How Do You Keep Your Boat Cool In The Summer

In the 90-100 degree weather, that we have in Louisiana, how or do you try to keep your boat cool while in the marina when no one is aboard. I had the a/c on last summer for 4 months and cooked a unit. I have fans that I leave on but it just moves hot air.

Trying to keep an empty boat "cool" in those conditions sounds like a losing proposition. Shade the boat, and use solar or 12v vents to expel the hot air. Moving the air around inside the boat as you say just moves the hot air. I would think you need to be able to draw the hot air out much like a house vent.

kartracer said:

In the 90-100 degree weather, that we have in Louisiana, how or do you try to keep your boat cool while in the marina when no one is aboard. I had the a/c on last summer for 4 months and cooked a unit. I have fans that I leave on but it just moves hot air.

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Did the same thing, toasted the salon unit. This summer I'm gonna set the thermostat at 80 degrees instead of 74! Might help take the stress off the units somewhat....

We just keep our boat in the Pacific NW. Problem solved!

Moonfish said:

We just keep our boat in the Pacific NW. Problem solved!

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Ha! I was just going to suggest that a trip to Maune would do it...
Bruce

Or keep your boat in Maine.

We set our 3 units on "moisture control" which keeps it from being hot and runs a couple of times an hour for a few minutes.

I use open hatches and beer...

Florida. Keep two of the four units on - one down in the cabin area and one in the salon. Set at 78.

kartracer said:

In the 90-100 degree weather, that we have in Louisiana, how or do you try to keep your boat cool while in the marina when no one is aboard. I had the a/c on last summer for 4 months and cooked a unit. I have fans that I leave on but it just moves hot air.

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When we're not aboard in that kind of weather, I usually leave the ACs running with 'stats set to 80° or 82°F.

Two 14 year old 16K BTU ACs.

What cooked your unit?

-Chris

Tech said unit ran 24/7 even with unit set at 78. Compressor will no longer compress.

kartracer said:

Tech said unit ran 24/7 even with unit set at 78. Compressor will no longer compress.

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When I had to explain the reason for a component failure to a customer, I used to like saying..." It reached the end of its service life"!
Bruce

I installed a SolarStar ventilator onto the hatch in the pilothouse roof, which is the highest point internally. It has a high airflow when the sun shines, much better than the tiny boat vents that are available. I leave the insect screened ports in the cabins open, and thereby draw air right through the boat. It works really well to keep heat and humidity down to a reasonable level even with doors and windows locked up. I would not be comfortable leaving air conditioners running on shore power while not on board.

Solar Star Solar-powered Attic Ventilation Systems | Solatube

Do the ac's have a dehumidify setting. Energy efficient and keeps the interior dry.

I'm in a covered slip so that helps but I have a small fan in a open window that draws hot air out too.

Kevin

tallswede said:

I'm in a covered slip so that helps but I have a small fan in a open window that draws hot air out too.

Kevin

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Where does the air come from that replaces the air you draw out?

kartracer said:

In the 90-100 degree weather, that we have in Louisiana, how or do you try to keep your boat cool while in the marina when no one is aboard. I had the a/c on last summer for 4 months and cooked a unit. I have fans that I leave on but it just moves hot air.

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Shade all exposed to the sun decks that have overhead in cabin or staterooms. If you can draw tarps down to rails to protect bulkheads all the better. Go to fore or aft hatch and install a strong fan blowing out. Go to the opposite end of the boat and open a hatch, a large hatch or 2 Windows. Close all other Windows, hatches, doors and so forth. Suck air in and pull through the boat and blow it out. You should be ok with the attic fan concept.

Bruce B said:

When I had to explain the reason for a component failure to a customer, I used to like saying..." It reached the end of its service life"!
Bruce

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Can I have permission to use that quote!!!!

dwhatty said:

Or keep your boat in Maine.

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Or a covered slip.

menzies said:

Where does the air come from that replaces the air you draw out?

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At the very least you have air intakes that go into your ER. Keep the ER hatch open and the air runs through the typically cooler ER then exits out of the hotter Pilothouse.

Brian, those residential units look like decent option. With global warming, summers are getting warm even here in the PNW. I don't need AC, but a good way to vent the PH without opening the doors would be nice.

If it ran 24/7 for 78 degrees then it was either undersized or old and already had issues or had a freon leak or something.

We run ours, set on a moisture control as the mode. Yours may or may not have mode settings. The other option is to program them to come on at intervals.

dhays said:

At the very least you have air intakes that go into your ER. Keep the ER hatch open and the air runs through the typically cooler ER then exits out of the hotter Pilothouse.

.

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He is in Texas.

I have this junky old LG 9000 BTU unit that I leave up on the berth or on the galley counter with the exhaust taped to a port-light or window and the drain through a piece of hose to either the galley sink or through a propped up hatch into the bilge. It keeps the boat below 80 on 95 degree days and dehumidifies as well. I usually add a small fan for circulation. I don't trust to leave my boat A/C on when I'm gone, and these things are comparitively cheap so I dont care much if it craps out. It takes 8 amps to run it and I see them at Home Depot up to 12k BTU's. My boat is only 36 but has huge volume on a single level so air is easy to move.

How old was the unit? How warm is the water that circulates through the unit? Does the water your boat sits in reach 90 degrees. The unit looses efficiency trying to transfer heat to the already warm water. As the cooling water gets warmer, the compressor runs hotter which leads to compressor failure. Also, most people never bother to clean the cooling coil that the water circulates through. Scale builds up inside this coil reducing heat transfer, which also makes the compressor run hot.

If it's possible, pick a larger btu unit for a replacement. Understand that switching to a larger unit may require larger size wire from the breaker panel to the unit and possibly a larger water pump.

Ted

LOL. It's an old boat and not well sealed. Leaks around the doors and hatches. I will often leave one cracked in the cabin across from the fan.

Kevin

menzies said:

Where does the air come from that replaces the air you draw out?

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On my little boat I don't run the air conditioner unless I'm aboard. I do have a compact dehumidifier that runs 24/7. It keeps the humidity in the low sixties. No mildew.

menzies said:

He is in Texas.

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hm... I didn't realize that thermodynamics worked differently in Tx.

Seriously, I am used to water temps being cooler than the air temps in the summer. Cooler water temps generally mean a cooler bilge and ER. Are the water temps high enough that the lower compartments in a boat are warmer?

As noted here in the PNW its not a problem, even in summer, its never above 100F, and only rarely in the 90's. Just open a door or window or go cruising, its always 10 degrees cooler on the water. Its our trade off for all the fall and winter rains, mild summers.

Water temperature in Rockport TX in August-89 degrees. Galveston Bay 87 degrees. Cannon Bay, FL 90 in June (it's on the gulf coast). Miami peaks at 86.

Water temp in the summer in Puget Sound and environs is about 50F degrees!