The Journal of Professor P. Aronnax

(Commentary by the Webmaster)

The opinions expressed here are my own. All writings displayed here serve the legitimate purposes of disseminating information, raising public awareness, and stimulating intellectual debate; are copyrighted; and may not be reproduced in any form without written consent of Pat Regan, Webmaster, VulcaniaSubmarine.Com.

Homebuilt Submarines

(SUBBER: an experienced homebuilt submarine enthusiast. One who has built and operated his own submersible vessel.)

The first thing a prospective subber needs to understand is that (because they are complex machines which carry people through hostile environments) ALL SUBMARINES ARE INHERENTLY DANGEROUS. Homebuilt submarines are an area of endeavor where what you don’t know can hurt you. Now that you have been so advised, if you decide to build or operate a submersible you do so at your own risk.

Traditionally, modern submarines are produced by state-of-the-art design and manufacturing facilities. Does that mean the individual craftsman can’t build a sub in his own shop? No. Many people have already done so, and more are doing it every day. Be that as it may, the roster of accomplished homebuilt submarine enthusiasts is relatively small in comparison to, say, the ranks of those who make homebuilt aircraft. Why? Because building a sub requires a broad range of technical skills, and information about subs has always been fairly esoteric.

Since the 1970’s, R. Frank Busby’s MANNED SUBMERSIBLES has been the most significant text describing the civilian submarine experience; but while it is an excellent catalogue of information about subs and their components, Busby really doesn’t tell the prospective subber how to go about building one. Clearly, there is a need for a comprehensive and reliable how-to manual about homebuilt submarines.

VulcaniaSubmarine.Com is a Website where homebuilt submarine enthusiasts can obtain technical information and advice directly from experienced subbers, and only from experienced subbers. And, the how-to manual soon to be released through this website will define the processes of design, construction, and operation, based on the practical experience of those who have been living the homebuilt submarine lifestyle for decades.

Experienced Subbers may be the smallest class of craftsmen in existence or history. For the most part we are non-aligned, self-taught artisans who take fierce pride in what we create. The truth is: most of the people reading this essay will never build a submarine, if for no other reason than it’s a lot of hard, dirty work. But there may be one person out there reading this right now who is sincere about wanting to become a subber, and if I can help that person safely achieve his goal, then this Website will have served its purpose.

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Analysis Paralysis

Many homebuilt submarine enthusiasts are hindered by something I call analysis paralysis: the tendency to “get stuck” at the R&D phase and not progress to actual construction. If you are serious about building a submersible, you want to avoid this trap. Fortunately, that’s not hard to do.

Take a critical look at where you’re at with your sub project, and if you think you might suffer from analysis paralysis, be advised: the quickest way out of that trap is to start building something. There’s a lot to be learned from building a working model submarine, ROV, DPV, or wetsub. It’s important to break the inertia and get started.

Homebuilt submarine design doesn’t require an Engineering Degree or a CAD program. The knowledge required to build your own submarine is fairly simple, actually; and you can design one on a piece of graph paper with nothing more sophisticated than an ink pen. If you need information: read books, study actual submarines, and / or ask an experienced subber. But try to avoid getting stuck in the “analysis paralysis” trap.

Hull construction, like welding, is as much an art as it is a science; it’s not something you can learn by study alone, you must get in and practice it. If nothing else, go buy yourself a torch and a buzzbox and start fabricating with steel. Before you can turn your dreams into reality, the day must arrive when you start working with technologies. The sooner you do that, the sooner you’ll be building the sub you’ve been thinking of.

To quote an old phrase: “There aint nothin’ to it but to do it.” Take enough time to be sure you know what you’re doing, of course; but after that, get it on.

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DEEP FLIGHT?

Graham Hawkes’ DEEP FLIGHT and DEEP FLIGHT AVIATOR are among the nicest looking submarines I’ve ever seen, but some of the claims regarding their performance seem questionable.

Some say Hawkes’ boats are the first to fly down to depth, but there’s nothing new about subs maintaining a small reserve of buoyancy and being forced underwater by the hydrodynamic effect of the motion-relative flow acting upon planes and other structural surfaces. That’s called diving the boat dynamically, and sub pilots have been doing it for a long, long time.

It’s said Hawkes’ boats don’t operate like other submarines do; but rather, they fly like airplanes underwater. As a Flight Instructor and submarine pilot, I disagree. To achieve flight, airplanes rely on an aerodynamic force known as LIFT generated by their wings to overcome gravity. In contrast, submarines (DEEP FLIGHT and DEEP FLIGHT AVIATOR included) are more like dirigibles than airplanes: endowed with sufficient buoyancy to float in their operating environment, driven by thrust, and maneuvered via dynamic control surfaces.

So, while DEEP FLIGHT and DEEP FLIGHT AVIATOR may be highly maneuverable, it doesn’t seem to me that they’re really doing anything that’s actually new or unique.

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The Need for Speed

Submarines are built for a variety of reasons: modern nuclear missile subs dissuade large-scale aggression through the promise of Mutually Assured Destruction (MAD); research subs like ALVIN explore deep wrecks like the RMS TITANIC; tourist subs like the ATLANTIS carry passengers on shallow excursions to the ocean’s floor, and so on.

Homebuilt submarines have been achieved to serve various purposes, too: my NAUTILUS MINISUB was built to prove the feasibility of the Goff-Disney design; and Karl Stanley’s CBUG gave tourists a more personalized submarine experience. Some of my other friends have built subs as a learning tool, to prove they could do it, and just for the fun of it. It seems the reasons why submarines are built are almost as numerous as the types of submarines themselves.

Karl Stanley’s new sub, IDABEL, was designed and built to operate at a particular divesite alongside a steep and deep sea wall; and he has hopes of one day building another submersible to set a new World’s Solo Depth record. Karl is adamant about going deep: “If you’re only going to 100 feet, you might as well make a SCUBA dive”, he told me. I have a lot of respect for Karl, and I do see what he means. Then again, I also see reasons for developing boats with capabilities other than extreme depth: like high speed and long endurance, for instance.

A while ago I was talking with my friend Tom “Doc” Rowe about his Variable Attitude Submersible Hydrofoil known as THE BIONIC DOLPHIN. Tom and his partner Dennis “Dusty” Kaiser built this amazing craft because they thought it would be fun to go zooming around in a boat capable of fast trans-environmental operations. They succeeded admirably, too. The DOLPHIN can run at high speed on the surface, submerge for short runs, and leap into the air like it’s living namesake. Obviously, going fast underwater is a concept Doc Rowe likes.

