Hello, would like some advice please

My boat has allot of (what I think is) gellcoat flaking off around the
underside of the hull and on the keels. The flaking is exposing the
GRP underneath, and the flakes are about 3 - 4mm thick I would say -
as far as I know this is the gellcoat. The flaking is not in any sort
of pattern, it is not centered around any stress points etc, it is
more random looking, just looks like old paint flaking off from age
really. The boat is about 40 years old. There is no sign of any
blisters (I know this doesn't mean there is no hydrolysis). I
obviously want to seal it back up to prevent any more moisture getting
into the hull.

So, my question is, what is the best way to go about this? Should I
use a belt sander to strip the flaking gellcoat away, and apply a new
coat? Anything better than a belt sander? I'm not looking to dry the
hull out and fully restore it, I just want to stop more moisture
getting in when I use it this season.

Any advice, opinions, etc welcome

On Thu, 8 Apr 2010 09:44:19 -0700 (PDT), wheewhoo wrote:
Any advice, opinions, etc welcome

What size boat? Can you flip it upside down to work on it?
Look at thread " Peeling fiberglass surface" that was running a couple
of weeks ago.
Does your peeling look like this?
http://s958.photobucket.com/albums/a...0Seas%20Skiff/

Rick

On Apr 8, 10:33*pm, wrote:
On Thu, 8 Apr 2010 09:44:19 -0700 (PDT), wheewhoo wrote:
Any advice, opinions, etc welcome

What size boat? *Can you flip it upside down to work on it?
Look at thread " Peeling fiberglass surface" that was running a couple
of weeks ago.
Does your peeling look like this?http://s958.photobucket.com/albums/a...0Seas%20Skiff/

Rick

Hi Rick, it is a 20ft boat, but access is ok to the effected parts. It
does look similar to those photos, but my coating is much thicker, and
is flaking off in much smaller parts, with only very small areas of
fiberglass showing where pieces have fallen out. The surface looks
more shattered than peeling, but that is due to the thickness of the
coating I suppose.

I'm thinking to just remove the coating, or gel coat if that's what it
is, and seal it up again. A very gritty belt on a belt sander would do
it I think. If this is a gel coat, is it normal to be so thick? Could
this also be layers of paint applied over the years? When crushed the
flaked pieces snap and are brittle. I suppose you are going to ask for
a photo now

On Apr 8, 10:33*pm, Phantman wrote:
On Thu, 8 Apr 2010 09:44:19 -0700 (PDT), wheewhoo wrote:
Any advice, opinions, etc welcome

What size boat? *Can you flip it upside down to work on it?
Look at thread " Peeling fiberglass surface" that was running a couple
of weeks ago.
Does your peeling look like this?http://s958.photobucket.com/albums/a...0Seas%20Skiff/

Rick

Hi Rick, it is a 20ft boat, but access is ok to the effected parts. It
does look similar to those photos, but my coating is much thicker, and
is flaking off in much smaller parts, with only very small areas of
fiberglass showing where pieces have fallen out. The surface looks
more shattered than peeling, but that is due to the thickness of the
coating I suppose.

I'm thinking to just remove the coating, or gel coat if that's what it
is, and seal it up again. A very gritty belt on a belt sander would do
it I think. If this is a gel coat, is it normal to be so thick? Could
this also be layers of paint applied over the years? When crushed the
flaked pieces snap and are brittle. I suppose you are going to ask for
a photo now

Well... yeah, a photo is worth 1000 words. But even a photo might not
be enough. If you can actually see the resin and the glass though,
then the gel coat is missing. So either it's flaking off now, or it
was knocked off previously and somebody painted over the ding and now
the paint is flaking off. Or possibly someone tried to patch it with
Bondo or something and now THAT is falling off. Lots of possibilities
I suppose. But without actually seeing it, it's tough to know. And
even a photo might not show the situation clearly. You'll have to
scrape around under there to figure out what layers are (or were)
there, and if you're looking at a new situation or an old failed patch
job. But sounds like you'll need to clean out the dings or whatever
they are and then fill and fair the bottom. Then repaint with bottom
paint if you're leaving it in salt water.

Rick

On Thu, 8 Apr 2010 15:32:24 -0700 (PDT), wheewhoo
wrote:

On Apr 8, 10:33*pm, wrote:
On Thu, 8 Apr 2010 09:44:19 -0700 (PDT), wheewhoo wrote:
Any advice, opinions, etc welcome

What size boat? *Can you flip it upside down to work on it?
Look at thread " Peeling fiberglass surface" that was running a couple
of weeks ago.
Does your peeling look like this?http://s958.photobucket.com/albums/a...0Seas%20Skiff/

Rick

Hi Rick, it is a 20ft boat, but access is ok to the effected parts. It
does look similar to those photos, but my coating is much thicker, and
is flaking off in much smaller parts, with only very small areas of
fiberglass showing where pieces have fallen out. The surface looks
more shattered than peeling, but that is due to the thickness of the
coating I suppose.

