Electric Water Heater with Heat Exchanger Volt: 110v Gallons: 6. Atwood's engineering, manufacturing and application expertise have been honed by time and the experience of supplying millions of water heaters to the recreation vehicle market for more than 30 years. Almost 20 years ago, Atwood applied this specialized knowledge to meet the needs of the marine industry. In doing so, we designed the water heaters that have become the standard in the boating industry. Performance: Atwood water heaters have been designed not only to heat water quickly and efficiently, but to also deliver every ounce of usable hot water possible from the tank. Atwood water heaters perform reliably, assuring full use of hot water benefits designed in your pleasure boats.