Adding Air Conditioning: A Helpful Digression

Lisa and I don’t do well together when it’s too hot to sleep. We bicker. Tempers fray. Harley the dog tries to find a place to hide. None of that works well on a small boat.IMG_1618

A couple of summers ago we solved this problem by jerry rigging a window-type AC on deck to keep us cool.  While cost effective and functional, the jerry-rigged solution is (as a friend of mine put it) ghetto-fabulous. It also makes taking Pearl out sailing a major production causing us to stay in rather than go sailing.

Having turned 50, I relented. I decided that I should follow Lisa’s advice and we should bite the bullet and install an self contained reverse cycle air conditioning system. The upside is that we can have air conditioned (both heating and cooling) comfort wherever we go — particularly if we add a a generator. The downside is the expense, installation aggravation, and loss of storage space.

Having finally consumed most of the stuff we provisioned for going to the Bahamas last year we agreed we could use the lose the roughly 2 cubic feet of space the the air conditioner and 4 cubic feet the ducting would consume. Note to self: don’t over provision. Also, we’ve been freeing space by tossing out stuff we (mostly I) thought was essential.

One can spend truly egregious amounts of money on an ACs and installation. Yes. There are such things as “bespoke” air conditioners — custom made units to fit in specific places in a boat — and it’s really easy to get sucked into thinking you need one. Having looked at the options, however,  and friends who’d done their own installs, Lisa and I decided that we would purchase a kit and do the installation ourselves. It’s not rocket surgery, after all.

What we learned from out experience:

  1. Measure several times, cut once.
  2. Lay out every component and ensure that you have the space to do what you need to — e.g. connect fittings, hoses, and hose clamps — and leave extra hose and wire so that you can do maintenance.
  3. Ensure there is a constant upward. flow of water from the through-hull to the filter, then the pump, and air conditioner — if you do this, you don’t need to worry about priming the system.
  4. You don’t need to install a sump and possibly separate thru hull  for draining condensation. A couple of vendors (Marvair and Mermaid) offer venturi pumps that attach to the discharge hose.
  5. Double the time you think it will take to get anything done.

Also, consider taking yoga classes to prepare yourself for the unique positions in which you will likely need to pose yourself to install some of the components.

Fortunately for us, Beneteau offers the 373 with a factory installed air conditioning as an option. Beneteau’s Customer Service very helpfully provided us with the schematics and a parts specifications for the ACs they install, as well as pictures of someone else’s installation. While we did purchase several parts from Beneteau for the installation, we didn’t get all of them — in some cases because they just weren’t available.

As it turns out, the Dometic Marine Air 16000 BTU Retrofit Kit fits perfectly in the space mapped out. We tried a Webasto 16k BTU but despite the specs indicating it would fit, we just couldn’t wrangle the unit into place. We bought our system from West Marine, and avoided getting the install kit in favor of buying individual components. This ended up being less expensive than buying the “kit” and had better components — e.g. brass rather than plastic fittings.

AC Installation Picture
The AC in place under the Port side settee. The grubby bilge is from the condensate buildup — which should be addressed by the Marvair Condensator.


The most demanding part of the installation was running the plumbing. While we had a “spare” through-hull fitting that we were able to use, getting the water filter, pressure pump, and air conditioner on a consistently increasing gradient was a bit of a challenge. We still need to fiddle around with this whenever the filter gets clogged.

Fortunately, Lisa is both small and flexible. Running the pipes and attaching the necessary hose clamps and fittings in tight spaces required some impressive contortions on her part. Regrettably, there is no photographic evidence of her feats as my picking up a camera would have resulted in “bad things” happening. I am not sure what the bad things are, but i prefer not to find out.

The most traumatic part of the install was cutting into Pearl’s cabinetry and drilling a hole in her hull. With the right tool, anything is possible. We ended up getting a Rigid Multi-Tool from Home Depot for cutting the holes for the return air vent, ducting, and the thermostat/control head. The multi-tool was far easier and more precise  and manageable in the confined spaces we were working in than either a rotozip or a jig saw — we tried to use both. The mutl-tool was well worth the $65 cost. Prior to this, I thought they were completely pointless.  For the vent into the salon, we needed a Milwaukee 5″ hole for which we used a hole saw. These tools, along with a nut drive for tightening the hose clams made the install quite manageable.

The other part of the story was hooking up the power. This wasn’t too bad. Instead of trying to patch into the existing wiring and adding a circuit breaker, we opted to run a completely seperate dedicated 30 amp circuit for the AC — complete with a Beneteau standard Merlin Gerin Circuit Breaker. There is nothing else on the circuit. This way, if we choose to run the AC while at anchor all we theoretically need to do is plug in the generator.

There is one other component we need to install. It’s a Venturi pump made by Dometic/Marvair that evacuates the condensation pan that currently drains into the bilge. While, once again, you can jerry rig a much less expensive solution using fish tank supplies, we figured the potential downsides out weighed the higher cost. Hopefully, once this is complete, we’ll be back to having a clean, dry bilge!

We love having our AC so far. It works much better than the ghetto fabulous cabin-top jerry rigged unit we had. It dries out the inside of the boat — which is nice — and keep the outside of the boat cleaner and less cluttered. Good call Lisa. Stay tuned for more.

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