AC when away from the boat

[cardude01]

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? Or, if the hose pops off or breaks or whatever will the AC unit and the pump shut down due to a lack of cooling water?

I’m wondering about a portable AC unit that I can run an exhaust duct out a porthole that’s sheltered from the elements. But I’ve heard those things will barely cool down a boat when it’s 95-100 degrees outside.

I’d love to install a mini split but don’t think I have room for the compressor, except for in the lazarette and I don’t think it would get the airflow needed down there.

 

[rgano]

I completely agree with your rationale for not running a marine AC unit unattended. Another thing which can happen is that the strainers become clogged shutting down the unit which will then allow the boat to cook and encourage MOLD which is about as bad as anything which can happen to a boat in hot climes. My brother runs one of those portable units in his GG42 and made himself a blank plate wth exhaust hole to slip into an open saloon window to which he attaches the exit hose for one of those portable home units. My boat is in a covered slip in a lift with a tiny dehumidifier running all the time.

 

[Larry M]

We always ran just a separate dehumidifier that drained into the galley sink. The inside got hot but we never had any damage from the heat.

The potable AC units may work but you have to deal with the moisture that they take out of the air. Some dump the water into the discharge air others you have to dump the water manually or route it into a sink or the bilge. We had one when we were in Trinidad and the routing of the discharge air was a pia.

 

[cardude01]

Yeah I really don’t want to spend $500 on one of those indoor AC units. Plus it’s another thing I will trip over.

I have a big home style dehumidifier that runs when I’m away. It is in the shower and drains into the shower sump. It keeps the humidity down really well, but it also puts out additional heat.

I haven’t had any interior heat-related damage that I know of, but just worrying about the heat I guess.

I installed a solar mini split in my garage last year, and would sure love to have that setup on the boat so I could enjoy cold AC while underway with no loud ass generator. I just don’t think I have the room on this little boat. The system will run off three big 72 cell panels and I think I have the room for those, but the compressor location is the problem. The lazarette is roomy enough I think, but I would have to rig up some pretty big vent fans for airflow in there and not sure it would ever get enough air.

 

[HTurner]

Heat will not hurt things inside as long as you keep any wood well oiled, especially if they are veneers. The humidifier is good, you do not want mold to get started within your boat. Mold is much harder to remediate than you can imagine, on a boat in will get into places that you will never be able to reach.

 

[IRENE]

We have left ours on as needed for our (now departed) doggy. I understand the concern that a hose could flood the boat, but keeping the senior dog comfortable won out.

Our AC has a moisture mode we used at the dock when away. Every 4 hours, the fan circulates air for 30 minutes. The compressor then runs to lower the temperature 2 degrees or 1 hour maximum. This repeats every 4 hours. Works well. Explained in the Marine Air manual.

If it ever warms up here this year, we will “set it and forget it” when hot and on the dock as we are aboard full-time.

 

[rslifkin]

I leave one AC running to limit heat and humidity when I'm away from the boat over the summer. But the boat is rarely unattended for more than a few days. Worst case if a hose failed, we're not talking about a massive volume of water. The way my units are mounted it'll drain into the engine room, make a bit of a mess and the bilge pumps will handle it.

 

[cardude01]

There is an unattended boat next to me that has water circulating 24/7. I saw some workers at the boat last time I was there and they said that boat has the AC running full blast 24/7. They thought that was crazy.

I’ll ask again— if an AC cooling hose ruptured, would the system shut down and then shut down the seawater pump?

I wish there was a way for my AC system to run only from like noon to 6pm.

 

[Comodave]

I leave one AC running to limit heat and humidity when I'm away from the boat over the summer. But the boat is rarely unattended for more than a few days. Worst case if a hose failed, we're not talking about a massive volume of water. The way my units are mounted it'll drain into the engine room, make a bit of a mess and the bilge pumps will handle it.

I wonder, have you tried unhooking the output hose from the pump and see if your bilge pumps can keep up? For piece of mind I would test it to make sure.

 

[Comodave]

There is an unattended boat next to me that has water circulating 24/7. I saw some workers at the boat last time I was there and they said that boat has the AC running full blast 24/7. They thought that was crazy.

I’ll ask again— if an AC cooling hose ruptured, would the system shut down and then shut down the seawater pump?

I wish there was a way for my AC system to run only from like noon to 6pm.

The A/C would shutdown, whether or not the pump would shutdown is another question. It depends on how the pump is wired. In our last boat the pump was on a separate breaker so it would run until the power went away. I don’t know if the pump is wired from the A/C if it would shutdown or not.

 

[cardude01]

The A/C would shutdown, whether or not the pump would shutdown is another question. It depends on how the pump is wired. In our last boat the pump was on a separate breaker so it would run until the power went away. I don’t know if the pump is wired from the A/C if it would shutdown or not.

