) air pressure should enter the pressure hull.
I'm happy with how the design turned out but the best part of this is, those watertight bearings usually sell for about $120 each plus shipping, and last night I bought two of them for $40 each INCLUDING free Priority Mail to Hawaii. So basically I got those $120 bearings for $25 apiece. Love that eBay! J
With jobs like this; first I have to recognize the problem, then invent a way to solve it. THEN I have to design the adaptation in such a way that it can be manufactured, installed, serviced, and removed easily if needs be. Did all that last night and the bearings should be here in a week. Very happy with the progress we're making so far.
Tuesday, December 04, 2018: BENCH TESTS, BOAT SPEED, ETC.
Apparently, those who say my Nautilus Minisub is limited by factors that govern displacement hull speed are unaware of the venerable Mark 14 torpedo.
Depending on which online hull speed calculator is used; at 20.5 feet in length, it should only be able to reach a top speed of 5.9 to 6.1 knots and no more.
Surprise! The Mark 14 torpedo can travel at 31 knots for about 8,000 meters; or 46 knots for half that distance.
According to those same online hull speed calculators, the Nautilus Minisub's top speed is between 5.9 and 6.1 mph. But as I've just shown: those calculators don't work with submersibles.
So what will she really do? We're about to find out.
This week I will assemble and test the Nautilus' new electric drivetrain; on the bench and in a water tank.
According to the technician's printout that came with this motor, it has already attained 4500 rpm on the bench unloaded, and is capable of about 5,000 rpm WOT at 48 volts.
Power output is rated at about 6 hp sustained and 18 hp during one minute sprints.
This same motor can drive a full-sized motorcycle at more than 50 mph so it has plenty of torque.
My first tests will be direct drive, 1:1 ratio, coupled to a bearing-supported driveshaft and 12X12" four-bladed bronze propeller.
Calculated with a 30% prop slip, all I need to hit 6 mph is 754 rpm.
If I cruise at 1000 rpm that's a prop speed of 8.0 mph.
And if all I get at top end is 2000 rpm out of the prop, that's still 15.9 mph and in this boat that will be scary.
If 2000 rpm is a strain in direct drive, I'll use a 2:1 gear reduction to get that same prop rpm while the motor spins at a cooler and more efficient 4,000 rpm.
(In effect, it's kind of like shifting gears in a car; where the transmission gearing reduces the load on the engine and enables it to operate more freely.)
What will the actual RPM be with the propeller submerged? I'm within days of finding out and the anticipation is driving me nuts.
Film at eleven. J
Monday, January 14, 2019: BATTERIES! FINALLY!! YIP-EEEEEE!!!
No, I haven't bench-tested the motor yet. Schnit happens. Priorities, interruptions, holidays, etc. I did get the right bearings for the propeller support and made other advances; but BATTERIES are what's been delaying the motor tests.
Remember: Vulcania is a volcanic island in the Pacific ocean; sometimes, supply is difficult. The companies with good prices wouldn't ship to Hawaii and their CSR's were literally too stupid to comprehend why they could and should.
Long story short; at the last moment before I was gonna have Doc receive the batteries and ship 'em to me here (bless your heart, brother) I found a company that had them at a low price with free fast shipping to Hawaii. As I write, I have the four-battery pack enroute via Priority Mail; first one arrives today and the last two by the end of the week or thereabouts.
So now we have a 48-volt 35 amp/hour battery pack that weighs in at about 90 pounds. That's what we'll run for drivetrain bench tests and open water proving tests. If I want to double the amp hours, I can mount a second pack; they're not very big and I can fit it into CG.
Free shipping deducted, I'm getting these for about $55 per battery and that's rock bottom in today's market. Battery Bill wants exactly twice that for items stocked here in Hawaii. But they don't have enough of them and what they do have has been sitting on a shelf for a long time. So it's like I bought all four batteries for $220 plus shipping. I scored.
Of course, I could pay about five times more and go to a lithium pack but in this application the weight savings aren't needed so the extra expense and complexity of the lithium battery is redundant.
These are deep cycle SLA batteries intended for the demands imparted by motorized wheel chairs, trolling motors, and the like. Not a starting battery, per se. This is the right kind of battery for the submarine.
I've been wondering what kind of Cold Cranking Amps these 12V-35AH batteries put out. I saw a report where actual tests put that value at 650CCA. That gives us an idea how hard these puppies will crank at WOT, and 650 is pretty respectable; what you'd expect out of a physically larger battery intended for heavy duty use; starting a large V8 engine as in a truck or the like.
According to the online info specs: the ME1117 draws 120 amps continuous and 220 amps peak for 1 minute. With the 35AH pack, that's 48 volts for a maximum of 17.5 minutes; or 9.54 minutes of 1 minute sprints.
Actual endurance will vary because (1) I'm not going to suck the batteries flat; and (2) when I'm just maneuvering I'll be using way less than continuous (cruise) power.
We'll know for sure what the numbers turn out to be when we bench test it; soon, now that the batteries are in the mail. But looking at these numbers and considering the actual energy demands test operations will put on the pack; it looks like we'll get much better performance and endurance than we had in 1991.
P.S. I just rechecked the ME1117 info page online and it says 80 amps continuous; not 120. Both values are listed without any explanation, so that's how I got it mixed up. But if that's accurate then she'll cruise at about 6 hp for 26.25 minutes; not the 17.5 minutes I mentioned above. Even better.
So if we're cruising at about 8 mph, with the 12V-35AH SLA battery pack, I should be able to travel about 3.5 miles and still ram a ship. Double that distance if I drive slower. LOL!
And again, I can double that with a second SLA pack. But considering the mission this boat is built for; that oughta do it.
P.S.S. WAIT! It's even better than that! I just checked the dynoplot printout and at 1000 rpm the unloaded motor is only drawing 29 amps. Factoring drag, etc; let's say it takes 35 amps to turn our direct-drive propeller 1,000 rpm for a cruise speed of 8 mph. That's an hour endurance at cruise speed and a range of eight statute miles. And that should be more than sufficient for our purposes.
Looking better all the time.
BUT WAIT! THERE'S STILL MORE!
Let's say our one minute "ramming speed" at WOT is 16 mph. That's 1408 feet per minute; about 470 yards; almost five times the length of a football field.
(In scale, that would be like the real Nautilus travelling almost 2.7 miles at top speed on an attack run.)
If we take it easy on the motor and limit the NautMini's ramming runs to 100 yards, she'll cover the length of a football field in about 12 seconds.
And with about 9-1/2 minutes of ramming sprints available, she is easily capable of more than 40 such 100-yard ramming runs per battery charging cycle.
And we can calculate an estimated maneuvering speed and endurance, too. The unloaded motor draws 10 amps at 500 rpm; so let's guess we can get 500 rpm prop speed out of twelve amps. That's almost three hours maneuvering at 4 mph; covering a distance of nearly 12 miles.
At about 1/10th scale, if we propel the Nautilus Minisub at a speed of 16 miles per hour; that's like a full-sized Nautilus traveling at about 160 mph and of course that's ridiculous.
