Shortcut for replacing plywood core?
 

I have a Rhodes 22 sailboat with some plywood core in the bow that turned to
mush. Water entered through a poorly sealed hole for a cowl. Last October I
scraped out the rotted core using wire. I was able to do this from the
existing cowl hole. The core I now need to replace extends about 1 foot back
& 180 degrees from the edge of the cowl opening. Ideally I would push in
epoxy with filler to fill the void but can't see an effective way of doing
that & repair such a large area. Then I thought about how handy it would be
to use an expanding foam to fill this area & then seal the edge with epoxy
at the cowl. The deck is very strong & does not flex. I don't think my foam
idea is a smart thing to do but I thought I would ask your opinion before I
abandoned the idea entirely. Any thoughts on fixing this without cutting
some fiberglass skin would be appreciated though I do have excellant access
to the damaged area from inside the boat.
Thanks
Marc

Shortcut for replacing plywood core?
 

On Fri, 27 Feb 2004 07:27:26 -0500, "Marc Beroz"
vaguely proposed a theory
.......and in reply I say!:

I don't think my foam
idea is a smart thing to do but I thought I would ask your opinion before I
abandoned the idea entirely.

nuff sed.

It's a boat. Your life may depend on it. It's a stress area. You have
access. Do it properly. I would also be looking at what is wrong with
the design/surrounds that the ply turned to mush. Why did the water
get in? Design or build? Accident? rebuild the area and some around
it.

Boats are not cheap.

I have a Rhodes 22 sailboat with some plywood core in the bow that turned to
mush. Water entered through a poorly sealed hole for a cowl. Last October I
scraped out the rotted core using wire. I was able to do this from the
existing cowl hole. The core I now need to replace extends about 1 foot back
& 180 degrees from the edge of the cowl opening. Ideally I would push in
epoxy with filler to fill the void but can't see an effective way of doing
that & repair such a large area. Then I thought about how handy it would be
to use an expanding foam to fill this area & then seal the edge with epoxy
at the cowl. The deck is very strong & does not flex. I don't think my foam
idea is a smart thing to do but I thought I would ask your opinion before I
abandoned the idea entirely. Any thoughts on fixing this without cutting
some fiberglass skin would be appreciated though I do have excellant access
to the damaged area from inside the boat.
Thanks
Marc


************************************************** ** sorry

..........no I'm not!
remove ns from my header address to reply via email

Spike....Spike? Hello?

Shortcut for replacing plywood core?
 

I'd make use of that access from below, cut GOOD plywood (marine or ext fir)
to fit and glue it in with West System epoxy making sure theply is well
bonded with the old (solid) ply.
My opinion fwiw.
Merlin.
"Old Nick" wrote in message
...
On Fri, 27 Feb 2004 07:27:26 -0500, "Marc Beroz"
vaguely proposed a theory
......and in reply I say!:

I don't think my foam
idea is a smart thing to do but I thought I would ask your opinion before
I
abandoned the idea entirely.

nuff sed.

It's a boat. Your life may depend on it. It's a stress area. You have
access. Do it properly. I would also be looking at what is wrong with
the design/surrounds that the ply turned to mush. Why did the water
get in? Design or build? Accident? rebuild the area and some around
it.

Boats are not cheap.

I have a Rhodes 22 sailboat with some plywood core in the bow that turned
to
mush. Water entered through a poorly sealed hole for a cowl. Last October
I
scraped out the rotted core using wire. I was able to do this from the
existing cowl hole. The core I now need to replace extends about 1 foot
back
& 180 degrees from the edge of the cowl opening. Ideally I would push in
epoxy with filler to fill the void but can't see an effective way of
doing
that & repair such a large area. Then I thought about how handy it would
be
to use an expanding foam to fill this area & then seal the edge with
epoxy
at the cowl. The deck is very strong & does not flex. I don't think my
foam
idea is a smart thing to do but I thought I would ask your opinion before
I
abandoned the idea entirely. Any thoughts on fixing this without cutting
some fiberglass skin would be appreciated though I do have excellant
access
to the damaged area from inside the boat.
Thanks
Marc


************************************************** ** sorry

.........no I'm not!
remove ns from my header address to reply via email

Spike....Spike? Hello?

Shortcut for replacing plywood core?
 

On Fri, 27 Feb 2004 21:59:12 +0800, Old Nick
wrote:

nuff sed.

It's a boat. Your life may depend on it. It's a stress area. You have
access. Do it properly. I would also be looking at what is wrong with
the design/surrounds that the ply turned to mush. Why did the water
get in? Design or build? Accident? rebuild the area and some around
it.

Plywood is not a suitable core. It has the same problem as any
non-end-grain wood core. Moisture travels along the grain.

Water will get in somewhere sometime.


Rodney Myrvaagnes NYC J36 Gjo/a


"Accordions don't play 'Lady of Spain.' People play 'Lady of Spain."

