What temperature to keep the boat when not occupied

[Norm Mayer]

I am going out of town for a few weeks, and want to leave the AC running to keep the humidity down, and not damage the boat from extreme heat. I live in South Florida and the boat CAN get hot in this sun. I don't know whether to set the temp to 85 or 90 degrees, or just use the humidity control setting on the thermostat. Any advice would be appreciated!

[Traveler 45C]

I leave my environmental systems on all of the time, as I’m on the boat everyday for lunch. When I leave, I set the temp to 80F and that works well. During the peak heat in the summer the A/C will run all day and hopefully can get a break at night.

[Pascal]

when I'm away, I leave the ACs at 80. Keeps the interior cooler, humidity low but that's a high enough setting to keep them cycling on and off, not running full time.

[Norm Mayer]

Thanks for the input, guys!

[StratPlan61]

I must admit, you guys have more guts than I do. I would fear a hose failure filling my boat with fresh water at a rate far exceeding my bilge pumps! YIKES!! I admit I am envious of the boats I walk past, whose interiors are cool and crisp. But, fear overtakes me and I can't bring myself to temp my hoses, hose clamps and a/c units when I am not close by to attend.

Bear'
1984 61' MY Strategic Plan

[SKYCHENEY]

I'm with you, Bear. I just can't leave my boat with the A/C on or with the dockside water hooked up.

[ThirdHatt]

I agree! I am afraid to leave the A/C on for more than a few hours without anyone on board. That's ALOT of electrical current flowing to the boat and ALOT of water flowing through the boat to not have anyone aboard for extended periods of time. I happened to be on board my 36C back in the 1990's when an electrical fire started from the wires powering the salon A/C. I caught it just as it started because I was on board at the time. I know that I would have lost the boat had I not been there at the time.

Sure the boat will get pretty hot while sitting in the slip down south in the summer, but someone please tell me how it could that actually "damage" the boat? I doubt anything will actually melt! Humidity concerns are easily taken care of by the inexpensive mold/moisture control products readily available at West Marine, etc. I believe that it just boils down to people not wanting to be uncomfortable for the first few minutes when they step on the boat in the summer. I, for one, would rather deal with the 10-minute cool down period when I step on my boat and turn on the A/C's rather than worry about the A/C's on the boat cycling on and off for endless days or weeks on end for no good reason, not to mention hoping that the A/C water pump doesn't give out, start leaking or become fouled by a clogged sea strainer.

[MikeP]

I agree with the last several posts. With no one on board, I never leave the A/C on overnight. If we are anchored out and leave the boat for more than an hour or two, I also shut 'em off. It's not like the house A/C system - there are too many interelated systems to leave unmonitored that can cause problems from little PITA problems to sunk boat problems.

Same is especially true of hooking up exterior water - I never do this at all. Not ever!! The external water hookup is a tool of the devil and serves no useful purpose while, at the same time, providing great potential to convert the boat from floating to not. I just fill the water tank as necessary. Doing this also keeps the tank water "fresh," reducing the potential for another problem.

[Angela]

When I lived on my prior boat, I used dockside water during the week, and my tank on the weekends when I was out of the slip. I would usually remember to turn off the water when I left the boat in the morning and went to work. Occassionally, I forgot and would be nervous about it all day until one day when Ed was down in the bilge washing it with a garden hose running full blast continuously the whole time and my aft bilge pump out ran the amount of water a wide open hose could put into the boat - out ran it by a long shot. I had more than one bilge pump, but never had enough water in the boat to kick those on. After that, I felt much better about knowing the water was on when I wasn't there (only when I forgot - I still made it a habit to shut it off when I left for work). We were very surprised, and pleased, that that one pump would stay well ahead of a wide open hose.

As for the AC on my new boat....that scares me a little. The pump has a 2" hose connected to it and that's a lot of water if the hose pops off. My delimma is that when I go to work, I don't think I can just shut off the AC in south Florida - my cat will be living on that boat with me too and he needs to stay cool during the day. So, I think to begin with, I'll be replacing those hoses and clamps ASAP if for no other reason, to feel better about it. I've been gone from the boat for several weeks now and I had it turned off - hope nothing is in too bad of shape when I get back there next week.

Ang

[REBrueckner]

For those with sufficient money, 80 degrees is a nice setting for air conditioning. Just be sure your insurance coverage is up to date: There is a lot than can go wrong with multiple a/c systems when no one is aboard. For those concerned about electric bills, even a 100 degree setting will keep interior conditions under control. And of course, many boats are left with no climate control whatsoever.

Natural ventilation is easy and safe. Leave a vent (say a bow porthole) open at a low and another at a high point (say saolon door) to promote natural air circulation. A fan to draw in outside air at a low point and/or an exhaust fan at a relative high point speeds up the natural circulation. A household fan in front of an open porthole (say the bow cabin where rain is less likely to get in) can draw in outside air and if a salon door/window is left open, air will rapidly circulate out the higher opening where it's warmest...

Window shade covers to prevent thermal heating from direct sun will greatly reduce ventilation/air conditioning requirements. When aboard, eyebrow covers do a geat job, but they can be damaged in high winds, as during sudden thunderstorms.

An alternative arrangement is to use a household portable de humidifier. It's really a mini air conditioner and is much less costly to operate than a/c systems. A drain hose can be directed to your shower stall to permit condensate to drain.