So, one day we got to talking about the possibility of an “underwater dragster”: a vehicle built for the single purpose of seeing how fast a manned submersible could go. At the time we were also participating on a website submarine discussion group, and the subject came up there. Obviously we drew a lot of ridicule from people who don’t build submarines, but Doc and I (and a few others) knew the idea had merit.

There are all kinds of World manned speed records: fastest airplane, land speed, fastest boat, etc. What about the fastest submarine? From what I can tell, the Guinness Book of World Records doesn’t have any such classification, so it looks like it’s wide open for anyone who wants to try to set a record. But what might that record be? How fast has man gone before?

In 1940, the Perhydrol-fueled WALTER V-80 hit speeds as high as 26 knots while completely submerged and operating on internal systems alone (no schnorkel). At the time, conventional subs were doing 6 to 8 knots underwater on battery-motor propulsion.

Nowadays, the fastest submarines are Navy boats that achieve speeds in excess of 35 or 40 knots on nuclear power. (I’ll bet they’re faster, but they aren’t telling and I don’t blame ‘em!) So with that in mind, if we want to establish a manned underwater speed record, how do we go about it? We know we’re going to have to develop a scenario in which a sub goes at least faster than, say, 50 knots: but since (as far as we know) this has never been done before, just how that boat will be configured, and how the feat will be accomplished, is open to development.

The idea Doc and I were kicking around was for an underwater dragster that would be timed through a measured quarter mile, either from a standing or rolling start, depending on how we decide to do it. Another concept might be something a bit further: say, a “flying mile” or two, or maybe five or more?

Obviously, the systems used to achieve these goals might be very different from each other, and designed to meet specific needs; but the required technologies exist and it can be done. In any case, I think a primary requirement should be that the submarine must operate on internal systems while completely submerged, and mustn’t “cheat” through the use of a snorkel or other device enabling it to breathe air from the surface. The record-setting run must be performed with the boat entirely underwater.

What’s the point of all this? Well, the technological genesis of most vehicles has always involved improvements in performance. Besides being a lot of fun, the development of an “underwater dragster” would no doubt engender advancements in general submersibles with practical benefits for both civil and military applications.

As Chuck Yeager said: “We are entering the ugh-known here.” How fast can a submersible go? Water is about 800 times more dense than air is, and is virtually non-compressible: will we run into some kind of “speed barrier” that our hulls simply can’t penetrate, and beyond which acceleration becomes impossible due to the overwhelming opposition of drag? How must a hull be built and reinforced to survive the additional stresses that movement through a fluid mass at extreme velocities will impart? At what speed will a hull, designed to survive at a certain depth, fail and implode under the additional hydrodynamic stress? How do we calculate such a failure point, if it does in fact exist? These questions and others are among those we will have to answer as we push forward in the quest for greater speed underwater.

At present I am working on a high performance submersible I call THE HYPERSUB II. My goal is to build the World’s fastest submarine, bar none. I intend to go faster than any manned submarine has ever gone before. Anybody want to race?

(NOTE: This article was written before supercavitation took high speed submersibles to a new level. If it sounds dated now, that’s why. Stand by for something more up-to-date to follow when priorities permit. Pat Regan, October 2004.)

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The NAUTILUS MINISUB

World’s First (and still the only) Real Submarine of Disney NAUTILUS Configuration in any Scale.

I’m frequently asked how and why I built the NAUTILUS MINISUB. People also want to know what, if any, significance the submarine has. I’ll try to address those issues here; but first, I’ve got to lay down a foundation of background information.

I was born and raised in California, and have always had a love for the ocean in general, and aquatic sports in particular. Like a lot of “baby boomers”, as a young boy I was very much impressed by Walt Disney’s movie version of Jules Verne’s 20,000 Leagues Under the Sea: it started an interest in underwater technologies that stayed with me all my life.

As a boy, I was always tinkering with things: working on bicycles, making scooters and skateboards, flying model airplanes, working on mini-bikes and go-carts, and so on. I made my own skin diving mask from a surplus gas mask in the 1950’s. Got into surfing and scuba diving in the 60’s, and was a varsity swimmer in school. As a teen, my interest turned toward automobiles and motorcycles, and I worked for one summer at an airport where I got my first real exposure to general aviation as a mechanic’s assistant.

After a hitch in the Marine Corps, I went to work in the automobile manufacturing industry to support myself, and worked on cars, trucks, and motorcycles as a hobby. I also got into skydiving, and was soon assisting the mechanics working on jump planes. Eventually, I bought and modified my own airplane; so when I say “I’ve worked on everything from skateboards to aircraft” I’m not kidding. But the point here is not to laud my accomplishments; it is merely to point out that all my life I’ve been working with mechanical technologies, and gained a lot of practical experience that proved valuable when I decided to build a submarine.

In the 1970’s I got the invention bug, and built a small backyard R&D facility where we worked on prototype devices we hoped would make us rich: aerodynamics, anemodynamics, and electronics were some of the areas we researched in our quest for fame and fortune. Times were more thin than thick, as you might imagine.

We renovated our facility and included a swimming pool where we got serious about experimenting with underwater technologies. We built and successfully tested improved snorkels, rebreathers, air-supplied diving helmets, human-powered swimming machines, wetsubs, ambient subs, and Air Independent Propulsion systems, among other things. Ultimately, I came up with an idea for a high performance submersible that I called THE HYPERSUB, and got started building it.

I had the basic steel pressure hull of the HYPERSUB pretty much finished when, one night, I was designing a crash bar to protect the pilot’s front windows from impact with floating debris. I did a crude sketch, and visualized the boat running awash at high speed, and the image of Captain Nemo’s NAUTILUS from Disney’s 20,000 Leagues came to mind. Since that movie started my interest in underwater technologies in the first place, I was immediately compelled to try to build a functional NAUTILUS. I did a basic design study and calculated what it would take to build a NAUTILUS replica hull around the HYPERSUB pressure hull. It was close, but the numbers said it might just be possible. From that moment on, the HYPERSUB project became the NAUTILUS MINISUB.

What’s so special about this particular sub? Well, a few things, really. For one, there had never been a functional manned submarine of Disney NAUTILUS configuration in any scale: only models and stage sets. A few people told me they thought the design was unfeasible: that a free-roving sub of this style would either be top heavy or tail heavy, and unstable in the water. But the numbers indicated it could be done; and though I was self-taught in design math, I believed my calculations were correct.

