Earl Colby Pottinger wrote:

Second, a boater who has to worry about if his wiring will work 10,000 feet
down has other problems more important than some silly wires.

If a splice fails it will usually fail on or near the surface. Water
just gets in faster and further at depth, the damage it does to the
system is the same so it is well worthwhile to make your splices good ones.

Rick