How many air conditioning units do you have on your boat, and how many BTU are they? Do you find that they are sufficient for the cooling needs?
This is an interesting question that really gets to the heart of how boats are used.
Air conditioning, from a power usage perspective, is a luxury. We spend over 90% of our time aboard in remote tropical locations, so we’ve tailored our setup for that style of cruising. We run 2.5kW of solar and have a large battery bank. Our hot water is electric and automatically switches on when solar output exceeds 1300W.
We have the standard two 16,000 BTU Webasto air conditioning units, which do a reasonable job cooling the hulls.
On our boat (hull 69), the air handling setup is a bit odd. The units are in the saloon, drawing in warm air and pushing cooled air into the hulls. This means cold air in the hulls is constantly being displaced by warmer air from the saloon—an inefficient loop. It would be much more effective if the intake and output were located in the same zone. This could be easily improved with some additional ducting and venting.
The saloon itself gets minimal direct air conditioning and mainly relies on cool air drifting up from the hulls. Combined with sloping windows that let in a lot of sun, it takes quite a while to cool down.
Once the system is up and running for a while, it works well enough. In a marina with unlimited shore power, it performs quite well. If I were starting fresh, I’d relocate the raw water pump—currently under the owner’s bed—to somewhere quieter, perhaps on the starboard side. I also don’t like having the seacock hidden in a hard-to-access cupboard under the bed, though this location may have changed in newer SE models with engines under the beds.
We’re full-time liveaboards and usually anchored in remote, beautiful spots. Most of the time the saloon doors are open, and we don’t run the air conditioning. With ample solar, we rarely use the generator. Marinas are a different story—with insects, no breeze, and unlimited power, air conditioning becomes more relevant.
In summary:
Zone control would be a useful feature
Intake and output air should be in the same space
The raw water pump location could be improved
But we use the AC so infrequently that we haven’t bothered to modify the system.
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We have 3 units in total. I requested Webasto because i have had no problems with the brand on previous boats. I have upgraded the salon unit to 20k btu and the master or port side hull to 16k. The starboard unit, which o ly feeds the aft starboard cabin is 12k. I’m an A/C junky and on a 90F day the port side still run constantly and will cool down to about 75F. The salon unit will also run constantly and will cool to about 78F. If you run multiple units at the same time there is no problem keeping the boat cool. We are at the marina in Grenada and electricity is very expensive so we usually leave the A/C off during the day and just use it to cool down at night.
I have 3200 watts of solar and 40k W/hr of battery. We usually leave the port side on all night with plenty of juice the make it through the night.
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We are not big “AC” people - but in a marina it has been helpful - although we do tend to avoid marinas when we can.
We have three units 16000 BTU in the salon, 10000’s in each hull. Combined with sunshade blinds and a good fan it does keep the salon temperature down during the day.
It’s rare for us to run the a/c at anchor but the system runs with no issues. We tend to use it in de-humidify mode if we run at night.
The hull units are fine for overnight cooling use. To be honest we have probably used the guest hull unit more for keeping engineers cool when they do work than any other reason!
We opted for the Frigomar “inverter” technology units - but at 230v not 24v - I doubted the additional cost for 24v was justified and we have plenty of inverter capacity to run them. They are also lighter and I felt that Mastervolt/Victron would make a more efficient job of the power conversion than Frigomar.
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