An actual speed of five to six mph should be all the NautMini needs to mimic the velocity of the full-sized Nautilus at ramming speed; not to create a realistic bow wave; but to move realistically in terms of scale distance travelled.
Monday, January 28, 2019: Received the fourth battery today. Made the inter-battery leads and connections to the motor harness plug. OPERATED MOTOR FOR THE FIRST TIME TODAY; bolted to the work bench. Excellent! Sevcon display shows voltage, amp draw, and RPM. Unloaded it's pulling only about 9 amps at 3700 rpm. Forward and reverse work fine. Next it's time to make the tube and mounts for the drivetrain and get it put together on the bench turning a propeller.
Monday, February 04, 2019: Been doing a few things to the sub; working steadily on design and fabrication.
PREPARATORY METAL WORK. Removed more steel hull plates to access the tailcone. Got the boat up on blocks; checked for level and symmetry; straightened the tail fins and motor mount that got bent years ago when it fell. Got the longitudinal centerline "bore sighted" using a length of 1/2" pipe centered in the old MK motor mount and aimed at the apex of the pressure hull inside the bow. I'll use a laser later but for now this is close enough to proceed.
PROPSHAFT TUBE: Today I welded two pieces together to make the pressure-compensated propshaft housing tube out of metal I have in stock; rather than spend $36 to buy another piece of tube downtown. Depending on how it turns out, I may buy and use that other piece of steel anyway, but I think I can make-do with what I have and my shopping list for metal, grinding stones, welding rod, and the like is long enough already.
GEAR RATIO REDUCER: I almost bought the gear reducer last October but was advised EMS is getting a new supplier and I should wait. So I waited and last night the new gear boxes became available online. Instead of cast iron housings made in China; these are really nice-looking aluminum boxes with helical gearing made in the USA. My order is being processed now and I hope to have the "transmission" for the submarine next week. Will post some pics and info on REFURBISHING 4 later.
MOTOR COMPARTMENT HATCH: It's almost time to cut the access hatch aperture. I'll wait until the gearbox arrives to measure directly so I can know for sure where the hatch needs to be. Then I can make the mounts, install the motor in the pressure hull, and test the drivetrain here in the shop.
access hatch also makes it possible to install and service mechanisms actuating
the rudder, dive planes, and aft ballast tank valves & vents. Coming right along.
Thursday, February 07, 2019: Steadily working on it. Since I can't proceed with the drivetrain until the gear reducer arrives; I'm focused on the through-hulls and mechanisms for the diveplanes, rudder, and the two remote ballast valves located in the tail cone.
I will counter-balance the diveplanes with heavy-duty springs and move them with medical-grade 12-volt linear actuators rated at 220-pounds of push / pull capability. The rudder will also be moved by a linear actuator. Pushing the joystick forward or aft gives us like plane action for a dive or ascent; leaning the stick left or right gives us opposed plane action to roll left or right; as might be desirable intentionally or to resist adverse rolling tendencies, should there be any.
Friday, February 08, 2019: Working on a new, pressure-compensated design to replace the rudder and dive plane through-hulls.
In true 19th Century style, the originals are stainless steel shafts riding on brass bushings in iron packing-glands welded to the hull. Made those "Blacksmith Style" using plumbing parts available at the hardware store. And they worked but packing them is difficult and I can build better now. Bearings, seals, and pressure compensation, coming right up.
I know: I'm compensating all four tail-cone through-hulls; so why not just compensate the motor compartment area of the tail-cone? Because (1) The open space requiring compensation inside the propshaft tube and directional control plane through-hulls is extremely small and won't require much air. (2) Compensating the tail-cone will require a lot of air plus the installation of a bulkhead able to resist depth pressure and requiring through-hulls of its own for ballast pipes, wire conduits, and the like. That's complex, weighty, and, if it fails under pressure it could act like a piston moving forward under great force to effectively squash the passengers into the forward 6 inches of the pressure hull nose cone.
I could build a bulkhead that won't pop but why all that extra work and weight when I don't need it? The KISS rule applies here.
Today I bought two nice-looking 12-volt servo valves that will eliminate the need to adapt an actuator for that purpose, too. Everything I need in one package; just plumb it in, wire it up, and flick the switch. (The original system has remote plumbing bringing the aftmost valves up amidships; I had long steel-rod extensions bolted to the valve handles so I could operate them from the cockpit.) Simpler is betterer. J
Tuesday, February 12, 2019: POTENTIAL. I'm refurbishing the Nautilus Minisub with a 48 volt motor; about 16 horsepower should be enough for now. But if I want more performance, there are more powerful 96 volt motors that will bolt right in without modification. And if I want to spend the money for a Lithium battery pack, I can triple my present endurance while getting over 50 horsepower out of the motor. How fast will it go? As fast as I dare, apparently.
Been working on mods for the cabin and hatch. Latest design seems most doable and would look pretty cool; it's gonna slide open like the canopy on an F-86 jet fighter.
Anxiously awaiting the drivetrain gear reducer. Meanwhile, the work continues.
Wednesday, February 13, 2019: 12-volt Servo valves received and will be tested tonight; interested in seeing how well they work.
Repaired the petcock on the Hyster with a new OEM viton rubber seal. That old Continental flatty is purring like a kitten now. (The forklift is vitally important to my work at Vulcania Submarine.)
TECH TIP: Always bring the large adjustable crescent wrench. J
Laser-sighted the alignment of the propeller shaft housing and bearing box mounts relative to the longitudinal centerline of the pressure hull. Bullseye! Thrust vector is right straight down the middle from the propeller hub center to the center of the pressure hull nosecone. Good enough. J
Working on the design and mockup for the new cabin hatch. Did some math and realized the Key-Brodeen 66" Nautilus model is 1:32 scale to a full-sized Nautilus; but also about 1:3 scale if I want to use it as the basis for a replica Nautilus Minisub showing all the internal components and systems. 1:3 pilot figurines are commercially available and stand about 2' tall. It would be a pretty cool model, I think. Put that on the list of things to do.
Okay, lunchtime is over. Back to work! J
Thursday, February 14, 2019: Post Office says my 12-volt actuator valves were delivered to a person who picked them up Tuesday morning; only that wasn't us! Probably a paperwork error. Looking into it.
Did a lot of work on the design for the cockpit, hatch, and control panels last night. All on graph paper. Old school is all I know.
Decided to keep the 3/4" stainless shafts I've had for the rudder and dive planes, but gave up on packing glands in favor of bearings, seals, and pressure compensation. I'm building new boxes from scratch with a flange that will bolt onto a welded hull boss. Decided to use VINTAGE HARLEY DAVIDSON wheel axles and bearings backed up by rubber seals. Bought those today. J
Each through-hull requires two bearings and two seals; the combined height of which is only two inches. That means the housing can be about three inches deep with a one-inch air gap in the center which will be pressure-compensated by a depth-sensitive external regulator. The other side of the housing will be drilled and tapped to receive fittings for a common overpressure valve.
The intent is smooth, watertight transfer of pilot inputs to control planes; I'm operating on the belief that the bearings, seals, and compensation are going to give us that.
Looking forward to building and pool-testing the prototype. Parts are in the mail and I sure hope we get that delivery problem straightened out!
