Condensation issues

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Bill Wertz	Condensation issues		Lead	[-]
Posts: 7 08/30/07 16:58:07	Tags : None What have others done to minimize or eliminate condensation and sweating of the interior hull below the water line? We live aboard and are located in the San Juan islands where the water is cool year-round. In the 2 months we've been here I could 'tap' the water running down the inside of the hull and have, in essence, a water maker. We have put a total of 10 passive air vents in the boat, 2 on the starboard side locker, 3 more on the portside lockers, 4 in the V-berth under our center-line berth, and 1 in the cabinet door below the forward head sink. This has helped but it's not enough. In reading the excellent "The Warm Dry Boat" by Roger McAfee, he suggests all that we've done plus more. Our C42 hulls are solid glass below the water line so, in theory, they are almost as good insulation wise as a wood boat. Only a 'cored' fiberglass boat is better and that carries the very real possibility of delamination if the skin's integrity is breached so we're much better off that Frank Butler provided a solid hull. I've just purchased a West Marine Turbo Dryer that can run constantly and is designed to raise the ambient temperature so the air can carry more moisture and I've also ordered a Golden Rod from West Marine to put under the V-Berth to, in essence, do more of what the Turbo Dryer is supposed to do. Do these work? I hope the answer is yes as it's driving us crazy that we have to aggresively monitor the situation to prevent mold. I am most interested in replies from people who, like us, live aboard or at least spend a significant amount of time aboard. I am, however, open to any and all suggestions. Having moved to the Pacific northwest from the Great Lakes where we sailed for the past 20+ years this is the BIGGEST problem we've encountered. Dealing with saltwater as opposed to the fresh water seas is, by comparison, a MINOR issue.
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rbetzing		#1	[url]	[-]
Posts: 60 08/31/07 05:12:17	We use the Turbo Dryer Dehumidifier placed on the chart table and D-Humidify packets in the pullman berth and the rear berth. This combination has worked for us in preventing mold and mildew while we are away from the boat. Ron Desperado 2000 C42/2 cabin #708 San Diego, CA
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oscar		#2	[url]	[-]
Posts: 475 08/31/07 11:08:11	people who, like us, live aboard or at least spend a significant amount of time aboard You are the source of the moisture. And the stove....and a few other things. Although I have not actually dealt with this issue, logic would dictate that you need to separate the moisture from the cold hull. So you need to close off the bilge as much as you can. Separate it from the living quarters. Yes, you need to ventilate it, but the air needs to be drawn in from outside, not from the moisture laden cabin, and re-deposited outside. This also means that air returns for AC's need to be ducted so as not to mix with the bilge air as the negative pressure will draw cabin air into the bilge. Just thinking out loud here...... Lady Kay, C42#76, 1989, WK 3C. Chesapeake/Fort Lauderdale.
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tinolanza		#3	[url]	[-]
Posts: 212 08/31/07 14:00:04	I second Oscar's thinking. The human lungs are remarkably efficient. No matter what the temperature and humity of the air we inhale, we exhaled at 92 deg. F and 100% humity. People put a lot of moisture into a closed environment. By isolating the bilge compartment, it should soon equilibrate and stop sweating. If open and circulating then you are introducing more moisture and feeding the condensation cycle. Concentrate the venting from the main cabin and exterior. Tino Lanza, Dancing Dolphin (#739/3 cabin pullman, Westlake Village, CA)
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pwinterfeld		#4	[url]	[-]
Posts: 108 08/31/07 14:50:07	Hi Bill I too have kept our boat in the Gulf Islands for a year (that was the year it rained for 29 days straight -2006) and found that the condensation issue was extreme, we did have two WM turbo dryers running at all times - that did not help. We have the two cabin centerline model - even with the heater on - the condensation and dripping on us, when sleeping in the forward bed was a nuisance. We actually had mold forming on the bedspread from the constant dripping from the aluminum surrounding the hatches- nothing we did to remedy the situation seemed to help. What we did to remedy the situation was to move the boat to Southern California and removed all the green lines and ropes plus the bedspread (green from mold) in a responsible environmental manner. Sorry thats the best advice I have. Peter C'est la Vie Hull #746
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kenfischer		#5	[url]	[-]
Posts: 172 08/31/07 19:01:02 Moderator	Bill: The conversation here is right on target. The big question is what to do about it. I have a few ideas - implementation is a different story. 1. You are making moisture primarily by breathing, and by burning propane. 