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geoleo 12-11-2017 21:43

Do RV rooftop Air Conditioners work well on boats?
 
Jut wondering if RV rooftop style Air Conditioners work OK on boats?

newhaul 12-11-2017 21:52

Re: Do RV rooftop Air Conditioners work well on boats?
 
That is essentially what the cruiseair carry on is.
https://www.google.com/url?sa=t&sour...-DboaSRrEeVuji

https://www.amazon.com/dp/B0002YGIZ0...l_8iwt9qctmy_e

valhalla360 12-11-2017 23:47

Re: Do RV rooftop Air Conditioners work well on boats?
 
If you have the open rooftop area, it can be a nice option.

Not such a great idea on sailboats as the boom and various lines can snag on it.

The other issue would be if you are frequently out in big water taking waves over the cabin top. Some occasional light splashing shouldn't be a big issue as long as you rinse it out with fresh water (they are designed to live outside in the rain) but full on submerged as a big wave goes over the cabin top could be problematic.

CaptTom 13-11-2017 05:23

Re: Do RV rooftop Air Conditioners work well on boats?
 
I'd be concerned about the effect of salt spay, and even salt air, on them. I've seen all kinds of automotive-grade things corrode badly in a very short time.

Otherwise, they should work fine. There are reasons for using raw water as a heat sink; it makes the unit smaller and easier to tuck out of the way on a boat, plus being able to duct the air to where you want it helps. Overhead units can be uncomfortable to sit under, and I've heard condensation can drip from them. In theory, using water as a heat sink can be more efficient, but probably not enough to sway anyone's decision.

Sailmonkey 13-11-2017 05:32

Re: Do RV rooftop Air Conditioners work well on boats?
 
They work well on boats used as condos, or on lakes. However for boats that are actually used in the salt....not so much. Look under the cover sometime, theyíre wide open electrically and mechanically. None of the materials are corrosion resistant when exposed to salt.

Yes they work in the rain and on RVís but this is a completely different enviroment

valhalla360 13-11-2017 05:37

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by CaptTom (Post 2517561)
I'd be concerned about the effect of salt spay, and even salt air, on them. I've seen all kinds of automotive-grade things corrode badly in a very short time.

Otherwise, they should work fine. There are reasons for using raw water as a heat sink; it makes the unit smaller and easier to tuck out of the way on a boat, plus being able to duct the air to where you want it helps. Overhead units can be uncomfortable to sit under, and I've heard condensation can drip from them. In theory, using water as a heat sink can be more efficient, but probably not enough to sway anyone's decision.

RV's park on beach campsites all the time, so a little salt spray shouldn't be a big deal. Worst case give it a fresh water rinse occasionally. Full dousing with a wave crashing over the top though may be pushing your luck.

Getting rid of the thru-hull and associated plumbing is more than worth any hassle and at less than half the price, even if they don't last quite as long, you may still come out ahead replacing it every 10-15yrs.

If condensation is dripping inside the living space, there is something wrong with the unit or the installation.

Again, the big challenge is finding a location to install it.

SailFastTri 13-11-2017 05:49

Re: Do RV rooftop Air Conditioners work well on boats?
 
The only advantage is price. Water heat exchange is MUCH more efficient, and all the other negatives of an RV unit have already been mentioned. I also think it would devalue your boat (and junk up the look) if you installed an RV unit. (Just add a blue tarp cockpit tent to complete "the look").

newhaul 13-11-2017 07:52

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by SailFastTri (Post 2517569)
The only advantage is price. Water heat exchange is MUCH more efficient, and all the other negatives of an RV unit have already been mentioned. I also think it would devalue your boat (and junk up the look) if you installed an RV unit. (Just add a blue tarp cockpit tent to complete "the look").

hey now I use silver tarps as my dodger fabric. And white for boom tent.

SailFastTri 13-11-2017 08:00

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by newhaul (Post 2517614)
hey now I use silver tarps as my dodger fabric. And white for boom tent.