Friday, February 15, 2019: False alarm! Not only did the one actuator valve get delivered to us on Tuesday; so did our replacement battery and both were in the back of my wife's vehicle all along. Miscommunication. No problem at the Post Office.
The battery checked out fine but there was only one valve in the box and I bought two. No problem. Quick email with the seller and the other one is in the mail at this time.
I bench tested the valve at 12 volts and it works nicely.
Been doing a lot of design work lately. With the new hatch, the cockpit layout is going to change dramatically. I'm still using rudder pedals; but they operate an electrical system, not a mechanical one like we had before. A joystick controls the diveplanes either in synch (to pitch) or opposed (to roll); and a potentiometer with a forward/reverse switch for "go and whoa." Then there's the ballast and air valves; hull vents and valves; and accessories like video, audio, comm, special effects, SONAR, electric compass, gas analyzer, servcon display, fans, scrubbers, lights, and more. Lots of things to fit into a very small space. All of it's gotta be wired or plumbed to interact with something elsewhere in the boat. And most of what I'll need to make that happen will have to be handmade.
I'm working on what I can when I can, but when the gear reducer arrives and direct measurements of the actual drivetrain can be made; it will be time to roll the boat outside, remove the superstructure and plating, and perform major surgery on the pressure hull. Besides installing the drivetrain propeller shaft tube, I'll cut out the through-hulls for the rudder and planes; cut a motor compartment access hatch aperture in the tailcone; and cut the cabin and "wheelhouse" off. After that I'll remove the ballast tank plumbing and sandblast the interior.
Then the real fun starts. J
Wednesday, February 20, 2019: Where has this month gone??? 2019 is speeding by faster than (insert your own analogy here). J
Been doing lots of design work while the drivetrain gear reducer is en route to Vulcania. The cockpit layout is pretty well set now, too; as far as where all the valves and switches will be.
Bought some carbide hole saws, diamond tipped drill bits, bearings, seals, shafts, etc. They've been arriving on a regular basis. Need to buy a few more actuator valves and electrical switches soon; will probably do that today or tomorrow.
The gear reducer FINALLY has a shipping label now and should be delivered in the next few days. YAY! That's an important part; the last major component I need before cutting an access hatch in the tailcone and installing the drivetrain.
Have a great day; I'll be working on the submarine. J
EVENING: A fairly productive if sometimes frustrating day. The gear reducer is en route, at least.
Today I worked on taking measurements and making templates of the existing cabin, wheelhouse, and aft deck; necessary references for the rebuild. Found some minor discrepancies in deck height between port and starboard side, relative to the longitudinal fins. Will have to correct that.
Received the new bearings and seals for the through-hulls I'm making for the rudder and dive planes. Checked them on the original 3/4" stainless shafts from 1991; the seals fit sweet and the bearings are just a tad tight but it's nothing one couldn't fix with a little steel wool and some elbow grease. I could use the old shafts but I've decided to go with genuine HARLEY DAVIDSON axle shafts; cut to size and adapted to purpose. They are machined to ride in those bearings.
But just fiddling around with them tonight, I can see this is going to be a great improvement over the old manual, "pushrod, bellcrank and packing gland" arrangement we had before. The bearing mounted shafts are smoother and quieter; and the seals look like they will ensure the pressure-compensated housing is leak-proof. It's looking good. I think this could work. J
My plan is to make the through-hull units with a bolt-in flange. Next I need to size the bearings up with the proper diameter steel tube. Looking forward to getting these built; we'll need 'em when we open up the motor compartment and that day is drawing nearer.
Thursday, February 28, 2019: The 2:1 gear reducer arrived a couple days ago. I've staged the drivetrain on the workbench, taken measurements, and done a large graph-paper drawing on the motor compartment, et al. (Still don't have CAD.) According to my measurements and best guesstimations, there should be 1/8" clearance between the top of the motor and the inside of the pressure hull. And when I did a graph paper drawing using those same measurements, it also shows a fraction of an inch clearance at that point. So once again it looks like my math worked out and everything is going to fit.
Is 1/8" clearance sufficient? Yes and no. The drivetrain will fit inside the hull at the station we've assigned to it; but I want more clearance than that to ensure proper air-cooling of the motor.
Not to worry! The high-point of the motor will be directly under the motor compartment hatch and the coaming will allow an extra inch or two in height; depending on how I build it. So I don't foresee any problems there.
Looking good and forging on. J
Friday, March 01, 2019: Been acquiring small parts and hardware necessary to bench-test the drivetrain. Still have a few more parts to get.
That possible 1/8" conflict between the motor and hull has yet to be resolved. Latest drawing I did shows a conflict. It's hard to be more precise than 1/8" when you're working with a tape measure and graph paper; won't really know what the clearance is until I get there. But in any event it's no problem because I have to install an access hatch to the motor compartment anyway; and I'll get whatever clearances I want there.
At this point, all I need is the mounting bolts and I am ready to bench-test the motor and gear reducer paired together. So that's next on the list: BENCH-TEST MOTOR AND GEAR REDUCER AS A UNIT.
The thing about bench-testing something like this is you can't do it half-assed; it all has to be mounted down tight and with no flexibility between components and couplers; pretty much as staunch as it will be in the boat. Parts of this drivetrain may spin at between 2000 and 4000 rpm; and the components aren't lightweight. When you get a coupled steel shaft spinning at these kinds of speeds; the forces generated if it is only a little bit "sloppy" or out of balance are enough to do serious damage.
So I've got to make sure I get it set up right before I test anything on the bench. One doesn't simply "clamp it down and run it." That's a good way to toast your new motor. J
Tuesday, March 05, 2019: Been developing the final production drawings for the guidance control through-hulls, working on the instrument panel layout, and acquiring many small parts like 3/16th shaft keys and genuine Evinrude propshaft pins for our pin drive propeller. Bought a cable-operated throttle lever for the potentiometer, and four brass 12-volt servo valves for the ballast and cabin ventilation systems.
Will be using Harley Davidson wheel bearings in the through-hulls. I've found a source of machined and polished stainless steel shafting that is a micrometer-measured .7495" in diameter. That's the industry standard so that's what I'll make the new shafts from. But the bearings are genuine Harley Davidson. J
DIVER COMM: Back in 1991, Lynn and I had to yell at each other. This time, a speaker will be concealed under the aft deck. I bought a commercially-available "fish talking" speaker but it has no treble; junk for my purposes. So I'll do what Phil Nuytten suggested: cut a plastic net float in half, install a car stereo speaker, and seal it back up with epoxy. That way, the Nautilus Minisub will be able to broadcast sounds like, say, the 20,000 Leagues theme or the "turbine-whine" of the Disney Nautilus' motor; plus talk in a normal tone of voice to people on the surface AND divers underwater. I remember what it was like back in 1991. When it comes time to start working the boat with surface crews, support divers, and cameramen above and below the surface; an underwater speaker is really going to help.
EXTERIOR DETAILING: I've thought of cladding the entire submarine in panels (cut from thin copper sheeting and embossed with faux rivet heads) that would be soldered onto the existing steel surfaces; much like the method used to construct Disney's 11-foot filming miniature Nautilus. I could make a device that would emboss copper sheet with simulated rivetheads and the copper is available. But when I consider the electrolytic ramifications of copper in contact with steel in salt-water; I have concerns.