Shortcut for replacing plywood core?
 

"Marc Beroz" wrote in message ...
I have a Rhodes 22 sailboat with some plywood core in the bow that turned to
mush. Water entered through a poorly sealed hole for a cowl. Last October I
scraped out the rotted core using wire. I was able to do this from the
existing cowl hole. The core I now need to replace extends about 1 foot back
& 180 degrees from the edge of the cowl opening. Ideally I would push in
epoxy with filler to fill the void but can't see an effective way of doing
that & repair such a large area. Then I thought about how handy it would be
to use an expanding foam to fill this area & then seal the edge with epoxy
at the cowl. The deck is very strong & does not flex. I don't think my foam
idea is a smart thing to do but I thought I would ask your opinion before I
abandoned the idea entirely. Any thoughts on fixing this without cutting
some fiberglass skin would be appreciated though I do have excellant access
to the damaged area from inside the boat.
Thanks
Marc

Hey Marc,
It sure was nice of "OLD NICK" to give out such good advice for free!

Here's what I understand of your situation: 2 layers of fiberglass,
1/2 to 3/4 inch of mush in between them for diameter of approx. 2
sqft. and you have access to this mush through a small (6in.max)hole
in the middle once you removed the cowl.

The "right" way to fix this would be to rip off the top fiberglass
skin and expose all of the rotten plywood, then replace the core
material and apply a new fiberglass skin, then re gelcoat the whole
thing recreating the antislip patern on the deck somewhere during the
process.

I suspect that this may not be the best solution for you for whatever
reason. A 22 ft sailboat with a cabin trunk does not have a very
large fordeck,and does not have a large unsupported area.

So lets look at the the desired outcome before we go straight to
fixes. You want to replace the core with as little effort as possible
and still have a safe boat. The core simply seperates the two layers
of f/g to make for a stiffer panel section. To do this, the core
needs to be VERY WELL bonded to both top and bottom skins.
If your deck feels stiff with the mush inside, it's probably fairly
well build (or at lease the top layer is fairly thick).

Using 2 part polyurathane foam is an accepted practice in boat
building, especially by power boat builders. They tend to use 2 part
P/U foam to do everything from filling holes and deadair space to
bonding (non structual- eg: fish wells) items to the boat. This stuff
sticks to anything and is just as dense as cheap end-grain balsa core
- which is used in most boat decks built post 1975ish.

I would suggest that you go ahead and try the 2 part P/U foam but with
these precautions: get ALL of the rotten wood out, throughly clean the
area between the skins with acetone (3+ times), mix very small batches
of foam and let it expand and dry before applying the next batch(this
stuff expands so much that it WILL push the 2 layers of f/g apart if
it is trapped. once all of the foam is in, router out (or cut
manually) about 3/4 of an inch back from the opening where you filled
and replace with thickened epoxy. Give yourself enough room so that
the screws that keep the cowl on bite into the epoxy rather than the
foam.

IMPORTANT things to remember:
1. Get all of the "soft" wood out
2. clean throughly with acetone
3. mix small batches
4. let each batch cure before applying next batch(make sure you get it
into all of the corners
5. seal all edges with epoxy (just like wood, the foam will absorb
water, so keep it dry at all cost
6. Spend more of your time on the water

Cheers
R.

Shortcut for replacing plywood core?
 

Thanks for your comments. I've responded to some of your points below.

Here's what I understand of your situation: 2 layers of fiberglass,
1/2 to 3/4 inch of mush in between them for diameter of approx. 2
sqft. and you have access to this mush through a small (6in.max)hole
in the middle once you removed the cowl.

That's correct. The core is 1/2" plywood.

The "right" way to fix this would be to rip off the top fiberglass
skin and expose all of the rotten plywood, then replace the core
material and apply a new fiberglass skin, then re gelcoat the whole
thing recreating the antislip patern on the deck somewhere during the
process.

I figured if I removed a fiberglass skin, it would be the inner one since I
have good access & I wouldn't have to deal with the non-skid. This leads me
to another question if I go this route. In one area the mush core has been
removed all the way to the edge of the deck. To replace this core, how close
to the hull/deck joint should I cut the fiberglass skin? If I cut too close
to where the deck meets the hull, I won't have enough space to grind out a
bevel & then reglass the skin back into place. On the other hand, the
further out from the hull I stay with my cut, the harder it will be to get a
good bond between the new core I install & the inner fiberglass skin that I
did not cut out along the edge of the hull. (I'm having a hard time
describing this.) I've been mulling this over for awhile & been been
thinking I'd cut the deck's lower fiberglass skin about 2.5 inches away
from the hull. Any thoughts?


I suspect that this may not be the best solution for you for whatever
reason. A 22 ft sailboat with a cabin trunk does not have a very
large fordeck,and does not have a large unsupported area.

The only reason I was looking for an alternative is that I want to minimize
down time. I was looking to make the quickest repair without sacrificing
safety. I thought that if I made a foam repair & that failed, I could always
do the traditional repair at some point in the future.


