Condensation on the ceiling

hArpOoN · #1 (**permalink**) 03-20-2008

Hello everyone,

I'm looking at picking up a new boat and when I went to check it out, it was stored outside for the winter up in Canada without a tarp on it. It looked in fairly good shape but I noticed condensation on the ceiling in the main cabin. This wasn't in any one particular spot but spread over the entire cabin in certain spots. I didnt notice any leaks and there was no snow/ice/rain on deck that would be seeping in. Is this a normal thing for boats stored outside and not covered?

Thanks!

sailingdog · #2 (**permalink**) 03-20-2008

Harpoon-

It would help if you said what kind of boat it is. If the boat has a solid fiberglass deck and no interior overhead added, then condensation might be a very common issue. The interior of the boat would heat up in the sun, increasing its ability to hold moisture, and then at night, it would cool off, and the excess water would condense out.

Generally, more information when asking a question is going to get you better answers. BTW, ceilings on boats are the interior vertical surfaces that line the hull...not what is overhead, which is generally called an overhead on a boat.

I'd also recommend you read this post to get the most out of your time on sailnet. Welcome to sailnet.

hArpOoN · #3 (**permalink**) 03-20-2008

Hi Sailingdog,

Thank you for your response. My bad on the lack of info: It's a 1970 Grampian 30 and it was sitting out on a sunny day this week when I went to see it in the afternoon. And you're correct, I was referring to the overhead and not the vertical surfaces that line the hull.

Thanks again.

sailingdog · #4 (**permalink**) 03-20-2008

It is probably because the boat heats up and the as the air warms and picks up more moisture, when it hits the solid fiberglass cabintop, it condenses out onto the cabin overhead. Did you look in the bilges of this boat. My guess would be that they have some water in them.

TrueBlue · #5 (**permalink**) 03-20-2008

As SD stated, this is normal. Condensate (the vapor changed in matter from a water state) which is present inside the boat as the interior warms during the daytime, condensates back into a water state on colder surfaces - typically the hull and cabin overhead surfaces.

TrueBlue · #6 (**permalink**) 03-20-2008

Dog - you type too fast.

sailingdog · #7 (**permalink**) 03-20-2008

TB-

You're just figuring that out now...

petegingras · #8 (**permalink**) 03-20-2008

come back in a few weeks and that condensation will have given you a garden of mold if there's no ventalation.

When it's your boat or you've bought another take the speed log or depth sounder out over the winter (remember to replace it in the spring) you'll get air circulating without water incursion.

Maine Sail · #9 (**permalink**) 03-20-2008

This is why you MUST cover your boat in the snow belt!! True Blue and Dog are spot on.

The reason this happens is because the air in the cabin warms and the deck stays a constant 32F, unlike the cabin, because it has SNOW sitting directly on it!

With no snow on the deck the it can heat and cool at the same rate as the rest of the hull. this leads to NO condensation. Always cover a boat where snow is possible especially if you have a boat with a headliner!

If that owner did not care enough about the boat to cover it then how bad are the rest of the systems?

sailingdog · #10 (**permalink**) 03-20-2008

My real question is how dry are the bilges in this boat. Many boats won't have obvious leaks, but small ones, and on a warm winter day, water can leak down into the bilge. This is most often the source of water that condenses out onto the interior of the boat. Keeping a boat well ventilated and dry is very important to keep the boat clean and mold-free.