Listen to Terry. Filled resin has no place in this repair.

Terry Spragg wrote:
Chris wrote:

Howdy all,

I've got some visible cracks at the bottom of my hull on my 16ft
runabout. This past summer when using the boat I was getting a bit of
water in it after having it sit for a while in the water (the bilge
pump easily took care of it). I'm now thinking that these cracks may
be the cause and water slowly seeps into the boat.

Now, my question about how I should attempt to fix this giving the
following considerations 1. It's an old boat. 2. I use it a 4-5
weekends a year. 3. I don't want to spend a lot of money as its not
worth it.

My ideas have been the following:

1. The ugly job
- rough up the area around the crack and put a few fiberglass
patches on it (poly resin & cloth)
- paint over it

2. Cleaner job
- grind out the crack and a bit of the area around it (make a V)
- fill with fiberglass resin, or epoxy resin using a filler
- not sure if a cloth patch on top of this would be necessary.
- paint over it

What do you guys think given the considerations?


Close, no cigar. Grind the Vee on the outside, feathering out 5 times
the thickness of the glass, leave it rough. Wash it with acetone.
Laminate several layers of glass, starting with a narrow strip, covering
with wider strips until you fill up the Vee. Smooth and paint /
gelcoat. Wet the glass, but try to use more glass and less resin.
Squeeze the bubbles out (don't mix the goo too vigorously, just
thorougly) using a serrated roller made from 2 sizes of washers loose on
bent threaded rod with locked nuts. Clean tools with acetone.

You should also do the same on the inside, or could just lay a couple of
wider strips on the roughened inside, where you can, washing the cleaned
inside with acetone before laminating.

You will find polyester strong enough, if you get enough thickness and
surface area covered and well bonded. Epoxy would be stronger, but is
overkill, and will make the question of refinishing the exterior gelcoat
into a can of worms, because poly gelcoat doesn't stick to epoxy, so you
would need to redo the entire hull with epoxy paint to achieve a Bristol
appearance.

Polyester Gel coat is just catalyzed polyester resin with pigment and a
little thickener, like silica gel, or, I am sure others have their
favorites. You can brush it on with several / many thin freshly mixed
coats applied while the hull is still tacky and buff it flat and smooth.
It is self levelling, especially if you can turn the boat so you are
painting on the level. If you get a good colour match (on the bottom?
who cares?) you won't be ashamed of it. Don't use bondo, it just isn't
as good as it could be, with automotive fillers, etc.

Are you sure the cracks go right through? If so, gring the crack a
little beyond the torn glass. You may only want to redo the gelcoat, if
that is as deep as they go.

Water collects in boats, even condensation can get inches deep, and rain
could be getting in, too.

Terry K

How I would fix it:

I would grind the inside, only, and put 3 to 4 good layers of glass
inside, starting with mat, then roving, then mat, then roving, in
progressively larger pieces. Do it all at one time.

The resin that seeps outside then is sanded smooth to the hull. A
little gel coat with some scotch tape over the patch, then sand with 600.



Jim wrote:

Listen to Terry. Filled resin has no place in this repair.

Terry Spragg wrote:

Chris wrote:

Howdy all,

I've got some visible cracks at the bottom of my hull on my 16ft
runabout. This past summer when using the boat I was getting a bit of
water in it after having it sit for a while in the water (the bilge
pump easily took care of it). I'm now thinking that these cracks may
be the cause and water slowly seeps into the boat.

Now, my question about how I should attempt to fix this giving the
following considerations 1. It's an old boat. 2. I use it a 4-5
weekends a year. 3. I don't want to spend a lot of money as its not
worth it.

My ideas have been the following:

1. The ugly job
- rough up the area around the crack and put a few fiberglass
patches on it (poly resin & cloth)
- paint over it

2. Cleaner job
- grind out the crack and a bit of the area around it (make a V)
- fill with fiberglass resin, or epoxy resin using a filler
- not sure if a cloth patch on top of this would be necessary.
- paint over it

What do you guys think given the considerations?



Close, no cigar. Grind the Vee on the outside, feathering out 5 times
the thickness of the glass, leave it rough. Wash it with acetone.
Laminate several layers of glass, starting with a narrow strip,
covering with wider strips until you fill up the Vee. Smooth and
paint / gelcoat. Wet the glass, but try to use more glass and less
resin. Squeeze the bubbles out (don't mix the goo too vigorously,
just thorougly) using a serrated roller made from 2 sizes of washers
loose on bent threaded rod with locked nuts. Clean tools with acetone.

