For more than 50 years, Walter Keel Coolers have remained the most trouble-free and economical form of marine engine cooling -- proven service on US Navy vessels , US Coast Guard vessels, workboats, fishing boats, ferry boats, tug boats and pleasure yachts! Closed circuit cooling extends the life of propulsion, generator and auxiliary marine engines -- and minimizes downtime -- by eliminating salt, silt and debris in the engine jackets. Unlike inboard heat exchangers, Walter Keel Coolers require no seawater inside the hull -- preventing the headaches of clogged sea strainers and raw water pump failures, while eliminating the need to drain the cooling system in freezing temperatures. Proper cooling protects your engine investment and allows the engine to run more efficiently, saving on fuel and maintenance. Walter Keel Coolers are available in 3 models & hundreds of sizes to suit every application from 10 horsepower auxiliary engines to 5,000 horsepower propulsion engines!