Another thing I think is special about this sub is the general era in which it was created, and what the state-of-the-art of homebuilt submarines was at that time. When I started talking about building submarines, most people thought I was nuts; said it couldn’t be done. In fact, I didn’t know anyone else who had done it, and the few subs that had been built prior to this were fairly well unadvertised. There was no HOW-TO MANUAL on homebuilt submarines, so I had to make my own up as I went along. There was no computer Internet at the time, so everything I needed to know came through my own research at the library, experimentation with systems test models in the pool, and my own experience as a diver.

It wasn’t until after the NAUTILUS MINISUB was finished and operational that I learned about a submarine called DENNOCH, which had been built from a converted propane tank by four Stanford University engineering students. On the tailfin of their boat, they painted the motto: “Because it can’t be done.” I suppose they were answering the question of why they built their sub; but their statement serves to illustrate the general public mindset towards homebuilt submersibles at the time: they were so few in number, and so scarcely publicized, that most people figured they were impossible. Suffice it to say I received a lot of heckling about my project, but I was determined to see it through.

What made the NAUTILUS MINISUB especially difficult (in comparison to more “basic” subs like DENNOCH) was the complexity of the weight and balance calculations. Building a sub is like a mathematical jigsaw puzzle: everything has to be of a certain size, weight, and strength; it all must fit together, and in the end it’s got to balance on a pinpoint or the thing won’t work. That’s hard enough with a simple cylindrical hull adapted with a single tower; but when we consider the modified teardrop shape of the HYPERSUB pressure hull and its naviform cabin modification; and then complicate that further with all the ornamental metalwork necessary to make it a NAUTILUS replica (tailfins, keel, rakers, ram, and so on) the math became a lot more difficult.

Remaining within the visual constraints of the Disney Design added still more challenges to the project. Hiding things like the hatch, for instance; and making the boat operational while limited to a very shallow freeboard; required a lot of creative thought. In the end, I managed to find room for a pilot and passenger, air system, E-motor, guidance controls, sonar, and a hydrobatic ballast system that would give the sub exceptional attitude control.

Actually doing all that ornamental metal work (literally cutting all those rakers and fins out of steel and forming them to shape by hand) increased the workload of this sub (over what the HYPERSUB would have required) at least three-fold. More than a manned submarine, the NAUTILUS MINISUB is very much a work of functional art metal sculpture. I can’t think of another all-metal homebuilt submarine design that comes close to being as aesthetically intricate as this one is.

So in terms of mathematical complexity, design constraints, hydrobatic ballast capabilities, and the additional ornamental metal work required to produce a functional NAUTILUS replica, this sub was pretty far advanced over contemporary homebuilts at the time.

The close ratio between weight and buoyancy, and the possible variables in the weights of steel, were especially daunting factors. Throughout the project, we were always worried about it being too heavy. It took a lot (400+ pages worth) of design and re-design to get it all to come out right. But what was really scary was the fact that there was only a very small difference between floating on the surface and submerging at neutral buoyancy; and there can be a ten percent variable in the weights of steel, depending on who makes it and where it comes from. I weighed what I could as the project was coming along; but I was never able to actually weigh the entire submarine; so for the most part I had to rely on estimates and calculations alone. Everything I did was based on self-taught math, and calculation methods I devised myself based on what seemed right to me. Still, even if I was precise in my calculations, that old “10% gremlin” was always lurking nearby, ready to turn my hopes into failure when it came time to put the boat into the water. So, there was plenty of room for self-doubt, but I plowed ahead on blind faith anyway.

Working with such a heavy project alone in my backyard wasn’t easy, either. A sub usually weighs tons, and this boat was no exception. One develops an appreciation for the Egyptian Pyramid Builders when doing something like this, and learns to devise his own machines and methods for dealing with large heavy objects without getting crushed. Beyond building the submarine, I had to make a lot of tools and equipment to be able to build the sub.

In the final analysis, it took about 2-1/2 years of developmental research, followed by another 2-1/2 years of continual metalwork and on-going redesign, through all kinds of weather, with many people telling me I couldn’t do it, and a couple people actually trying their best to stop me. As if the work itself wasn’t hard enough, my family also suffered personal tragedies and I incurred numerous injuries throughout the course of the project. There were days when I thought I’d never see the boat finished. I was pretty much exhausted and in poor physical condition from the continual grind when one day, much to my surprise, I had reached the part of the worklist that read, “Proceed to Float Test Number One.”

We needed a high tide to float the sub off the trailer at the nearby Marina Launch Ramp; and that first opportunity came at about 05:00 hours on a cold morning in March of 1991. I got about 45 minutes of sleep the night before, due to last minute preparations. When the alarm clock rang, I wanted to roll over and go back to sleep. I was dog-tired, and not totally thrilled about the prospects of doing something this morning that might cost my life. (There are a lot of ways a guy can get killed testing an experimental homebuilt submarine.) But what I was most afraid of was the thought that it might not float, and all those who’d predicted my failure would make me the laughing stock of the small town in which I lived. So I hit the snooze alarm and laid there for a moment or two thinking about it. But it was out of my hands already. I had come this far with it. I had to see it through. So we got up in the early-morning darkness, hauled the sub to the Marina, and conducted the first operational proving test.

Over the next five months, we conducted a series of nine proving tests, including seven dives in zero visibility water. When we were done the sub was a complete success. And that design math I was worried about? Well, as it turned out, all she was missing was the weight I’d allocated for the passenger. We hit the weight-and-balance right on the head; and our calculations were accurate to within one pound. Not bad for a self-taught homebuilt subber, eh?

In building the NAUTILUS MINISUB, we proved to ourselves and everyone else that we could do it. In successfully operating the boat, we proved the Disney NAUTILUS design was indeed feasible as a manned, free-roving, pressure-hull-type submarine: something that had not been done before, and a feat which hasn’t been duplicated since. Nowadays, our NAUTILUS MINISUB serves as the “symbol” of VULCANIA SUBMARINE. We are known internationally through the World Wide Web, and we continue to get fan mail on a regular basis.

Today, we still have the World’s only functional submarine of Disney NAUTILUS configuration in any scale. And wherever she’s been seen, the boat brings smiles to the faces of those who love the movie and this particular sub design as much as we do. To me, that alone makes it worth all the time, expense, and effort it took to build this submarine. But that’s only the beginning.

Because of our success with the NAUTILUS MINISUB, we chose Hawaii as a new home base for VULCANIA SUBMARINE; and here we are busy working on other projects. I am refurbishing this sub in preparation for a video we hope to shoot soon. We’ve built the NEMOSUIT, which will be the subject of another article here in the JOURNAL; we’ve made a lot of new friends, are in the process of building THE NAUTILUS DIVER, and have still more diving suits and submarines in the works. Our HOMEBUILT SUBMARINE HOW-TO MANUAL is being prepared for distribution, and the end of all this is nowhere in sight.

