Portable 10,000BTU A/C on a 40Ft.

[Maka]

Originally Posted by Enchantress

I think your location plays into whether a portable (one that exhausts via a hose) will work or not. Here in Florida we had a new LG 8000 BTU portable that would only cool us down to 75-77 on a hot, humid 90 degree day.

We replaced it with a cheap 8000 BTU window unit in the hatchway and that unit takes us down to 68 on the same hot, humid day.

I think number of people onboard effects performance as well as the portable worked better when it was just myself -- when it's me, the admiral, and our 3 small dogs it did way worse.

Dogs will do that.
I'm sure the Admiral is HOT ( which logic says is the issue ) but we don't want to be blaming her.

[Manos1955]

Originally Posted by kimmyd

Has anyone used a portable A/C unit on their boat and if so did it operate ok for you? Trying to figure out if this is an option until we can fix ours properly. Thanks in advance!!

I would say that 10,000 BTU is already very big. I had a 6,000 BTU portable on my 45 racing sailing and it was extra good
Remember the rule 300 BTU for each 3 cubic meter of space to cool or 400 if there is no isolation

[pbbmorton]

I bought an LG 14KBTU for my 50ft ketch. It worked fine. I tried with multiple 8K's and it just did not work so well, they just don't move enough air. I ordered a second exhaust hose and routed it out a window. My boat is too deep for one exhaust hose to work. I made a simple cover over the window out of FRP board with a whole cut for the exhaust hose fitting. On really hot days I had one tower fan to move the air to the aft cabin.

To be clear it did not replace having separate marine air for each cabin but it worked in a pinch. The biggest issue was the space it took up. I had the space next to my nav station.

[GordMay]

Originally Posted by Maka

Why wouldn't a swamp cooler work? ...

In order to work, Swamp Coolers need a hot, dry climate, such as in the arid southwest USA.
The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor (evapouration). In extremely dry climates, evapourative cooling of air has the added benefit of conditioning the air with more moisture.

[valhalla360]

Originally Posted by Maka

Why wouldn't a swamp cooler work?
Could be set up w 12v pump and fan ( fans? )
Nothing draining.
Might need a deeper sump to compensate for rocking and rolling.

Swamp coolers only work if the humidity is very low. While there are cruising grounds that meet that requirement, they tend to be the exception.

In a more typical cruising ground like florida, they will do nothing.

Also we need to clarify a few variations that are being talked about:
- Traditional Marine Units: The entire unit is inside with a water pickup and discharge absorbing the heat. Condensate either goes in the bilge to be pumped out by the bilge pump or you can insert a veturi pump in the water line to suck up the condensate. We hated our marine unit as our bilges are otherwise dry and the venturi pump constantly clogged, so it overflowed into the bilge.
- Window units: The small box units that where the entire thing sits in the window. Simplest and cheapest but least attractive. Condensate typically drips outside via gravity.
- Portable units: These units sit inside on the floor with a 4-6" diameter hose led to a window. Condensate is routed to fall on the exhaust fan where it is flung out as a fine mist in the exhaust. They come in two flavors. The single hose, uses air from inside the cabin to cool the unit. The downside is that means hot outside air gets drawn in to replace that exhaust air. This reduces the efficency. The higher end units have two hoses, so it can pull in outside air to cool the unit meaning you don't exhaust already cooled interior air.
- Split Units: There are two pieces. One mounted on the exterior and one on the interior with hoses carrying the coolant connecting them. These are nice but they require a permanent mount for both parts. I haven't seen one on a boat but it should be viable.

[a64pilot]

I think there may be some misunderstanding, possibly.
First there are "window units" box looking things of course meant to be mounted in a window, the condenser is outside and they circulate outside air to cool it, the evaporator is inside and the condensate drains and drips outside.
Then there are "portables" in which the whole unit is inside and you have two hoses to draw outside air in to cool the condenser and the other hose exhausts the hot air, condensate I believe is caught in a pan like a de-humidifier.
Then of course there are "spilt" units, meaning the compressor and condenser is outside and the evaporator is inside, In the past few years, many smaller spit units made seemingly by Korean companies have become popular.

Then I have seen RV air conditioners sitting on top of hatches, some apparently manufactured to fit a hatch opening

[dlockhart]

We put a 10,000 btu unit on the coach house roof behind an open hatch and I built a 1" blue Styrofoam duct box like thing that encompassed the business end of the ac unit and the hatch opening. Inside the box I put a piece of the same Styrofoam to separate the cold air out from the warm air in. I covered the box with a piece of a cheap blue tarp and taped the joints with blue duct tape. I drilled a hole in the case of the ac towards the back where the condensate collects and epoxied a 3/8" tube into it so I can direct the water over the side of the boat so as not to have a bunch of rust stains. A fan inside moves the air around inside and it works well. Easy to remove the whole thing for leaving the dock and if have to do it again the only thing I'll do different is make the tarp covering out of Sunbrella with bungy cord around the openings and would get a reverse cycle ac so we could also have a little heat if needed.

[dlockhart]

I should have added that we tried a much more expensive portable unit first but they take air that you've spent money to all ready cool and expel it through the unit to the outside through the hose and are not very efficient. Only really cools the room it's in. Gave 2 of them away.

[kimmyd]

Thank you everyone!!! We have decided to fix the Aft A/C first and get a portable for the salon,galley & forward stateroom for now. Again, thanks for the info.