The most readily available alternative for simulated rivet heads has been hemispherical acrylic cabochons; they come in the sizes I'd need, are very uniform, and don't cost much. The question has always been: "How to attach them so they won't come off when used in the ocean?"
There's a few choices. I thought about attaching them with Super Glue and covering that with a layer of fiberglass resin. Might work; might not. But then, what about the exposed ballast tank surfaces and other parts of the submarine that need to be made to look like plating the rivets hold together? I need something more.
I thought about covering those areas with fiberglass cloth and resin, and then using either Super Glue or an epoxy like JB Weld to glue them on. Might work but would also be a lot of cloth-glassing and that's a real laborious, sticky job. And even then, how well would the adhesives stick the acrylic cabochons to the fiberglass surface?
I tested by actually gluing acrylic cabochons to FRP and plastic; both of which are readily available in 4X8' sheets for about $25. That's a cheap source of siding but again; what to glue acrylic to FRP with? Liquid Nails? I don't think so. I tried Elmer's Glue, carpenter's glue, model airplane (styrene) cement, contact cement, Ace Hardware epoxy, Super Glue, JB QUIK, and JB Weld. Of those, only JB Weld had any real grip to it. But I could pop the cab off with sideways pressure from my thumb when I really wanted to. So none of those were good enough.
Acrylic is made to bond to acrylic with a water-like liquid cement that chemically fuses both pieces together; sort of like welding. Is it waterproof? They make saltwater fish tanks out of it. Is it strong? Some of those fishtanks are huge. And an open can of, say, Weld On acrylic solvent doesn't have a limited working time like, say, JB Weld does. Easier to work with and less expensive, too. Works for me. J
Acrylic sheeting in 0.093" (3/32") thickness is readily available at Home Depot at between $3 and $4 a square foot. Won't really need that much; a few hundred bucks, maybe. But of all the things I've thought of so far; this is the easiest, most economical, and most reliable way I've found to replicate the exterior plating and rivets of the Disney Nautilus. So it's decided: that's what's going to happen.
The advantages are obvious. For instance: when I make the new cabin / hatch / pilot-house structures from steel; I can simply make the templates, cut the parts, trim to fit, and weld them together. That's the functional side of it.
When it comes to cosmetics (i.e., replicating how the Disney Nautilus "looks" in 20,000 Leagues Under the Sea, circa 1954) by using thin acrylic sheet with solvent-bonded acrylic cabochons, I should be able to replicate every panel and rivet line and be certain the heads won't be popping off when she's running around in front of the cameras. Me likey! J
But what about the SALON WINDOW FAIRINGS?
I had wanted to make those out of copper with embossed rivet heads, if only as a work of metal art. But again; copper + steel + salt water = electrolysis. I don't want to encourage corrosion.
What I've got so far is a set of wooden frames forming the general shape of the fairings bolted to the Nautilus Minisub; to which cardpaper templates of each required panel have been attached, forming the basic shape. I could build it up with fiberglass; reinforce the interior for strength; and use that as a plug to either vacuum-form or cold-cast an acrylic fairing shell to which the cabochons can be chemically-fused with Weld-On acrylic solvent! TA-DAAAAAAAAA! J
Tonight, I'm totally stoked. When she's ready to make her debut for the cameras, the Nautilus Minisub will be a lot faster than she was back in 1991; and with exterior detailing based on acrylic sheeting and cabochons, she's going to look good, too. J
Tuesday, March 12, 2019: Bought another $500 worth of steel and hardware yesterday. Altogether, probably spent about a grand so far this month on parts and tools AND I still need to buy a new drillpress. Such is the life of a metal fabricator. It's only money. (ouch!)
When I built the Nautilus in the late 1980's I was paying about $0.15 per pound for steel at ALCO Metals in San Leandro and Joe Garske's boatyard in Benicia. Didn't matter what kind; mild or stainless; it was fifteen cents a pound. Yesterday, among other things, I spent $60 for 30" of 2-1/4" diameter schedule 80 pipe. At least now I have all the steel to finish the cabin and hatch rebuild.
Things are so much more expensive these days but hopefully it won't cost too much more before we're done. Either way, I have to finish this project and that's all there is to it. I've come this far; can't stop now.
Friday, March 15, 2019: Operated the ME1117 motor and Electra Gear 2:1 gear reduction as a unit for the first time today. At first, the output shaft was slipping; the shaft key had slipped out when I re-mated the motor to the gear box while adjusting the mounting bracket and because it was internal I didn't notice it.
After attending to that, they both ran beautifully; very quiet and smooth. I was seeing about 4200 rpm on the Sevcon display at only about 70% on the potentiometer.
If it was only 3750 rpm at a 2:1 ratio with our 11" (pitch) prop: that's a speed of approximately 13.7 mph.
Of course, prop speed will be slower with the weight and friction of the drivetrain and propeller resistance against the water added in. But the motor has 30% more available power so I'm still optimistic as to what the realized performance will be.
I'm babying it for the time being; just making sure everything works before proceeding. So far; real good! J
Tuesday, March 19, 2019: PROBLEM: At first, I just checked to make sure the two units would run together. Yesterday I tested it again and noticed the gear reducer makes the propshaft spin opposite of what the motor does; opposite of how I told the manufacturer I wanted to spin the propshaft!!! Shouldn’t my supplier have mentioned that? AAARRRGGGHHH!!!
Also: me no likey the jaw-type couplings. Too sloppy.
Wednesday, March 20, 2019: PROBLEM SOLVED: Decided to use a keyed SS shaft coupling, 7/8" X 36" shaft, and a 12 X 13 7/8" straight bore prop. Dumping the JS-550 bearing box and shaft; modifying the pressure compensated propshaft tube to fit 7/8" bearings and seals. Already had the SS coupling and bought the prop last night. Arranging to buy and ship the shaft now.
Funny how the project has morphed. I started wanting to use the JS-550 shaft and bearing box as a watertight through-hull, and to protect the motor from axial loads. Then I decided to build a PC shaft housing as added insurance for the watertight box.
Then I got the gear reducer which also protects the motor from axial loads; making the JS-550 box redundant in that regard.
The jaw-type couplings (needed to mate to the JS-550) proved sloppy at high rpm. So, because I already have a 7/8" keyed coupling (same as the gear reducer output shaft); and because the gear reducer protects the motor from axial load and the pressure-compensated propshaft housing will provide watertight integrity to the pressure hull; the JS-550 can be replaced with a straight 7/8" shaft, bearings, and seals.
This will move the motor forward; closer to the CG and into a part of the hull with better clearance. It will simplify and lighten the drivetrain, reduce complexity and friction, and we're getting a better propeller, too.
The road is not ever straight but I eventually get where I need to be. Go wit' da flow, braddah! J
Thursday, March 21, 2019: Okay! I have the stainless steel shaft coupler, the propeller is in the mail, and I just bought the stainless steel shaft; should arrive in a week. As soon as it gets here we can start putting this together.