And so the story has come full circle. Like many of my era, I saw 20,000 Leagues as a boy and dreamt of sailing beneath the sea like Captain Nemo. Today, in my own small way, I’m living that childhood dream in my spare time. We all have dreams, but not all of us get to see them come true. I’m one of the lucky ones, I guess.

We at VULCANIA SUBMARINE hope you will enjoy seeing our projects as much as we enjoy building and operating them. In one very real sense, you are a big part of the reason why we do what we do.

“MOBILIS IN MOBILI”

ADNOTE December 2007: Since this article was first published, a couple things have happened that might call into question our claim that the NAUTILUS MINISUB is “still the only” real submarine of Disney NAUTILUS configuration in any scale.

1. A few years ago, a green vessel turned up on eBay and was quickly embraced by a few non-subbers as “another Disney NAUTILUS submarine”. As most people recognized: the vessel in question didn’t possess even a marginal resemblance to the Disney NAUTILUS; and was not a functional submersible. Therefore, it was not a Disney NAUTILUS submarine.

2. More recently, Herve Jaubert’s Dubai-based company produced a 10-place tourist submersible called the EXOMOS NAUTILUS. Many have called this a Disney NAUTILUS submarine; but this commercial submersible (which does appear somewhat Nautilus-like in some regards) is not a Disney NAUTILUS.

Fact is, Jaubert himself says his boat is not a Disney NAUTILUS replica, and he prefers that people do not refer to it as such. Herve went to great lengths, and included numerous major design modifications, to ensure that the EXOMOS NAUTILUS would not be visually confused with a Disney NAUTILUS. By intent of the builder, the visual differences between the EXOMOS and Disney NAUTILUS are sufficient to avoid infringement. And if it can’t infringe, it can’t be a Disney NAUTILUS.

In contrast, I always intended for the NAUTILUS MINISUB to be a manned scale Disney NAUTILUS replica; I tried my best to emulate the design as represented in the published Disney plans; and I have consistently represented it as such. Furthermore, the Disney CEO, the President of Disney Imagineering, and attorneys of the Disney Legal Department all agreed with me in writing that my boat “is a visually accurate depiction of the Disney NAUTILUS”.

And that’s why I continue to say, “The NAUTILUS MINISUB is the World’s First, and still the only, real submarine of Disney NAUTILUS configuration in any scale.”

Personally, I think the EXOMOS NAUTILUS is a beautiful submarine, and I’d like to take a ride in it. It’s not a Disney NAUTILUS, but I wouldn’t mind if it was. I’m coming up on my 17^th anniversary as the World’s only Disney NAUTILUS submarine pilot, but that doesn’t mean I covet that distinction, or that I don’t want to see someone else earn their wings. In fact, I encourage others to build manned-scale submersibles, and have provided technical assistance to individuals who said they wanted to build a manned scale Disney NAUTILUS submarine. I welcome the day when someone else finally succeeds. But so far, it hasn’t happened yet.

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The NEMOSUIT

World’s First Functional Replica of Disney’s 20,000 Leagues Diving Gear.

As a follow-up to the article above on the NAUTILUS MINISUB, I’ll take this opportunity to answer frequently asked questions about our recent project, the NEMOSUIT: what it is, why and how we built it, what our plans are, and so on.

Several years ago I was participating in a few Internet Website Discussion groups dealing with underwater technologies and homebuilt subs. I was displaying my NAUTILUS and going by the nickname “Captain Nemo” back then. Experienced subbers would share information about their projects, and aspiring subbers could seek help in getting started, and for the most part it was pretty cool. I made contact with some really great people that way, and one in particular was TY ALLEY.

At the time, Ty was an experienced diver and also interested in building a submarine, so we got started swapping email about technical questions, and we hit it off right from the start. We both had a lot of enthusiasm for diving and subs, and our sense of humor was pretty much the same, too. Like a lot of folks, Ty really liked Disney’s 20,000 Leagues Under the Sea, and said he thought my NAUTILUS MINISUB was pretty cool, too. So through the course of a lot of email, we became friends over the Internet.

I didn’t know it at the time, but Ty turned out to be one of those guys who does more than just talk about stuff: he gets all the way involved. One day he wrote and told me that he’d acquired the AQUALA SPORTS MANUFACTURING COMPANY, and had his shop set up in Shreveport, Louisiana. For those who might not know, AQUALA is probably the premier maker of drysuits for diving use in the United States, and was the company who built the rubber suits used by Disney in the filming of 20,000 Leagues way back in 1954.

We got to talking about the Disney Divers, and Ty said, “If you ever want to make a functional Captain Nemo diving rig to go along with your submarine, I can make the drysuit for you. I’ve got the patterns and materials.”

I had been making my own skin diving gear and replicas of Captain Nemo’s diving suit since my early youth; the idea of making a real one had always appealed to me. So I thought making a Captain Nemo diving suit was a great idea, but at the time I was working on the submarine and trying to get things together for a program the DISCOVERY CHANNEL wanted to shoot, and I just didn’t have the time to get into any new projects.

Time passed, the company producing the Discovery Channel show changed their mind about sending an underwater film crew all the way to Hawaii, and that project went down the drain. About that time I started thinking about making a Leagues-related project I might finish in a short period of time: and I got started making a fiberglass replica of Captain Nemo’s diving helmet. I was pretty much finished with the prototype, and starting to organize the shop to make molds and produce replicas. I did a logistical study of what it would cost to tool-up my metal-oriented shop to do fiberglass casting work, and it wasn’t going to be cheap. Considering I was already set up to work with metal, I figured it might be just about as easy to turn out an actual diving helmet like Nemo’s. I decided to do that, and began the R&D to make patterns and replicate the original Disney metalwork. Later, I started thinking about taking it one step further. I contacted Ty again by email, and asked if his offer of making a drysuit for my Nemo project was still good, and he was all for it. Ty offered me a good price on the drysuit, too. So I figured, “Why not go all the way?” And that’s how the NEMOSUIT project got started.

I bought a brand new deep-sea diving helmet and began researching ways to aspirate it from SCUBA. Ty went to work fabricating the rubber drysuit in Louisiana. Meanwhile, I also bought a set of a set of 16-inch high-top diving boots from Ken Downey at the MORSE DIVING COMPANY in Boston. So the project was really getting underway.

At first, while waiting for delivery on the Aquala drysuit, I made my own homemade diving garment (called the “Lo-quala”) for use with the helmet, and experimented underwater with modern regulators to aspirate the helmet and provide a reserve backup. Then, I found a pony bottle on eBay that looked like the ones used in the movie. I bought it and eventually decided to go with an all-authentic air system: vintage AQUA MASTER double-hose regulator, steel duals with manifold, and so on.

