Air Conditioning size for 1983 Mainship 34

Seriously considering installing AC on my boat. I know there are cheaper ways to get cool on these boats but I want to install marine AC. My question is what size? 16,000 BTU or is 12,000 enough? I also have only a 3.5kw genset, but I don’t think I would be running the AC with it.

I recently installed a 16000. No way I would different. This was in an 82 Mainship 1. I used a Wabasto FCF installed next to the fridge Very quite unit

I have 16000 btu. It's adequate. I wouldn't go with less on a new install. No problem with 3.5 kw generator if you manage load a bit.

On my 38 I put a 12k in the pilot house and a 6.5k in the two cabins below. System works fine. In full summer heat and sun it won't get it super cool, but good enough to be comfortable. Just needs to take the edge off the heat, and it does. At night when temps are super important for good sleep, the units just cycle on maybe 25% run duty cycle.

The 12k by itself and pump draws about 12.5A at 120v which is 1.5kW. A 16 would be about 2kW, your 3.5kW gennie should be able to handle that.

I'd go with a 12 or 16 for your boat, depending on how hot your cruising area is.

I have a NextGen 3.5 which runs a 12k btu a/c fine in my Mainship Pilot 34 and draws about 12 amps. I am sure it could start and run a 16k btu ok too.

For use in lower lattitudes in the summer definitely go with 16k btu.

David

Flagship Marine has a really good write up and formula for figuring out A/C size.

https://www.flagshipmarine.com/sizeboat.html

That formula will probably come up with more than 16,000 btu for the Mainship 34. But I wouldn't try to run more with a 3.5KW genset. And for a single unit of more than 16,000 btu you will probably have to go with a 240V unit which won't work with a single phase 120V genset supply.



David

AC units can be ordered with a "soft start" option , it would be best factory installed.

If you need Air Cond , you will need it underway , as well as dockside.

Thanks for all the very useful replies. I was leaning towards the 16,000 btu unit.
Chris K, did you install your unit where the waste receptacle is beside the fridge or did you install it in the cabinet on the port side in the saloon?