My NDK explorer took a smack when I was not looking.
I have a star crack about 2 feet long and 6 inches wide just under the
water line. There is no dent, just cracked jell coat. Any idea how to
fix this or stop water permeating into the glass underneath and
causing delamination in the freeze thaw cycle?
Thanks
Alex

Alex McGruer wrote:
My NDK explorer took a smack when I was not looking.
I have a star crack about 2 feet long and 6 inches wide just under the
water line. There is no dent, just cracked jell coat. Any idea how to
fix this or stop water permeating into the glass underneath and
causing delamination in the freeze thaw cycle?

I'd use gel coat filler, which your friendly neighbourhood ship's
chandler should have. The stuff I got was "Plastic Padding" and came in
hardener/goop two part. Mix together, apply along the wound after
giving it a rough sand to key it first and then once it's dry sand,
sand, sand. Start with rougher gauges and gradually move to finer, end
up using a polishing paste for best results.
Worked okay on my Selkie, and I'm hardly an expert handyman.

But since you're going to someone who knows about it to get the goop to
start with, have a word with them about it anyway. A couple of times
I've gone to get first aid stuff for minor repairs and been directed to
a much more suitable idea after discussing it with the chaps the they
do fibreglass for a living and know a helluva lot more about it than I do!

Pete.
--
Peter Clinch University of Dundee
Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

Peter Clinch wrote in message ...
Alex McGruer wrote:
My NDK explorer took a smack when I was not looking.
I have a star crack about 2 feet long and 6 inches wide just under the
water line. There is no dent, just cracked jell coat. Any idea how to
fix this or stop water permeating into the glass underneath and
causing delamination in the freeze thaw cycle?

I'd use gel coat filler, which your friendly neighbourhood ship's
chandler should have. The stuff I got was "Plastic Padding" and came in
hardener/goop two part. Mix together, apply along the wound after
giving it a rough sand to key it first and then once it's dry sand,
sand, sand. Start with rougher gauges and gradually move to finer, end
up using a polishing paste for best results.
Worked okay on my Selkie, and I'm hardly an expert handyman.

But since you're going to someone who knows about it to get the goop to
start with, have a word with them about it anyway. A couple of times
I've gone to get first aid stuff for minor repairs and been directed to
a much more suitable idea after discussing it with the chaps the they
do fibreglass for a living and know a helluva lot more about it than I do!

Pete.


Thank you Peter
Richard Hayes I think came up with the rest of the recipe. A Dremmel
Tool with a fine stone to rout out the cracks and fille ach crack.
I am going to take your advice and the little I know and see if i can
find a garage to beg or borrow and have at it.
I went to an auto body place to see what they could do. $1,000 Cdn.
ouch. Now it would look like new but I am not woried about that right
now.
Thanks again Richard and Peter.

Rick Hayes here. Since Alex mentioned my e-mail to him, I thought I'd post
it for the benefit of others.
Several repair strategies are possible - which I'd use
would depend on two things - the actual nature/shape of the crack itself,
and secondly how important the cosmetic finish is to you.
If the crack simply radiates in widely separated lines, you have the option
of routing out the cracks - maybe using a Dremel tool (very carefully) with
a fine bit or stone - then filling the resulting trough with either a
thickened epoxy paste (silica filler) or a two part epoxy putty. Allow to
cure, then sand off to fair the repair. Paint/gelcoat if appearance is
important.
If the damage is too extensive for routing out - lots of concentric circles
of cracks, for example - you can sand out the gelcoat from the entire area,
then rebuild it using thickened epoxy fillers and perhaps a top layer of
gelcoat. I don't bother with gelcoat - find that thickened epoxy fillers
work just as well. Of course, it leaves an off-colour patch, and it can be
difficult to get it faired in really well. But then, I tend to worry a lot
more about 'solid' than I do about 'pretty'.
A third option, although a rather barbaric one, is to simply whack a
fibreglass cloth/epoxy patch over the area - then fair in the edges and the
weave of the cloth as well as you can with thickened epoxy, and sand to
fair. Isn't pretty, but it'd at least keep water out of the laminate.
Finally, if the boat is stored outdoors, and freeze/thaw is a concern in the
short term - I'd be inclined to temporarily cover over the cracks with
TuxckTape until I got a chance to do the repair - the tape will leave a
sticky
residue, but hey, better a minor cleaning job than laminate problems.
Hope this helps.
Regards,
Rick

