Marine source heat pumps

[Carnival Eddie]

Hello, I am researching the possible use of water source heat pumps on board ships. After all the ocean is a fairly big reservoir and a ship moving forward at 20knots has a fair flow rate going under its keel. Anyone know of anyone who is doing anything on board ships or a related application? Thanks

[The Viking]

Not strange to use the sea as the heat source, plenty of manufacturers are using closed loops sunk in to everything from muddy riverbeds, lakes to the sea.

The big question must be why...
Normally onboard ships the problem is the opposite, there is this big lump that generates more heat than what the ship could ever use even in arctic conditions and that requires sea water to cool it.
If you really want to use a heat pump, one solution would be to put a heat exchanger in the engine's cooling water and use that as the heatpump's evaporator, that way you wouldn't need a separate pump. Another option would be to use a heat exchanger plate, similar to the marine refrigeration plants' condensers as an evaporator. Only imagination is the limit, lots of different solutions out there.