I have discovered that I have wet core in several locations on my
cabin top. My limited experience with fiber glass has been with West
System Epoxies and I am comfortable with their use. The bottom skin
has been removed, the wet core excised and the top skin abraded and
prepped for bonding. I intend to wet out the underside of the top skin
and use Baltek Contour Kore AL600/10 to replace the core. After that
cures, I need to build up a bottom skin of at least 3/16". I need a
layup schedule that will give me max strength with the fewest number
of plies. This is a winter project. I will be able to maintain 40* in
the boat and intend on using the fast hardener. All suggestions are
welcome and hints as to technique or alternate methods are
appreciated.

Marc wrote:

I have discovered that I have wet core in several locations on my
cabin top. My limited experience with fiber glass has been with West
System Epoxies and I am comfortable with their use. The bottom skin
has been removed, the wet core excised and the top skin abraded and
prepped for bonding. I intend to wet out the underside of the top skin
and use Baltek Contour Kore AL600/10 to replace the core. After that
cures, I need to build up a bottom skin of at least 3/16". I need a
layup schedule that will give me max strength with the fewest number
of plies. This is a winter project. I will be able to maintain 40* in
the boat and intend on using the fast hardener. All suggestions are
welcome and hints as to technique or alternate methods are
appreciated.

Is that 40* Celcius ot Farenheit?

Look at the underglass surrounding your area.

One thin skin? Mine was. The shape is concave, an archway that does
not depend on tension for support.

Try building a bench or support up under the application, a foot
below it. Consider a plastic or disposable drop cloth or papers.
Lay out a prepared plastic garbage bag under target area. Lay out
wetted glass on bag, resin dipped or poured, and wet brushed
overhead. Inflate bag.

Use as much glass as you think you need. One or two scrims aught to
to it. You could level it all under with peanut butter mix first,
but does it matter much, overhead in the wet locker? Catch drips.
Heat outside, too, with plastic bag tube with small vent filled by a
little heater fan? A vacuum cleaner exhaust should do it.

Maintain pressure until cured. It may be possible to seal the bag
and stop the fan. Air pressure in the bag should then push the
glass up to cure.

You may want to add a little thickener.

If you use a clear bag, you may see any bubbles trapped between top
and cloth. You might sweep them out with a soft bag and extra hands.
Good game of twisters, what?

You can feed the air through a tube made from plastic film and duct
tape, or a plastic bag pulled through a bisected "goose strangler"
beer can tether or two, or dryer vent. A twist tie will leak after a
while, so maintain pumping capacity (inhale!) until cured or tacky
enough to press up geotex, cloth or paper. This would be a good time
to properly dispose of the orphan beers. You can paint fuzzy geotex
any colour, but you may be happier with burlap, or some safer finish
coating, even simply paint, considering fire and fumes.

You could constrain the inflated shape with a piece of tape or
fishnet laced to whatever shape you need. If you surround the bag
with net, lay it out and cover it with waxed paper taped together
securely before you lay out the glass and proceed with pumping.

Try a dry run with wet newspaper simulating the weight. The bag may
push sideways when filling. Find and eliminate pokey hole makers, or
protect with a wad of tape.

I tore up my topsides, portside. Let us know how you do. I am
pondering the starbord side. There's a lot of stuff in the way under
the side decks!

Terry K

In spite of the added complication of repairing the finished deck
surface, this kind of repair is usually done by removing the top skin,
then working down. That's easier. Is it possible to turn the boat
upside down so you're working downwards? You didn't identify the type
of boat, so I had to ask.
If not I'd think about vacuum bagging and sucking from the top side
through the top side.
Get the West System booklets on fiberglass boat repair and on vacuum
bagging techniques. They're very good and complete.
I'm sure that others will think of refinements , but here's my rough
outline of the 'stack" from bottom to top:
I'm assuming that the deck has some compound curvature.
- the vacuum bag itself
- a layer of peel ply
- a layer of glass cloth, saturated
- maybe 36-48 oz./yd^2 of knitted glass, saturated
(the glass plies to be tapered out over the feathered edge of
the old laminate.
3/16" is probably much thicker than the FRP needs to be.
Consider using slightly thicker foam.)
- your foam, kerfed from both sides so that it'll pass resin and vacuum
- some thickened resin, to bond the foam to the upper skin
- the old upper skin, with holes drilled at intervals to pass excess
resin and vacuum
wax the upper skin well and spray with PVA before drilling
- another sheet of peel ply
- a layer of bleeder-breather
- the upper bag, with vacuum tap(s) in it.

