A/C for Venture 23.

KevinMc · Posted: Mon Jun 16, 2025 3:14 pm Post subject: A/C for Venture 23.

Ahoy there! Thinking about a roof top A/C for my 23.Any thoughts and ideas,warnings would be appreciated.I have looked into the cooling loads for buildings but would trust a fellow C.Dory sailor who might have cracked this nut. Thanks Kevin Mc. south Florida.Gulf coast.

thataway · Posted: Mon Jun 16, 2025 10:13 pm Post subject:

Please see my album for what we did with our Tom Cat. Most folks do not go to that extreme. I would at least build up the area around the cutout so it will be level, and not distort the cabin top when the AC sits on it.

I do not know about your 23, but some Cdorys have a core in the center and some do not. One of the main features of a "dry" air conditioner, is to allow the boat to be a fully functional "boater home" on the high way and stay in camp grounds.

Coleman still makes a 9200 BTU RV roof top Air Conditioner. I feel this is a better size than a 13,500 unit, which is larger, uses more power and is marginal without soft start to run off a 2000 watt Honda. The 9200, especially with "Easy Start" added will run off a Honda EU 1000, although I prefer the Honda 2200 for a number of reasons. The Army Corps of Engineers use these types of air conditioners on their small boats.

Below photo is in the process of building up the top where there will be a perfect seal, with no distortion of the cabin top. This is a cored center of the top--it is even more important in a non cored top.

BigSwede · Posted: Mon Jun 16, 2025 10:58 pm Post subject:

My 23 Venture has a roof AC, but the boat is new to me so I know nothing about the install process.

KevinMc · Posted: Sat Jun 21, 2025 1:06 pm Post subject: A/C for Venture 23.

Big Swede,Can you tell me the make and model number of your unit I would like to research your unit,Have you had any experience with it.Does it cool the whole boat? any info would help.Thanks KevinMc.

RDiemidio · Posted: Sat Jun 21, 2025 8:51 pm Post subject: Ac for a 23 Venture

I am very interested in a A C for a C Dory. The technology is starting to catch up to roof top Rci units . I know Dometic makes a commercial unit. I am looking for a virable compressor unit that can withstand a saltwater environment. I use a 5000 btu unit that I slide in the from window. Pain in the butt to remove and install.

KevinMc · Posted: Sun Jun 22, 2025 12:30 pm Post subject: A/C for Venture 23.

I agree, technology is moving forward,especially in battery capacity and compressor efficiency.I am looking at installing a 12V DC roof unit in my 23 Venture,with AC/DC inverter for pedestal use and battery use on the water overnight.One of the units I am considering (not recommending at this point)Is the Countrymod.Inverter 12V-DC 10K Rooftop unit.Has anyone in Doryland considered this or a similar unit for their AC needs? I would welcome any constructive input pro/con.P.S Shout out to Captain Bob for his installation instructions,well appreciated.Thanks KevinMc.

thataway · Posted: Sun Jun 22, 2025 1:56 pm Post subject: Re: A/C for Venture 23.

thataway · Posted: Sun Jun 22, 2025 11:07 pm Post subject: Re: A/C for Venture 23.

double post

RDiemidio · Posted: Mon Jun 23, 2025 10:59 am Post subject: A C for 23 Venture

I would prefer to have a 120 volt A C unit. When anchor, we would just run a inverter generator.

KevinMc · Posted: Mon Jun 23, 2025 11:03 am Post subject: A/C for Venture 23.

Thanks Bob,I have installed 3x100amp LiPo batteries and roof top rigid panels which charges at 13.5 volts.I will have to do more research!I am confused about auto switching and how to integrate 120V A/C shore power.I was considering a panel switch and two separate circuits.,What are your thoughts can you recommend a guidebook? and as always,safety,safety,safety.

WCF · Posted: Mon Jun 23, 2025 6:49 pm Post subject:

The term is "transfer switch."

Most inverter chargers (and many standard inverters) have a transfer switch built in. This switches back and forth from shore power as it is available. Some offer configurable amp draw from shore power to ensure you do not overload a small generator or sketchy shore power. The shore power and inverter power can work together to power larger loads (Like AC.)

I just installed traditional marine AC in my 25. An energy efficient 6,000 BTU reverse cycle unit with integrated/factory soft start. I run it off the new 1200W Victron 120V Multiplus inverter/charger with a 12V 460Ah LiFEPO 4 bank. It will run the AC off grid overnight at full blast continuous.

Strongly suggest looking into getting a unit with soft start (or modifying whatever you buy;) it will pay dividends in smaller inverter size, smaller wire sizes, etc.

thataway · Posted: Tue Jun 24, 2025 12:48 pm Post subject:

The Victron Multiplus inverter / charger Booster has a built in transfer switch-easy to wire in. Take those circuits you want to run off the inverter, directly to the 110 V inlet of the inverter, and then back to their respective circuit breakers for control of the circuits--for example, you do not want/to run water heater or a battery charger off the inverter, but you have outlets which run the microwave, an induction burner, or Air Conditioner which you want to wire to the inverter. The Multiplus 3000 has either a 80 amp or 120 amp battery charger, and 50 amp "boost" as well described by "WCF". The Multiplus 1200/50/16 is a bargain at less than $500--half of the 3000. It charges batteries at up to 50 amps, an boosts current at up to 16 amps. For my uses it was a little small, and perhaps I could have gotten away with the Multiplus 2000. But remember you want the "cruising" draw to be what is your max. 3000, is 2400 practical and continous watts.

Here is a great guide and graphic for the various multiplus units.

I stick with Victron with the hardware, they integrate well. I go with other batteres because they are considerably cheaper. But if the budget is "unlimited" then go with the Victron batteries, and there are some advantages. Victron 12 V 200 amp battery is $1665 vs Renology for the same battery specs at $564. Even less for the "Dumfume" at $288! This battery gets good reviews from Will Prowse (I encourage anyone considering upgrading view a number of the Will Prowse videos. He does excellent tests.
. Here is a iink to the video on the 100 amp hour battery.

These are less than AGM batteries! Longivity unknown on a boat. But heck-It seems a no brainer.

I use Victron remote controls and monitor displays--so the can be read or programed from the Galley area.

WCF · Posted: Tue Jun 24, 2025 1:59 pm Post subject:

Appreciate the clarification of my poor description; the transfer switch is one function, the boost feature (Victron terminology) is another.

I tried the Multiplus 2000/80 for one season on our 25. As soon as I was able I traded it for the new Multiplus 1200/50. This was based on my experience with the Multiplus 500/20 on my 22.

The size and weight of the Multiplus 2000 (with supporting wire, fuses, etc.) wasn't for me on a 25.

My max continuous total AC draw is under 1200W (Air conditioning at Max is 800w.) If I ever need more, I will take a hybrid approach with the generator.

Just offering my strategy and experience, it may not be for everyone, and it may not even be relevant for KevinMc's plans Smile