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Hot Water on Your Boat

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In Hot Water


Illustration by Steve Karp

If you’re on an extended cruise, you can never have enough of two things: privacy and hot water. Both problems can be solved, but the solutions are different in scope. You can take care of the former by purchasing a bigger boat. The hot-water issue is easier and less costly to resolve: Install a more efficient water heater.

One good option is Anacortes, Washington-based MarineTec, which offers water heaters that are made in the United Kingdom but are now sold in the United States. (They’re sold under a different name in the U.K.) Nordhavn uses Solaris heaters exclusively, and Selene is starting to install more of them on its boats. Many other overseas builders use Solaris, including Sunseeker and Jeanneau, which favor them because they can be installed vertically or horizontally and can even be suspended on brackets on the overhead.

Solaris units offer three other advantages: They are copper clad on the inside; they have a larger heat exchanger than conventional household-style water heaters; and some models have dual heating elements, which means they can provide hot water more quickly than similarly sized conventional heaters with single elements.

The Solaris exchanger is made of “fin tubes,” which are exactly what they sound like—tubes with small fins on them. Think of each one as a tiny radiator. The additional surface area provided by the fins transfers heat to the water more quickly than a non-finned tube. In addition, the Solaris Superyacht series, used on the Nordhavns and the Northern Marine 85, has two electrical elements and dual heat exchangers, providing almost instant hot water.

The most popular Solaris heater is a 20-gallon model that’s wrapped in stainless steel on the outside. It’s priced at $1,395, which is a little more than competitive models. But that price includes a mixing valve so you can add cold water to keep users from getting scalded. Most water-heater manufacturers charge extra for the mixing valve.

Because the Solaris heater tank’s inside lining is copper, the company says it acts as a natural biocide and eliminates the need for anode protection. MarineTec’s Lars Nilson also points out that the copper liner should last longer than steel or even stainless steel, which he says can corrode and need to be replaced after as few as five years. Nilson estimates that a Solaris unit will last as long as 20 years.

The company’s 40-gallon heaters ($1,975) come with dual heating elements—choose from 110V/1kW, 230V/2kW, or 230V/3kW power ratings—and are recommended for yachts that use a great deal of hot water. For a refit on a 130-foot Christensen, MarineTec will replace the original single water heater with two Solaris units equipped with triple heating coils and dual heating elements to supply hot water for five staterooms, crew’s quarters for four, a galley, and laundry facilities. The original stainless steel tank was custom built and used a single 4.5kW electric element and two heating coils made of bent stainless steel tube. Having reached the end of its life due to corrosion and pitting, the water heater would be expensive to replace with another custom tank. The Solaris system is expected to heat the water faster than the original tank, because it uses the cooling water from all three generators to supply heat to the water heaters instead of an in-line heat exchanger before being dumped overboard. It will also retain heat better thanks to polyurethane foam insulation, rather than rockwool or fiberglass. MarineTec is also working on creating heating systems to warm yacht accommodation spaces using the water from the generator cooling system.

MarineTec offers three Solaris lines of heaters ranging from 2 to 40 gallons finished in either the blue fiberglass outer skin or stainless steel and in vertically or horizontally mounted versions. For retrofits or to fit a tank into a tight spot, it also offers custom shapes. Fittings to bring the heating water and generator cooling water to and from the water heater are -inch pipe. Water is carried through -, -, or one-inch pipe, depending on the unit size, and to make it even easier to move hot water throughout a boat. Now if only you could have more privacy.

(877) 417-8339.

This article originally appeared in the November 2011 issue of Power & Motoryacht magazine.