I'd think about laying up he whole lower stack from bag to foam on a
slightly oversize piece of plywood.
Assemble the upper stuff, lay up the stack, offer it to the opening,
tape off the bag, start the pump, fix the leaks and have a beer.
If the deck has NO compound curvature, you might think about using a
sheet of Formica (with pva & wax) instead of the lower bag and peel
ply. If you pull this off, it'll be a very neat trick.

This will take long enough to cure that there is no substitute for a
vacuum pump. It would be BAD THING if a shop vac crapped out when the
layup was at the gooey stage.

I recommend that you first do some other small jobs using vacuum bagging
for practice.
Also, do a dry run, pulling vacuum on the bag glss and foam, to make
sure that there aren't voids in the deck core which prevent pulling a
vacuum.

This is a complicated job. Don't jump into it. Ask questions. It can
be done right.



Marc wrote:

I have discovered that I have wet core in several locations on my
cabin top. My limited experience with fiber glass has been with West
System Epoxies and I am comfortable with their use. The bottom skin
has been removed, the wet core excised and the top skin abraded and
prepped for bonding. I intend to wet out the underside of the top skin
and use Baltek Contour Kore AL600/10 to replace the core. After that
cures, I need to build up a bottom skin of at least 3/16". I need a
layup schedule that will give me max strength with the fewest number
of plies. This is a winter project. I will be able to maintain 40* in
the boat and intend on using the fast hardener. All suggestions are
welcome and hints as to technique or alternate methods are
appreciated.

Marc,

I replaced 16sqft of the deck core (22sqft total) of my S2-7.9.

I did it all lots of ways, but the one that worked best was vacuum
bagging. Not quite accurate in this description, but close enough. If
you can close of the rest of the core enough to get a good "suck" and
can get a hold of a suitable pump. You will have a better finished job
faster.

The inner deck does not have to be as heavy as it was laid in the
factory, because you get get the glass there with a lot less resin.
Three layers of 9oz cloth will do fine. Do remember that the last layer
has to overlap the existing glass by 1-1.5", and the others maybe 3/8
less.

As a vacuum job, you wet out the layers of glass, wet the surfaces of
the core and existing glass. Maybe put a coat of epoxy filled with
microlight or fillet blend on the surface that will go against the
inside of the upper deck to make it bed flat. You do all of this on
top of a board that has already got the sealing film, bleed layer and
peel-ply on it. You can even have the duck tape at in place if you are
very careful. With the pump running, slather it together and slam it
up there. You have to be sure how you are going to hold it until you
get it sealed off, but a friend's hand or a pre-cut stick will work.

Get the Gougeon brother's book on vacuum bagging and start there.

Matt Colie A.Sloop "Bonne Ide'e" S2-7.9 #1

Drop the west system and go to System 3 epoxy.
Go to their website and read the specs.
Theirs is the best low temp and in my opinion is an overall better product
line. Mertons is priced well and has great service.
http://www.mertons.com/index.html
Read the system 3epoxy manual. Good reading even if you use another brand.
A plastic covered piece of cork covered plywood jacked up from the floor
works well for that kind of repair.
The over promoted west system of the vacuum bagging is not something I'd
try for that project.
Read everything you can on fiberglass repair.
If you must try the vacuum stuff save some cash and get the $10 venturi
valve from harbor freight.
The insane price of over $100 for the west system one is a joke. Try a
few lay ups on the bench and you'll see it's useless. Epoxy dries too slow
for a compressor type vacuum system on large work and the overall system is
not suited for large repairs anyway.
You'll find a nice peanut butter consistancy for the epoxy works well for
the first batch and is pretty much a must for the core replacement part.
If there is a chance for any small holes through the top deck without too
much trouble to fix it makes a world of difference in this type of repair.
I'v done several and it was a dream on the one where I was replacing the
handrail and not only for excretion,through bolts to help hold the bottom
form worked well.
Drop a line if you'd like to get further into this discussion.