Suppose I could simulate that by removing a cooling hose and letting it run into the bilge. Would also be interesting to see if my one bilge pump could keep up.

As you can probably tell, I’d really like to leave my current AC running at a high temp setting (like 85), but just for a few hours of the day when it’s hottest.

 

[Comodave]

Suppose I could simulate that by removing a cooling hose and letting it run into the bilge. Would also be interesting to see if my one bilge pump could keep up.

As you can probably tell, I’d really like to leave my current AC running at a high temp setting (like 85), but just for a few hours of the day when it’s hottest.

Before I did it I would do a test and see if the pump could keep up. Let us know how it goes.

 

[HopCar]

Suppose I could simulate that by removing a cooling hose and letting it run into the bilge. Would also be interesting to see if my one bilge pump could keep up.

As you can probably tell, I’d really like to leave my current AC running at a high temp setting (like 85), but just for a few hours of the day when it’s hottest.

Dude! You’ve been doing this along time. Only one bilge pump?

 

[rslifkin]

On my A/Cs a loss of water flow will cause a high pressure fault which will also shut down the pump. Thinking about it, that means the only big risk would be a hose rupture near the pump (below waterline). We're only talking about a 3/4 inch thru hull (about 20 inches below waterline) and 5/8 inch hoses. I've got more than enough bilge pump capacity to keep up with that.

 

[cardude01]

Dude! You’ve been doing this along time. Only one bilge pump?

Yes. Only one. [emoji15]

My boat is basically a sailboat hull and the only accessible part of the bilge is where the one lonely bilge pump resides. It’s kind of like a deep, mysterious hole down there about 24” wide and maybe 30” deep.

In don’t know where another pump could be mounted on this boat.

Do most sailboats only have one bilge pump?

 

[jimdavi]

We have 3ea. 16k reverse cycle units and when warmer, and away for a few days, we run in humidity mode. No water flow and circulates lots of air. Seems to work well.

 

[cardude01]

No water flow in humidity mode? Didn’t realize that.

Also didn’t realize there was humidity in San Fransisco! I’m currently in New Orleans, and man, the humidity is insane.

 

[Flatswing]

Most boats in my marina run AC all summer, many are unattended for months. Just too hot & humid here not to. AC pumps are low pressure pumps, but will not shut down if leak occurs on outlet side of water cooling circuit. Ergo, check hoses & double clamp.

 

[cardude01]

Will do. Thanks.

 

[O C Diver]

First of all, add more pumps. I have 4, 2 in each compartment. Second, add a security system that will notify your phone with an app or email when the water is above the minimum level in your boat.

If your boat is located in a remote location (from you), you should have someone check on it periodically and be able to get in side and determine the cause of a high water alarm.

Ted

 

[rslifkin]

Yes. Only one. [emoji15]

My boat is basically a sailboat hull and the only accessible part of the bilge is where the one lonely bilge pump resides. It’s kind of like a deep, mysterious hole down there about 24” wide and maybe 30” deep.

In don’t know where another pump could be mounted on this boat.

Do most sailboats only have one bilge pump?

Even if all water drains to one area, there should be at least 2 pumps. A small one all the way at the bottom to minimize nuisance water left behind. And then at least one big pump mounted a bit higher as a backup (with an alarm on that one). In your case, you may need 2 big pumps in that main bilge if there's nowhere else on the boat to put them.

Personally, I like to size pumps to keep up with a failure of the largest underwater fitting (after accounting for de-rated pump performance as installed, rather than their optimal rating). The more water you can pump, the more time you have to deal with it when a flooding problem shows up.

Realistically, many boats (probably the majority) leave the factory with grossly inadequate bilge pump setups.

 

[Hippocampus]

My sailboat had the following bilge pumps
One manual whale inside. Another manual whale with pump mounted in cockpit next to helm. This is a fairly standard arrangement as it’s a mandated requirement for some ocean sailboat races.
Two electric pumps. One at bottom of bilge in a recess. Less than a couple of ounces in the bilge at anytime so little moisture in the boat. A second high water pump. A third prevent sinking pump off the engine.

The biggest problem in my current boat which is common with many trawlers is the lack of natural ventilation. This is quite different than sail as most have multiple dorades that can be left open except in severe storms with massive green water. With us on the boat you can open the forward hatch, the pilot house doors and the saloon door and you’re fine. But on the current boat there’s no way to get natural ventilation when buttoned up. My concern isn’t heat but rather moisture. Have three bilges with four pumps. Still there’s always a bit of water in the bilges. Work around has been to place bilge heaters if away for awhile. Once doors and hatches are open boat cools off very quickly. Then run the three AC units and you have really dried things out. Have thought about a wind scoop on the most forward hatch rigged to not allow rain in. Wife’s pretty good with sunbrella and the sewing machine. Then crack one of the aft salon windows which are well protected by the boat deck. That should give sufficient natural ventilation. Have lived on a sailboat in the tropics. Rarely ran the AC. All you need is shade and ventilation nearly all the time. On sail in the tropics you commonly see awnings hung to cover nearly all horizontal surfaces. That makes a huge difference. Our solar panels cover much of the boat deck but thinking of devising some sort of awning to get the same effect.