You should also do the same on the inside, or could just lay a couple
of wider strips on the roughened inside, where you can, washing the
cleaned inside with acetone before laminating.

You will find polyester strong enough, if you get enough thickness and
surface area covered and well bonded. Epoxy would be stronger, but is
overkill, and will make the question of refinishing the exterior
gelcoat into a can of worms, because poly gelcoat doesn't stick to
epoxy, so you would need to redo the entire hull with epoxy paint to
achieve a Bristol appearance.

Polyester Gel coat is just catalyzed polyester resin with pigment and
a little thickener, like silica gel, or, I am sure others have their
favorites. You can brush it on with several / many thin freshly mixed
coats applied while the hull is still tacky and buff it flat and
smooth. It is self levelling, especially if you can turn the boat so
you are painting on the level. If you get a good colour match (on the
bottom? who cares?) you won't be ashamed of it. Don't use bondo, it
just isn't as good as it could be, with automotive fillers, etc.

Are you sure the cracks go right through? If so, gring the crack a
little beyond the torn glass. You may only want to redo the gelcoat,
if that is as deep as they go.

Water collects in boats, even condensation can get inches deep, and
rain could be getting in, too.

Terry K

Chris wrote:

I've got some visible cracks at the bottom of my hull on my 16ft
runabout. This past summer when using the boat I was getting a bit
of water in it after having it sit for a while in the water (the
bilge pump easily took care of it). I'm now thinking that these
cracks may be the cause and water slowly seeps into the boat.

Now, my question about how I should attempt to fix this giving the
following considerations 1. It's an old boat. 2. I use it a 4-5
weekends a year. 3. I don't want to spend a lot of money as its not
worth it.

snip

Based on the above, you need a functional repair, but this is no gold
plater, so the finish of the repair can basically be slim or none;
however, the repair should do a proper job.

My solution will be prejudiced since I run an epoxy shop.

IMHO, polyester is for shower stalls, not boat repairs.


1) Buy a 1 qt kit of laminating epoxy, a yard of 17 oz biaxial, knitted
glass, some 2" chip brushes and some latex gloves.

2) Flip boat upside down and grind back from the crack about 4" using a
24 grit, right angle sander. Leave the sanded surface ROUGH, the rougher
the better.

3) Lay 2 layers of 17 oz glass using the 2nd layer to over lap the first
layer about (1")-(1-1/2") all around.

4) Let cure 48 hours, then scuff up with 24 grit sander and lay 2 more
layers of 17 oz glass as above.

5) Wait 48 hours then fair edges of patch fair with boat using 24 grit
sander.

6) Flip boat over, scuff up inside and lay 2 layers of glass, same as
outside.

7) Get a beer, maybe 2.

8) Allow inside patch to cure about 72 hours, then relaunch boat and enjoy.

Notice the lack of labor intensive finish work?

OK, if you are fussy, fair out edges of inside patch, otherwise, forget it.


Lew

Lew Hodgett wrote:

so the finish of the repair can basically be slim or none;
however, the repair should do a proper job.


Very true

My solution will be prejudiced since I run an epoxy shop.

IMHO, polyester is for shower stalls, not boat repairs.

Since the rest of the boat is polyester, why should a patch be stronger
than the rest of it? I do use WEST for little things, but a patch
should be the same material the rest of the boat is made of.


Step 1)
Since the boat was built from the inside, I would just do the repair on
the inside. This way there's no finish work on the outside.

Steps 2-6) Grind, mat, roving, mat, roving, gloves, resin, hardener,
roller, don't make a mess. . .


7) Get a beer, maybe 2.

Admire your work while drinking beer.

8) Allow inside patch to cure about 72 hours, then relaunch boat and enjoy.

Notice the lack of labor intensive finish work?


Jim

Jim wrote:
Since the rest of the boat is polyester, why should a patch be stronger
than the rest of it? I do use WEST for little things, but a patch
should be the same material the rest of the boat is made of.


It's not an issue of strength of the material itself, but of bonding
strength. What you are making is called a "secondary bond" meaning that
it's trying to stick to something that's already cured.

Polyester is OK for lay-ups but it's bonding properties are poor, even
to polyester.

It is cheaper, but unless you are really dedicated to squeezing pennies,
and have already wrung the expense out of everything else on the boat,
and don't have any other little projects that epoxy would be best for,
then it's false economy IMHO.

Fresh Breezes- Doug King