Re: overheating
Yes, the water pump is shot. Luckily, it must be in one piece still, as it pumps a little water when it's running at a higher RPM. But if it were my boat, it would be docked until the impeller and thermostat was changed-out. When it grenades inside the housing, pieces go throughout the cooling circuit. Sometimes when this happens, a complete tear-down is needed to remove the chunks....ungood. So you probably caught it in time.