The box cooler is a relatively new cooling system that pumps the engine’s cooling water through a bundle of tubes enclosed in a sea chest mounted against the hull. Inlet and outlet slots are cut into the hull and sea chest to provide an uninterrupted flow of water over the cooling tubes.
“It is something the Europeans came up with. It does the same thing as keel coolers do,” said Sean Fernstrum of R.W. Fernstrum & Co. After realizing how much Europeans are attached to their box coolers, Fernstrum joined forces with the Netherlands-based Weka Boxcoolers BV to build and market box coolers in Europe and the Americas.
Fernstrum doesn’t see too much difference between the two, but as more European designs are built in the U.S., more box coolers are being used.
One place they are being used is on offshore service vessels. “With diesel electric and when heat rejection gets to a certain point, it’s a viable option because you get into needing multiple keel coolers versus one large box cooler,” said Rich Lockhart of Duramax Marine. “It’s more of a heat-source requirement.”
The cooling tubes on the first European box coolers didn’t have a protective coating. That’s OK for fresh water, but not for saltwater. On the Duramax box cooler, the tubes have an epoxy coating to negate corrosion issues between the rods and steel sea chest. — M. Crowley