Why sea-air temperature differences have not powered surface ships

Could a surface ship use a Stirling engine powered by the temperature difference between the sea and the air?

The idea has been studied, but so far it has not produced a useful service solution.

The proposal uses the temperature difference between seawater and the surrounding air to drive a Stirling engine. The idea has been examined repeatedly. The answer remains negative for practical service so far, although engineers continue to revisit the concept rather than treating it as permanently closed.