RE: Stealth boat
you could stick a lithium polymer (lipo) battery but the ESC needs to be lipo capable plus the relevent charger for the battery
OR
go brushless
if you go brushless, its no major thing, tell us the lenght of your boat, if its 20" plus then a motor with a diameter of 28mm or 36mm will be fine, kv rating motor for the boat will be 2500kv - 3500kv, then you use a brushless ESC, depending on how fast you want to go depends on the ESC, most people use 60a, 120a or 200a ESC's plus you need to replace the reciever, get a TRANSMITTER package (transmitter, receiver, servo) rudder aswell, it is advisable to buy watercooled motor and ESC, keeps everything cooler, longer runtime then
transmitter types for boats are 27Mhz, 40Mhz or 2.4Ghz (the 2.4 requires no crystals) the last one is better
list of parts
- battery (lipo plus charger)
- motor
- ESC (brushless)
- transmitter/receiver package
-rudder
you can use the exsisting motor mount, prop shaft and prop
the simplest solution is buy a lipo capable ESC and battery, some soldering may be needed