--
"You Shouldn't Have Joined
If You Can't Take A Joke"

Royal Navy Axiom
replace vk1nf with rhayes to reply



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On Thu, 19 Feb 2004 01:31:54 -0330, "VK1NF" wrote:

Rick Hayes here. Since Alex mentioned my e-mail to him, I thought I'd post
it for the benefit of others.
Several repair strategies are possible - which I'd use
would depend on two things - the actual nature/shape of the crack itself,
and secondly how important the cosmetic finish is to you.
If the crack simply radiates in widely separated lines, you have the option
of routing out the cracks - maybe using a Dremel tool (very carefully) with
a fine bit or stone - then filling the resulting trough with either a
thickened epoxy paste (silica filler) or a two part epoxy putty. Allow to
cure, then sand off to fair the repair. Paint/gelcoat if appearance is
important.
If the damage is too extensive for routing out - lots of concentric circles
of cracks, for example - you can sand out the gelcoat from the entire area,
then rebuild it using thickened epoxy fillers and perhaps a top layer of
gelcoat. I don't bother with gelcoat - find that thickened epoxy fillers
work just as well. Of course, it leaves an off-colour patch, and it can be
difficult to get it faired in really well. But then, I tend to worry a lot
more about 'solid' than I do about 'pretty'.
A third option, although a rather barbaric one, is to simply whack a
fibreglass cloth/epoxy patch over the area - then fair in the edges and the
weave of the cloth as well as you can with thickened epoxy, and sand to
fair. Isn't pretty, but it'd at least keep water out of the laminate.
Finally, if the boat is stored outdoors, and freeze/thaw is a concern in the
short term - I'd be inclined to temporarily cover over the cracks with
TuxckTape until I got a chance to do the repair - the tape will leave a
sticky
residue, but hey, better a minor cleaning job than laminate problems.
Hope this helps.
Regards,
Rick

The second option here is the best.

The latter is cheap and nasty and the former creates a weak repair.

Fibreglass is a rare bast that can actually be repaired to original
strength. feather back the damaged area to the fibreglass - carefully,
then lay on some matt and resin, sand, fill and sand, and then recoat
with gelcoat.

Two pack fillers are NOT waterproof which is why car bodies repaires
with filler end up with rust around the edges just before the filing
falls out :-)

The middle option is the hardest work but the best solution.

Ewan Scott

Ewan Scott wrote:

Two pack fillers are NOT waterproof which is why car bodies repaires
with filler end up with rust around the edges just before the filing
falls out :-)

Some may not be, some I think are. The one I used specifies boat
repairs as one of its jobs and was sold to me on recommendation by a
specialist fibreglass boat builder. Mileage varies...

Pete.
--
Peter Clinch University of Dundee
Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

On Sun, 22 Feb 2004 11:19:10 +0000, Peter Clinch
wrote:

Ewan Scott wrote:

Two pack fillers are NOT waterproof which is why car bodies repaires
with filler end up with rust around the edges just before the filing
falls out :-)

Some may not be, some I think are. The one I used specifies boat
repairs as one of its jobs and was sold to me on recommendation by a
specialist fibreglass boat builder. Mileage varies...

I'm not a chemist, but I did once research the commercially available
fillers on the market and at the time - three years ago, there were
none that were waterproof. They all use a filler material to bulk out
the mix, usually talc - which absorbs water.

It may be that there are some specialist fillers but you would need to
be sure that what you were buying was the right one.

Ewan Scott

Ewan Scott wrote in message . ..
On Sun, 22 Feb 2004 11:19:10 +0000, Peter Clinch
wrote:

Ewan Scott wrote:

Two pack fillers are NOT waterproof which is why car bodies repaires
with filler end up with rust around the edges just before the filing
falls out :-)

Some may not be, some I think are. The one I used specifies boat
repairs as one of its jobs and was sold to me on recommendation by a
specialist fibreglass boat builder. Mileage varies...

I'm not a chemist, but I did once research the commercially available
fillers on the market and at the time - three years ago, there were
none that were waterproof. They all use a filler material to bulk out
the mix, usually talc - which absorbs water.

It may be that there are some specialist fillers but you would need to
be sure that what you were buying was the right one.

Ewan Scott

Me Again.
This time I may proof read this.

