. You will know when you got it all cleaned up well with the grinder/sander…don’t go wild

Boat
bottom blisters look like just that, a blister. Multiple blisters
look like a bunch of pimples and they might be in various sizes. Some
of these boat blisters can get the width of a softball and stick out
from your boats bottom quite a ways. Blisters
don't care if you have a Powerboat
or
Sailboat,

and
it can get pretty ugly
if not taken care of at early stages, but if you do catch it early,
(which you usually can) there’s no big deal about it. I know it
might seem like a big deal, when you see all those boat
blisters/pimples when you haul out, but it really isn’t. You can
really handle this, just take it one step at a time…no problem.

Boat
Bottom Blisters form basically from water/moisture being absorbed
under the gelcoat where an air pocket/space might have been. If there
is raw fiberglass fibers, it will also move into that…. There are
many reasons. As more water in an area gets absorbed, its pressure
gets greater than the surrounding water and bulges out, thus a boat
blister. Many boats and yachts in the northern waters don’t have
this problem as much because of the temperature of the water and one
other factor. They haul-out for the winter months, giving the bottom
time to dry out. They get hauled Oct-Nov and don’t go back in till
April-May. This gives the hull bottom 4 to 5 months to dry out, so
the water absorption stays in check. Another way a boat gets all
those small blisters and pimples all of a sudden is when they haul
their
boat
or yacht
out
on a hot sunny day. The water that has been absorbed under the
gelcoat expands quickly from the heat, and out they come. I’ve seen
this myself in Ft. Lauderdale, Florida when a boat was being hauled
out. The boat had black bottom paint and a perfectly smooth bottom.
As it was still in the slings, the pimples/blisters like chicken pox
started appearing! Some small, some bigger, but a whole bunch. Funny,
it was just in the area where the bright Florida sunlight was hitting
the boats bottom. It was the sun heating up the water beneath the
gelcoat. Now let’s get to repairing these…

Basically
if you just have a small area of them, or a few here and there, this
is one way to repair them. For more extensive areas or real large
blisters that ooze with gooey liquid, I’ll have to do another blog
if visitors are interested on the repair….Email meat
info@yachtauthority.com
or leave it in the “Comment” area below.

First
I would take chalk or a crayon and circle the boat blisters.
Sometimes a few will disappear which you would think would be good,
but in the long run, why let it fester? You see it, know where it is,
and you’re doing the others, so do the ones that disappear. Pop the
blisters/pimples by using a pick, punch, flathead screwdriver or a
small narrow chisel to scrape the gelcoat off and expose the
fiberglass bottom under the gelcoat. This lets any water out.

Next
wipe away any water/liquid, and using a grinder or good orbital
sander with 60-80 grit sandpaper grind/sand away any loose material
on, in, around the boat blister/pimple (remember to use a mask and
read all instructions and cautions on anything you use). You will
know when you got it all cleaned up well with the
grinder/sander…don’t go wild, these small ones (up to about ?
inche) don’t need that much grinding and sanding. Once the area
looks uniform with no loose material or discoloration, that should be
fine. Don’t dig in too much, you don’t need to. Take a
screwdriver and pick around where the blisters/pimples were to see if
there are any hollow spots.

Now
the hard part…Drying time! This would be great if you can leave it
for a few months out of the water like up north. If you don’t have
the time (month or more) to leave it to dry, you can accelerate the
process by adding heat, like heat lamps or flood lights that give off
a uniform warming heat…nothing that becomes too hot to touch. This
will get the moisture out, and a moisture meter will give you the
information you want…one of those small great gadgets! You and I
know you’ll only give it so much time to dry, but the longer the
better…for the whole hull a matter of fact!

Wipe
the areas with a moistened rag with acetone, clean the areas well. To
fill in any irregularities, make-up a filler using resin and those
micro fillers from any Marine
Supply
or
on Yacht Authority.com (Leftside Menu Bar). Thicken your resin to
almost a paste, remember to use the hardener and apply with a putty
knife. On bigger depressions, use a little bit of filler at first to
get all the way in, leaving no air spaces. Then add more to level it
out to the original surrounding surface. Again you can tape the areas
off (read
Boat
Fiberglass Tabbing),
so to keep your working area tight which will mean less to sand. Let
your filler dry, sand with 180 or 220 grit sandpaper, using an
orbital sander or hand block sander depending on the area to be done.
If you need it smoother, finish with 320.

It
is amazing, but you’re done…easy and you just added more value to
your Boat!…and if you have larger areas, you can do it in sections
so you don’t get overwhelmed… It would be good to use a barrier
coat product before putting on your bottom paint…it makes it harder
for the water/moisture to get back in, especially if your boat or
yacht stays in the water year round…..plus since you did such a
nice job… Why Knot?