When the Aquala suit finally arrived I was absolutely thrilled: Ty’s work is nothing less than excellent, and he really put his best efforts into it. As time went on and we communicated more, we became more than manufacturer and client, we became good friends.

In October 2002 Ty attended an HDS show in Santa Barbara, and was approached by some pretty big names in the diving equipment business who said they were interested in making LEAGUES gear. (An interesting coincidence? Who knows?) Anyway, Ty handed them the printed flier I’d made about the NEMOSUIT, and explained that I was already doing that very thing. As time went on, I heard from a few people that they were also interested in building something like what I was working on; and Ty did sell at least one drysuit to someone interested in making his own LEAGUES rig; but as far as I know, nobody ever followed through on it.

Working alone (as always) in my small shop; and doing endless hours of research on the internet; I continued to overcome one obstacle at a time: finishing the helmet, pony bottle system, regulator fairing, and all the other parts that combined to make the NEMO rig. If I said it wasn’t a lot of work, I’d be lying. I knew the helmet was going to be difficult, but what I hadn’t counted on was how difficult the regulator fairing was. It turned out I needed to cut and shape more than 80 pieces of metal to form the structure; not to mention the metal framework needed to mount it to the tanks. Suffice it to say, when it was all finished, I was pretty happy to see it come to a conclusion. That was in January of 2003 as I recall without checking my records; and the NEMOSUIT project had taken me about seven months to complete.

A creation is always more than the sum of its parts. What you see is the finished NEMO suit. What you don’t see is all the hours spent searching the computer, chasing down and buying parts and equipment, experimenting with systems, working on design development, making the tooling necessary to make parts with, and then the actual work needed to fabricate the components from scratch. It takes a lot of time, effort, and money to do something like this; but when it’s done, you have the satisfaction of knowing you have the only one of its kind in the World, and that’s pretty satisfying. Moreover, other people enjoy seeing it, and that’s cool, too.

After the work was finished, the next thing was to prove it worked; so I performed a series of underwater tests of the completed helmet and air system in our swimming pool at home, and was pleased to note that everything worked exactly as expected. Now, we were ready for an ocean dive. In all, it would take some preparation, and require quite a few people, because this would be an event requiring launch and recovery personnel, camera-persons, safety divers, and so on.

I ended up getting my Nemosuit featured in some magazines, on several websites, and in the Summer of 2003 we sent a display to an event called the 20,000 LEAGUES UNDER THE SEA EXPO in Anaheim, California. There, the display was signed by BILL STROPAHL, one of the original Disney divers who performed the underwater scenes during the filming of LEAGUES in 1954. Bill was kind enough to autograph my display, and we are proud to have it showcased here in our home.

In August of 2003, after the NEMOSUIT had been proven successful, we got together with ACE PARNELL: a well-known and very experienced commercial diver now living in Kona, Hawaii. I let Ace dive the rig in Keauhou Harbor for his 60^th Birthday. A great time was had by all, and you can see pictures of Ace’s dive here at VSC on the page entitled DIVING THE NEMOSUIT IN HAWAII.

But before that dive took place, and by the time we sent the VULCANIA SUBMARINE display to the 20,000 LEAGUES EXPO, I was already well along with another companion project: the NAUTILUS DIVER. That, however, is another story…………

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The NAUTILUS DIVER

The Next Stride in Recreating Disney’s 20,000 Leagues Diving Gear.

The NEMOSUIT was a companion project for the NAUTILUS MINISUB, and the NAUTILUS DIVER is an extension of that line of endeavor. At first, I thought the DIVER would be easier than the NEMO, since we’d already done the one suit beforehand. The exact opposite proved to be true, however. The DIVER project required all the tooling and preparation of the NEMO, and then some.

The manufacture of the crown assembly proved to be especially difficult. I didn’t want to make just one: I wanted to produce the tooling to make crown assemblies, and that involved a lot more time, work, and expense. And, I could have made it easier on myself by “cheating” and casting the assembly out of fiberglass or the like; but I wanted this to be a functional helmet in keeping with the Disney method of all-metal construction; so fiberglass was out. In the end, we had to equip our shop with a blast furnace and forging equipment to produce some of the parts we’d need.

As before, I bought a drysuit from TY ALLEY of the AQUALA SPORTS MANUFACTURING COMPANY for the NAUTILUS DIVER. Again, we were especially happy to have AQUALA make this suit for us, as they were the original parent company that produced the suits used by Disney back in 1954.

Another Disney supplier, the MORSE DIVING COMPANY of Massachusetts, had produced the high-top boots we bought and modified for the NEMO, and I went to them again for the DIVER project. Many thanks to KEN DOWNEY and the fine people at MORSE for their excellent customer support all along the way.

The SCUBA, of course, is all vintage equipment based on a set of twin steel 72’s connected by a US DIVERS manifold, and breathing through an AQUA LUNG two hose regulator like Disney used. Some of it was bought on eBay, and other parts came from our principal dive supplier (fittingly), the NAUTILUS DIVE SHOP in Hilo, Hawaii. Bill DeRooy has always been most helpful to us in all our diving needs, and helped us a lot with both the NEMO and DIVER projects.

When it came to small parts of the system, I tried to pay as much attention to detail as possible. The diver’s knife is the same as Disney’s crew wore in the movie. The belt is a reproduction of an authentic 1860’s piece made for Civil War re-enactors, and so are the black leather gauntlets: which makes them accurate in style to the time period 20,000 LEAGUES is based upon.

The “spools” comprising what I’ve always called the “air filter” atop the DIVER’s visor are authentic antiques of the type used by Disney back in 1954: the company that made the originals went out of business, and parts like this are hard to find.

On all of the surviving Disney helmets I’ve seen, the rubber hoses attached to the “air filter” have long since rotted away, and the original manufacturer no longer produces them. Resultantly, I’ve seen them replaced with a simple expedient: hoses from surplus gas masks. Most people can’t tell the difference, but I didn’t want to settle for anything less than authenticity if I didn’t have to. So, I searched for and found a company that makes accurate reproductions of the original-type hoses for people who restore antique diving gear. Again, this took more time, work, and money; but now mine is the only LEAGUES helmet on the planet presently sporting hoses that look like they are supposed to.

Altogether, The NAUTILUS DIVER took about 16 months from start to finish. The NEMOSUIT only took seven months. But my DIVER replica is more accurate than what’s presently on display at Disney theme parks around the World; and, I have the required tooling to make more helmets, should the need arise. So as far as I am concerned, it was worth it.

