# Air Conditioning - RV Roof vs Carry-On



## jamesnewsome (Jul 30, 2000)

Sailboats without built-in HVAC face a real challenge when summer arrives. I've used a traditional CARRY-ON brand 5k BTU unit set over a forward hatch for years, but the results I would describe as barely acceptable.

Frankly, I think the CARRY-ON units/brands are rip-offs. The company just happens to have a good cabinet design that a mostly standard small air conditioning unit is adapted to fit in. I pull mine apart each off season and clean it, and cannot see that there's anything especially "marine" about the construction of the actual AC unit.

Some fellow sailboat owners and I are discussing the possibility of just using a RV ceiling type air conditioning unit and are wondering if anyone else has tried this. A 13.5k BTU unit can be purchased for around $600 and can easily be fitted over a hatch as small as 14"x14."

I look forward to hearing the feedback.


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## PBzeer (Nov 11, 2002)

I've never seen rooftop units on anything but houseboats. If you just want it for dockside use, most of what I've seen has been window type units with their own hatchboard, set in the companionway. When they leave the dock, they either stow it on the boat, or put it in their car.

I even saw a sailboat in FL with a hard bimini that had a ceiling fan on it.


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## lans0012 (Jul 16, 2008)

*Here in FL*

It's not uncommon to see the rv style units on boats in the marina. I've never seen one out sailing though with one of those things on it.

A lot of people who don't want the expense or have the space to fit internal AC use a standard big box store ac unit built into the companionway hatch boards. Here's a picture of mine. It's 5k BTU and plenty for my 27 footer on the hottest days and nights. When we're out sailing I just stick it on the v berth. This setup will cost you about 130 with tax and materials assuming you buy the ac unit new. I just cut it into 1/2" plywood board and use some angled brakets drilled right into the shell of the ac unit. Use the spray foam to fill the gaps and you are good to go.


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## JimMcGee (Jun 23, 2005)

jamesnewsome said:


> Some fellow sailboat owners and I are discussing the possibility of just using a RV ceiling type air conditioning unit and are wondering if anyone else has tried this. A 13.5k BTU unit can be purchased for around $600 and can easily be fitted over a hatch as small as 14"x14."
> 
> I look forward to hearing the feedback.


James, I don't think it's a practical solution. I had a 5K carry-on for a couple of seasons and finally bit the bullet and installed AC on our boat.

The 5K carry-ons are 68lbs. They're a pain in the ass to get on board if you keep it in a dock box. That step from the dock over the life lines is VERY awkward with that much weight in your arms. When I kept it on-board it was a ***** to feed up through the forward hatch (at least on our boat) and I managed to twist my back more than once doing the contortions.

I checked the RV units on one of the RV web sites and the 13.5K units are 117lbs! The site didn't have dimensions (only height) but I guessing from the photo you couldn't feed it up through the hatch. Imagine carrying 117lbs up through the cockpit, then forward over lines and along narrow side decks on a day when it's hot enough to need AC. Remember it's an awkward carry. It's not like a 70-80lb bundle of shingles you can just throw over your shoulder.



PBzeer said:


> I've never seen rooftop units on anything but houseboats.


I think that's why...


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## lans0012 (Jul 16, 2008)

*carry on*

I also have a carry on unit that came with the boat. I've actually never used it because it takes up so much space. The 5k BTU window units are a lot lighter. I would say <40lbs including the plywood it's attached to. It also is easy enough to store. It's a pain sometimes to step over it, but the trade off is $s. Built in AC Wouldn't be practical for my boat. If I had a larger boat, I think i might spring for it though. from what I hear, they can be very costly to purchase, install and maintain.

The window unit is built to be half indoors and half outdoors, so like the rv unit it is already "marinized." I can just imagine taking a wave over the boat and have that thing torn from the deck and washed overboard. Although, I have seen the RV units on several sailboats in Tampa Bay, however none actually sailing. Most of the boats just sit at the dock all year. Every now and then someone comes and grills a burger on it and that is about it.


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## chef2sail (Nov 27, 2007)

We have used the carry on unit for 7 years with no problems. Whenb sailing it sits on a towle wedged under the filler for the V berth which is inserted. never moves.

