A GIANT OF A BOAT!
By Dwight Brooks
1799 Correa Way
West Los Angeles, CA 90049
For those of you who have the time and interest in World War Two submarines you might just want to visit San Francisco, and go on down to Pier 41 next to “Fisherman’s Wharf” and go aboard the Pampanito. You’ll be given a nifty little listening device, and you can tour the entire boat, on your own, and spend as much time aboard as you so desire. It’s clean, well maintained, and open seven days a week to be looked at.
I was told by one of the men who helped maintain her that she could be made ready for sea in less than a week so it was obvious she wasn’t really all that “pickled.” The odor of diesel fumes was ever present, and she was very much afloat which one seems to notice once in her belly because the gentle motion of the harbor swells seems to be more evident when you can’t see out! I was also told the noise from the engines inside a sub is absolutely deafening so earplugs were always a must, assuming you were even close to the engine rooms. I’d never thought of this, and count my blessings I never had to serve aboard one of these monsters. Let’s face it, submarines are awesome members of the Fleet with little regard for comfort for anyone. If you haven’t stepped aboard one and have the opportunity to do so, I strongly suggest you visit one in order to really understand what those poor guys went through. The computer age Trident subs would make one of these old Gato boats look like a floating toilet!
Anyway, the Pampanito had a decent record having sunk five Japanese ships (over 13,000 tons), and damaging five others. She did six patrols in the South Pacific before returning to the States where she became an auxiliary sub back in 1971.
She was loaned to the San Francisco Museum in November of 1975. I must say, by comparison, I’ve never felt the Gato class sub had the lines of her German counterpart, the TYPE VII-C. The American boat is longer, has less range, and lacks the maneuverability by comparison to her German counterpart. However, this is only my opinion.
The Model Itself
The entire hull is molded in fiber glass with a large removable deck which provided ample space in which to mount the brass radio box. With the help of Jerry Siler of the Model Boat Yard it was decided that all the electronics as well as the engines should be placed within a brass box with a removable Lexan top. Through-box connections and link ages were silver soldered to prevent any sort of leakage and it really worked out well. Mine never did leak a drop which speaks well for the idea. In prior subs I’d used the old wood box fiberglassed method and always had some problems with leaks.
The model was designed to be a full flooding negative buoyancy boat which meant it could be sent to the bottom in no more than five feet of fresh water. This was simple to accomplish through the use of two ballast or trim tanks, one mounted in the bow and one in the stern both being powered by electric pumps (each had its own). The rest of the procedure was standard. Flood the forward and aft tanks to achieve decks awash trim and then either power the boat down dynamically, or, stop the boat and fully flood both fore and aft tanks which would gently take her to the bottom. Now here’s where the “hooker” came in use.
Jerry had devised a neat system utilizing an electric solenoid valve attached to a small “Propel” tank which, in turn, was hooked up to a standard bicycle inner tube. The tube itself was simply laid across the top of the radio box on the outside. Attachment of the deck held it in place inasmuch as the tube itself had to be left somewhat loose in order to adjust the attitude of the boat while surfacing. Once I found this magic location for the tube I taped it into position which, during the actual surfacing operation, gave the hull a lightly bow up angle to create some realism. Now, the whole problem with this setup became obvious from the beginning. How do you know when you’ve sent enough air into that inner tube? After all, there’s nothing to prevent blowing the thing up and really creating some havoc (to say nothing of losing the sub itself) because you can’t see how much air you’ve delivered to the tube! We finally figured the best way would be to simply look for some bubbles initially inasmuch as several pin holes had been put into the tube itself in order to ensure its eventual deflation so we could dive again. Then, it became a matter of literally timing the short bursts of air sent to the inner tube through the solenoid valve. The resuit was a very slow rise to the surface, but it did work! I never tried it in more than five feet of water and I must say I had the sub in sight the whole time so I could see what it was doing. I felt elated to say the least!