Plans for the future include diving the NAUTILUS MINISUB, NEMOSUIT, and NAUTILUS DIVER all together in Hawaii, and filming the event for a Vulcania Submarine Video. I am also thinking of making a photographic reproduction of the original Disney movie poster from 20,000 LEAGUES, using NEMO, the DIVER, and the NAUTILUS in the distance behind them.

My LEAGUES projects exist because (1) I really enjoyed the movie as a kid; and (2) it’s a lot of fun owning and diving them. I used to dangle a spaceman toy clad in clay Nemo gear in a water tank; and now I have the real thing. These are one-of-a-kind works of functional art: the only working specimens of this type in the World. As I’ve said before, it’s kind of neat having something nobody else has. But the greatest satisfaction I get comes from showing them to other people who enjoy seeing us on the Internet, or in the water.

As you might imagine, the appearance of functional versions of the submarine and diving suits from 20,000 LEAGUES UNDER THE SEA never fails to attract crowds of enthusiastic spectators with great big grins on their faces. And I enjoy that a lot. To me, that’s a large part of what this is all about.

Please be sure to check the pages here at VULCANIASUBMARINE.COM showing how we developed, built, and tested the NAUTILUS MINISUB, NEMOSUIT, and NAUTILUS DIVER projects. And if you have any questions or comments, don’t hesitate to email us.

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Statistics

VulcaniaSubmarine.Com is the number one Disney NAUTILUS website in the World.

This is a “free” website: anyone can visit and we do not require you to sign up to a membership to view what we have here.

For those searching Disney Nautilus on all of the major (and some secondary) search engines (Yahoo!, Lycos, AltaVista, Google, Metacrawler, Mamma, etc.) VulcaniaSubmarine.Com is number one on the list of user-frequented websites. We also lead in searches of Homebuilt Submarine and Homebuilt Submersibles.

On all search engines, we have at least one and sometimes as many as three or four other websites (friends) dedicated to our work showing up in the top ten.

Server statistics show that we are being seen in over 54 different countries Worldwide. Every week I find new websites in other countries (Italy, Spain, Russia, Malaysia, China, etc.) that are featuring our website on their pages.

Stats show many of our visitors come from Disney related website groups. When I follow the thread back to its origin, I find very favorable discussions going on about our website and our work. People in the Disney community use words like “impressive” when they speak of VSC, and express amazement over our submarine, diving suits, and pages dedicated to 20,000 Leagues exhibits at Disney theme parks. We are pleased!

According to server statistics: In the past, we have averaged upwards of 60,000 hits per week from viewers around the World: that’s over three million hits per year.

In the recent weeks since the NAUTILUS DIVER PROJECT was completed, our server stats show a jump to over 105,000 hits per week; if that trend continues, it will project out to almost 5.5 million hits per year! Not bad for a website that started in 2001 with an annual traffic count of about 350 hits per year, eh?

I just want to say “THANK YOU!!!” to all of you who visit this site. I trust you enjoy what you find here. The MESSAGE BOARD is still down, because frankly I’m too busy working in the shop to monitor it right now. Maybe it will be back again in the future. In the meantime, if you have any comments, questions, or suggestions about things you’d like to see featured here at VSC, please feel free to submit your thoughts via the EMAIL TO THE WEBMASTER function.

Very Best Regards,

Pat Regan

VULCANIA SUBMARINE

Hawaii

ADNOTE, December 2007: Long after publishing this article, I learned that position on search engine lists can be controlled by manipulating the code by which a website is represented on the Internet; and in other ways, as well. I’ve never used them, but there are companies out there who, for a fee, will guarantee you top position in the search engine lists. So, being at the top of a search engine list does not necessarily mean one website is better than another, any more than the inverse might be true. I stand corrected.

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Building the NEMO II

An ‘Honest-to-Goff’ Functional Replica of Captain Nemo’s Diving Helmet.

2003 was a great year for us at Vulcania Submarine: we completed our NEMOSUIT project; we sent a display of our work to the 20,000 Leagues Expo in Anaheim, California: we were well underway with our second Leagues diving rig project, the NAUTILUS DIVER; and we filmed ocean diving operations with the NEMOSUIT here in Hawaii.

We completed the DIVER in 2004, drawing favorable reviews from members of the Helmet Diving and 20,000 Leagues communities. During this period, we also received inquiries asking how much we might sell our replica Leagues Diving Suits for. Our answer was always the same: “These are one-of-a-kind works of functional art; they were created for art’s sake and for our own personal use. They are not for sale.”

Eventually, however, the question of what our rigs might be worth arose enough times that I myself became curious. So I asked veteran dive shop owners and recognized experts in the helmet diving field what they felt a fair asking price for the CAPTAIN NEMO helmet from my NEMOSUIT might be. The average estimate was $8,000.00 based on several factors: (1) the cost of the basic helmet itself; (2) cost of materials and tooling to convert the helmet into the finished project; (3) a very modest fee for labor; and (4) the novelty factor such a one-of-a-kind item might possess.

The people I surveyed had been in the business a long time, and I valued their opinion. Actually, I had no intention of selling my artwork, but in time I began to wonder if others felt the same way about its value. So, as a test more than anything else, I decided to put my CAPTAIN NEMO helmet up for auction at eBay. With an opening bid of $8,000.00, I had little expectation it would actually sell. Even though I believed it was worth that much, that was still a lot of money and I had never seen a diving helmet garner that high a price on eBay before.

Accordingly, I was somewhat surprised when my CAPTAIN NEMO helmet drew multiple bids and sold for $8,775.00; and apparently, so were a lot of other people who had been following the auction. I received several congratulatory messages, HISTORICAL DIVER did a short piece in their Auction Watch column, and I was offered a page at the well-known DIVING HERITAGE Website.

But there was a downside. I’d offered my CAPTAIN NEMO helmet up for sale, and somebody actually bought it. Now I would have to build a replacement if I wanted to continue diving my NEMOSUIT. Suddenly, after considering the effort I’d already made, plus the additional work and expense ahead of me, the money I’d receive didn’t seem like a lot any more. But a deal is a deal. I began making preparations to ship the CAPTAIN NEMO helmet, and started building a second variant dubbed the NEMO II.

Work on the NEMO II was facilitated by several factors: (1) I already had another brand new Asian diving helmet, ready to be modified; (2) in the months following the creation of the first NEMOSUIT, I had acquired additional (and superior) graphic reference materials (including some made by Disney Production Designer Harper Goff himself) and had already done some design development work toward a second (and more accurate) NEMO helmet; (3) I had all the tooling left over from the NEMOSUIT and NAUTILUS DIVER projects, and would not need much more to accomplish the new design; and (4) I already had my sources of material and parts supply, as well as my production methods and procedures, well-organized and ready-to-go. With this, I launched headlong into creating a replacement for my soon-to-be-departed CAPTAIN NEMO helmet.