2. You need to get the moisture OUT of the boat. Gagets like the golden rod are effective in cool areas of the boat where you get hit by condensation. They keep the ambient temp above the dew point and the water in the air. What they don't do is get rid of the water - it's still there. If you run your blower to vent the boat, you are taking warm moist cabin air and sucking it into the cold bilge. Instant condensation. So, my ideas. Do you cook on the boat a lot? The boat really needs a range hood, just like you have at home. This could be as simple as installing a nicro-vent in the deck directly above the stove, though I don't know about the aesthetics. I have often pondered the idea of running a duct from above the stove back to the laz, through a bilge blower, and out a clamshell vent. This would be extremely effective, if you can figure out how to run the ducting. The other thought is heating. Our first boat, a C30, had an Espar Airtronic heater that pulled outside air, heated, and pushed it into the cabin, forcing "old" air out the hatch. That REALLY helps the moisture level. However, if I recall correctly, you have hydronic heat and, as like ours, no source of fresh air. We just recirculate the inside air. If you can find some way for one of the heat exchanges to pull outside air, running the heater in the morning, even in the summer, will significantly aid in drying the boat, far more than any other gagets. We tend to let the heater really run by keeping the hatch open. It's not the most efficient, but it does dry out the boat. The bottom line is that you have to get warm moist air out of the boat. If the air exiting is the same temperature as the ambient, because it has run through the bilge, it's likely already dropped its water inside the boat. Ken Fischer 2005 C42 #906 "Solaria" 3 Cabin Pullman, Fin Keel, Mast Furling Main, 155% Genoa
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afterglow		#6	[url]	[-]
Posts: 54 09/02/07 19:16:12	We purchased our last boat in Annapolis and because of the heat, we had an air conditioner installed for dockside comfort. We later moved to the Puget Sound area and moved the boat with us. No need for the air conditioner, but since it was a "heat pump" design, it worked great in the winter and whenever it was cold in the "heat" mode. Now, to your point, it even had a "humidity" mode where the unit's sensor would come on every few hours, test the humidity in the boat, and then -- as required -- it would "dehumidify" the boat. The blower really circulated air in the boat and you could set the thermostat at, say, 60 deg. in the winter and not have to worry about things freezing or mold forming. Never a speck of mildew in the boat. We've since sold the boat and bought our Catalina 42, but I sure miss the heat pump.
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captrick		#7	[url]	[-]
Posts: 195 09/03/07 21:11:52	I have a Mermaid A/C with a "condensator" device that sucks the water from the drip tray and squirts it out with the sea water discharge. It is very effective at reducing humidity-easily drops it from 90% to around 25%, even with the companionway open. I don't think it takes a big A/C to dehumidify. You can find dehumidifiers on the web. Just be sure to get the condensate off the boat. Rick 704-3
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wcstrain	condensation issues	#8	[url]	[-]
Posts: 8 11/25/07 22:09:54	The problem is that the dew point of the air in your boat is above the dew point of the cool surfaces of your hull and metal parts. The only way to prevent condensation is reduce the dew point of the air in the boat. When you have shore power this is easily accomplished by using a dehumidifier and being sure that drain from dehumidifier drains into one of your thru hull drains ( sink etc) . Heating the air in the boat will not keep condensation off inside of the hull. Heating the hull would be thing to do but is not practical The dew point of air is when air has the maximum amount of moisture that it can hold at a given temperature. If this air is cooled below this temperature it cannot hold the all of the moisture thus condensation. You need to read and understand this law of physics to appreciate your problem. If you would like further discussion contact me . wcstrain@yahoo.com
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george lyons		#9	[url]	[-]
Posts: 10 11/26/07 08:07:30	I also have a turbo dryer / dehumidifier from West Marine and use it as directed when we are on the boat ( two Cabin Pullman ) . I do not use it for time periods in excess of one day when we are not on the boat . This weekend the weather report called for a low of 38 degrees and we were staying on board without any other source of heat . We placed the turbo dryer in the forward stateroom on the floor and closed all hatches except the forward head hatch , which was left 2 inches open with the head access door closed . We also closed the door separating the forward stateroom from the main cabin on the assumption that the heat from the turbo would keep us warm. ( I was worng --as my wife was quick to point out ) Not sure the tempretaure got as low as predicted , but it certainly got into low 40s . Turbo did very little to warm stateroom , if anything , and roof and hatches generated a significant amount of condensation - enough water to soak a bath towel . I believe I will start looking for a heater that does not present a Carbon Monoxide danger or add too many strange smells to the cabin .
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wcstrain		#10	[url]	[-]
Posts: 8 11/27/07 07:49:50	To help you understand dew point and relative humidity the attached web site has tables in both degrees C and F. The discussionat at the top of tables should explain how to understand your conditions . http://www.lamtec.com/dew-point-calculator.htm For your area the water stays 50 o F (+ or -) 3 oF.You air has high humidity plus you are adding humiiidy by breathiung and cooling. From experience you are seeing condensation frequently ( when interior air makes contact with your boat interior) . "Unlike an air conditioner a dehumidifier does not cool or heat your boat but only removes the moisture. Recommend you also try to keep the bilge dry ,most bilge pumps do not do this as they leave ~ 1/2 inch of water in bilge. you will have to removed remaining water with a sponge or other device . Hope this is helpful.
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