Advising Skip to install a stronger belt is like doubling the size of
a fuse when the correct one plows. The belt slipping is preventing a
battery fire or boat explosion right now please follow the reported
history, Battery charger meltdown, Alternator belt replaced several
times even after batteries show a full charge. Overloading a shorted
battery or overloading an alternator is bad advice I hope Skip reduces
the alternators output until this dangerous problem is corrected.
Installing a heavy duty Gates belt from NAPA to extend belt life is a
common practice but not a fix for a serious overload, remember the
alternator's output is not fused except by a slipping belt.