Hey, some people like the trashy look. Worn and torn jeans are fashionable, why not silver tarps? :whistling:

zeehag 13-11-2017 08:01

Re: Do RV rooftop Air Conditioners work well on boats?
 
considering folks remove em to sail and reinstall em to sit at a dock in hurricane season, they seem to work nicely. they are made for the job, as opposed to a small window unit, and hold up better than window units.
keel cooled air cond units fail here in 85 f water, ours is to 100f in summer, when air is needed, with high humidity.
when you are repairing your boat in 100f air with 9900000 percent humidity, what will you do. your keel cooled air wont work, as the water under your keel is 100f, and you are not going to be able to effect many repairs without something. if an overhead hatch mount air is available, it is better than the alternative,. not permanent and is stowable.
oh yeah. the rigging of your boat does NOT interfere with the function and placement of the unit. i have seen more sizeable items sitting on top of folks's boats without incident... dinghies etc. and how is a stowed unit going to interfere with sailing.
so what are your real issues with this mode of cooling a hot boat???


oh. my silver tarps are green, and i use screens as tarps as well.... without shade, one dies in this almost tropical sunshine. gets warm and bakes you. tarps make a HUGE difference. about 10 f cooler under the tarps here. other boats --even snotty yotties use silver tarps here.
in a sea of silver tarps, green is a statement. you kids need something real to gripe and whine about

so much pure judgemental ism... good luck in real life with real issues.

newhaul 13-11-2017 08:02

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by SailFastTri (Post 2517620)
Hey, some people like the trashy look. Worn and torn jeans are fashionable, why not silver tarps? :whistling:

it actually looks good. :biggrin:

SailFastTri 13-11-2017 08:04

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by zeehag (Post 2517622)
considering folks remove em to sail and reinstall em to sit at a dock in hurricane season, they seem to work nicely. they are made for the job, as opposed to a small window unit, and hold up better than window units.
keel cooled air cond units fail here in 85 f water, ours is to 100f in summer, when air is needed, with high humidity.
when you are repairing your boat in 100f air with 9900000 percent humidity, what will you do. your keel cooled air wont work, as the water under your keel is 100f, and you are not going to be able to effect many repairs without something. if an overhead hatch mount air is available, it is better than the alternative,. not permanent and is stowable.
oh yeah. the rigging of your boat does NOT interfere with the function and placement of the unit. i have seen more sizeable items sitting on top of folks's boats without incident... dinghies etc. and how is a stowed unit going to interfere with sailing.
so what are your real issues with this mode of cooling a hot boat???

Ha! zeehag, where do you have 100f water? Are you docking over a hot spring?

rwidman 13-11-2017 08:08

Re: Do RV rooftop Air Conditioners work well on boats?
 
While an RV roof top AC would "work" on a boat, simple observation of boats should tell you that most people opt for the traditional marine AC using sea water as the cooling medium rather than air. When you go shopping for a new boat and specify air conditioning, the manufacturer will use a marine unit, not a rooftop unit.

My point is, many people before you have come to the conclusion that the water cooled units give better performance than the air cooled RV units. If you have a reason to use the RV unit, fine but don't use it because you think it will be better in any way.

valhalla360 14-11-2017 04:27

Re: Do RV rooftop Air Conditioners work well on boats?
 
I think we need to clarify: You are talking about the CruiseAir carry on Units that fit in an existing hatch. We had one of those way back. It was better than nothing but not by a lot. Because it didn't seal around the hatch very well, a lot of the cooling was lost and it was only 5000btu to start (I think the new ones are 7000btu). It also had to be stowed and reinstalled every time the boat was taken out.

This thread is about a permanently mounted RV unit presumably mounted on a hard top above the salon. There are typically 15000btu, so they put out a lot more cold air. These will conflict with the boom and lines.

The guts are essentially the same and again as long as they aren't submerged by breaking waves, they should hold up fine (hence putting them on the hard top). On a later boat we had a water cooled Marine Unit that had corrosion problems, so don't count on them being a lot better made.

As far as the water temperature making a difference on traditional marine units, that is absolutely correct. There was a very noticeable difference in cooling power between the great lakes where at the peak of summer, the water might get up to the low 70's vs S. Carolina with 90+ degree water.

I can't find it but I know there was a trawler brand that offered them and they looked fine.

I suspect you don't see more because of some of the unsubstantiated ideas you are seeing on this thread.

Quote:

Originally Posted by zeehag (Post 2517622)
considering folks remove em to sail and reinstall em to sit at a dock in hurricane season, they seem to work nicely. they are made for the job, as opposed to a small window unit, and hold up better than window units.
keel cooled air cond units fail here in 85 f water, ours is to 100f in summer, when air is needed, with high humidity.
when you are repairing your boat in 100f air with 9900000 percent humidity, what will you do. your keel cooled air wont work, as the water under your keel is 100f, and you are not going to be able to effect many repairs without something. if an overhead hatch mount air is available, it is better than the alternative,. not permanent and is stowable.
oh yeah. the rigging of your boat does NOT interfere with the function and placement of the unit. i have seen more sizeable items sitting on top of folks's boats without incident... dinghies etc. and how is a stowed unit going to interfere with sailing.
so what are your real issues with this mode of cooling a hot boat???


smj 14-11-2017 05:20

Re: Do RV rooftop Air Conditioners work well on boats?
 