When we dock we use the spinaker halyard to winch it up through the forward hatch over the V berth and place it on top of that. No issues. It can be a comical sight when we pull into a marina when we travel as it is part of our post docking routine and we have seen people staring at us as this "beast' emerges getting winched up through the hatch. It works fine and takes the humidity out of the boat..and cools it in the dead of a Chesapeake summer. Takes us 54 minutes. I would rather have built in AC but this works fine.

Dave


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## JimMcGee (Jun 23, 2005)

chef2sail said:


> When we dock we use the spinaker halyard to winch it up through the forward hatch over the V berth


Good idea...


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## MARC2012 (Mar 17, 2008)

I had the rv type on two trawlers & worked great but on a saiboat think would be VERY much in the way.Had a cruiseair,hated it with a passion,heave,difficult to stow.Kept it in the aft cabin and no matter what i needed it was in the locker under it.Had one regular marine reverse cycle marine unit,forever changing pumps.Now have a lowes win. worked fine 2 yrs & still going.marc


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## jamesnewsome (Jul 30, 2000)

I agree that the best option is a built-in unit, but it's also the most expensive and sometimes not possible on smaller boats. I don't think the RV ceiling unit is realistic for use over a forward hatch because (as suggested) it's too bulky. I did check the weight on the Coleman Mach 3 - 13.5k BTU and it weighs in at 108 pounds.

To me the main issue is how much time is going to be spent on the boat and if it's considerable then creature comfort outweighs some of the drawbacks. My objective is finding the most efficient & practical cooling system for the fewest dollars. I really like the idea of an inexpensive residential type unit modified to fit in some opening and I have seen several boats with the units in the main companionway. Not sure I can deal with the restricted access to the cabin.

I do think the RV ceiling unit would work well on a larger boat with a center hatch (under the boom) over the main cabin and may not be in the way when sailing. I've seen folks with a dingy strapped down sailing and these roof-top units are far smaller.

Unfortunately, my boat only has a small 16"x16" hatch over the v-berth.


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## chef2sail (Nov 27, 2007)

Our cruise air portable will fit your 16X16 hatch I beleive. You just have to stow it under your filler at the V and make sure it doesnt bang aorund. It is a nice thing to have when in the marina on the Chessie in July when at night it is brutally hot and humid with no air vs anchorage. Using the halyard and set up takes 5 minutes. They are way more expensive now, but there are used ones to be had. e bought ours new 7 years ago for 500 dollars.

Dave


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## Sailormon6 (May 9, 2002)

You can maximize the cooling power of your air conditioner by putting insulated covers over all the portlights and hatches, and putting up a boom tent to shade the coach roof. I used a small casement AC unit in the hatch to cool my boat for several years, and it was adequate until the temps got into the 90s. When the hot mid-day sun is streaming through numerous portlights and hatches and radiating through the coach roof, it heats the interior of the boat faster than the AC unit can cool it. My boat now has central AC, and even it needs help when it gets that hot. It also helps to close doors to the v-berth and head during the day, so you aren't cooling areas that you aren't using. Those areas can be cooled more easily after the sun goes down.

I recently came across this idea on Sailrite for insulated covers: Make Your Own Snap on Window Curtain Panels for Summer - YouTube


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## ftldiver (Sep 9, 2002)

No one considers the 'rollable' portable units that only need the exhaust to go out?

they are more bulky, but go up to 14k btu... and don't block the companion way.

strap it to something, and its pretty good.

cruise air= fail and stupid money.

example: 
SoleusAir® 14,000 BTU Portable Air Conditioner/Heat Pump/Dehumidifier | Staples®


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## JoeDiver (Feb 2, 2011)

I guess it depends on your boat....there's a guy in my old marina with a C25 like mine, and he installed one of those stand alone units. He wedged it back by the quarter-berth and starboard settee, but it still takes quite a bit of room. He led the drain hose to the bilge and cut a hole in the starboard bulkhead to the cockpit for the exhaust hose.

It works okay, keep the boat cool for his "woman", so he says....but it was tricky getting it to exhaust just right and on humid days it dumps alot of water into the bilge....plus, it uses half it's energy just fighting the heat the unit itself throws off.

I saw it in action....sat down there in the cabin and yes, it works....but from all the solutions I've seen, for my boat personally, the little $99 Walmart window unit in the bottom of the companionway is the way to go.


