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