U-boat construction in the MWC is still open to many schools of thought as subs and U-boats are still relatively unheard of in the sport. At 1-144 scale, German U-boats would be very difficult to build as fighting vessels, the difficutly being in getting working parts into such small quarters and maintaining weight allocations. To get an idea of MWC-allowable sizes, just look at the statistics (approx. historical dimensions):
***Type XXI---length: 76 m., height: 6 m., width: 8 m.
***Type X---length: almost 90 m.
***Type IX---length: 76 m.
***Type VII---length: 67 m.
(***Type XI---length: 115 m. [never built, although Trident Research hopes to prove otherwise and is currently attempting to examine a wreck they believe to be one of these U-Cruisers])
>>>Of the types known as having been built, the Type XXI still offers decent length, and with better girth than the IX or even X overall, in my own opinion. In the hobby, here are the approx. stats for a scale model Type XXI:
***Type XXI---length: 20.7 in., height: 1.7 in., width: 2.2 in. (using the formula 39.3701 times actual historical dimensions, divided by 144 to arrive at hobby figures)
>>>If we then assume to build a Type XXI (historically 1621 tons displacement, surfaced), here is some data I have experienced/considered in previous trials with this type:
1.) Weight of the model is about 2.2 lbs. allowable (formula: tons displacemment [surfaced] times 2240, divided by 144 three times---this result [in pounds] times 16---to this result [in ounces] can be added another 25% of the result OR 16 ounces, whichever is greater, to give final allowable model weight in ounces [divide by 16 to give pounds]). Although a scale hull I built over a year ago sank like a rock when ballasted with just 2 lbs. It only floated at something like 1.7 lbs. So micro-parts and positive bouyancy need to be worked in here to achieve a floatable model in the end.
2.) Diving Theory: Does one want a model that dives by use of forward motion along with appropriate dive plane angles (a simpler plan that doesn't involve a servo, etc.) or does one want to use a bilge pump to control ballast (MWC subs are allowed pumps ONLY when used to control diving---not for damage control)? Weight and space considerations have to be taken into account in this decision.
3.) Gun Type: A U-boat would be allowed a one-unit gun that could be a standard 50-rd. cannon or a 15-rd. spurt gun. MWC rules say no gun can be placed at or near the waterline, but with such a low profile in the water to begin with, this is a rather moot point with U-boats. Also, guns can be placed in/through superstructure only when historic positioning is not possible. A U-boat gun would have to be placed thru the conning tower, due to model size, I would think. Now the Type XXI had no deck gun at all historically (only AA guns in the con), but still all subs are allowed a gun by MWC rules, so a gun would be more representative of a U-boat's main armament--torpedoes--anyway.
4.) Fighting Theory: ANY bb holes in a U-boat at all will spell its doom. This pretty well dictates it can't just linger about on the water--the longer it does so, the more the odds tip against it. A U-boat would have to hide well, get in fast for a "torpedo run", and get off the water as fast as possible. Plain and simple.
>>>I hope this provides some good background concerns in building a U-boat. They could never really be competitive in the sport as a whole, but might well provide some interesting action and enjoyment.
SUBMARINES IN THE HOBBIE