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?

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?

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.

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."

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."

On Fri, 27 Feb 2004 23:10:29 -0500, "Marc Beroz"
wrote:

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

Closed cell foam or end grain balsa, if bonded properly, will isolate
places where water penetrates. You could also glass it solid, although
you would be adding weight just where you don't want it.


I think you are right about cutting out the inner skin, leaving enough
edge to feather and glass it back.

If you started with a piece of good marine plywood with no voids and
covered it in epoxy before starting, you might be able to keep it dry
as long as the rest of the boat will last.

You could also get away with solid _white_ oak for a good while. Not
red oak.

Do you know how old the boat is, and how long it took to get the
current problem? Also, do you know there is not more of the same
elsewhere?

Rodney Myrvaagnes NYC J36 Gjo/a


"Biologists think they are chemists, chemists think they are phycisists,
physicists think they are gods, and God thinks He is a mathematician." Anon

Rodney Myrvaagnes wrote:

On Fri, 27 Feb 2004 23:10:29 -0500, "Marc Beroz"
wrote:

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

Closed cell foam or end grain balsa, if bonded properly, will isolate
places where water penetrates.

I agree with the foam, but you are dead wrong about the balsa... I've
replaced the balsa core in many decks where the endgrain balsa has acted
like a sponge and totally rotted out.

Don't believe me ? For an example, take a look at:

ftp://ftp.sailnet.com/pearson/pearso...ted%20core.jpg

(sorry about the long address).

Brian Cleverly (to reply direct, replace the first "z" with an "n" in
the header address)

On Sat, 28 Feb 2004 18:24:10 -0800, Brian Cleverly
wrote:



Rodney Myrvaagnes wrote:

On Fri, 27 Feb 2004 23:10:29 -0500, "Marc Beroz"
wrote:

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

Closed cell foam or end grain balsa, if bonded properly, will isolate
places where water penetrates.

I agree with the foam, but you are dead wrong about the balsa... I've
replaced the balsa core in many decks where the endgrain balsa has acted
like a sponge and totally rotted out.

Don't believe me ? For an example, take a look at:

ftp://ftp.sailnet.com/pearson/pearso...ted%20core.jpg

Pearson used balsa in non-end-grain orientation in early boats.

I have a 24-year-old boat that has suffered numerous insults and
repairs and is still strong and just passed a survey. It is cored with
Baltek end-grain.

If the end-grain core is not bonded to the outer layers, water can
travel between, as it can with any core. It does not travel fast
across the grain inside the wood.



Rodney Myrvaagnes J36 Gjo/a


MOM CASTS TOT IN CEMENT

Most experts voice cautious optimism

Rodney, Brian and Marc,

Boy, I wish I had time to tell you all everything I've seen and done in
the last fifty plus years. But - let my start by saying that the
picture - though good - is a bad example. Just like so many things,
when it was first done, builders didn't understand how much trouble they
were starting.

Many builders used endgrain block filler like that. The only ones that
made it work use a filled area around each block the sequester them.
The companies the used block without that left a gap between the blocks
that served as a conduit for any water that got into the construction.

They builders that used bound sheet of end grain balsa did a little
better, but since those where largely laided up construction, the inner
layup usually left at small gap the the core edge that again was a good
conduit for water.

There were places in my current boat that had marine plywood for a high
stress area in a layup of balsa core. In some of those where the
bedding on deck had gone bad, the plywood was shot, though the adjacent
balsa core was saturated and delaminated it was still there. I could
have dried it out and reused it.

Closed cell foam is no answer either. I have a Whaler sailing dink out
here that was mistreated and now weighs in at 300+. I have also ben
contracted to repair laid-up foam core structures that were delaminating
because of water intrusion damage.

The only answer I have come up with that makes any sense is:

Do not trap water.

If there might be a place it can get in, make sure it has a way out. Do
your best to keep it out, but the thing that caused the problem was the
the water stayed in. Drain holes in the inner deck skin will stop the
migration of moisture in the core right there.

If you are going to rebuild a cored structure, learn all about vacuum
techniques for laminating. That is the only way that I have found to
create the solid lamination required.

Matt Colie

Rodney Myrvaagnes wrote:
On Sat, 28 Feb 2004 18:24:10 -0800, Brian Cleverly
wrote:



Rodney Myrvaagnes wrote:

On Fri, 27 Feb 2004 23:10:29 -0500, "Marc Beroz"
wrote:


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


Closed cell foam or end grain balsa, if bonded properly, will isolate
places where water penetrates.

I agree with the foam, but you are dead wrong about the balsa... I've
replaced the balsa core in many decks where the endgrain balsa has acted
like a sponge and totally rotted out.

Don't believe me ? For an example, take a look at:

ftp://ftp.sailnet.com/pearson/pearso...ted%20core.jpg


Pearson used balsa in non-end-grain orientation in early boats.

I have a 24-year-old boat that has suffered numerous insults and
repairs and is still strong and just passed a survey. It is cored with
Baltek end-grain.

If the end-grain core is not bonded to the outer layers, water can
travel between, as it can with any core. It does not travel fast
across the grain inside the wood.



Rodney Myrvaagnes J36 Gjo/a


MOM CASTS TOT IN CEMENT

Most experts voice cautious optimism

Rodney Myrvaagnes wrote:

On Sat, 28 Feb 2004 18:24:10 -0800, Brian Cleverly
wrote:



Rodney Myrvaagnes wrote:

On Fri, 27 Feb 2004 23:10:29 -0500, "Marc Beroz"
wrote:

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

Closed cell foam or end grain balsa, if bonded properly, will isolate
places where water penetrates.

I agree with the foam, but you are dead wrong about the balsa... I've
replaced the balsa core in many decks where the endgrain balsa has acted
like a sponge and totally rotted out.

Don't believe me ? For an example, take a look at:

ftp://ftp.sailnet.com/pearson/pearso...ted%20core.jpg

Pearson used balsa in non-end-grain orientation in early boats.


If you look closely, you will see that this was in fact endgrain.

I've had exactly the same situation with Cal (not early ones), and
Ericson boats.

I have a 24-year-old boat that has suffered numerous insults and
repairs and is still strong and just passed a survey. It is cored with
Baltek end-grain.

If the end-grain core is not bonded to the outer layers, water can
travel between, as it can with any core. It does not travel fast
across the grain inside the wood.


Agreed, certainly it can travel like that. It is not obvious in the
photo (I wish I had a better one) but there was clear evidence of the
blocks being bonded top and bottom, plus I had to break off numerous
polyester ridges that existed between the blocks.

However, the original poster asked your recommendations for core and you
didn't even hint that he would have to be extremely particular with the
way he installed balsa. FWIW, when I install new balsa I saturate it
with Sys 3 "Clear Coat" epoxy.

As an aside, that particular Pearson has been cut-up and buried in
landfill due to the discovery of gross amounts of delamination in the
hull layup.

Brian Cleverly (to reply direct, replace the first "z" with an "n").

Rodney Myrvaagnes J36 Gjo/a

MOM CASTS TOT IN CEMENT

Most experts voice cautious optimism