I'm thinking to just remove the coating, or gel coat if that's what it
is, and seal it up again. A very gritty belt on a belt sander would do
it I think. If this is a gel coat, is it normal to be so thick? Could
this also be layers of paint applied over the years? When crushed the
flaked pieces snap and are brittle. I suppose you are going to ask for
a photo now

If you can actually see the underlying fiberglass material, and you
know that it is fiberglass then, if you want to fix it, you will have
to at least sand the areas back until you know that you have reached
some sort of solid foundation. The "blisters will need to be "dished
out" with the, now, sharply delineated indents, sanded back to blend
them into the remaining surface. You can then paint the repair area
with activated epoxy resin (this wets out the area and ensures that
you do have 100% epoxy coverage) and then fill the dished out area
with epoxy filler made with epoxy resin and a thickener. Sand smooth,
paint with epoxy high build primer and sand again, spray finish coat
of two part polyurethane paint.

Have a look at the WEST System web pages for more detailed information
complete with pictures.

..
Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Hi guys, thanks for the replies.

So what I need to do is sand off the gelcoat (and whatever other
layers are there), as I can definitely see the fiberglass where flakes
have come away.

Do I just need to prepare the bare (fiberglass) surface, and apply a
new gelcoat? Or do I need layers of other stuff also? Lets say I have
a large area of hull/keel that I have sanded back to the fiberglass.
What are the steps I should take? Phantman mentioned bottom paint, and
Bruce mentioned epoxy. Would it be epoxy, then gelcoat, then bottom
paint?

Thanks for the help!

On Sun, 11 Apr 2010 11:13:54 -0700 (PDT), wheewhoo
wrote:

Hi guys, thanks for the replies.

So what I need to do is sand off the gelcoat (and whatever other
layers are there), as I can definitely see the fiberglass where flakes
have come away.

Do I just need to prepare the bare (fiberglass) surface, and apply a
new gelcoat? Or do I need layers of other stuff also? Lets say I have
a large area of hull/keel that I have sanded back to the fiberglass.
What are the steps I should take? Phantman mentioned bottom paint, and
Bruce mentioned epoxy. Would it be epoxy, then gelcoat, then bottom
paint?

Thanks for the help!

The basic task if to protect the underlying fiberglass from UV damage
(a real threat in tropical climates) and water ingress which may take
place over a longer period of time. There are two basic methods, to
apply a gel coat or to paint, usually with an epoxy based paint.

The gelcoat is much harder to apply and have a nice smooth shiny
surface. The paint is much easier to apply but perhaps not as long
lasting.

Gelcoat Method.

Grind/sand, the damaged areas back to a good solid surface. This
surface can be either fiberglass or gelcoat but it MUST be a good
solid surface. If gelcoat you must be certain that it is attached
firmly to the underlying fiberglass.
Once you have reached your base surface you must then "fair" the
surface as smooth as possible as any craters, dips humps, etc. on the
surface will be mirrored in the final finish. You can do this by
grinding/sanding the surface until it is flat or you can build up the
low spots with an epoxy filler using any of the harder, stronger
fillers.
Once things are fair you then sand with varying grades of sandpaper to
about a 500 grip sandpaper.

Gelcoat is nothing more then polyester resin with a coloring agent in
it and comes in many colors. The mix also has a "wax" incorporated in
it that when it is applied floats to the surface and causes the
polyester to harden with a non-sticky surface.

The gelcoat can be applied with a brush or by spraying but no matter
how it is applied will probably not be the smooth, shiny, beautiful
coating that you have envisioned. It needs work.

Sand the gelcoat with progressive grades of sandpaper down to at least
1,000 grit and preferably finer. Once you have the surface as smooth
as possibly then buff the surface to the required finish using a
buffing wheel and polishing/buffing compounds as used for paint.

If you did a good job it will be beautiful.

Painting - Basically you do all the preparatory steps to get the hull
smooth and fair and then apply two coats of epoxy resin to seal the
hull. One method to avoid the "epoxy blush" problem is to apply the
second coat of resin before the first coat is completely hardened.
When it is no longer sticky but not hardened completely so that you
can press your finger print into the epoxy apply the next coat.
Finally after the last coat of epoxy (before it completely hardens)
apply at least one coat of epoxy high build primer.

Sand the hardened primer with about 400 grit sandpaper and do any
touching up, sand again if necessary, and spray two coats of two part
polyurethane paint.

It will be beautiful if you did a good job.

But don't kid yourself , either method is a substantial amount of
work. The gelcoat considerably more work, but neither is a Sunday
afternoon project.


Cheers,

Bruce
(bruceinbangkokatgmaildotcom)