AC when away from the boat

[Larry M]

I wouldn’t be worried. I think about our van or car. I’ve seen inside temps over 110 and no damage other than things I’ve left on the dash.

That temp is probably the highest in the boat. You engine room will be cooler since it’s surrounded by water and no windows.

 

[rslifkin]

I don't worry so much about high temps hurting the stuff in the boat, but if it's well over 100 in there, the fridge is going to be running non-stop and may have trouble maintaining a safe temperature for anything we've left in it. And any other electronics that are powered will be cooking as well, which can't be good for any of the equipment.

 

[cardude01]

I don’t leave the fridges on when I leave the boat.

The flip side of all the heat in the boat is it was pretty dry when I first walked in. 44% humidity according to this new sensor I hooked up. So that’s a plus I suppose!

 

[rgano]

When I got to the boat yesterday it was 103 inside according to the temp on the AC panel when I turned it on. Not sure how accurate that sensor is, but that seems a bit too hot!

Boat is in New Orleans.

Open the engine room hatch; put circulating fan in there; and find a way to put a Nicro-Vent or such through the overhead or high on the cabin side.

 

[LarryM]

Quality hoses and well maintained systems don't just break. My view is you're over-thinking it. Yeah, if you have no idea what your systems look like down below then something COULD happen.

*IF*, however, you have new, quality hoses and good clamps, and you inspect them and the rest of the system often, there is no reason not to leave the AC on.

We left ours running on all of our past boats. I knew those systems inside and out -- everything was rock solid and no way anything was going to "pop off".

Update your system components if needed, inspect them regularly, and sleep well.

JMHO....

+1 Precisely what he said!

 

[OldDan1943]

When I got to the boat yesterday it was 103 inside according to the temp on the AC panel when I turned it on. Not sure how accurate that sensor is, but that seems a bit too hot!

Boat is in New Orleans.

Carded, yup. Did you have one AC running?

 

[GoneDiving]

Following

 

[cardude01]

Carded, yup. Did you have one AC running?

No. Nothing running. This was when I first arrived at the boat.

After more investigation I think my sensor on the AC control panel was incorrect. After running for hours the inside temp would not get under 90 according to the panel, but I know it was not that hot inside. The other AC panel showed 80. Anyway, that caused the one AC unit to freeze up from too much running and not enough air flow over the condenser I found out.

I recalibrated the sensor on the panel and increased the air flow to the unit so testing it now.

 

[OldDan1943]

Based upon my training a long time ago ..... one way to freeze up a unit involves the amount of refrigerant .... low.

 

[cardude01]

Based upon my training a long time ago ..... one way to freeze up a unit involves the amount of refrigerant .... low.

Yeah I think that’s a common culprit, but this time I think it was due to a lack of airflow across the coils. My AC unit is in a stupid place BEHIND THE TRASH CAN DRAWER [emoji35], and if you don’t leave the drawer slightly open the unit starves for air. My two college kids are staying on the boat and I forgot to tell them about that. *

I need to relocate the trash can. It’s so stupid having the return air flow across the trash to get to the AC.

*I’ve noticed it’s really hard for me to tell anyone how to live on this boat without screwing things up. It’s OK if I’m there to fix everything quickly, but really hard when I’m not there.

 

[Jmarsh203]

Quality hoses and well maintained systems don't just break. My view is you're over-thinking it. Yeah, if you have no idea what your systems look like down below then something COULD happen.

*IF*, however, you have new, quality hoses and good clamps, and you inspect them and the rest of the system often, there is no reason not to leave the AC on.

We left ours running on all of our past boats. I knew those systems inside and out -- everything was rock solid and no way anything was going to "pop off".

Update your system components if needed, inspect them regularly, and sleep well.

JMHO....

Agree completely. A well designed system properly maintained won’t just fail. I regularly leave my boat for days at a time with my ac running. Don’t think anything of it. I regularly check all my below water systems monthly and if anything looks questionable it gets replaced before it fails. When I bought my boats the a/c systems were the first things I went through and I replaced all hoses, clamps and a few of the barbs and strainer were questionable so they got replaced as well.