I've decided to go with carbon-ceramic seals (spring-loaded waterpump shaft seals)in the control through-hulls and pressure-compensated propshaft housing. They can be expensive but they are way better than the seals I was going to use and I bought them at a good price from China. I'm waiting for them to arrive.
Going to have to get 7/8" bearings and redesign exactly how I'll fabricate the PC housing tube. No problem; under $10 each.
Yes, things are progressing nicely. Me likey again! J
ADNOTE: Today I bought two 7/8" four-bolt flange bearings and one Dorman 7/8" X 14 tpi castle nut (spindle nut) with cotter pin for the end of the shaft. I already have the 3/16" shaft keys. So at this point I have the whole drivetrain, prop included, ready to bench test; minus the machine work to the shaft. The sooner the U.S. Mail can get it here; the sooner it can be running. I'm guessing two weeks. We'll see.
Tuesday, March 26, 2019: Early morning update. The propeller shaft, bearings, and cap nut are on the island; I'll have them in my hands tonight. Then, all I have to do is take the shaft to my machinist friend and have him cut two keyways and thread one end. At that point, I can assemble the drivetrain on the workbench and dry-test it.
After that, I'm going to enclose the open end of my forklift dump-box with an old sheet of leftover T-111 siding to make a big mobile water tank out of it.
I'll drill a hole in the siding and mount the aft flange bearing directly to it with mechanical fasteners and RTV sealant. Then, I can just wheel out the workbench with the drive train and batteries attached; position and align everything with the forklift; and slide the propshaft right through the bearing into the water tank. Slip the prop on with a 3/16 key, tighten the cap nut, and we are ready to water test with a 12 x 13 prop. Stoked! J
Yeah, the box will probably leak a little bit; I could caulk it but why? We'll just keep a garden hose in it and it will work well enough for testing purposes. And this way we'll have accurate performance data on the motor and prop. I'll be able to see exactly what it does because it will be right there doing it in actual wah-wah. God! I love what I get to do! J
And then, I'll just unscrew that piece of siding (and return it to the supply we use to cover windows in hurricanes) and have my dump-box back. Cool!
If I can get the machining done before Friday, I can be running it this weekend, I think. Yeah, I know. That's probably too optimistic. We'll see.
I learned a long time ago; one does not pressure machinists. You just take the man your material, tell him what you need, and be grateful he's doing it for you at all. J
Friday, March 29, 2019: Exhaustion! Several days of non-stop R&D; countless drawings; dawg tired! J
DRIVETRAIN AND P/C PROPSHAFT HOUSING: The entire drivetrain is now stainless steel except for two flanges (chromed brass ala US Divers SCUBA hardware) the propeller (brass) and the cap nut (chrome-plated chrome molly).
And, I found a way to make the carbon-ceramic shaft seal seat and pressure compensation chamber of the propeller shaft housing out of 1-1/4" stainless steel pipe and fittings that will thread together and not require any welding. Got good prices on the fittings at eBay and they are in the mail now.
From the motor and gear reducer aft, these parts of the drivetrain are now stainless steel: shaft coupling; 36" propeller shaft; forward shaft bearing; tailcone bulkhead; close nipple; cross tee with two reducers; nipple; pipe coupler; close nipple; aft propshaft bulkhead; aft propshaft bearing; and aft propshaft collar.
(I couldn't wait more than a month for those bargain pump seals to arrive from China, so I bought a Dayton carbon-ceramic seal from the USA and it will arrive in less than a week.)
Here's what brought on the change from schedule 40 pipe and welding, to SS fittings:
According to published specs (and without having actually tried it yet) the seal fits neatly inside the stainless steel pipe coupler and the rotary part looks like it has clearance to spin with the shaft, but it's close. (If not, a 1-1/2" x 1-1/4" NPT bell reducer will provide a "chamber" with more clearance.) I extrapolated from there and this system was the result.
In the pump for which it was made, the seal's rubber side is exposed to water so I should vent the aft-most nipple so the chamber stays flooded; sealed watertight at the carbon-ceramic boundary on the shaft.
An alternative to venting the seal chamber to the sea would be to run it sealed and completely filled with the right kind of oil. I haven't ruled that out but will test first to see if it's needed or worthwhile in this application.
Forward of the seal chamber, the cross tee comprises a pressure-compensated chamber (air inlet at the top; overpressure valve at the bottom).
The seal should be reliable for what I'm doing with the boat. If not, any water that might get past it would be discouraged by ambient pressure compensation and I can also manually purge the chamber from the cockpit.
Plus, where the shaft enters the forward bearing; the pressure compensated chamber is further sealed with carbon-graphite shaft packing under mechanical pressure providing watertight and airtight integrity for the pressure hull.
So with all that going for us; we oughta be dry inside. J
And the whole thing screws together out of SS pipe fittings and two pieces of 1/4" SS plate that I'll drill and cut to serve as bulkheads and mounting brackets. How cool is that? J
BENCH / WATER TESTING: I've come up with a design where I can build the drivetrain and motor on a bench for dry testing; then build a 2' X 2' plywood box around the propshaft housing and propeller mount which can be fit with a water inlet, a drain, an air pressure hose connection, and a plexiglass window. With the propshaft in the box; the box filled with water and sealed shut; we can get realtime feedback on how the propeller works underwater.
And, when I pressurize the water box, it will be as if the prop and housing are running at depth. This way I can know if the seal and pressure-compensated chamber actually work to keep the pressure hull dry.
So that's bench-testing it dry, wet, and pressurized; without having to move it from the bench to a water tank, reassemble it, or any of that. Damn I'm good! J
Sunday, March 31, 2019: ENGINEERS: Because I regularly admit (and laugh about) the fact that I am only an engineer ipso-facto, self-taught and without certification; one might think I have disdain for trained engineers. Not so.
I have infinite respect for the science of engineering and personal skill. But I've had trolls clash with me about submarines on the basis that they have some sort of (non sub-related) engineering sheepskin on the wall; when in fact they didn't know jack about submarines and (until they read my SIMPLIFIED SUB DESIGN MATH program)wouldn't know where to start if it ever came to building one.
(And now they are online spouting the elements of SSDM to make themselves look like the real steel! Caveat emptor! Big time! There's phony posers everywhere online! Homebuilt subbers have their bogus hangarounds, too. They're really just online to cyber-socialize under the pretext of being involved with the genre; and usually that sort of thing is harmless. But what you don't know about subs CAN hurt you! Beware of those who do not walk their talk. They're out there.)
So anyway; that's where my memes about "I'm not an engineer; I just build stuff" are coming from; a humorous slap at preposterous people. (And they know who they are.)
So if you are an engineer and think I was talking about you; don't go there. It's not always about you. J
BILGE PUMP SUMP: That said (and now I feel better, thank you!)I recently remembered something I thought of years ago that I want to do to the NAUTILUS MINISUB pressure hull.
You know that DIVE HATCH amidships in the Disney Nautilus keel? Well, that's the perfect place for a bilge pump in my sub.
