mike walker

Keep it from sinking is a fine line of balance and checking for leaks that dose not always work.

First put it in your test cell ( Bath tub) make sure you have no leaks in your radio box
try to get your motor and battery pack as far forward as you can with out changing your C/G
tape your radio box lid with good tape. Put your R/X in a balloon, rub a little vasaline on your servo seams also pack some in your rudder linage seal.
as you get your boat more dependable and running up on plan this won't happen as much
above all STOP swimming after your boat. fishing pole and a tennis ball works great.