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Hull Drying



I have a 72' hull in great condition. The hull has never had an
inspection port. I installed one and at the end of the season I stored
the hull in my dry garage. When I first felt the inside of the hull it
seemed very dry. Now every time I feel the inside of the hull
it seems to develop more and more condensation. My garage is completely
dry. Is this possible?


Very Senior Member
A lot depends on the atmospheric conditions where you live. I'm in NC, and recently with our screwy weather, it's possible to have someplace that is cool, such as inside a hull, reach dewpoint because the warmer outside air around it is loaded with humidity. If this is the cause, it will, in NC, go away later in the winter, as the atmosphere gets dryer.

Google dew point calculations, then enter what you think are reasonable numbers for your area. You can get the rel. humidity from the weather on TV for the area, then throw a thermometer inside the boat... the humidity inside the boat and at the TV station are basically the same if you have that port open. So you can calculate it it is raining in the boat or not...


Thanks. I see that even if the boat is stored inside,
changes in temperature will cause condensation.
I was hoping to have the hull completely dry before next season.

beldar boathead

Well-Known Member
If you leave it in that dry garage all winter, then set it out in the sun for a couple hours next spring with the ports open, it oughta be bone dry!


We've boats that "seem" dry and collect some moisture over time. In most cases, especially with older boats, the moisture actually is coming out of the foam blocks. It takes a long time for it to migrate back to the surface of the block and "collect" on the fiberglass surfaces.


Have you ever weighed the hull? It takes 2 people and a bathroom scale with the sunfish on edge so you can read the scale dial. SHouls show up as less than 135 pounds. Over that and the rest of the weight is water in the foam blocks.