Keeping Cool:  Hatch A/C & Fans

Submitted by Mark Melchior

It gets plenty HOT here in Texas, so we added a few items to make our onboard experience a bit more pleasant.  Expensive dedicated marine air-conditioning units are available from companies such as Taylor Made Environmental (Cabin Mate or Cool Mate) and Mermaid Marine Air.  Don't be surprised to spend well in excess of $1200 for these units.  A somewhat less expensive solution ($700-$1000) is a carry-on marine unit from AquaCal (Kruzin Kool) or Taylor Made Environmental (Carry-On Cruiseair). 

We spent even less for our dockside cooling needs . . . a hatch-mounted, 5000 btu household A/C window-unit made by General Electric.  Sam's Wholesale Club had a good deal on these units: $139.  The drawing below provides approximate dimensions of the A/C unit and the replacement hatchboard I constructed to hold this unit.  I recommend that you use your factory-supplied hatchboard as a template to ensure a perfect fit.  An A/C hatchboard made from either Starboard or epoxied (then painted) plywood works equally well.  I chose 1/2" CDX plywood with a single application of epoxy and finished off with an alkyd-based primer and gloss paint.

This 5000 btu GE A/C unit draws less than 5 amps (at 110v AC).  It will cool our boat from 95°/80% humidity to 70°/45% humidity within 30 minutes or so.  Don't expect to use any A/C unit away from your 110v AC power source.   There isn't an inverter/battery combination around that will supply the "juice" needed to keep one of these things running for long.  The same holds true for any portable or fixed marine air unit.  When away from your AC source, use your 12v DC-supplied cabin fans.  Keep your A/C unit stored in your dockbox.    I installed a pair of Hella "Jet" fans near the compression post in the cabin.  These were wired into my "Cabin" circuit so that I didn't have to fish another wiring run to my breaker panel.  Hella fans are high quality and quiet.  The "Jet" model rotates 360° and folds up out of the way against the deck liner.  Cost?  About $25 each.

Oh, and what about the noise generated by that GE A/C unit?   The sound level in the cabin interior is very acceptable.  When we approach the boat while docked in the wetslip, we cannot hear the unit until we round the cockpit corner.  Even then, the sound is minimal. 

[NOTE:  the "rear support" that appears on the drawing below is NOT NEEDED.  Initially, I was worried that the unit's 45 lbs. were too much for the hatchboard with such a large square cut out.  I tested it before fabricating the support and found it to be rock solid.]

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Sorry for the shadows . . . note how the pop-top curtain is rolled up to
allow the exhaust vents on the outside of the A/C unit to breath.

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This photo shows a partial view of the A/C unit as well as the location I selected for my fixed VHF radio.

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Here are those Hella "Jet" fans.  They keep us cool while on-the-hook (and away from shorepower).
They swivel 360° to provide relief to those seated at the cabin table and to those sleeping in the v-berth.

 

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Mark Melchior
1999 Catalina 250, #384
"LORELEI"