I am thinking of building a Type VIIC and was wondering about the total costs. But as i am sure i will miss something if i do it myself, and some things i am unsure of, so i came here. First off there is the kit, the WTC, ballast, drive, and control systems, and radio gear. But i probably already missed something. Now the real issue is i don't quite know what some of these would actually need.

Like if i got a RCABS system (so far of what i read its the best thing in my mind) for the U-boat, that would take care of the WTC and drive motors and ballast system, but i would still need to finish the drive shafts and propellers, get a speed controller, correct? But what about driving the pump? Is that with an on/off, direct to receiver, with a servo, or another speed controller?

What about simply building my own RCABS type system instead of purchasing one? I know where to get the plastics needed, and have a small lathe to work with (among other tools), but the pumping system, bladders and seals would probably be an issue without knowing a good source or a solid plan. Or is there a simpler system that is, how do i put it, maybe self contained? As in, it doesn't need to be filled with gas or something, and can go to the bottom and come back without fail as long as the mechanics work and the battery lasts.

I already have a nice radio, and could either reuse a receiver or get another, some cheap servos (as i doubt the loads on any of the control surfaces is anything like a heli), but then comes the battery (never been an electric guy before). Would a receiver battery (4.8v 3000 mAh NiMh) suffice, as this isn't some speed daemon, or does it need more volts, or simply more capacity so it won't die that fast (not that retrieval would be an issue ever)?

And if the battery system is sorted, how do you dial in a realistic speed? Do you size the props until full throttle is correct or can the speed control handle being at part throttle all the time and just limit it on the radio (electric helis as i understand should be voltaged/geared to run near full throttle so you don't burn up the speed control being in part throttle hover all the time)? Does the speed control need to be cooled or is the air in the WTC enough?

I didn't list brass tubing and sheet specifically, but those would go in drive and control, and shouldn't be an issue. Nor should skills and tools, unless i'm overlooking something entirely, everything seems within my abilities (and i have the internet too if all else fails).