Dealing with Condensation

[Spammy]

ventilation:yes. But that is not sufficient. If the temperature of the hull falls below the dew point for the relative humidity of the air inside, condensation will happen, whether there is air movement or not. Inslation will help by keeping the temperature of the inside surface of the hull closer to that of the air inside, and of course, dehumidification of the air inside the boat works. For us, in sunny South Florida, an air conditioner is the answer, but of course it is an energy hog, and not a great solution for when you are on the hook, unless you have a genset and enjoy the noise and diesel fumes of the exhaust...

[thinwater]

A great formula for mold.

Although insulation will prevent condensation where you can see it, if the humidity is above the dew point at the coldest surface of the hull the air will find, there will be condensation. This is avoided in homes by using a vapor barrier on the inside and having insulation that breaths to the outside; but hulls do not breath.

So, unless your hull is cored everywhere - unusual to say the last - you will need to dry the boat below the dew point. That depens on the climate, it will be perhaps 10-20F above the outside temperature (since the inside of the FRP will be ~ 1/2 way in between inside and outside temps).

Insulation is fine; just make sure there is ventilation between the layers and that the boat remains low in humidty too. Otherwise it will be like the pesky condensation beteen storm windows that just won't go away.

[avril25]

So fare I've got good ventilation. A solar powered vent fan, worked great all summer
I was thinking of adding another. I like the idea of a small wood stove, where can you find those, any recommendations. I currently have a Kenyon alcohol stove. Have not used it in the winter yet. Today is the coldest day so far. I'm going down to the boat to check it out and see it like inside with the heat on.

[michaelmrc]

dickenson makes a nice small solid fuel heater its a small unit designed to work with bbq briquettes coal or small pieces of wood. i have no experience with it but from talking with dickenson it seems to be quite popular.

[rustypirate]

Back when my family were cruising we encountered this same problem. We were able to recitfy it simply by putting a layer of styrofoam sheet against the hull wherever accessable, and this practically eliminated the problem.

Now, many years later, I would not recomend styrofoam to ANYONE considering it's toxic fumes if ignited.

There are several manufactures of spray-on foam kits that are closed-cell, and have an E84 flame retardent rating. You can also paint them with flame retardent latex paint available at most paint retailers to gain yet another level of flame retardence. The spray foam eliminates the possibility of condensation building up between the foam and the hell/deck as it bonds to the material it is sprayed onto if properly prepped.

The real downside to spray foam is that it is hell to get off if you need to work on the area that is covered.

[zeehag]

keep more ports open ...ventilation--i have no problem whatsoever with condensation--havent since i learned to keep all my hatches and ports open year round--even in winter when it is 38 degrees---i keep the ports open with the heating system turned on ...and wear lots of clothing for warmth and feather quilts.....and more ventilation.....

Originally Posted by michaelmrc

dickenson makes a nice small solid fuel heater its a small unit designed to work with bbq briquettes coal or small pieces of wood. i have no experience with it but from talking with dickenson it seems to be quite popular.

best ventilate with this or will find you deader than fred.....

[Sharkman]

We also have an aluminium hull, but instead of sprayed on foam we have 5cm of board type insulation for the deck and the hull down to the waterline. This has been cut to shape to fit snugly between the frames and stringers of the hull that are themselves covered with glued neoprene strips around 10cm wide, which also help to hold the insulation in place. Last December we had temperatures down to -6 C and had no major problems with condensation beyond the aluminium hatch frames (a problem we hope we're working on for this winter). We use just a small fan heater and occasionally our Webasto diesel blown air heater when it's really chilly, and wrap up if we need to, but we're generally very comfortable.

Insulation makes a real difference to an aluminium or steel boat, and the latest techniques seem to work well - without it (and good ventilation!!) a metal boat can be about as welcoming as a crypt in winter. I'm sure that some of the same techniques could be applied retrospectively to a GRP boat and could make a real difference, although it might be a big job to get behind the joinery.

[SemperParatus]

Soleus

[illusion_realit]

We lived aboard three winters on the Chesapeake w/o condensation issues. We were insulated from the waterline up, well ventilated, heated with a newport propane stove and showered on shore. Think about condensation on a single pane of glass, it is the same as your 1/4-1/2 inch of fibreglass between you and the outside. We also had dri-dek under the v-berth foam. The newport could burn 24/7 on high for 4 days on 20 pound tank or 7 days on low. Very dry heat with no smell and totally sealed from the inside.
Mike

[Maine Sail]

Dry your bilge and add some ventilation. Having a wet bilge is basically like a small scale indoor pool.

Our bilge is always bone dry, we have solar vents and a dorade, and even in Maine during the early and late seasons we don't get any condensation.

Oh and don't try and heat your vessel with non-sealed combustion LP as it gives off copious amounts of moisture as part of combustion.

[feelsgood]

Originally Posted by avril25

I was wondering how people who live aboard deal with condensation that develops on the walls and ceilings. in winter or summer. Does insulation help.
what type of insulation works best. I see a DIY spray on high density foam,
1 inch equals 7.7 r factor Has anyone tried this. Do those electric dehumidifiers work. Any suggestions.

I have just insulated a Sadler 32 for a client with 4mm cork he now has NO condensation and the boat is both warmer in the winter and cooler in the summer. if you want to know more give me a call.
Regards Pete

[rebel heart]

Haven't had any condensation problems myself on my current boat (Hans Christian). Had a bunch on my previous (Ericson). I have a lot of airflow, and use a cabin heater in the winter. Electric at the dock, diesel on the move/hook. Anything that generates dry heat, and enough airflow to move that dry heat around, dries the boat out.

The worst times are when it's raining buckets outside, and there's wet gear and wet footprints in the cabin. Even with the heat and ventilation, there's a lot of water getting turning into vapor.

[KairosKona]

Here's another dehumidifier to consider:

About DryZone Systems | Dehumidifiers for boats and motor homes

David

[feelsgood]

Originally Posted by avril25

So fare I've got good ventilation. A solar powered vent fan, worked great all summer
I was thinking of adding another. I like the idea of a small wood stove, where can you find those, any recommendations. I currently have a Kenyon alcohol stove. Have not used it in the winter yet. Today is the coldest day so far. I'm going down to the boat to check it out and see it like inside with the heat on.

Try one of these.
http://www.marinestove.com/codinfo.htm

[feelsgood]

Originally Posted by thinwater

A great formula for mold.

Although insulation will prevent condensation where you can see it, if the humidity is above the dew point at the coldest surface of the hull the air will find, there will be condensation. This is avoided in homes by using a vapor barrier on the inside and having insulation that breaths to the outside; but hulls do not breath.

So, unless your hull is cored everywhere - unusual to say the last - you will need to dry the boat below the dew point. That depens on the climate, it will be perhaps 10-20F above the outside temperature (since the inside of the FRP will be ~ 1/2 way in between inside and outside temps).

Insulation is fine; just make sure there is ventilation between the layers and that the boat remains low in humidty too. Otherwise it will be like the pesky condensation beteen storm windows that just won't go away.

All insulation ina boat should be glued in place.