Should I insulate my headliner space?

[gnashty]

My wife and I just bought our 1987 Hunter 40, which we're living aboard, and we are battling the elements a little bit right now.

In this picture, you can see we have some weeping coming through the fiberglass tabbing that connects the headliner to the hull:

Here is a close-up -- you should be able to see some sheen near the middle of the image:

It's not pictured, but water is also running to the end of the tabbing and dripping out nearer to the shelves, which are starting to rot and grow mildew:

I'm working on rebedding deck hardware (weather permitting) and looking for other potential leaks aboveboard, but just discovered that there is no insulation in the space in the headliner behind the outlets and spotlights. Aside from wiring, the space is an empty void.

As a result (I think), a pretty significant amount of condensation is forming in that space. Big drops. All over the place. Running down the hull.

You can't see the condensation in the above picture (although maybe you can see what looks like mold on the deck-hull sealant running down the center), but trust me -- it's there!

So, my question is, What should I do about this?

Insulation? This space is only accessible by removing the lamps and outlets along the headliner. A spray foam would be the easiest, but if I ever had to run additional wire it would be a nightmare. I would consider stuffing regular old fiberglass insulation in there, if recommended, but I'm sure it would soak up water and need to be replaced regularly.

Ventilation? I could install small 12 volt fans and/or add ports to ventilate the space, drawing in warmer air from the main living space.

Heat? I guess it's conceivable to insert some bar-style heaters in there.

Calcium Chloride? The holes behind the lamps aren't really big enough that I could easily put and in take out any significant amount of this stuff.

Any thoughts would be much appreciated.

 

[Don S/V ILLusion]

Sounds like you have two problems - leaks and condensation. The latter is easier. You can insulate inside the liner, outside the liner which is easier or the less elegant method of laying insulating blankets on deck. Unfortunately, without fixing the leaks, you are just rearranging the deck chairs on the titanic.

 

[Bill Roosa]

Hey gnasty
You get condensation when the surface is below the dew point temp of the air in the boat. Adding insulation will lower the temp of the boat hull due to less heat getting to it from the cabin. So the outside of the boat cools down and the inside is at what ever temp you keep the boat. Somewhere in the middle (in the insulation) the temp drops to the dew point and that is where condensation will continue to form. Adding insulation does not stop the condensation it just hides it from view. It also makes a breeding ground for lots of nasty stuff later when the weather turns warmer.
The solution is to add a vapor barrier which keeps the moist air in the warm part of the boat. Any moisture in the air between the vapor barrier and the hull does not amount to much and can be ignored. Any leaks behind the vapor barrier spell doom for the insulation.
Alternately you can lower the humidity in the boat with a dehumidifier. As the boat has several sources of moisture this is also a loosing battle. The gas stove, your breath, prop shaft glands and any other leaks add enough water to make using a dehumidifier kinda futile.
I solved the problem when I lived on my 40.5 by just closing the door and letting the room dry out. The water condensed and drained to the bilge and the room was then dry. i just did not open the door. Course, I was by myself so I could get away with that solution.
I'm thinking the long term solution is either insulate and put on a vapor barrier after fixing the leaks or move south to warmer climes.

Good luck

 

[Deadline]

If on the other hand the problem is leaks, you have to find them. They are usually from rain, so the best thing to do is have someone gently arc hosewater onto the boat as you move from bow to aft. Spend an hour to really observe for leaks.

 

[Doug13104]

I have an 1988 Hunter 40 with the same problem. I have just this week ripped out the hull liner in the V berth because of mould growth between the inside hull and the liner. The problem with our boats is the lack of an air gap between the two. The hull liner is glued directly to the inside of the hull and any difference in temperature between the inside and outside creates condensation. This is the perfect spot for mould to form!!
So what to do??? Check out this Web-site.
http://www.frugal-mariner.com/Insulating.html