I'll just flip her over on the roller, cut a hole in the bottom, and weld in a 4" x 6" section of schedule 80 steel tube and weld the outer end shut with 1/4" mild steel plate. That will form a sump in the lower part of the floor where the bilge pump can reside. (====|PUMP|====)
Any water that enters the hull will collect in that sump and be pumped either overboard while running surfaced; or to a 2-gallon onboard tank that can then be purged overboard with compressed air. A water sensor will activate the pump. And yes, I have all the parts. Bought them years ago.
Point is: she's GOTTA have a bilge pump and the Nautilus dive hatch is the perfect place to conceal it. J
DRIVETRAIN: The propshaft is 36" long. The propeller bearing's 1/4" stainless steel mounting plate is 13-3/4" aft of the pressure hull's tailcone boss and there's about 5" of shaft aft of that for the locking collar, propeller, washer, and nut. That's leaves about 17" of exposed shaft inside the hull, from the motor coupling to the tailcone propshaft bearing.
I bought a 10" SS pipe nipple and two more SS flanges. I could extend the manifold further into the pressure hull. The tailcone bearing would mount to the forward flange; reducing the amount of exposed shaft to about 2-1/2" between the bearing and the motor coupling. This additional housing could also comprise a second chamber that could be pressure compensated if we want to. I don't expect that would be necessary but we do have that option.
Then again, do we really need a shaft support bearing 2-1/2 inches from a rigidly-coupled motor/gear reducer unit? The original location at the tailcone bulkhead puts the bearings roughly midway and at the end of the shaft. With the motor on the forward end, that seems an equal distribution of bearings. Still noodling this one out but have the parts to build it either way.
The manifold parts and steel are in the mail and have already begun arriving. By mid-next week I should have all the parts and also have the machine work (propshaft keyways and threading) done.
Then I start building the drivetrain, et al, on a bench that will include an eight cubic-foot water-testing tank for the propeller and manifold; to enable dry bench tests, wet tank tests, and wet tank tests under pressurization to simulate depth; all in one spot and without having to move, disassemble, or reassemble the drivetrain for different phases of testing.
That way we will know for sure what the drivetrain performance is; it will be right there on the Sevcon display.
And we'll know if the propshaft housing manifold provides a watertight seal on the surface and at depth before I install it in the submarine.
Almost looks like I know what I'm doing, doesn't it? LOL! This is all experimental and I'm figuring it out as I go along! Sure fooled you! J
THOUGHT FOR THE MOMENT: So much of my time is spent thinking about the project; designing, finding ways to overcome obstacles, finding parts, making what I can't buy, and waiting for stuff to be shipped to this island. All part of the process for a homebuilt subber here on Vulcania. But once these parts come together, this boat is gonna rock. J
Tuesday, April 02, 2019: DRIVETRAIN: Yesterday I took the shaft to the machinist for threading and keyways. Also received most all the stainless steel fittings needed to make the pressure-compensated propeller shaft housing manifold.
ADAPT OR PERISH: The specs say the diameter of the carbon-ceramic pump seal seat is 1.54 inches; and the inside diameter of a 1.25" sleeve coupling is 1.66". So the seal seat should slip right into the coupling. Only it doesn't.
And the 1.25" x 1.5" bell reducer coupling I bought to replace the sleeve coupling does give 1/8" clearance around the rotary portion of the seal; but it's not quite long enough to accommodate the length of the mechanical seal assembly.
So I redesigned the seal chamber; bought two 1.25" x 2" bells and a 4" x 2" SS nipple to give the needed length and clearance for the rotary part of the seal. I'll drill vent holes in that nipple so that part of the housing will be open to the water because that half of the seal needs to stay wet.
I'll also fabricate an insert out of PVC that will provide a suitable foundation for the seal seat.
This larger chamber will provide 1/4" clearance around and between the rotary seal and housing, and more length than.
The instructions for this type of mechanical shaft seal say you MUST get the carbon and ceramic surfaces to mate evenly and not be cocked. Commercial pumps that use the seal have a foundation formed in to receive these seat and keep it level. I'll make one out of PVC.
The problem with aligning the carbon and ceramic surfaces seems due to the fact that they tell you to put the seat in and then the spring portion. My plan is to put the seat in the foundation, put the two halves of the seal assembly together on the shaft' temporarily held together with a bit of Gorilla Tape; and (by threading the nipple into the coupler) torquing the seal seat foundation onto a bead of sealant in the bell coupler. After the sealant dries, all I have to do is reach inside the nipple with a pair of hemostats and pull off the tape. We won't have to wonder if we got the two separately-installed halves of the seal to mate properly; we mated them before we installed them and the seat; and the shaft keeps everything straight. Wile E. Coyote would be proud. J
And with the second bell reducer, the manifold will step back down to 1.25" to work with the flange I already have.
The parts to patch this bump in the road cost me another $48; shipping included. Won't have them until next week. Meanwhile, I can begin building the bench setup using only the bearings and leaving the manifold off for now. All I need for that to happen is for the machine work to be completed; Wednesday or Thursday, maybe.
Coming along!! J
Friday, April 05, 2019: RIVETS: Back in 1997 when I made a cover for the pilothouse, I glued acrylic cabochons to sheet metal with Super Glue. When cured, I could pop them off quite easily. Fail.
Recently tested gluing acrylic cabochons onto various surfaces of the submarine with Weldon 3 and JB Weld. Bare steel (bright or rusty); the old, original, black acrylic enamel paint; and panels of the ballast thanks painted with fiberglass resin; I tested every type of surface on the Nautilus Minisub and saw a chemical fusion process going on in all instances.
Weldon 3 and JB Weld both set fast; JB takes 24 hours to fully cure. After three hours I tried to pop them off until my fingers and thumb couldn't take the pain anymore; and not one of them failed.
That's good adhesion. I'll be able to bond the cabochons directly to the submarine in most cases.
For areas needing "plating" (outer panels of the ballast tanks)I was thinking of using thin acrylic sheet. The cabochons would bond to acrylic better than anything else. The problem is; that kind of thin acrylic is hard to cut without breaking. I could see myself wasting a lot of time and money.
The answer: make paper templates of the required panels; cut them out of medium weight fiberglass cloth; and place them with acrylic casting / coating resin. The cabs and acrylic enamel paint will fuse to that.
Being able to rotate the submarine to keep the part I'm working on vertical will help with the wet work. What once looked like a nearly impossible task is now looking a whole lot easier. Whew! J
PROPSHAFT MANIFOLD MOUNTING BRACKETS: I was going to cut them out of a piece of 6X6" square tube; but that would yield a 6" bracket whereas the motor mounts are 8". (Long story how it all got there.) I was going to compensate with a wooden 2X4" spacer but since I'll have to do some cutting and drilling anyway; I'm going to save that piece of square tube and build 8" brackets out of plate and angle. They will match the motor mounts and eliminate the need for a spacer. Should make lining it up on the bearings easier, too.
SHAFT: My understanding is the machine-work is finished and the stainless steel fittings I needed to increase the size of the chamber housing the rotary shaft seal are on the island; should have them in my hands tonight.
