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From: (no name) (no email)
Date: Sat Jan 13 2001 - 18:45:35 EST
In a message dated 01/11/2001 10:58:58 PM Eastern Standard Time,
writes:
I have been researching and listening closely to anything said about
insulating the hull prior to installing a wall finish. Mine is a steel hull
and I have special concerns about condensation running down the hull sides.
Spray foam seems to be the norm for new boats but there is a lot of
controversy about not being able to get to a problem area, the mess to spray
in and clean up after, water mitigating into the foam from condensation, and
the high cost.
>>>>>>You get what you pay for. Spray urethane is costly, and a pain to do
and it is unthinkable to do anything else if you can possibly use spray
urethane. Water does NOT "mitigate" into the urethane foam which is closed
cell and quite tough.
Sheet foam type insulation is a problem because you must somehow glue it to
the hull without any air spaces or condensation will form between the
insulation and the hull.
>>>>>>>>Sheet Styrofoam can be glued to the hull using "Great Stuff" shaving
cream urethane. Simply run a bead completely around the panel and a big "X"
from corner to corner. Put the panel up and hold it in place using two 1x2s
between the panel and a hard place. Put the 1x2s side by side, somewhat like
telescoping tubes, and held by two "C" clamps. The urethane will seal the
Styrofoam/hull connection. However, Styrofoam is not exactly closed cell and
moisture can go through it, but you will not have any condensation because
the moist air in the cabin will not reach the cold hull.
Fiberglass insulation holds moisture.
>>>>>>Fiberglas insulation has no place on a boat.
Others have tried products that are made for a variety of uses....except
insulating boats.
I don't think it need be such a complicated or costly thing to do because
the "need for insulation" is a matter of opinion anyway!
>>>>>If you air-condition the boat, insulation is a good thing.
>>>>>If you live in the boat in a place where the outside air temperature
gets below the dew point of the air inside your boat, water WILL condense on
the inside of the uninsulated hull on every square millimeter that has a
temperature below the dew point of the interior air, that's why it is called
"dew point". Mildew and other nasty things will grow on the wet surfaces.
The mildew and other nasties will make you sick. I know.
To add a couple of more suggestions for products to use for insulation and
soundproofing that might be less expensive to use than the marine products
available............for those who like alternative ideas....
Automotive soundproofing sheets...are under the floor carpet and on the
firewall in cars. Why not use it in boats under the cabin carpet or for
engine room sound insulation.
Synthetic carpet ( most all is nowadays anyway) glued to the hull sides
would insulate and provide a non-dense area for condensation or humidity to
evaporate. (air space) Put a piece of carpet over a cold floor and what do
you get?
>>>>>This would work as long as the outside temperature is not too cold. If
the carpet itself gets below the dew point water will soak the carpet.
What would be some ways to glue the carpet?
>>>>>Contact cement, rubber cement, "Great Stuff"
Could you then add unfaced fiberglass batts over the carpet?
I know these are not the "accepted materials" to use but they are, or can be
fire rated for flame spread and would be inexpensive products for some of us
that are trying to convert or restore older boats to use for live-aboards.
>>>>>>>I have experience in having professionals come in and spray the
interior with urethane foam.
Yes, it took about a week to prepare. This consisted of removing all
removable items and exposing all of the interior of the hull. Then every
surface that will not be sprayed must be masked off. During the spraying the
entire interior of the boat will be filled with wet urethane "snow" which
will coat every surface.
You should also complete all attachments to the hull so all the steel
possible can be covered with foam.
One day the crew, who mostly do fish holds in commercial fishing boats,
showed up with their truck and sprayed the boat.
It took two of us about a week to remove the masking and excess foam.
Yes, it is a pain to do. Yes, you get what you pay for. There is absolutely
NO condensation anywhere except on the portholes, which of course, are not
insulated.
Yes, it is best way to do a steel boat. The urethane is closed cell, has a
skin on the outside surface and does eliminate corrosion of the inside of the
hull. Do everything, the underside of the deck, the hull, and the bilge too.
Norm
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