In the months that followed, I devoted most every available moment to the completion of this new project. When I finally reached the end of the work list, I photographed my new creation, compared them to pictures of the original Disney Nemo helmet, and was happy with what I saw. Seeking confirmation, I disclosed the new helmet to an authority with intimate knowledge of the real Disney Nemo, and his opinion was, “You haven’t just come close with this one. This time you’re totally on target.”

We have all seen scale models of the Leagues technologies described as “exact replicas” of the originals. But in every case, there was something we could point to that wasn’t quite like the “Real McCoy”; and if the artists who made those replicas will be honest about it, they’ll have to admit that’s true. So I will not stand here and say my NEMO II is an “exact replica” of Disney’s Hero. I believe all such claims are presumptuous when it comes to replicas engendered by processes wherein the human mind relays information from eyes to hands, which then do the work of replication. But that process is not a bad thing; it’s art.

Until someone puts one of the Disney originals into a machine that can scan it in its entirety and transmit that information to a computerized mill capable of turning out precise copies, a truly “exact replica” has yet to be seen. And if that ever does happen, the result will be “photocopies” rather than works of art, because art is the direct expression of the soul, and machines do not have souls.

Until mechanization replaces artistic expression, we must still content ourselves with the handiwork of human craftsmen who put something into their work no machine can ever provide: a bit of themselves. But to my way of thinking, therein lie both the challenge and the beauty of this particular artform. Harper Goff’s creations were handcrafted by people, and reflect both human strengths and frailties; and that is still (and I think rightfully so) very much a part of every Leagues replica I’ve ever seen.

Artists strive for perfection, knowing that it may be beyond their reach; but they continue to try anyway. Insodoing, they live and grow; and hopefully, their work improves with each attempt. That’s what art is all about. It’s a human thing: the difference between a photograph and a masterful painting. One conveys the appearance of the subject with cold mechanical precision; the other expresses a part of the human spirit. One hundred years from now, someone may look upon my humble efforts and appreciate the fact that I built these things all by myself, in a modest backyard shop, by hand. No photocopy will ever evoke that same emotion in the human heart.

Now that the NEMO II is done, will I try to build yet another? Of course I will. And another NAUTILUS DIVER? Sure, why not? What’s the point? The point is to strive: as the song says, “to reach the unreachable star”. For me, that’s what it’s all about.

To quote an old saw: “Oftentimes, getting there isn’t as important as going.” I, for one, intend to enjoy the ride, and allow myself to be continually challenged by what I attempt next. And I hope others will continue to do the same. Our handcrafted Leagues replicas may not be “Memorex”, but as long as they are “Honest-to-Goff” I believe Harper would have approved.

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Scale Speed

For the purposes of this discussion, I'm talking about scale model submarines. Generally, when it comes to scale models, there are three kinds of speed:

1. ACTUAL SPEED is the velocity of the scale model relative to the full-sized "real world" environment.

2. SCALE SPEED is the velocity of the model relative to a theoretical scale environment.

3. CORRESPONDING SPEED is the velocity of the model necessary to produce a realistic hydrodynamic effect: a bow wave or control reactions, for example.

To calculate ACTUAL SPEED, all we'd have to do is: know how many inches long our model is; use a stopwatch (or other suitable

chronometer) to time how many seconds it takes to drive past a fixed point; divide inches by seconds to get Inches Per Second; multiply by 60 to get Inches Per Minute; multiply by 60 to get Inches Per Hour; divide by 12 to get Feet Per Hour; divide by 5,280 to get Miles Per Hour. And if we want to convert that into Knots, divide by 1.15. That would tell us the ACTUAL SPEED at which the model is traveling in "real time".

Or, we could just time how long the model actually takes to travel a fixed distance, and figure it out that way. Same result.

But we might want to calculate SCALE SPEED if we were working for, say, Disney; and were making a large-scale diorama of, say, the San Francisco Bay. If we wanted a scale submarine on the surface to cruise past a scale model of the Golden Gate Bridge, and we wanted that relative movement to look realistic in comparison to the scale environment, we'd need to calculate the correct SCALE SPEED relative to "scale time and distance". In that case, the formula would be:

(Where): Vk = Actual Velocity in Knots; S= Scale; and Vs= Scale Velocity ("scale speed" expressed in inches per second)

Vk X 1.15 X 5,280 -:- 60 -:- 60 -:- S X 12 = Vs

Since it's difficult to write math symbols in this format, I'll explain that in terms.

Take the actual velocity of a real submarine in knots; multiply that by 1.15 to convert Knots into Miles Per Hour; multiply MPH by 5,280 to get Feet Per Hour; divide FPH by 60 to get Feet Per Minute; divide FPM by 60 to determine how many Feet Per Second the real submarine is moving. Now, divide the real sub's velocity expressed in FPS by the Scale of the model we want to build; and multiply that by 12 to determine SCALE SPEED expressed in Inches Per Second.

If we use that formula; and if a real submarine passes the bridge in, say, 60 seconds; we'll know how many inches per second our scale model sub must move in real time to pass a scale model bridge in 60 seconds.

As they used to say on the old Monty Python show: "And now, for something entirely different!" ;-)

CORRESPONDING SPEED is a concept presented in 1868 by an English engineer named William Froude in his work LAW OF COMPARISON, where he also refers to it as "wave form speed". As I mentioned above, CORRESPONDING SPEED is the speed a scale model must move through water to create a realistic hydrodynamic effect: bow wave, control reactions, etc.

CORRESPONDING SPEED is what nautical engineers use when running scale model hulls through testing tanks.

Why do we need CORRESPONDING SPEED? Because while the size of the model is smaller than an actual boat, the size of the water molecules it interacts with does not change. We need to compensate for that relative difference between the hulls and the element they operate in.

The formula for CORRESPONDING SPEED is: Actual Speed divided by the square root of the Scale. Pretty simple, actually.

Let's do some sample problems to consider the difference between calculating SCALE SPEED and CORRESPONDING SPEED. For our example, let's say we're talking about a 1:96 scale Los Angeles 688 Class submarine; actual length 360 feet; scale length 45 inches.

We'll compute SCALE SPEED and CORRESPONDING SPEED for an LA sub moving, say, 30 knots.