The “Fiasco” Takes Place
I had decided that, prior to giving my usual Gull Lake “launching” party for models like this I’d best be sure the submarine would work, and dive as it should. So, having completed all the initial testing I thought would be required before becoming the local model submarine “hero” I went ahead and put out the word that I’d be giving a demonstration on Saturday afternoon right around cocktail time. Boy, that really drew a crowd and before I knew it there were seventeen boats of all types tied to my dock, pulled up on the beach, and some just floating free. It was a beautiful day to boot with hardly any wind, and glassy water.
The scene was set, and there was a lot of interest in this thing by everyone. “You mean that thing will really submerge?” etc., etc. I assured them it would! Some took to betting which I’ll never live down! Oh yes, I forgot to mention one thing prior to this large event. I had decided, during the testing period, that it would be a lot more realistic if I could make the sub surface faster thus creating a more or less “bursting” to the surface type of visual. So, I figured this would be simple enough . . . just get a larger inner tube that’ll hold more air! Nothing to it, and so off I went to purchase two larger tubes both being different in size, but larger than the one Jerry and I had tested in my pool prior to shipment to Gull Lake. I never even tested the new inner tube!
With the crowd gathered in size all around me I placed the new tube on top of the radio box, and proceeded to attach the one piece deck to the hull itself by simply threading in two screw bolts through the deck itself which were then threaded into a large solid chunk of plastic “Hot-Stuffed” to the top of the radio box. Here again the top of the radio box was clear plastic so I could see any leaks developing as well as anything else that might be out of place. This clear plastic top was Allen-screwed to the brass radio box itself. So now you have the picture as best I can describe it!
With the sun glistening off the flat grey hull surfaces I gently lowered the 10 foot model into the water and waited for the hull to fill with water. The twin Astro 40 motors were working fine and so were the rudder and dive planes. I gave it a good shot and cruised out off the end of the dock where all could see it and brought it to a standstill so all could witness the submerging and resurfacing! That’s what they all wanted to see anyway! So did I. So, I flooded both fore and aft ballast tanks and sent her to the bottom . . . ever so slowly. It really looked impressive I must admit. Once on the bottom, and clearly visible to all, I sent the signal to the servo activating the solenoid valve to permit air to escape from the propel tank into the inner tube. Lots of bubbles, but no movement from the sub itself. More shots of air . . . still no movement. OK, I’ll give it one hell of a shot whereupon it looked like the entire bay was boiling water bubbles followed by a dull “pop.” The sub started to slowly rise to the surface just before the “pop,” but then started down again. Actually, it was partially surfaced when the motors went into reverse and the forward ballast pump decided to activate itself! I had literally blown the deck off the sub which, in turn, tore both of the plastic hold downs off the top of the radio box which left two large holes for the water to pour into the radio box itself. In something like fifteen seconds the entire model tried to go back to the bottom, but luckily a friend was nearby who helped me keep her above water. Obviously I had not allowed for the size of the inner tube itself once it was filled with air so it just pushed the deck off the hull and took the radio box hold downs with it!
A week later, and thanks to a good hair dryer and compressed air, I had everything back together. Actually all I lost were three S-28 Futaba servos which do not like water at all!
The Second “Fiasco”
I’d replaced the servos, water tested the box for any leaks, run the model around for a couple of hours on the surface and decided it was now time to take her out into the bay for some good photo shots away from the shoreline. A breeze had picked up creating some rather large scale waves and we were running alongside the model in a powerboat in around sixty feet of water when I noticed the sub seemed to be flooding because it was riding lower than when we’d started. I immediately engaged the “empty tanks” control on the transmitter only to be horrified when I saw it getting even lower in the water, and yelled at the driver to get over to the sub as fast as he could. It was very definitely going to the bottom.
By the time we got to it everything but the after hull propeller guards was headed straight for the bottom. I reached out and managed to get hold of one of the guards with my right hand. The hull was still filling with water, and the weight became almost more than I could handle. After all, the model weighs 100 pounds out of the water to say nothing of what it probably weighed full of water! We slowly motored back to the dock where I let go of it in shallow water and watched it go to the bottom thinking all the time the radio box had sprung a leak. I went into a state of utter depression! After loading the boat onto the model crane I raised the hull out of the water just enough to remove the deck and see if the radio box was full of water. It wasn’t, and I damn near fell back in the lake.