So lets look at the the desired outcome before we go straight to
fixes. You want to replace the core with as little effort as possible
and still have a safe boat. The core simply seperates the two layers
of f/g to make for a stiffer panel section. To do this, the core
needs to be VERY WELL bonded to both top and bottom skins.
If your deck feels stiff with the mush inside, it's probably fairly
well build (or at lease the top layer is fairly thick).

Using 2 part polyurathane foam is an accepted practice in boat
building, especially by power boat builders. They tend to use 2 part
P/U foam to do everything from filling holes and deadair space to
bonding (non structual- eg: fish wells) items to the boat. This stuff
sticks to anything and is just as dense as cheap end-grain balsa core
- which is used in most boat decks built post 1975ish.

I would suggest that you go ahead and try the 2 part P/U foam but with
these precautions: get ALL of the rotten wood out, throughly clean the
area between the skins with acetone (3+ times)

I assume you get the acetone in there by shooting it in with a syringe &
then allowing it to evaporate out?

, mix very small batches
of foam and let it expand and dry before applying the next batch(this
stuff expands so much that it WILL push the 2 layers of f/g apart if
it is trapped.

I've looked at the foam products & have wondered how I could get 2 part foam
back far enough between the skins. Is there any way to spray it rather than
pour it? Or are you thinking that I close off the cowl hole in the inner
skin and then pour 2 part foam in from above the deck. I don't have
experience with 2 part foam. Is it real viscous prior to setting up or will
it flow? What if I used 1 part spray foam?

once all of the foam is in, router out (or cut
manually) about 3/4 of an inch back from the opening where you filled
and replace with thickened epoxy. Give yourself enough room so that
the screws that keep the cowl on bite into the epoxy rather than the
foam.

Agree

IMPORTANT things to remember:
1. Get all of the "soft" wood out

I can get all the soft stuff out that I can move with a 1/16 inch diameter
piece of wire but that won't be as good as having good access to the problem
area with a skin removed.

2. clean throughly with acetone
3. mix small batches
4. let each batch cure before applying next batch(make sure you get it
into all of the corners
5. seal all edges with epoxy (just like wood, the foam will absorb
water, so keep it dry at all cost
6. Spend more of your time on the water


The more I consider the obstacles, the more I think I may just have to bite
the bullet & get to work cutting glass. I'd be interested in what you think.
Thanks, Marc

Shortcut for replacing plywood core?
 

Rodney,
What do you suggest I use for core?
Marc

"
Plywood is not a suitable core. It has the same problem as any
non-end-grain wood core. Moisture travels along the grain.

Water will get in somewhere sometime.


Rodney Myrvaagnes NYC
J36 Gjo/a


"Accordions don't play 'Lady of Spain.' People play 'Lady of Spain."

Shortcut for replacing plywood core?
 

Merlin,
Since I want to re-gelcoat the patch on the inner skin, I was thinking I
should use a polyester laminating resin. Am I wrong here?
Marc


"MMC" wrote in message
. com...
I'd make use of that access from below, cut GOOD plywood (marine or ext
fir)
to fit and glue it in with West System epoxy making sure theply is well
bonded with the old (solid) ply.
My opinion fwiw.
Merlin.

Shortcut for replacing plywood core?
 

Nick,
Your point is well taken. Water intrusion was due to the plywood never
having been properly sealed at the cowl. The caulking at the cowl failed &
that's the tragic end.
Marc

"Old Nick" wrote in message
...
On Fri, 27 Feb 2004 07:27:26 -0500, "Marc Beroz"
vaguely proposed a theory
......and in reply I say!:

I don't think my foam
idea is a smart thing to do but I thought I would ask your opinion before
I
abandoned the idea entirely.

nuff sed.

It's a boat. Your life may depend on it. It's a stress area. You have
access. Do it properly. I would also be looking at what is wrong with
the design/surrounds that the ply turned to mush. Why did the water
get in? Design or build? Accident? rebuild the area and some around
it.

Shortcut for replacing plywood core?
 

On 27 Feb 2004 14:27:24 -0800, (RodiniaOne) vaguely
proposed a theory
.......and in reply I say!:

Apart from this comment, I am going to ignore your silly dig.

2-part PU foam is _crap_ core, by the way.

The "right" way to fix this would be to rip off the top fiberglass
skin and expose all of the rotten plywood, then replace the core

I suspect that this may not be the best solution for you for whatever
reason. A 22 ft sailboat with a cabin trunk does not have a very
large fordeck,and does not have a large unsupported area.

So the right way is not the best way....hmmmmm.

Using 2 part polyurathane foam is an accepted practice in boat
building, especially by power boat builders.

It is also done for economy and is _questioned_ by many many people in
the boating industry.


************************************************** ** sorry

..........no I'm not!
remove ns from my header address to reply via email

Spike....Spike? Hello?