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## CaptainForce (Jan 1, 2006)

On a former boat without a built in unit I cut a hole in the end of my quarter berth bulkhead that held a window unit that exhausted into my lazarette. This would not have functioned well, but I mounted a window fan in a horizontal position just under the outside portion of the AC unit in the lazarette that blew the exhaust air straight out the opened seat locker. This worked extremely well and for sailing all I needed to do was turn off the unit and close the seat locker. Take care and joy, Aythya crew


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## chef2sail (Nov 27, 2007)

So where does the heat produced by the compressors of the free standing units go. It is radiated in the boat. Very inefficient to have the unit cooling and heating the air at the same time. Bad design for a boat.

Dave


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## wingNwing (Apr 28, 2008)

The boatyards in Trinidad have created a way to provide A/C when your boat's on the hard. They use a standard window-type air conditioner, mounted in a plywood frame so that the unit sits on your foredeck. You open the forward hatch and mate the front half of the air conditioner to your hatch using a canvas tent-like cover they provide, that will direct the cold air down the forward hatch. Nice racket - they rent you the unit for $20/month (which everyone willingly pays) I imagine the same setup would work on a boat in the water. For a bit of carpentry, you could have the cost savings of a cheap window unit without blocking the companionway.


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## jamesnewsome (Jul 30, 2000)

Sailormon6 said:


> You can maximize the cooling power of your air conditioner by putting insulated covers over all the portlights and hatches, and putting up a boom tent to shade the coach roof. I used a small casement AC unit in the hatch to cool my boat for several years, and it was adequate until the temps got into the 90s. When the hot mid-day sun is streaming through numerous portlights and hatches and radiating through the coach roof, it heats the interior of the boat faster than the AC unit can cool it. My boat now has central AC, and even it needs help when it gets that hot. It also helps to close doors to the v-berth and head during the day, so you aren't cooling areas that you aren't using. Those areas can be cooled more easily after the sun goes down.
> 
> I recently came across this idea on Sailrite for insulated covers: Make Your Own Snap on Window Curtain Panels for Summer - YouTube


Great idea on the Sailrite insulated covers. Thanks for the video link!


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## ftldiver (Sep 9, 2002)

chef2sail said:


> So where does the heat produced by the compressors of the free standing units go. It is radiated in the boat. Very inefficient to have the unit cooling and heating the air at the same time. Bad design for a boat.
> 
> Dave


The better stand up portable a/c units, evaporate the water in the hot air exhaust. no water in the bilge unless there is a problem. only need to vent the hot air, and it should fit in an opening port. (replace the plastic hose with a/c duct for better efficiency ). the cost more than a window unit, and take up space, but also offer more btu's.

this what I have for hurricanes on land. works very well... in the august in so fla... can't get more hot and humid.

Look at the images... 
http://www.amazon.com/NewAir-AC1200...Q8YQ/ref=sr_1_6?ie=UTF8&qid=1328972324&sr=8-6

^ this not the unit I own... just an example...


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## TakeFive (Oct 22, 2009)

ftldiver said:


> The better stand up portable a/c units, evaporate the water in the hot air exhaust. no water in the bilge unless there is a problem. only need to vent the hot air, and it should fit in an opening port...


These units have a fatal flaw that makes them very inefficient. You can't exhaust air without a source of makeup air coming in. So they either pull hot air from the outside through every crack you have in your boat, or if your boat is sealed too well, they don't exhaust effectively and the heat from the unit offsets most/off of the cooling. They are a very poor design.


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## ftldiver (Sep 9, 2002)

I'm surprised to hear that... but not going to argue.

They work very well cooling 1 room in my house, far better than the 5000btu window unit I also have. And I have read other boat owners using them just fine. 
if you have the room to mount it..

yes you have forced air going out, but I never noticed any vacuum from doors. but I guess you would have low pressure in the cabin.

all I know is, it cools a 12x15 room from 95 to 76 in 2-3 hours. in august in miami. the window unit doesn't get below 78 in 5 hours...

I use the window unit on my 26' but would use the stand up unit if I had more room to store it.

anyway, I'm happy with mine.

cheers!