What the hell had happened? I couldn’t, for the life of me, figure out what went wrong. Nonetheless, the box was bone dry. I immediately lowered the model back into the water and engaged both ballast tanks only to find they were reversed. Emptying was filling and vice versa! Obviously I’d put the three new servos in backwards! Here again, I had failed to properly test the boat before going all the way! From then on, and for the balance of my stay the model operated beautifully for the most part. I went back to the original inner tube, and performed proper checks before going out.
While I had built the sub to scale the size of both the diving planes and the rudder needed to be increased by as much as forty percent to allow for proper control. There isn’t a model submarine around that turns worth a damn and neither, I’m told, do the real boats. The rudder on a model this size needs nothing less than an S-14 servo, and it should be cross-linked to keep it rigid.
Any model submarine must have “baffling” installed to prevent water from sloshing from one end of the boat to the other or, at least, slow it down. If you fail to do this the bow will always come up when you engage forward propulsion, and vice versa while in reverse. It’s a simple “fix” and has been accomplished in my boat.
If you decide to go for the solenoid valve and propel tank method be sure to use surgical tubing. Plastic tubing doesn’t like freon and eventually becomes very brittle.
While not scale it is a good idea to install some thick wire guards around both fore and aft dive planes because I’ll guarantee you they’ll get hit by something! Also, set both dive planes up for maximum deflection for better control. I’ll get arguments on this one!
Ensure that deck hold downs are not attached to the radio box itself, but rather to some part of the hull.
General Building Comments
Inasmuch as the hull was premolded there was no frame and plank buildup. The decks were strip planked with 1/8 inch teak strips Hot-Stuffed to the various areas. Thin thread was used on the hull to simulate welding strips and Hot-Stuffed into position, and later filled with primer prior to finishing. Rivets were simulated throughout with the use of small pins each individually hand drilled and glued into position. The conning tower alone has over 1400 pins installed. 208 holes were drilled and filed on the main hull itself to simulate venting or flooding holes.
The four deck guns were handmade out of metal as were the conning tower masts, periscopes, and ladders. Antennas were installed with springs to facilitate quick disconnection when removing the deck from the hull itself.
The model, in view of its size, was not greatly affected by rough water. Turns were sluggish despite the fact I’d doubled the size of the rudder from the scale version. Undoubtedly part of this was caused due to the twin screw effect on the rudder itself because both electric motors ran at the same speed with Counter-rotating propellers. A possible solution to this problem would be to have the “outside” turning propeller slow down during turning maneuvers. It’s possible I’m told, but I didn’t have time. Forward and reversing action was positive with ample power to control the boat. Excessive “stress” was placed on the rudder linkage from the servo to the rudder itself which later had to be “beefed up” to take the forces. At one point the linkage actually broke while reversing at high speed. The two “Astro 40s” provided good scale speeds forward and perhaps a bit more. In rough water testing I found the boat to have very good thrust, and she never slowed down due to waves but just kept boring in.
Initial runs showed the boat to be listing heavily during turning maneuvers due to the fact it needed more lead ballast placed lower on the hull which I did by placing an additional six pounds of steel to the bottom of the keel. You couldn’t see it unless it was out of the water anyway. This solved the problem.
As mentioned earlier in the article, “baffling” is a “must” throughout the boat because you don’t want water rushing around fore and aft and upsetting the trim. This was easily accomplished later on.
The fore and aft ballast tanks had a two gallon capacity each with electric pumps which provided full filling in about one minute with emptying taking a bit longer. Venting for these pumps was through piping to the conning tower area where, once above water, the ballast tanks could be pumped dry or to whatever level you wanted the boat to float. Intakes for flooding the tanks were through the bottom of the tanks themselves. The restrictor valve on each tank (i.e., flooding and emptying) did leak so it was necessary to empty both tanks off and on during running. Otherwise the valve would permit small amounts of water to enter the tanks, thus upsetting the trim as you were cruising along. During rough water runs I kept these pumps running all the time. I wasn’t going to take a chance of losing her in deep water, and because it was rough you really couldn’t tell just what level the sub was running at. At times it simply went “through” the waves. The force of the waves on the hull made the diving planes far more effective also.
