Welcome to the forum, Gary.
In my opinion, the simplest way to balance a boat is to ensure that it sits in the water down to its waterline. This can be achieved by adding ballast, if necessary, as well as moving such things as the battery, if possible, to get the boat sitting "right". Usually a little bow high attitude is OK, but not too much. Boats are nowhere near as critical to set up as an aircraft, and can be very forgiving of incorrect set up. A boat that is too bow or stern high, or leans to one side, will still sail OK, but does not look right, as opposed to an incorrectly balanced aircraft, which can be very difficult to fly (as I'm sure you will know).
I have no experience of LiPo batteries, as I exclusively use sealed lead acid (SLA) batteries in all my boats, and brushed motors. A range of sizes and capacities is available, depending on the space in the boat, and they have the added benefit of acting as ballast. Rather than adding lead as ballast, I usually add another battery where practicable, or use a bigger battery, which also extends the running time of the model.
Peter.