Yes they absolutely work. We had a single RV rooftop 15 or 16,000 btu on our old 36' catamaran and you could hang meat in there on a hot humid Galveston summer day. The 16,000 btu marine unit wouldn't even remove the humidity.
A friend had his RV unit permanently installed on his 33' monohull which he routinely raced across the Gulf Of Mexico and he never had any problems with salt water intrusion.
But they can look a little funky......

a64pilot 14-11-2017 10:08

Do RV rooftop Air Conditioners work well on boats?
 
I see a whole lot of commercial boats with them, shrimp boats, tugs etc.
They work fine for a few years, everything wears out, but these are a lot cheaper to replace.
They do drip water continuously of course, the condensate has to go somewhere.

Sailmonkey 14-11-2017 11:51

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by a64pilot (Post 2518267)
I see a whole lot of commercial boats with them, shrimp boats, tugs etc.
They work fine for a few years, everything wears out, but these are a lot cheaper to replace.
They do drip water continuously of course, the condensate has to go somewhere.

As well as the accompanying rust stains.

Colin A 14-11-2017 11:54

Re: Do RV rooftop Air Conditioners work well on boats?
 
They actually make marine versions common on a lot of small workboats. Local contractor with a tug had one. Coleman marketed them under Sea Mach and Marine Mach. They seem to work well.

https://www.airxcel.com/coleman-mach...ne/marine-mach

Group9 14-11-2017 12:01

Re: Do RV rooftop Air Conditioners work well on boats?
 
I notice a lot of the commercial boats, and our state marine police, using them on their enclosed boats down here.

smj 14-11-2017 12:18

Re: Do RV rooftop Air Conditioners work well on boats?
 
Domestic also makes a marine model.
https://www.dometic.com/en-us/us/pro...0-btuh-_-20696

rwidman 14-11-2017 12:43

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by smj (Post 2518129)
Yes they absolutely work. We had a single RV rooftop 15 or 16,000 btu on our old 36' catamaran and you could hang meat in there on a hot humid Galveston summer day. The 16,000 btu marine unit wouldn't even remove the humidity. ......

A BTU is a BTU. You had some other issues or you're making a bad comparison.

smj 14-11-2017 12:48

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by rwidman (Post 2518350)
A BTU is a BTU. You had some other issues or you're making a bad comparison.



We have gone through this before. Once the water reaches a certain temperature the water cooled units aren't very efficient. Water temps in the 90's? Forget about it.

a64pilot 14-11-2017 18:38

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by smj (Post 2518354)
We have gone through this before. Once the water reaches a certain temperature the water cooled units aren't very efficient. Water temps in the 90's? Forget about it.



I agree with what your saying on principle, however both my ACís output air in in the 50ís with internal Boat temp in the high 80ís or 90ís. And water temp in the 90ís. A 40 degree drop is about all you can hope for.
Iíd suspect that maybe your water flow is lower than optimum.

However aircooled airconditioners can work just as well as water cooled ones or better, if properly designed.
Iím sure the regular Marine AC is water cooled more because it is easier, and there is a inexhaustible supply of water available, not because water cooling is more efficient or better, cause it isnít.

smj 14-11-2017 18:52

Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by a64pilot (Post 2518558)
I agree with what your saying on principle, however both my ACís output air in in the 50ís with internal Boat temp in the high 80ís or 90ís. And water temp in the 90ís. A 40 degree drop is about all you can hope for.
Iíd suspect that maybe your water flow is lower than optimum.

However aircooled airconditioners can work just as well as water cooled ones or better, if properly designed.
Iím sure the regular Marine AC is water cooled more because it is easier, and there is a inexhaustible supply of water available, not because water cooling is more efficient or better, cause it isnít.