I believe this is the unit I own. 12k btu actually.
not sure why it work in a house better than a boat... read the reviews at the bottom

http://www.google.com/products/cata...le+Air+Conditioner&cid=17200259040946673571#p

I ran a search here, and see you had the same opinion last year. joediver, and this guy have 1st hand experience..

http://www.sailnet.com/forums/hersailnet/66652-air-conditioning-28ft-oday.html#post624660

I also have been on boats w/ the the cruise air... just too small at 5000btu, for a decent size boat. imho. and damn heavy/ bulky. These are more boxy, and could be moved about easier if some creative straps were applied. but not light by any means.

YMMV!


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## TakeFive (Oct 22, 2009)

ftldiver said:


> ...They work very well cooling 1 room in my house...yes you have forced air going out, but I never noticed any vacuum from doors. but I guess you would have low pressure in the cabin....not sure why it work in a house better than a boat...


Your cabin pressure will go down until it is low enough to pull in the same amount of air as the AC exhausts. But your cabin pressure will not keep going down - it will always reach a point where the inlet air equals the exhaust air. Otherwise, your cabin would eventually implode (or the exhaust would stop). 

The reason an upright works better for a room in a house has to do with the air that leaks into the room. It probably comes from another room (or a return duct that often goes down to the cool basement), which is likely to be less hot than the air surrounding your sun-drenched boat. It may work much better at night, when the sun isn't shining on the boat.

A particular boat owner's satisfaction with the unit has a lot to do with his expectations and his actual configuration. If someone is sitting right in front of it and it's blowing the cool air directly over him, and the hot outside air is coming in somewhere away from where he's sitting, then it will probably be comfortable.

I don't mean to say that this is totally unacceptable for anyone. In fact, I could imagine myself giving it a try someday if I move my boat far enough away that I need to sleep over a lot. But I will go into it with my eyes open, and configure it to minimize the length of the exhaust run (so the heat can radiate out as well as convect out).


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## ftldiver (Sep 9, 2002)

your theory makes sense, but just try it and check back in...

-they wouldn't sell, if they didn't work...


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## LauderBoy (Mar 15, 2010)

I also have a 5k cruise air and while the mounting and hauling it on/off the boat isn't bad, it doesn't do much for my 32ft boat. It does a great job cooling the v-berth it sits over(although I have to find ways to keep it from dripping on me), which is a blessing for sleeping at night in Florida. But it doesn't output enough to manage the other cabins even if I circulate the air with fans. 

Last summer was brutal and I'm not looking forward to this summer. I hate the idea of burning up space for a cooling system I won't use while cruising, but I may have to break down and have an internal system installed.

On the flip side, a little portable heater has worked great for getting me through the winters in Florida. No complaints there.


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## CapnBilll (Sep 9, 2006)

The A/C in the lazerate is the best idea I've heard of yet, I'll have to try it.


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## jamesnewsome (Jul 30, 2000)

At LauderBoy - Your situation is why I think the RV overhead AC unit will work so well for folks whose top priority is comfort rather than convenience of removal for sailing. The units are designed to cool tents with less cubic feet of space than most sailboats and they do a great job, and they aren't that heavy - 110 pounds.

I've used the portable "Carry-On" brand for years and it is barely adequate at 5k BTU, and yes it is notorious for dripping. I've disassembled the unit, cleaned out and sealed the drain system (which will clog up) and there is still condensation that is going to drip. I've even insulated areas with 1/2" aluminum coated Styrofoam and it still drips.

West Marine only wants $1,400 for a 6,720 BTU Carry-On unit. I'd certainly install a built-in unit before spending that much money.

The Coleman 13.5k BTU RV roof top unit can be purchased for $509, and a Duo-Therm 13.5 BTU unit for $465 at COLEMAN 13500 btu RV AIR CONDITIONER with CEILING ASSEMBLY - $509.. Duo-Therm apparently was the 1st rooftop RV AC manufacturer. I just cannot see why this isn't the most reasonable option for "comfort."

I'm also considering fabricating a shroud which will fit over my forward hatch and accommodate a standard inexpensive window unit. No question that for the cost you can't 
beat this option. I just don't like the idea of a unit blocking the main companionway entrance onto the boat. I've seen several folks do this and it certainly works well, but I don't think my knees would handle the climb.


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## NautiC25 (Feb 15, 2012)

Frank Hopper on the C25 forums mounted a window unit in the "dumpster" that was flush with the adjoining wall.

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