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Opinions are are a great thing to collect - no one says you have to keep
any of them.
System 3 is less expensive, I use the Gougeon bros. stuff because:
a. they make it so they can build boats
b. I've been using it for nearly 20 years and I know what to expect
c. the technical support that I have gotten from them over the years has
been valuable to me.
Many of those reasons may be of no interest to you and I do not say that
they should.

I know System 3 is supposed to be better at low temperature, but if it
is that cold my old hands do work well either.

If you are repairing a deck from inside, investigate vacuum.
Twilk had the floor to jack from. When I rebuilt the entire foredeck
and then the port side over the galley, I did not. I did do a test suck
so I find out if the edges were leaking more that I could manage. So,
under the foredeck, I put up roughly 4 sqft of plywood, balsa core and
glass in a single pass.

Twilk suggests the cheap venturi pump from the cheap tool store. That
is a fine idea if you have the 1-1/2 hp aircompressor to run it. (The
compressor isn't a bad thing to have in any case.)

If you are working where there are existing holes in the deck, cover the
area with masking tape, cut out the holes, make matching holes in the
core and lay-up. Then you can tape a funnel over the holes and have the
pump and stuff suck from on top and out of your way.

Good Luck

Matt Colie

Twilk wrote:
Drop the west system and go to System 3 epoxy.
Go to their website and read the specs.
Theirs is the best low temp and in my opinion is an overall better product
line. Mertons is priced well and has great service.
http://www.mertons.com/index.html
Read the system 3epoxy manual. Good reading even if you use another brand.
A plastic covered piece of cork covered plywood jacked up from the floor
works well for that kind of repair.
The over promoted west system of the vacuum bagging is not something I'd
try for that project.
Read everything you can on fiberglass repair.
If you must try the vacuum stuff save some cash and get the $10 venturi
valve from harbor freight.
The insane price of over $100 for the west system one is a joke. Try a
few lay ups on the bench and you'll see it's useless. Epoxy dries too slow
for a compressor type vacuum system on large work and the overall system is
not suited for large repairs anyway.
You'll find a nice peanut butter consistancy for the epoxy works well for
the first batch and is pretty much a must for the core replacement part.
If there is a chance for any small holes through the top deck without too
much trouble to fix it makes a world of difference in this type of repair.
I'v done several and it was a dream on the one where I was replacing the
handrail and not only for excretion,through bolts to help hold the bottom
form worked well.
Drop a line if you'd like to get further into this discussion.


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.788 / Virus Database: 533 - Release Date: 11/1/04

"Marc" wrote in message
...
I have discovered that I have wet core in several locations on my
cabin top. My limited experience with fiber glass has been with West
System Epoxies and I am comfortable with their use. The bottom skin
has been removed, the wet core excised and the top skin abraded and
prepped for bonding. I intend to wet out the underside of the top skin
and use Baltek Contour Kore AL600/10 to replace the core. After that
cures, I need to build up a bottom skin of at least 3/16". I need a
layup schedule that will give me max strength with the fewest number
of plies. This is a winter project. I will be able to maintain 40* in
the boat and intend on using the fast hardener. All suggestions are
welcome and hints as to technique or alternate methods are
appreciated.

When I did it, I used sticks to prop chunks of core in place overnight
(bonded to the top skin with thickened epoxy).
Then I wet the bottom surface of the core, and pressed the glass cloth in
place relying on the stickiness of the epoxy to hold it in place against the
force of gravity. It worked.

Just be prepared to get dripped on a lot. Work in overlapping sections.
Expect stuff to not always stay in place on the first try. Extra hands would
probably help if you have room.

Good luck.

Jim

On Tue, 4 Jan 2005 17:14:37 -0500, "jimk" wrote:


"Marc" wrote in message
.. .
I have discovered that I have wet core in several locations on my
cabin top. My limited experience with fiber glass has been with West
System Epoxies and I am comfortable with their use. The bottom skin
has been removed, the wet core excised and the top skin abraded and
prepped for bonding. I intend to wet out the underside of the top skin
and use Baltek Contour Kore AL600/10 to replace the core. After that
cures, I need to build up a bottom skin of at least 3/16". I need a
layup schedule that will give me max strength with the fewest number
of plies. This is a winter project. I will be able to maintain 40* in
the boat and intend on using the fast hardener. All suggestions are
welcome and hints as to technique or alternate methods are
appreciated.

