Heat exchange systems for engine-powered watercraft and methods of using same

An onboard heat exchange system for a watercraft having an engine, the system comprising:

• a system intake arranged to draw water from an external water source;
• a first heat exchanger that transfers heat to the drawn water from a coolant circulated through the engine, and having an outlet that directs heated water toward an engine exhaust system for ejection therethrough;
• and
• a second heat exchanger that transfers heat to the drawn water from the coolant, and having an outlet that directs heated water toward at least one of an intake conduit proximate the water intake and at least one onboard accessory system for flushing thereof to kill aquatic invasive species.

A heat exchange method for use onboard an engine-powered watercraft having an engine cooling system, the method comprising:

• drawing water from an external water source through a water intake;
• directing water from the water intake to a first heat exchanger and to a second heat exchanger;
• directing coolant of the engine cooling system through a first heat exchanger to transfer heat from the coolant to water located within the first heat exchanger and thereby cool the coolant;
• directing coolant of the engine cooling system through a second heat exchanger to transfer heat from the coolant to water located within the second heat exchanger and thereby heat the water in the second heat exchanger;
• and
• directing heated water from the second heat exchanger to at least one of an intake conduit proximate the water intake and at least one onboard accessory system for flushing thereof to kill aquatic invasive species.