Re: Over heating when slowing down?
Overheating is only common in boats with something wrong.
Boat cooling systems are pretty simple. If the impeller is pumping cool water and there are no obstructions in the way of that water eventually reaching the thermostat, the thermostat is opening when the engine gets hot, the circulating pump is circulating, and the warm water is being returned to the lake/river/sea without leaking into something important, your boat will probably cool properly.
If not, start lookin! I found chunks of a thermostat down in the lower hose of my '89 when I got it, partially blocking water flow. Never know what you'll find.