I found that the smaller Propel tank provided about six “surfacing” maneuvers after which it ran out of air. Replacement was through a simple quick-connect at the bow of the boat. The electric solenoid we used to allow air to the inner tube was a leftover that seemed to work. It was bathed in black silicone for water proofing and worked fine.
This was the first full “negative” sub I’d ever built and that one thought is constantly on your mind when you’re running in deep water. The damn thing WILL sink! Dye markers attached to the hatches held shut by a normal aspirin which dissolves in twenty minutes or so were used assuming once under water one didn’t want to stay down for that period of time. The timing on this never did work out properly inasmuch as the aspirin did get wet even while “surface running” and eventually dissolved.
It was back to those good old Dietzler products which I’ve always used on my models. The stuff is readily available in most auto paint shops, is easy to apply, fast drying, and “bulletproof” in my book. Water doesn’t affect it, and it’s a lot cheaper than using hobby products. I’m not willing to pay the incredibly unfair prices we are charged for thinners, plastic fillers, and paint sold in most hobby shops. You can get the same thing in most auto paint shops.
Most of the large “Offshore” raceboats are now using “DELTRON” as an excellent salt water finish. The stuff is unreal and does require an additive as well as its own thinner. You can’t mix “DELTRON” with anything else! Anyway, the sub was painted in the usual flat black and grey colors. Flattener for Dietzler is available, but you’re restricted to something like 25 percent or else you’ll end up with a “chalky” finish.
Also, I’ve found that paints that have been “flattened” tend to really look raunchy after being subjected to water which, in the case of a sub, makes for good realism. You get a good “beat up” effect!
Submarines, generally, are quite limited detail-wise so I wasn’t particularly impressed with this one although I’d built it to scale. I suppose decking, and the conning tower area along with the guns is about the most you can work on to provide realism, but obviously nothing can be done “down below” so whatever you see in the water is all there is.
I don’t really know anyone who has this submarine business down to a
reliable working product. There are some kits on the market that will submerge, but I’ve seen nothing in the larger scale boats that really perform as a real submarine. I could be wrong on this because I’m told the Dutch now have some sort of pressure sensing unit that will hold the model at a given depth. That I’ve got to see and I have written a friend in The Hague to inquire about it. He’s found nothing as of yet.
Model submarines will draw a crowd wherever they are seen, however. There’s something awesome about a sub that fascinates people. Mine, however, didn’t fascinate a local fisherman at the lake this summer who upset me almost daily by trolling inside my dock with his stupid portable radio playing rock music and constantly yapping with his fat friend in the back of the boat.
In years past I used to get these guys with horns, water guns, rockets, and speakers which was really fun (I was out of sight and nobody was around) for the most part, and we usually ended up friends once I showed myself and the model. However, this one fisherman did need some attention so I simply followed him from the back and kept my distance. He knew it was there, and eventually departed when I sent her to the bottom in, thank GOD, shallow water. He wasn’t impressed!
Finally, I’m glad to see the larger model boats come on the scene along with their quarter scale model airplane counterparts. I hope it’s a trend, and while the larger boats aren’t for everyone they are impressive and provide so much more space for detail and realism which is what I’m into. There is a need for larger and more powerful electric motors which won’t interfere with our radios (brushes and all that) as well as an enlarged line of propellers. Hopefully it’ll all come to pass one of these days.
Length 312 ft
Beam 27 ft
Submerged Depth 300 ft
Weight (surfaced) 1526 tons
Speed (surfaced) 20.7 kts
Range 11,000 miles
Tour 75 days
Fuel (diesel) 11,600 gals
Max Submerged Time 48 hrs
Underwater Speed 3.5 kts
Builder Portsmouth Naval Yard
Launched 15 March 1953 [sic; should be 1943]
Length 10 ft
Beam 13 in
Power Twin Astro 40s
Speed Controls Futaba
Weight 113 lbs
Speed 8 mph (surfaced)
Batteries Three 6V aircraft
Props German 4-blade (2½” dia.)
Ballast Tanks 6” PVC (2 gals ea.)
Pumps German Radco
Building Time About 700 hrs.