 

[TWedd]

mold requires temps over 70 degrees and Relative humidity over 50%.
I've learned a few things about this in my 40 year HVAC career.
Seal the boat up tight when you are gone, no ventilation, turn off solar fans etc., this sounds wrong but follow along.
Also some form of dehumidifier, the small peltier type work well for this application. you might need two for a big boat, they use very little electricity.
If you keep the boat tight and run a dehumidifier the humidity stays low and no mold. If you have ventilation to out side you just keep replacing the humidity with more from outside.
Don't worry about the heat. the higher the temperature the lower the relative humidity and that's the main thing, keep the humidity low.
The final tip I have is open your bilge/engine hatches, and install some sort of dry bilge system or equipment, these can be built for less than a hundred dollars.

Ive been keeping boats and houses in Florida and Georgia mold free this way for years.
The portable A/c that that has 1 hose to blow hot air outside just keeps pulling humid air back into the boat, like digging a hole and throwing the dirt back into the hole.

Main thing is dry it out and keep it dry, keep the humid outside air outside and dry out he inside air. if your boat is tight it doesn't take much to keep it dry.

 

[cardude01]

mold requires temps over 70 degrees and Relative humidity over 50%.
I've learned a few things about this in my 40 year HVAC career.
Seal the boat up tight when you are gone, no ventilation, turn off solar fans etc., this sounds wrong but follow along.
Also some form of dehumidifier, the small peltier type work well for this application. you might need two for a big boat, they use very little electricity.
If you keep the boat tight and run a dehumidifier the humidity stays low and no mold. If you have ventilation to out side you just keep replacing the humidity with more from outside.
Don't worry about the heat. the higher the temperature the lower the relative humidity and that's the main thing, keep the humidity low.
The final tip I have is open your bilge/engine hatches, and install some sort of dry bilge system or equipment, these can be built for less than a hundred dollars.

Ive been keeping boats and houses in Florida and Georgia mold free this way for years.
The portable A/c that that has 1 hose to blow hot air outside just keeps pulling humid air back into the boat, like digging a hole and throwing the dirt back into the hole.

Main thing is dry it out and keep it dry, keep the humid outside air outside and dry out he inside air. if your boat is tight it doesn't take much to keep it dry.

This is basically what I have been doing. I have a big house style dehumidifier that drains into the shower sump. Humidity was very low when I got to the boat.

I will just leave it like this I suppose. I don’t trust my old ACs to run when I’m gone, and I’ve noticed that the humidity is higher when running the ACs than when I first got on the boat. My AC condensation runs into the bilge also so there is no way to keep the bilge dry when they are operating.

I just installed a MarCell monitoring device that takes temp and humidity readings every 30 minutes so and sends me texts if something is out of range.

 

[OldDan1943]

I used to leave both ACs running. One man would go and check on my boat, shut one AC off because it was so cold on the boat. LOL

 

[HopCar]

mold requires temps over 70 degrees and Relative humidity over 50%.
I've learned a few things about this in my 40 year HVAC career.
Seal the boat up tight when you are gone, no ventilation, turn off solar fans etc., this sounds wrong but follow along.
Also some form of dehumidifier, the small peltier type work well for this application. you might need two for a big boat, they use very little electricity.
If you keep the boat tight and run a dehumidifier the humidity stays low and no mold. If you have ventilation to out side you just keep replacing the humidity with more from outside.
QUOTE]

That’s exactly what I did. Worked great!

Did you know that the Peltier Effect can be used to generate electricity? Instead of running electricity through it and causing one side to heat and the other to cool, you heat one side and electricity comes out. It’s horribly inefficient but it works. In Jr. High I lit a flashlight bulb with a propane torch for a science fair project.

 

[Crux]

mold requires temps over 70 degrees and Relative humidity over 50%.
I've learned a few things about this in my 40 year HVAC career.
Seal the boat up tight when you are gone, no ventilation, turn off solar fans etc., this sounds wrong but follow along.
Also some form of dehumidifier, the small peltier type work well for this application. you might need two for a big boat, they use very little electricity.
If you keep the boat tight and run a dehumidifier the humidity stays low and no mold. If you have ventilation to out side you just keep replacing the humidity with more from outside.
Don't worry about the heat. the higher the temperature the lower the relative humidity and that's the main thing, keep the humidity low.
The final tip I have is open your bilge/engine hatches, and install some sort of dry bilge system or equipment, these can be built for less than a hundred dollars.

