Björn:
I never have figured out how to get
an umlaut out of my keyboard so I have to cut and paste ;-)
Condensation is a constant and
ongoing issue which is aggravated by uninsulated hull sides, and
the higher humidity from having people living in a boat. If
insulation is permeable, or there is paneling between the interior
and the hull the condensation simply is removed from the visible
surface to the invisible one. There really is no reason why boat
windows cannot be double pane, which would greatly reduce the
problem, as plexiglass or polycarbonate already have a
considerably lower thermal conductivity than glass. If the
humidity inside the boat is high, and the surfaces are cold enough
to lower the contact temp below the dew point for the relative
humidity of the air in the boat, you will get condensation.
Constant and sufficient ventilation is one answer, and one
trimaran owner built a venturi system that used the underwing to
create a draft, and created channels throughout his boat to direct
this outside air where it was needed, and completely eliminated
the problem for his boat that sat at a mooring unoccupied a lot...
correct me if I'm in error please, it's been awhile since I read
this.
http://www.trimariner.com/searunner/Vent_Sys_1.html
This would be applicable to any
boat swinging on anchor or mooring but is especially suited to
something like a multihull that has an underwing that creates a
natural venturi that is going to naturally align with the wind.
Another approach might be a "sacrifice surface". An uninsulated
smooth vertical surface that was easily accessible for cleaning,
and had a gutter. A muffin fan such as is used in computers
would run 24/7 in cold temps, circulating the humid interior air
across this surface, which would be behind a false front. This
cold surface would act as a natural dehumidifier, the water
created by condensation being directed to a sump. With a good
clean surface and a HEPA filter, this water would actually be
useable fresh water that could be directed right into the tanks
just like rain water if you designed it correctly. Sometimes it
makes sense to harness natural processes such as condensation
rather than fighting them. Control where condensation happens
and utilize the product.
Perhaps this is a strange "outside
the box" way of looking at this problem....... convention does not
appeal to me, and I've learned from men like Buckminster Fuller,
Burt Rutan, and Rob Denny to look outside the box for
answers..... some of them don't work, but others do.......
H.W.
Nobody buys boats based on insulation around
here.. Never heard anyone discuss it. And almost all boats
are solid glass/polyester with gelcoat. There are of
course some foam composite boats too, but not chosen for
their insulation properties.
When building the boat yourself it's of course a
parameter to consider. Especially if you, for example,
want to heat it with battery power. But the surface to
heat is small. There's not really a problem with
heating. I know a girl who have lived for years in a 28
foot monohull sailboat heated with a small radiator. No
issue with being cold, she says. The ocean is always
above 0 °C, so the gradient is not huge. That being
said, I would of course tend to choose a slightly
thicker foam in the WW hull if I would make my own boat.
Would be good just to prevent condensation. But it's
still going to be present at windows, so not sure if
it's worth it. But I guess with a completely
solar/battery energy source for heating it would be
possible to have a dehydration unit running inside. And
better insulation would reduce the consumption. But in
the winter a diesel heater or electrical connection to
the dock would be necessary still.
Do you imagine Steinar made decisions on his
boat to have thicker sections of foam between
the water and the interior? I wonder about his
ww hull, but think it is mostly speed
decisions.
Rob does solid glass for the radius of the
corners. The foam tapers into and out of these
radius as has been discussed That would be
easy to foam fill post infusion, as has been
discussed.
Steinar's lw hull is the older style rounded
box with contiguous foam. Perhaps that's more
appropriate for the cold?
How are Northern sailors/cuisers boats
different?
How would you modify a HP for above the Arctic
circle sailing?
Enclosed cabin with insulated doors seem to
make sense.
The North has fresh breezes that even Rob
could not tolerate for too long I imagine.