 

[cardude01]

Ok, I will mount another pump higher than the existing one, and put in a high water alarm for the second one. I have a cell based monitoring system that sends me texts on heat and humidity and I can easily add a water sensor I think.

On this additional pump, can I use the same hose and wiring as the existing pump? Like T into the existing discharge hose somehow? Also, does anyone use a check valve on the hose for a bilge pump? My pump always drains back a little water after it turns off.

 

[Hippocampus]

Believe best practice is a entirely separate circuit for juice and entirely separate hosing/through hull as well. Thinking is if one fails or gets clogged the other will function. No check valves as well which is a pain as you still have a slightly wet bilge.

 

[rslifkin]

Ok, I will mount another pump higher than the existing one, and put in a high water alarm for the second one. I have a cell based monitoring system that sends me texts on heat and humidity and I can easily add a water sensor I think.

On this additional pump, can I use the same hose and wiring as the existing pump? Like T into the existing discharge hose somehow? Also, does anyone use a check valve on the hose for a bilge pump? My pump always drains back a little water after it turns off.

Definitely add a separate thru hull, separate wiring, etc. for the second pump. It's hard to avoid back flow with a single hose and the existing wiring is likely not going to support a second larger pump.

As far as drainback, some of the small pumps do come with a check valve in the output, but I usually remove them as they sometimes cause the pump to air lock and not prime.

Ideally, make the lowest pump something small with a 3/4" discharge hose. You'll still get some drainback, but the small pump and hose will reduce the volume of water. My current setup in my main bilge areas can pump down to a little under 1/2" of water remaining, after drainback there's still less than an inch.

Depending on what your current pump is, you may want to add 2 more. A smaller one as low as you can get it (I like to use ones with an internal water sensor for this as they'll activate at a lower level than most float switches) and then a big one up a bit higher.

 

[Hippocampus]

Have found using one of the non mercury external float switches last longer. Hate working with my head lower than my body. Have had the internal Rule float switches fail frequently after a short time. As little as a month or three. Have gone over to using the Johnson switches which seem to last longer. Just redid my grey water switch for the reason. It was two months old and didn’t see much use before failure.

 

[rslifkin]

Have found using one of the non mercury external float switches last longer. Hate working with my head lower than my body. Have had the internal Rule float switches fail frequently after a short time. As little as a month or three. Have gone over to using the Johnson switches which seem to last longer. Just redid my grey water switch for the reason. It was two months old and didn’t see much use before failure.

Good to know on the internal Rule switches. The solid-state ones in the Whale Supersub pumps seem to be reliable, however. I've had 2 of those on the boat for a few years now with no issues. I know Rule now makes a similar solid state internal switch (in addition to the internal float switch units) but I don't know anyone who's used one.

 

[cardude01]

What are some good pumps to go with? I know nothing about bilge pumps and switches. My knowledge gaps after years of owing this boat always surprise me.

I forgot this boat also has a Whale manual pump with the pump lever located in the cockpit, but that’s obviously an emergency pump for when I’m on the boat. I’m pretty sure it uses the same discharge hose as the main pump, but I think it tees into the hose near the exit by the swim step and uses the same hull fitting. Is that acceptable?

 

[rslifkin]

For most purposes I'd just ignore the manual pump entirely. Most of us don't have enough crew on board to make one useful. The person that would be pumping is generally better off doing something about the leak instead.

 

[HeadedToTexas]

I installed a solar mini split in my garage last year, and would sure love to have that setup on the boat so I could enjoy cold AC while underway with no loud ass generator. I just don’t think I have the room on this little boat. The system will run off three big 72 cell panels and I think I have the room for those, but the compressor location is the problem. The lazarette is roomy enough I think, but I would have to rig up some pretty big vent fans for airflow in there and not sure it would ever get enough air.

I am surprised there aren't more folks doing this. I brought it up a couple years ago and was flamed for suggesting fragile domestic equipment in a marine environment. While it makes sense that salt spray would create corrosion problems uncommon in land-based applications, the cost (low), safety (no through hulls) and comfort (AC without a generator running) benefits seem to be worth exploring.

My idea is to put the evaporator split in place of the current Webasto marine units, and the condenser split in the fly bridge seating with condenser air flow ducted from "inside" the seats out the rear of the seats. Dry as I can get it.