Ive been keeping boats and houses in Florida and Georgia mold free this way for years.
The portable A/c that that has 1 hose to blow hot air outside just keeps pulling humid air back into the boat, like digging a hole and throwing the dirt back into the hole.

Main thing is dry it out and keep it dry, keep the humid outside air outside and dry out he inside air. if your boat is tight it doesn't take much to keep it dry.

For the portable a/c single hose problem, specify a dual hose model....some mfgrs offer a dual hose re-fit kit.....or if you're handy you can fab up an intake plenum box-to-hose arrangement.....either way, bring in outside air using another one of those very nice exhaust hose port adaptors pictured in an early post.

 

[Hippocampus]

When laying up with no electricity available the same thing works. Just use riddamp or like products in a airtight boat. Open all lockers, closets and bilge access. Good to go.

 

[hayesdvm]

In our marina on the river, there is too much trash/bark that will fill up my raw water strainer if I try to run the AC units at the dock for very long, so I have the dehumidifier set up below with drain running to the shower sump. Keeps the humidity down to 30%, but it is hot. Best we can do here in NC, and we just open the windows once we get to the boat and get the fresh air flowing ASAP!

Mark

 

[amapola]

We live in Florida so it's hot most of the time. Our boat is docked behind our house. We never run the AC when we are not on board. We haven't had any adverse effects.

 

[JRO]

What do most folks here do when in hot climates when away from the boat to keep the boat from cooking inside? I have two water cooled ACs on the boat but I never leave them running when away because I’m afraid a cooling hose will pop off and flood the boat. Do most folks run these units when away?

Asking what “most people” do on a international forum will not provide you any useful information. You’ll get plenty of “opinions” but useful? No.
In South Floriduh there are scores of beautiful big boats that rarely leave dock but have their ac running continuously…. And there are scores of beautiful big boats that never have ac running unoccupied. The dragons in your dreams are “the cooking your boat” and “the sinking of your boat” by leaving the ac on while unoccupied. IMO all your concerns are baseless. Your boat is an expensive “maintenance hobby” that can also provide spectacular fix-it vacations now and then. If everything is working… Your boat will not sink if an ac circulation hose pops uncharacteristically. Adequately designed modern boats of size are equipped with three bilge pumps of high capacity that will easily keep up with that unlikely demand.
The dragon that SHOULD BE in your dreams are your Rule Bilge Pump Float Switches. They are your weakest link in your maintenance effort to keep your boat on top of the water. They are notorious for not working while their importance is paramount to unattended yachts. As a betting man, I’d safely bet that “1 out of 5” Rule switches are not working if they have once been in contact with water.

 

[cardude01]

Asking what “most people” do on a international forum will not provide you any useful information. You’ll get plenty of “opinions” but useful? No.

In South Floriduh there are scores of beautiful big boats that rarely leave dock but have their ac running continuously…. And there are scores of beautiful big boats that never have ac running unoccupied. The dragons in your dreams are “the cooking your boat” and “the sinking of your boat” by leaving the ac on while unoccupied. IMO all your concerns are baseless. Your boat is an expensive “maintenance hobby” that can also provide spectacular fix-it vacations now and then. If everything is working… Your boat will not sink if an ac circulation hose pops uncharacteristically. Adequately designed modern boats of size are equipped with three bilge pumps of high capacity that will easily keep up with that unlikely demand.

The dragon that SHOULD BE in your dreams are your Rule Bilge Pump Float Switches. They are your weakest link in your maintenance effort to keep your boat on top of the water. They are notorious for not working while their importance is paramount to unattended yachts. As a betting man, I’d safely bet that “1 out of 5” Rule switches are not working if they have once been in contact with water.

Thank you, dragon whisperer.
I’ll check the pump switch.

And I totally disagree with your assessment that I’ll get no useful info by asking questions on this forum. The knowledge base here has been very helpful to me over the years.

 

[HTurner]

Your boat is an expensive “maintenance hobby” that can also provide spectacular fix-it vacations now and then.

This quote should be on wood plaques...

 

[Mambo42]

My boat is lying in Greece and in the summer time it gets truly hot there. Is a bit like the temps in Texas. 110 - 115 degrees is pretty normal there in August.