NEXT: I'm ready to start actually building the drivetrain bench test apparatus. Might even have the prop spinning under power this weekend. Feelin' stoked! J
ADNOTE: Brought the shaft home, rigged some improptu brackets, clamped everything to the work bench (wasn't even bolted down) and ran the drivetrain for the first time. Got it on video. Sounds sweet at 12 - 25% power. Was afraid to take it higher than that since it wasn't actually bolted down; just clamped to the table. This is a great day! It works! Now to assemble the manifold, get it tested, and install it in the submarine. J
EVENING UPDATE: Operated the drivetrain for a couple minutes this evening. It's not properly aligned but close to it. I'm seeing 2,500 rpm easy and it pushes to about 3,750 and seems to want to settle there. I might be able to push it harder but not the way I have it set up now; clamped down instead of bolted. I don't want to break it.
1,250 indicated on the Sevcon would be 625 rpm at the propeller; with a 30% slip factored in, that's 5.4 mph; hydrodyamic drag not withstanding.
Seems to run smooth at 2500 / 1250. That would give us a fast cruise of 10.8 mph.
And if I push it to 3,750 / 1875, that's a boat speed of 16.2 mph.
I can't be certain exactly what the boat's performance will be underwater; we'll know that when we do it. But the motor spins the prop easily and smoothly. I get the feeling there is adequate power for my purposes. I am confident enough that I've decided not to build a tank or wet-test the propeller. I don't feel it's necessary.
What I am going to do is build a temporary water jacket around the rotary shaft seal chamber in the propshaft housing manifold, so I can test it with the seal underwater and under pressure. That will tell me whether the seal is sufficient in itself to keep the propshaft housing dry.
In any case, we still have the pressure-compensation system in case the mechanical seal fails. That's all I need to test the drivetrain before putting it in the boat: to know that it spins true, nothing rubs, and it doesn't leak into the motor compartment.
So far, everything looks very good.
Tuesday, April 23, 2019: Wow! Several weeks since I posted to this page. Been steadily working and a lot has been accomplished. Got the mounting plates made and drilled; put the propshaft and manifold into the submarine's empennage for alignment checks and everything looks good. Visit the REFURBISHING 5 page for the latest information. J
Wednesday, April 24, 2019: Today I shortened the end boss of the original motor mount (made for a Minn Kota) by 1/2" with the torch and grinder. Still going to fine tune it but now there is adequate clearance between the aft apex of the propshaft cap nut and the leading edge of the rudder.
Thursday, April 25, 2019: Today I shortened the end boss of the original motor mount by another 1/2" with the torch and grinder, and trimmed it square to align with the tailcone bulkhead. Now there's a bit more clearance between the propshaft cap nut and the rudder. And now that everything's in it's proper place, I have measured to determine that the propshaft housing manifold assembly needs to be exactly 12-3/8" long from flange to flange, with any gasket I use at the tailcone included.
Saturday, April 27, 2019: The day's coming when we're going to have to put the sub into the water for initial testing. I can figure weight and balance on paper; put it on a fulcrum to see how it balances; and I have a crane scale that will weigh it accurately. But eventually I'm going to have to dunk it. It will be a pain taking it down to an available boat ramp every time we need to check something. So I've been looking into what it would cost to build a water tank in the back yard big enough for the submarine. I could put it on the cement slab next to the pool.
(Not going to use our pool. Forget it.)
If I made an 8x22x4' rectangular pool out of lumber and a liner, it will cost about $650 in materials. The sub is 3.5 feet shorter than that but it would be kind of close on the sides. And it will be a good bit of work.
But for only $499 I can get a complete 20x12x4' above ground pool. That's cheaper, easier, and allows a lot more room for people working in the water with the submarine. 4-feet is enough to actually submerge; and foam "boots" could protect the liner from the Nautilus keel.
This will be great for testing everything from weight and balance to ballast and life support; but best of all we can test the drivetrain, too. I can place the submarine in the pool with my forklift; then park the Hyster at one end of the pool and securely anchor the submarine to it. Chained or cabled to that piece of heavy equipment, that little sub ain't going anywhere.
But then, when I think about it, our 32 x 16 x 4.5' pool already has a few seasons on the liner. A new liner is only $542. If I didn't blow it, I could put the submarine into our existing pool with the forklift, anchor it as described above, do the tests, and take it out again without the pool being the worse for wear.
And if I did go through the wall at ramming speed, a replacement liner is still less expensive than that other pool or the materials for a wooden testing tank.
The pool has a nice big cement slab alongside it, too; perfect for the forklift to lift, deposit, and recover from.
Hmmmmm… Looks like I'm gonna be dunking the sub in our swimming pool after all. When I started thinking about this, I never thought I'd end up saying that. LOL! J
Sunday, April 28, 2019: Experimenting replacing the stainless steel propeller bearing plate with a fiber-reinforced neoprene rubber plate for improved vibration and sound abatement. Made, installed, and examined a successful prototype. Concept looks feasible as is but not sure of longevity in use. Wouldn't hurt to back the rubber plate with sheet metal. We'd still get the advantages of a rubber mount but it would have greater rigidity and strength.
OR, I could retain the stainless plate and mount everything with scratchbuilt 0.125" hard neoprene gaskets; tailcone plate and assembly included. Hmmmm…
Thursday, May 02, 2019: The prop bearing plate ideas (above) all look good; I could go either way: rubber or stainless steel. I now have both.
I've decided to forego installing the shaft seal until the motor is in the submarine. I'm going to cut the hull, install the motor, and then align the drivetrain (seal and all) once and be done with it.
I've got the motor compartment hatch aperture marked out and have finalized my design for the coaming and hatch. You'd think I'd be ready to climb on top with a torch or plasma cutter and go to town; but it ain't that easy. Before I can get to the pressure hull, I have to cut through the top surfaces of the aft ballast tanks and I DON'T want hot slag running around loose in my ballast system!
I think I'll put a thin cutoff blade in the 4" Makita angle grinder, work carefully in the direction where it's throwing sparks out instead of in, and peel the top tank skin back as I proceed. Shouldn't be a lot of nasty stuff left in there when I'm done; mostly grinding dust and I should be able to clean that out. It's those big globs of once-molten metal (slag) I want to avoid.
If that works, I'll have exposed the pressure hull and can cut that with either an O-A torch or plasma cutter; the slag will fall inside the hull where there's nothing it can hurt and it can be easily removed.
Yep, upon due consideration, it does look like I'll be able to cut the motor compartment hatch aperture without having to roll the sub outside, take it off the carrier, put it on the roller, and rig it to turn upside down.
Sounds good tonight. Let me look at it tomorrow and if I don't find myself asking "What was I thinking?" I'll go ahead and cut the hull.
Friday, May 03, 2019: Today I worked on the concept of using our 32 x 16' swimming pool as a testing tank when the Nautilus is ready. Looks good.
Also, so far I've been bolting the propeller bearing mounting plate to the submarine's frame with common 1/4 x 20 fasteners. Problem is, once the sub has the side plates on, I won't be able to get a wrench on the nuts inside the empennage. My thought has always been to use some long threaded hex nut couplings, welded to the frame; and today I bought some.
