Keeping Cool

Last fall, in anticipation of a trip to the Caribbean, the owner of a 1990 Hinckley 51 asked the GIBY team to include installation of an air conditioning system in the winter refit plan. The unit would be used while dockside, or while at anchor when running the generator to charge the batteries and make hot water. Conveniently, the boat was already equipped with excess generator capacity and had unused circuit breaker positions available on the ac panel.

“The challenges presented by this project primarily revolved around the interior of the boat not having been designed with air conditioning in mind,” says Bobby, Project Manager. “We had to find a location for a 12,000 btu self-contained unit, and then a way to exchange air through it.”

To create space, the owner agreed to give up a locker behind the settee.

“Discharging air to the cabin was tricky,” says Bobby. “For proper function, the unit depends on a certain minimum amount of air exchange within the space being cooled. This requires a discharge opening that, at first inspection, seemed impossible to locate on any of the remaining vertical surfaces not taken up by lockers and drawers.”

Rather than a conventional discharge vent, the team opted for a slot diffuser, a long rectangular opening located in the space between the outboard lockers and the underside of the deck.

“This required us to fabricate a custom plenum, to take the air from a conventional six-inch circular duct and route it out along the full length of the slot,” says Bobby. “We visually obscured the slot with a long cherry dam that will also serve to divert the airflow upwards.”

An additional duct was routed to the forward cabin, where a conventional vent will discharge cool air to that space. Between the slot diffuser and the forward vent, Bobby was able to achieve the required discharge area for proper operation.

Providing return air was easier, with a single return-air grill of adequate area placed below the chart table in a void space that opens to the locker where the unit is located.

Seawater for the unit’s condenser was plumbed from a seawater manifold in the salon bilge space.

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