[Norm Mayer]

Thanks again for the input, folks. I did leave the AC on, set at 85. I appreciate the concern of hose leaks, etc, however, I just replaced the entire AC system, and was involved every step of the way. All new hoses, thru hulls, clamps etc. Heat CAN cause damage to many things when cabin temps exceed 115 degrees, and it will in southern Florida. As someone mentioned, a few years ago I had a water leak when a fitting froze. (I lived in Cincinnati at the time. After 1/2 a day of the water running full blast into the boat the bilge pumps were still keeping up.
I believe most problems occur when there are multiple failures at the same time. The best way to keep that from happening is constant maintenance. IMHO

[Genesis]

If you have electronic stats and systems monitoring so the system will NOT try to repeatedly start into a dead unit (e.g. no water flow) then its probably ok.

If you have the MECHANICAL stats then its a VERY bad idea to leave them on. If the water flow fails, you will lose a condensing unit - guaranteed - over a period of a few days time.

[jim rosenthal]

If you have digital controls on the AC, you can set the system for a dehumidify setting that will circulate the air at low speed, and then about every twenty minutes or so, the compressor will kick on- and the seawater pump- and run for about five minutes or so, and then shut off again. The advantage of digital controls is that they will only run the seawater pump when the compressor needs seawater flow- otherwise it doesn't come on. If you keep the boat shaded, and the blinds drawn, it will stay fairly bearable inside. The small dehumidifier is also a good alternative.
Another way to help this out is to have shades which have insulating material in them- this used to be made by a company called Rocklon, I think- the shade material has air cells in it and is surprisingly effective at keeping heat out. I find that if I keep the curtains drawn, the front Windshield covered, and a few small windows open with a fan running, the boat stays fairly cool inside. I wish I had room for a dehumidifier- on a 36' boat, there just isn't.

[bobk]

Your refrigeration system is another consideration. I began to leave just the forward unit on a high setting, maybe 90 degrees, when we left the boat to prevent the Norcold from running continuously. The rest of the boat was shut down.

We have manual controls and two separate raw water pumps on ours (yep I'm speaking of the 41' Hershine trawler) and they only come on when the compressor runs.

But do check the metal components of the water system. A couple of years ago I noticed some blue/green copper salts on the hose barbs in both systems and they turned out to be brass and ready to break. Now they are all bronze.

Anyone looking for a good single screw sundeck trawler? 2.7 gph at 7.8 knots!

Bob

[Genesis]

The mechanical t-stat systems - IF they haven't been tampered with - have a seawater pump relay box and run only when one (or more) of the condensor units is on.

This is a good design in general, but see my archived posts on the trigger problem. If a trigger fails, you're hosed - the pump will not come on when that condensor does. If you're on board when it happens, you'll notice fast. If not, you won't, and the constant cycling on high head will eventually destroy the condensor.

[bobk]

The mechanical t-stat systems - IF they haven't been tampered with - have a seawater pump relay box and run only when one (or more) of the condensor units is on.

This is a good design in general, but see my archived posts on the trigger problem. If a trigger fails, you're hosed - the pump will not come on when that condensor does. If you're on board when it happens, you'll notice fast. If not, you won't, and the constant cycling on high head will eventually destroy the condensor.

Now this is a puzzle to me. In my current boat with 20 year old (flawless) King Air units, if I lose water flow the 110V breaker trips and there is no longer an attempt to start. Why doesn't that happen on the Hatteras installations? Seems like it should. Can they be protected with individual breakers or something?

[Genesis]

No. There is a high-head switch on the condensor that will trip and shut it off. However, it automatically resets, and it will then attempt to restart.

A breaker trip indicates there is no high head protection. This is very dangerous, in that if the breaker DOESN'T open first you can actually have an explosion in the condensor from overpressurization.

[ELECTRA VI]

I have an old Cruisair system that was apparently a dealer installed option with the old three knob controls. As soon as I turn on the fan, the pump kicks in and runs continuously whether the compressor is running or not. I talked to the Cruisair people at last year's Ft. Lauderdale boat show and they told me that the old three knob setup was the best they ever made. As such, I am reluctant to change out to digitals even though it is old and corroded (40 years).

[Wayne]

I have a portable A/C-dehumidifier in my salon that uses a 5" fresh air vent. I leave it on when away and use it to supplement the 2 cruiseair units in the summer. I can maintain 72 degrees even when it is 98 outside. Extra weight is worth it to me to keep interior fresh and mildew free.

[Banshee36]

55 degrees in the summer, 70 in the fall.

[Maynard Rupp]

I'm with you, Bear. I just can't leave my boat with the A/C on or with the dockside water hooked up.

Sky..I agree totally with you but, we live in what is called a temperate climate,(we know that it isn't always temperate). Those guys live on the inside of the oven door with a little guy throwing water in. I think if I keep the boat in Florida, the full time AC program is a must. I also wouldn't worry about flooding the boat. After all, if a Hatteras can survive two hurricanes per year, why worry about a couple hose clamps.

[SKYCHENEY]

Maynard,
Before leaving the A/C on, I would check the volume of the pump and then make sure I had at least double that capacity of bilge pumps, preferably mounted close to the AC pump just in case. Some might say "That's what we pay for insurance for". But for me, I would rather have my boat than the insurance money. It's just too hard to find another one to replace her.

[Genesis]

Yep-yep.

The problem with insurance is that it just pays you money. Then you have to find a boat you like with the money - and that's not easy!