At the moment am not in the boat, she is lying (closed up) in the marina, with all the sun shades attached. The one thing that truly does keep her cool is something the former owners installed and it works absolutely fine. They are sun shades made of material that can breath, it has thousands of little holes.



When the sun shades are hanging you can still walk on the side deck and since the sun shades don't let any sun through the temp is already quite a bit lower. But the sun shades also create a bit of a draft which causes an even lower temp. And only then that air will get in contact with the windows, which have anti heat foil installed as well.

Like this I don't have a need for air conditioning when the boat is in the marina. Of course, when the water temp reaches 85 degrees ultimately it is going to be around 85 degrees inside as well, but luckily not 110 or 115.
Might be an idea for someone here, in case they don't have it yet.

In our marina we are the only boat which has sun shades installed like this, the transom has one as well (can also ventilate air) and am very happy with it.

 

[healhustler]

Asking what “most people” do on a international forum will not provide you any useful information. You’ll get plenty of “opinions” but useful? No.

?? Not useful, this Forum?

Do agree that the Rule switches are a major weak link though.

 

[JRO]

Thank you, dragon whisperer.
I’ll check the pump switch.
And I totally disagree with your assessment that I’ll get no useful info by asking questions on this forum. The knowledge base here has been very helpful to me over the years.

I apologize for not being clear… This is an informative forum. What I was attempting to say is everyone has one… Just like opinions. This is a great place to filter content for useful information.
Your baking idea tied to a unlikely hose rupture is not perceived by everyone as an issue. I understand how something like that flying around in anyone’s head can become disturbing. It’s like “those” guys that use “those” car windshield shades everyday to protect their car’s dash from the evil Sun. There are dragons everywhere.
As far as popping a fitting or bursting a hose somewhere along your cold water heat transfer lines… It’s unlikely because it flows freely… Like a garden hose without a nozzle to build up pressure in the line. That said… You can create pressure in those lines by running your ac 24/7. Marine growth requires water flow, more flow more growth IN YOUR AC HOSES. This sucks because it will eventually slow the flow enough to stop heat transfer and that will shutdown your ac system. Now you are calling an AC technician to visit your boat with a jug of illegal acid to kill and flush barnacles out of your heat transfer hose system. You’ll do this at least once or twice a year… But your boat’s interior will be nice and cool for the benefit of nobody.
I spent a few years fishing and beering in the Bahamas and South Floriduh so I was a 24/7 ac kind of guy only because I lived on the boat. It was worth the time and expense to be comfortable. When I’d abandoned the boat to drink cold beer somewhere else I’d shut it all down nice and tight and taxi to the airport. The moral of the story is… “You can lead a horse to water but it’s up to the horse to drown”.

 

[JRO]

My boat is lying in Greece. At the moment am not in the boat, she is lying (closed up) in the marina, with all the sun shades attached. The one thing that truly does keep her cool is something the former owners installed and it works absolutely fine. They are sun shades made of material that can breath, it has thousands of little holes.

I’ve been thinking about doing this but have not seen it done before. Is this basically tennis court fence screening material?

 

[psneeld]

Possibly phifertex which is commonly used for vessel exterior window shades.

Blocks out varying amounts of sunlight depending on which fabric and resembles a dense screen.

 

[Hippocampus]

+1 on Rule switches being failure prone. They say the new non mercury ones are better but have had those fail as well. Slowly switching over to Johnson switches as hear good things. Others like Whale but have no input about those. Shade does make a big difference. Sunshade the exterior of the boat to the extent possible and have opaque shades over all ports, doors and windows. Totally passive. Nothing to break and no energy use. At 10 to 12 degrees north just doing that was good for a 20-30 degree F decrease. Leave a dry bilge and dorades/vents closed. No mold. White boats and those with cored house/topsides stay cooler. Colored hulls are hot. Teak decks or synthetic are hot.

 

[Seevee]

I have shades, and a household dehumidifier that runs all the time at the dock. Keep is sealed up and even though it's hot inside, the humidity is low.

Works well, and cools off surprisingly well when we take it out.

 

[bll99a]

Never the same power source and a "T" is certainly not recommended. Check valves can create multiple problems making the pump totally useless.