The cap screws will be stainless steel, so one might think I'd be using SS couplings; despite the fact they're expensive. But I want to weld them to the frame and it's mild steel. You can weld mild to stainless but it's not the greatest and when I've done it the outcome was dismal. So I decided to go with plain old steel.
Now the problem is the steel couplings I found are zinc coated and welding zinc is a big no-no; poisonous fumes. So what do we do?
TECH TIP: To remove zinc from metal, place those couplings in a jar with a strong mix of muriatic acid and water and let 'em sit for a few hours. (How long depends on how strong your mix is but don't make it too strong else you might damage the part.) The acid will cook off the zinc and then you can wash and dry the part. Nice, bare metal now. Perfect for welding. J
(OF COURSE: Take safety and personal protection precautions when handling anything potentially dangerous like acid. If you don't know what you're doing, find out before you start work.)
Tuesday, May 07, 2019: Well, let's see. What's been going on? I was gassed out from working and took a nap on Saturday. My wife swept up all the nasty stuff from the grinding, drilling, and torching and the shop looks great. Thank you, Babe! I am one lucky guy! J
MOTOR COMPARTMENT HATCH: I drilled a test hole in the top panel of the starboard aft ballast tank. Looks good. After thinking it through, I don't have to take it outside or put it on the roller to cut the hatch aperture.
I can cut the tank panel with my big Makita grinder and a cutoff wheel. The small amount of residue it leaves in that area of the tank can be removed with a rag, brush, vacuum, and a flush with Saltgone which I want to do anyway. No problem.
Then, I'll cut the exposed pressure hull with my plasma cutter and any slag from that will go into the hull where it can't hurt anything and can be easily removed.
NEW WELDING MASK: I have been using the same HUNTSMAN welding mask for 34 years; it was used when I got it and by now it's pretty shabby. Plus, I get flashed a lot operating with the lens ajar so I can see to align the electrode with the target before sparking an arc. Thankfully, those days are in the past.
Just received one of those new electric, auto-dimming, wide screen, true-color masks and used it for the first time today. I feel like a blind man who has just been given sight. WOW! I can SEE!!! That's going to improve my welding a lot, I do believe.
RUBBER TAILCONE PLATE: I made one out of fiber-reinforced 0.250" Shore 60A (maybe harder?) black neoprene rubber; haven't installed it yet but do believe that might be the way to go.
NEW CARPORT: It rains a lot here; one needs to protect his vehicles and that includes the sub if I take it outside overnight. With all our vehicles, an old Toyota and my forklift live out in the rain and if I took the sub outside in one of the carports; either our car or truck would be displaced. So for a long time we've been looking for one of those 10' x 20' tube-and-tarp carports as a temporary solution.
You see those things all over here in Hawaii. You'd think they'd be easy to buy, but no. The stores in town stopped selling them and don't ship 'em in; and nobody selling online would ship to Hawaii.
But after several failed attempts, we finally got Amazon Prime to ship us the top and frame; and today we received the sidewall kit. At last we have the additional covered parking that will enable us to take the sub outside and put it on a roller when we need to. That's been an obstacle to progress but is no longer. Such is life on a rainy volcanic island. J
So, everything is coming along and I've got a few details to take care of first but basically, as far as how the sub is sitting at the moment, it's about time to cut a hole in the motor compartment roof and install the drivetrain.
Wednesday, May 08, 2019: Spent the day doing manual labor and making workbench improvements for the shop: a wood pad for drilling thin metal on the drillpress; a 5 x 30 x 3/16" steel attachment for the workbench to facilitate small, fast welding jobs; and a 6-inch clamp-on machinist's vise with anvil. Used the Lotos 5000 plasma cutter and wasn't blown away by its performance. Maybe it's me. I'll practice more. My beensie little Craftsman compressor probably sucks, too. But I could have done it better with my torch. Hmmmm . . . .
Tonight I received the 2" stainless steel close nipple that will solve that 1/8" excess length problem I had with the propshaft manifold. Also received some nice hole punches that will help with making rubber gaskets. Oh yeah, received some rubber, too.
Friday, May 10, 2019: The other day, I posted a two-part video on my Facebook pages where an Italian machinist shows how to build a DIY plasma cutting table with manual pattern following capabilities. His is a real work of art and craftsmanship.
For the one-time job of cutting and assembling a new cabin and pilothouse for the Nautilus Minisub; I don't need anything that refined.
I can make a far simpler device that will do the same thing by tack welding the angle-iron track to the long side edges of the 4' x 8' x 3/16" mild steel plate I'll be cutting. I'll sacrifice a 1" metal strip on both sides, but that will still leave me with enough material to cut my parts from and I can probably use the scrap elsewhere.
With four V-groove (gate) casters and less than eight feet of 2" x 2" square steel tube I can cut and weld together a simple crawler; no need to fabricate all those fancy parts seen in the video.
I'll make the bearing box, torch holder, and guide arm the same way he did or thereabouts.
If I was making a machine that would see some use; I'd make mine like the guy in the video did. But this is a one-time thing and the more easily I can accomplish the goal; the better.
Saturday, May 18, 2019: Haven't cut the hull yet. Been acquiring lots of needed tools like a laser level, better plasma cutter and cables for it, contour gauges; lots of stuff coming in by mail. Takes time but with these tools I'll be able to do the motor installation correctly.
Absolutely beautiful night here last night and I stayed up finalizing the design for the motor-to-hull mount. It welds to the hull and is adjustable in height and pitch so we shouldn't have any problems getting the motor and transmission aligned with the propshaft along the longitudinal centerline of the pressure hull.
The mount will require two 8" x 12" x 1/4" steel plates. I could drive to town, buy the steel, cut it to shape and grind it to a precise fit; or I could simply buy the plates for $7.00 each (with free shipping) on eBay. They are in the mail as I write this.
Yesterday I ran some string lines and took some measurement; checking how straight the Nautilus is after all these years. The forward raker arch I've been fiddling with lately is leaning slightly to port; I knew that. It's not finished. But from the tip of the spur aft; following a line through the pilothouse, dorsal fin, cut-water, and centerline of the top tail-fin; she's straight as an arrow.
However, the bottom tail fin is bent to starboard about 3/16" of an inch; the bend centered near the corner of the prop cut-out. (Years ago, the submarine was on the roller when rigging supporting the tail failed. Broke the port-side prop guard ring, too.) I want to get that straightened out before I install the drivetrain; but I could proceed to cut the motor compartment hatch aperture as soon as I have the connector cable for the new plasma cutter.
Monday, May 20, 2019: On closer examination, the fins still aren't straight. We nudged them around a bit but that kind of cold-forming rarely solves the problem and didn't this time. There's a definite bend in the top cutwater right above where the gap for the tailcone modification was cut. That's where it bent when it fell.
I've got the apex of the bend marked out. I'll make a "bracket and bolt" clamp out of heavy angle and hardware and weld it to the convex side of the bent cutwater.
Then, when I heat the apex of the bend red hot; I can tighten the bolts in the clamp and pull it straight with mechanical precision.
Torch the welds to release the clamp and I'm done. Probably have to do the same to the lower tailfin, also. And it has to be done before I begin work on anything dealing with aligning the drivetrain. So that's next on the Clipboard.
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