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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
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