My opinion wasn't taken from experience with one unit on one boat but quite a few different units in different boats. I found I could get a 8000 btu window unit to produce as much cooling as a 16000 btu marine ac in the dead of summer. And the RV rooftop ac was far superior to anything we had owned. This includes over 18 years full time liveaboard on 5 different catamarans. From what I've read, the cooling of the reverse cycle ac starts to lose efficiency when the waters reach 85 degrees, and the heating when the waters reach 45-50 degrees. The water temperature in the summer time where we kept our boat would reach the mid 90, and in those water temperatures the air cooled ac's were far superior in my opinion. One must stick to and enjoy what they find to be the best option for them!

newhaul 14-11-2017 19:32

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by a64pilot (Post 2518558)
I agree with what your saying on principle, however both my ACís output air in in the 50ís with internal Boat temp in the high 80ís or 90ís. And water temp in the 90ís. A 40 degree drop is about all you can hope for.
Iíd suspect that maybe your water flow is lower than optimum.

However aircooled airconditioners can work just as well as water cooled ones or better, if properly designed.
Iím sure the regular Marine AC is water cooled more because it is easier, and there is a inexhaustible supply of water available, not because water cooling is more efficient or better, cause it isnít.

a little advantage for air cooled units . The good ones doing the condensate into the condenser coils to assist with the air cooling .

a64pilot 14-11-2017 19:55

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by newhaul (Post 2518584)
a little advantage for air cooled units . The good ones doing the condensate into the condenser coils to assist with the air cooling .



Even the cheap box store window units usually have a slinger ring on the condenser fans that slings the water around and of course through the condenser.

a64pilot 14-11-2017 19:58

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by smj (Post 2518565)
My opinion wasn't taken from experience with one unit on one boat but quite a few different units in different boats. I found I could get a 8000 btu window unit to produce as much cooling as a 16000 btu marine ac in the dead of summer. And the RV rooftop ac was far superior to anything we had owned. This includes over 18 years full time liveaboard on 5 different catamarans. From what I've read, the cooling of the reverse cycle ac starts to lose efficiency when the waters reach 85 degrees, and the heating when the waters reach 45-50 degrees. The water temperature in the summer time where we kept our boat would reach the mid 90, and in those water temperatures the air cooled ac's were far superior in my opinion. One must stick to and enjoy what they find to be the best option for them!



Your right at the correct numbers where the water cooled and or heated units lose efficiency, however excessive water flow will to some extent help make up for it, of course there is a point where it wonít. I doubt I have ever been in mid 90 temp water, maybe thatís it.
Mine worked fine in Key West in July and August last year, not sure of the water temp then.

smj 14-11-2017 20:14

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by a64pilot (Post 2518593)
Your right at the correct numbers where the water cooled and or heated units lose efficiency, however excessive water flow will to some extent help make up for it, of course there is a point where it wonít. I doubt I have ever been in mid 90 temp water, maybe thatís it.
Mine worked fine in Key West in July and August last year, not sure of the water temp then.



How many units and what btu are they? The Keys can be hot that time of year!
We were in Pine Island Florida this past October with highs in the upper 80's to low 90's. First time we have run AC on this 38' cat, but a 8000 BTU window unit kept us comfortable during the day and under a comforter at night. I was happy and impressed! We are now in the Keys and doing well with an open hatch and breeze, much my preference [emoji1303]

Idylles15.5 14-11-2017 20:20

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by Colin A (Post 2518320)
They actually make marine versions common on a lot of small workboats. Local contractor with a tug had one. Coleman marketed them under Sea Mach and Marine Mach. They seem to work well.

https://www.airxcel.com/coleman-mach...ne/marine-mach

I had one of the marine grade Coleman units on my 15.5 idylle. I made a fiberglass cover to fit right over the lexan cabin house sun lens, etc. All of the parts of the motor were made of stainless or powder coated. It was reverse cycle too, but couldn't heat up my saloon when it was really cold. As for the a/c. Holy crap it was freezing in the whole boat. As someone else mentioned I could of hung meat in there. I had to turn it down constantly. It's only about 10 inches high off the deck. I had no problem with lines, and I don't think anyone's boom sits right off the deck. I actually still have the unit and if anyone wants it, its for sale. I only used it one season. I made a butterfly hatch and installed that in it's place.

a64pilot 14-11-2017 20:35

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by smj (Post 2518601)
How many units and what btu are they? The Keys can be hot that time of year!
[emoji1303]


One Webasto 16K and a Webasto 6K

valhalla360 14-11-2017 23:22

Re: Do RV rooftop Air Conditioners work well on boats?
 
Quote:

Originally Posted by rwidman (Post 2518350)
A BTU is a BTU. You had some other issues or you're making a bad comparison.

A BTU is a BTU but....

The rating on the unit assume a standard set of conditions which includes the water temp for a marine unit.

The warmer the water the fewer the BTU.

And yes, water temps in the 90's are not uncommon and will impact output.


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