Taxidriver:
Clearly he is going to have 3 batteries as well [img]{akamaiimageforum}/image/s4.gif[/img] 3 subs in 1.Hope you dont have a frequency clash at pond side and have to change crystals. Regardless, make sure the compressable volume that each piston tank will act upon when submerging is great enough to avoid puting strain on the motor in your compartmentalised design. In a convetional design the internal pressure would equalise through out the WTC, and hence be lower.
I have this design of the electronics and batteries figured out with the help of VanTech.