How hard is it to add air-conditioning?

[Low Country Home Builder]

I'm looking at an older cat around the 39' range. I can see us using air-conditioning on some of the hotter days. But the older cats in this length don't have a/c. How hard is it to add. I also assume the generator in the boat would not be large enoug to handle added a/c. Is this a correct assumption?

What brands do you recommend? If have had Mermaid a/c on one of my boats and it did a good job.

[Sunspot Baby]

Two tricky bits with installing A/C on anly boat.
1. Space for the unit.
2. Ducting to areas to be cooled.

Pluming, wiring, through hulls, etc. can usually be worked out if you can get the 2 above.

Of course, you have to have enough amps to drive it either generator or shorepower.

George

[coot]

I expect you can find a way to cram an air conditioner into any boat. You just have to adapt your installation to the architecture of your boat.

For example, I used to have a Catalina 34. I added a Cruisair integrated air conditioner module under the v-berth. The duct went up along the wall of that room. The vent opened out both sides of the wall between the v-berth and the salon. (i.e. you could look into the vent and see somebody in the other room looking back at you.) I didn't even run ducting to the aft cabin, so if I wanted to be cool, I didn't go back there.

You might make similar compromises for a catamaran. For example, you might only air condition the main cabin, or only the main cabin and one hull. Or you may find a convenient way to run ducts for everything.

If you have a generator installed in your boat, I would be surprised if it can't operate an air conditioner. I bought the smallest diesel generator I could find (4200 watts) and it can run two air conditioners, enough for a 42 foot boat. If you have one of those hand-carry portable generators, maybe you can't run an air conditioner at all.

The air conditioner vendors publish information for estimating how much cooling you need for a given size boat. Look on their web site for this information, then from that you select one or two air conditioning units that give you that capacity. Then you look up the power requirements for the unit(s) you are considering.

It is common to add a second shore power circuit for the air conditioners, but it isn't strictly required. You just have to make sure you don't turn on too many things at once. So, if you have two air conditioners, a toaster, a microwave oven, and a water heater, you have a choice: Do you install enough shore power (and generator) to run them all at once, or are you happy to turn off an air conditioner when you make toast?

On my boat, the answer is that the generator can run the air conditioners OR something else, so I have to turn an air conditioner off if I want to make toast. I have two shore power cables, so at the dock I don't need to worry about it. (In a transient slip, I will often only use one shore power cable to save money.)

Conceptually, it isn't that hard to install the air conditioning, but if you do it yourself, it is the usual working-on-the-boat experience. You think it should only take 5 minutes to drill a hole to get a wire through the wall, but an hour later, it still isn't done...

I've used Cruisair and Marine Air (says MARINE AIRRRRRR on the side), and been fairly happy with both. (Actually, I think both are made by the same company -- the systems are remarkably similar.)

[44'cruisingcat]

The easiest to install would be something like an Aircommand rooftop A/C like you see on caravans / RV's. They do make marine versions.

[R&B]

We Had a 16000 btu installed last year in a privilege 39...It is in the main salon....It was split into the two forward state rooms....its only ok.....remember that cool air sinks to the low parts which means the hulls remain cool but the bridge deck is HOT during the day...If I had to do it again I would consider two units in the hulls feeding into the living area and state rooms......Also 16000 btu cruiseair a/c should not be split more than twice......(you think the Authorized dealer would have known that) .Good luck