Water-heat exchanger cooled (TEWAC/CACW) units are available from 500 kW to 12 MW. These generators are commonly used aboard ship or on off-shore drilling rigs where there is an abundance of ocean water for cooling.

The units are equipped with one or two internal fans. Air is forced up and through a large air-to-water radiator, which is within the generator enclosure. Air is continually recirculated with the heat created from the generator being displaced by cool water from the radiator coils. 

The radiator consists of an inner tube of 90-10 copper nickel for corrosion resistance and an optional outer tube to detect water leakage. A separate system to pump a continuous supply of cooling water throughout the radiator must be supplied.