With
a complete restoration and repower of an old boat there are lots of fiberglass
repairs. There are a lot of holes in the hull that need to be patched. Some
of them won't be needed with the restoration. Some of them will need to be relocated.
I'm going to fill every hole in the entire hull. When I am done if there are
any holes in the hull they will be nice, new, clean holes that I cut myself.
So, the holes for the exhaust, steering cable, bolt holes for trim tabs, etc.
need to be filled. There are also a lot of chips and gouges in the gel coat
that need to be filled.
Small holes, like the
bolt holes for the trim tabs can just be filled with epoxy putty, but larger
holes are structurally important and require more extensive repairs.
The first step is grinding
an angle around the holes. The angle should be 12:1 (the width of the grind
should be 12x the thickness of the hull). This gives a good area for the repair
to adhere to and gives maximum strength to the repair.
I'm doing the grinding
with a 6" disk sander with a very coarse disk (36 grit). The grinding
is miserable. Fiberglass dust gets everywhere and it is very irritating to
your skin. I have been wearing a dust mask.
I hope you've found my
web page useful (or at least amusing). If you're also restoring an old fiberglass
boat I'd like to hear from you.
Please remember that
I'm not advocating or recommending that you take any course of action. I'm
just describing my experiences. I will not accept any responsibility or liability
if you injure yourself (or someone else) working on a similar project. I'm
not a professional boat restorer. I have no affiliation with any company mentioned
on this web page except as a satisfied customer.
With
the outside of the holes ground to the appropriate angle, I applied a fiberglass
patch to the inside. I very lightly ground the inside (just to get down to a
clean surface) and applied a piece of fiberglass matt that substantially overlaps
the hole. This is really just to provide a backing for the repair.
For
each hole to be repaired (each large hole), I cut a series of fiberglass pieces
of gradually increasing size. Laminated into the hole with the angle ground
out these will fill the hole and create a very strong repair.
When
the fiberglass disks are laminated into the hole they fill the space completely
and the surface can be sanded down to match the original contour. This results
in a repair that will be invisible when painted and is at least as strong as
the original fiberglass.
Many
small holes and chips in the gel coat don't require such extensive repair. Many
can just be filled with epoxy. But, the epoxy resin is very thin and to make
it hang on vertical surfaces and convert it to a putty it needs a thickening
agent. I've been using fumed silica. Although some sources recommend 1:1 ratio
(by volume) I've found that it needs 1.5 or 2:1 to make a useful putty.
The
fumed silica is easily the most intractable substance I've ever tried to work
with! It is a very fine fluffy powder. Part of it clings tenaciously to any
surface it contacts. Part of it leaps out of any container and floats around
(until it finds a surface to cling to). It REALLY doesn't want to be mixed into
the epoxy resin. With patience you can use it to make an epoxy putty that can
be used to fill those chips and gouges. It's still not an easy to work putty.
It tries to pull out of the holes you put it in. It's also quite transparent,
so it isn't easy to see where the putty is and where it isn't. Despite all that,
you can fill the holes in the gel coat and then sand down the putty to get a
surface ready for painting. The fumed silica doesn't seem to make the resin
hard to sand.
There is an absolutely
incredible number of holes, chips, gouges, etc. to be filled. This (restoration
of this boat) is easily the biggest project I have ever undertaken (in terms
of man-hours required.
But...the transom is
looking pretty good with a bunch of patches all sanded down and ready for
paint.
Filling the chips/gouges
in the gel coat is proving more difficult than patching the big holes. The
thickened epoxy resin is tough to work with. It looks like the best approach
is to assume that every repair will require multiple layers of putty (thickened
resin). Apply a little resin, sand it down, apply more resin, sand it down,
etc.
The toughest repairs
are where there are big gouges along the chines of the hull. It's hard to
build these back to the original contours. Heck, it will be worth all the
work when the boat is all done! Right?
The
biggest hole to be repaired was where the outdrive was removed. This needed
to be completely closed up and needed to be as strong as the rest of the transom.
The process was similar to the repair of the other holes, but needed some minor
changes since this hole is so much larger than the others.
Just
like the repairs to the other holes, I started by grinding an angle around the
hole. The grind isn't even because the thickness of the transom varies a lot.
Because the transom is curved, when repairing a hole this large it is much more
difficult to match the original contour of the hull.
The main difference in
this repair is the piece of fiberglass applied to the inside of the hull to
back up the repair. This hole is too large to just hang a piece of dry cloth
across and try to wet it with resin. I cut a piece of cloth to cover (generously)
the inside of the hole and laid it on a plastic drop cloth. The I wet it with
resin and let it harden until almost hard. Then I glued it into the
inside of the hull with some blocks and supports to hold it into place.
The rest of the repair
was just like the other holes. Just a matter of laminating pieces of cloth
into place to fill the hole.
After
many (MANY) rounds of filling with putty and sanding down the repair finally
looks pretty good. With the paint on it it is barely noticeable. It isn't perfect,
but you have to look at just the right angle in just the right light to see
that it doesn't exactly follow the contour of the rest of the transom.