I followed Richard Hayes instructions pretty much to the letter.
I ground the beast out with a Dremmel and found the cracks much deaper
that I previously thought. I ground through the boat in two spots.
I put some packing tape inside he hull to keep things in order as I
worked the ourside and got the gouges filled.
It is not going to be perfect but it is not bad.
I had about 10 yards of 10 Oz Fibre Glass cloth left over from a canoe
I built a long time ago. I used a little of that to reinforce the hull
under the repair.
Seems to work.
I am wondering how you get a reasonable gell coat back on there or do
I just paint it.

Right now I am not sure but I should just have reinforced the inside
and painted the begger. I am told I shuold have just left it because
it can last that way for years and only requires that level or repair
when it actually starts to break down

During my efforts I found another less pronounced star crack around
the skeg box.
That one I likely deserve as I remember one drop os some consiquence.

Are the NDK boats prone to star cracks?? I have one other glass boat,
It has one well deserved crunch but no star cracks. It is much more
flexable all over. The NDK has been babied.

Me Again.
This time I may proof read this.

I followed Richard Hayes instructions pretty much to the letter.
I ground the beast out with a Dremmel and found the cracks much deaper
that I previously thought. I ground through the boat in two spots.
I put some packing tape inside he hull to keep things in order as I
worked the ourside and got the gouges filled.
It is not going to be perfect but it is not bad.
I had about 10 yards of 10 Oz Fibre Glass cloth left over from a canoe
I built a long time ago. I used a little of that to reinforce the hull
under the repair.
Seems to work.
I am wondering how you get a reasonable gell coat back on there or do
I just paint it.

Right now I am not sure but I should just have reinforced the inside
and painted the begger. I am told I shuold have just left it because
it can last that way for years and only requires that level or repair
when it actually starts to break down

During my efforts I found another less pronounced star crack around
the skeg box.
That one I likely deserve as I remember one drop os some consiquence.

Are the NDK boats prone to star cracks?? I have one other glass boat,
It has one well deserved crunch but no star cracks. It is much more
flexable all over. The NDK has been babied.

Star cracks are gebnerally quite small and IIRC occur when the surface
has had a good dunt. The substrate matting flexes and the top coat gel
cracks.

By th sounds of your first patch you needed to repair the hull anyway.

These smaller ones - I'd just rough sand them, and paint with gelcoat.

HTH

Ewan Scott

Ewan Scott wrote in message
...

Me Again.
This time I may proof read this.

I followed Richard Hayes instructions pretty much to the letter.
I ground the beast out with a Dremmel and found the cracks much deaper
that I previously thought. I ground through the boat in two spots.
I put some packing tape inside he hull to keep things in order as I
worked the ourside and got the gouges filled.
It is not going to be perfect but it is not bad.
I had about 10 yards of 10 Oz Fibre Glass cloth left over from a canoe
I built a long time ago. I used a little of that to reinforce the hull
under the repair.
Seems to work.
I am wondering how you get a reasonable gell coat back on there or do
I just paint it.

Right now I am not sure but I should just have reinforced the inside
and painted the begger. I am told I shuold have just left it because
it can last that way for years and only requires that level or repair
when it actually starts to break down

During my efforts I found another less pronounced star crack around
the skeg box.
That one I likely deserve as I remember one drop os some consiquence.

Are the NDK boats prone to star cracks?? I have one other glass boat,
It has one well deserved crunch but no star cracks. It is much more
flexable all over. The NDK has been babied.

Star cracks are gebnerally quite small and IIRC occur when the surface
has had a good dunt. The substrate matting flexes and the top coat gel
cracks.

By th sounds of your first patch you needed to repair the hull anyway.

These smaller ones - I'd just rough sand them, and paint with gelcoat.


You'll not like this, having "done" your repair, but the next time round I
suggest you do all your prep work and then use packing tape to cover the
OUTSIDE of the hole. Now apply your gel coat (colored as necessary) from the
inside and leave o/night. Now build up your repair from the inside using
your chosen glass material. When you remove the packing tape you'll have a
nice smooth external finish.

I've done substantial repairs with this method with extremely good results,
including rebuilding the foredeck of a general-purpose boat to the extent
that the job was done in 3 stages to cope with all the different angles.

If you have a rummage in the forum/community on the ukriversguidbook site
you'll find an excellent summary from one Jim Wallis on the subject of the
appropriate materials to use. He sometimes looks in on what remains of this
group so maybe he'll post a summary.

The packing tape trick can also be used to good effect on simpler external
repairs using gel coat or gel coat filler (chandlers will have it) by
applying it on top of the gel coat and leaving it until the gel has set.

Mike.