Blazer Bay 2170 all of a sudden has a problem with panel that sends power to GPS,livewells,and lights.Motor runs fine,and fuses are all good.

I'm sure there is someone here that can help you, but you may want to try a boating forum.
This stuff is completely unrelated to construction wiring.

Check your grounds, also even if fuses are good, it does not mean there is power to them, Follow back to battery, and check power from battery switch.
A cheap test light($5) will help follow problem, the hot AND ground. Good Luck.

Also if you have a Bilge pump toggle switch, Change it from the single pole double throw with center off switch, to spdt but no center off, so pump is manual or automatic. That off position has sunk MANY boats.
If it is sitting and stored, it will draw no current, if stored any length of time, you would disconnect Battery anyway.
NO reason for off position. I know it has this has nothing to do with your question.
Hope it can help.