Your solutlion depends on the boat. Your choices are sprayed PU, styrofoam
sheet and rock wool. If the boat is metal, preventing condensation is the
overwhelming requirement to prevent corrosion, so a vapor barrier is also
needed. Please remember that sprayed PU is NOT closed cell so it absorbs
liquid. It is terrible to remove and in fire, the fumes are deadly. The same
is true for polystyrene, but it does not absorb liquid and contact cement
melts the foam. Rock wool is the best for large boats that require more than
3 in. of insulation. It can come with an infra-red and vapor barrier and it
is easy to replace if it gets wet. Additionally it has the best R rating as
well. It does not outgas, nor does it create deadly vapor in a fire.
Steve

"MarshallE" wrote in message
...
Hi,

I am guessing that standard home insulation is not the normal for boats
due
to trapped moisture and mold.

What should I use and where should I buy from?

thanks
marshall