When I did it, I used sticks to prop chunks of core in place overnight
(bonded to the top skin with thickened epoxy).
Then I wet the bottom surface of the core, and pressed the glass cloth in
place relying on the stickiness of the epoxy to hold it in place against the
force of gravity. It worked.

Just be prepared to get dripped on a lot. Work in overlapping sections.
Expect stuff to not always stay in place on the first try. Extra hands would
probably help if you have room.

Good luck.

Jim

....but this method could easily turn into a nightmare. Ask me how I
know....

Brian W

Brian Whatcott wrote:

On Tue, 4 Jan 2005 17:14:37 -0500, "jimk" wrote:



"Marc" wrote in message
. ..


I have discovered that I have wet core in several locations on my
cabin top. My limited experience with fiber glass has been with West
System Epoxies and I am comfortable with their use. The bottom skin
has been removed, the wet core excised and the top skin abraded and
prepped for bonding. I intend to wet out the underside of the top skin
and use Baltek Contour Kore AL600/10 to replace the core. After that
cures, I need to build up a bottom skin of at least 3/16". I need a
layup schedule that will give me max strength with the fewest number
of plies. This is a winter project. I will be able to maintain 40* in
the boat and intend on using the fast hardener. All suggestions are
welcome and hints as to technique or alternate methods are
appreciated.


When I did it, I used sticks to prop chunks of core in place overnight
(bonded to the top skin with thickened epoxy).
Then I wet the bottom surface of the core, and pressed the glass cloth in
place relying on the stickiness of the epoxy to hold it in place against the
force of gravity. It worked.

Just be prepared to get dripped on a lot. Work in overlapping sections.
Expect stuff to not always stay in place on the first try. Extra hands would
probably help if you have room.

Good luck.

Jim



...but this method could easily turn into a nightmare. Ask me how I
know....

Brian W



For my money, using vacuum greatly reduces the likelihood of getting a
half-assed job.
Do you feel lucky today?

I agree working from the bottom can/will be a nightmare. I started out from underneath to repair my for deck. It was an area about 5-6 sq ft. After several attempts I abandoned it. I pulled out the trusty circular saw and cut out the deck. I then had to rebuild the lower skin. This required a makeshift mold. Once the skin was laid I was able to build up the core and upper skin. Unless the area you're repairing is small, say 1-2 sq ft, I would not ruin 2 days of work and $200 of resin/cloth/core material!

John
"Jionlin" wrote in message news:JeJCd.281274$5K2.77429@attbi_s03...
Brian Whatcott wrote:
On Tue, 4 Jan 2005 17:14:37 -0500, "jimk" wrote:

"Marc" wrote in message
...
I have discovered that I have wet core in several locations on my
cabin top. My limited experience with fiber glass has been with West
System Epoxies and I am comfortable with their use. The bottom skin
has been removed, the wet core excised and the top skin abraded and
prepped for bonding. I intend to wet out the underside of the top skin
and use Baltek Contour Kore AL600/10 to replace the core. After that
cures, I need to build up a bottom skin of at least 3/16". I need a
layup schedule that will give me max strength with the fewest number
of plies. This is a winter project. I will be able to maintain 40* in
the boat and intend on using the fast hardener. All suggestions are
welcome and hints as to technique or alternate methods are
appreciated.
When I did it, I used sticks to prop chunks of core in place overnight
(bonded to the top skin with thickened epoxy).
Then I wet the bottom surface of the core, and pressed the glass cloth in
place relying on the stickiness of the epoxy to hold it in place against the
force of gravity. It worked.

Just be prepared to get dripped on a lot. Work in overlapping sections.
Expect stuff to not always stay in place on the first try. Extra hands would
probably help if you have room.

Good luck.

Jim

...but this method could easily turn into a nightmare. Ask me how I
know....

Brian W

For my money, using vacuum greatly reduces the likelihood of getting a half-assed job.
Do you feel lucky today?