SCALE SPEED:

30 kts X 1.15 X 5,280 -:- 60 -:- 60 -:- 96 X 12 = 6.3 IPS.

What this means is, if the real sub is moving 30 knots in relation to the real environment; and we want to simulate the movement of a scale model relative to a scale environment, the model will be moving at a SCALE SPEED of about 6.3 inches per second.

(That's what we meant in our example where we wanted to simulate the time it would take for the model sub to move past a model bridge or other fixed surface feature: in this case, we'd move the model at about 6.3 inches per second.)

But if we want to simulate the scale effect of how the sub interacts with water (how it generates a bow wave or responds to hydrodynamic control deflections), then we'd use the formula for CORRESPONDING SPEED.

We'll divide the actual speed in knots by the square root of the scale to determine CORRESPONDING SPEED:

The Scale is 96; the square root of 96 is 9.79795897. So:

30 kts -:- 9.79795897 = 3.06 kts CORRESPONDING SPEED.

In this instance, we want the 1:96 scale LA sub to generate a bow wave that looks similar in relative size to that produced by the full-sized sub moving at 30 knots, so we'll have to move our model at an actual speed of about 3.06 knots (about 3.5 MPH, or 61.6 IPS.)

So, now we can see there's a big difference between an ACTUAL SPEED of 30 Knots in comparison to SCALE SPEED and CORRESPONDING SPEED. In this case: SCALE SPEED is about 6.25 inches per second, while CORRESPONDING SPEED is about 61.6 inches per second.

SUMMARY: When dealing with scale model velocities, there are several things we might want to accomplish, and just as many methods of doing it. The preceding formulae enable us to calculate model velocities for any of the three main purposes described above.

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“Collision Speed…FULL!!”

Will the NAUTILUS MINISUB receive an engine-driven hydrojet propulsion system?

INTRODUCTION

As I mentioned in previous articles: back in the 1980’s I built a working test model of a closed-circuit engine adapted to run underwater, and that project led to the construction of a steel pressure hull for a hi-performance submersible I called the HYPERSUB. Midstream in that project, I decided to build a manned Disney NAUTILUS replica instead, and that’s how the NAUTILUS MINISUB came to be.

I’ve been very happy with the NAUTILUS MINISUB, but always meant to improve appearance and functionality. After the proving tests, I wanted to finish the scale exterior detailing, and improve the various operational systems. But a change of locale, and changing priorities in life, impeded my progress.

One can be happy, and yet not satisfied. I was always happy with the fact that the NAUTILUS MINISUB worked well; but I was a little dissatisfied because the slow speeds she achieved were not very exciting to behold. When I first visualized the HYPERSUB running fast awash, it called to mind Captain Nemo’s NAUTILUS on the attack: and the NAUTILUS MINISUB was the result. Back then, it made sense to forego the closed-circuit engine in favor of making sure we could first produce a working NAUTILUS replica powered by an electric motor. But now that I’ve accomplished that, it’s time the project came full-circle and returned to its roots, so to speak.

At the time of this writing, much additional work has been done to the NAUTILUS MINISUB. The next time she takes to the sea, she will have improved scale detailing, life support, communications, and control systems. But perhaps best of all, she’ll have dual propulsion systems: a larger electric motor for silent maneuvering underwater; plus the drivetrain from a jetski for fast speeds on the surface, and short submerged runs.

This article documents the installation of an engine-driven hydrojet propulsion system in the NAUTILUS MINISUB; it is a work in progress, and will be written in stages as we move toward operational testing.

WE BEGIN

At first glance, installing a jetski drivetrain in our NAUTILUS seemed fairly straightforward. But as our understanding progressed, the physics behind how hydrojet pumps work, and their suitability for use in submersibles, became a hurdle we had to overcome.

Traditionally, pump-propelled submarines (like Cousteau’s diving saucer, the SOUCOUPE) have been extremely underpowered. In the submarine community, pump propulsion is generally thought to be undesirable; coarsely pitched propellers turning at slow RPM are the norm. In deciding to install an engine-driven hydrojet in the NAUTILUS MINISUB, we are bucking tradition and exploring new areas. And whenever one does that, others will wonder “Why?”

The Disney NAUTILUS design has but one propeller. In our MINISUB, that prop is driven by the Minn Kota electric motor we use underwater. I want a separate source of propulsion that is not affected by the pitch and RPM limitations of that single propeller; and which can be concealed in the NAUTILUS metalwork to provide invisible thrust. The hydrojet meets these basic design requirements. And we just happen to have a jetski, so from an economic standpoint it makes sense to try it.

THEORY VERSUS REALITY

Let’s look at some of the performance differences between propellers and jet pumps:

The propeller moves a wide column of water a short distance. It's like a screw boring its way through wood. The speed and distance achieved by a propeller can be determined by knowing prop pitch and rpm.

The pump moves a narrow column of water very rapidly over a long distance; and it is the momentum of the water ejected by the pump that imparts forward motion to the boat, in accord with Newton's Third Law of Motion: Action and Reaction.

The thrust column from a prop has a wide surface area; and thus, a wider area of water to push against. As an illustration: visualize trying to push the end of a baseball bat through a sail: the sail resists and pushes back.

The thrust column from a pump is much narrower: it doesn't have as wide an area of water to push against. In fact, the water tends to absorb the thin, high-speed thrust column. It's more like pushing a knitting needle rapidly against a sail: the needle penetrates, and the sail doesn't push back as efficiently.

When Sir William Hamilton invented the first jet boat in 1954, he discovered it’s best to project a hydrojet above the waterline because, underwater, thrust momentum is absorbed and pump efficiency is decreased.

To illustrate the momentum-absorbing capabilities of water, consider this:

In the air, the 7.62mm bullet from an M-60 machinegun travels at 2800 FPS for an effective range of over 3000 feet. In the water, that same bullet will stop in about six feet, because water is approximately 800 times denser than air is.

Likewise, when the jet pump projects a thrust column below the waterline, the water may quickly absorb the momentum, and thrust efficiency can be lost.

Therefore, generally speaking, hydrojet pumps work best when they project a thrust column at or above the waterline: which is what happens when a boat or jetski is “up on the plane” at high speed.

Now, if thrust loss at depth was all there is the equation, it might not be feasible to install a pump at a depth of 16 inches on our submarine. But it seems there’s more to it than just that. Pump efficiency is also dependant upon pump loading, intake ram pressure, internal pressure, and other factors that might even be improved under certain circumstances with a few inches extra depth.

Mechanically speaking, it would be easiest for us to mount a jetpump on the sub as it usually runs: in “direct drive” fashion. But as I’ve said, that will put it at a depth of 16 inches below the waterline.<