J T wrote:
Thu, Jul 15, 2004, 11:48pm lid (J.*Clarke) says:
snip On a canoe, I'd use resorcinol myself, but epoxy should be fine.
I wouldn't trust _any_ PVA glue on a stressed part of any boat. Having
your glue let go at sea can ruin your whole day snip
OK, I'll bite. Why would you imply that a PVA glue would "let go
at sea" on a canoe, stressed part or not?
Because having spent a fair part of my life out of sight of land I have a
great respect for the ability of the sea, lake, river, stream, or pond to
damage anything that is floating on it. It is a truism that the sea can
kill any ship and the wise sailor gives it as little help in that endeavor
as he can. Ever chip through the rust on a warship, built from the finest
steel in the world, and covered with high-quality marine enamel from the
time that it was first built (the Navy will spend for good paint because
they don't like to have their ships turn to rust) 90 feet above the
waterline where a landlubber would assume that it never gets exposed to
salt water, and find after chipping through an inch and a half of rust that
there wasn't anything there but rust? First time you do that you lose all
faith in the notion that distance above the waterline and protective
coatings guarantee that the material will never be wet.
tt's not going to be
submerged, at least not in normal use.
It's when things get abnormal that people die. In any case, the particular
part that he was replacing was rotted out. That means that it was kept wet
for a fair amount of time.
And, it's not like wood glue has
never been used in boatbuilding before.
Resorcinol glue _is_ "wood glue". It's just truly waterproof wood glue.
I'd imagine it'll wind up with
a varnish, or other protective coating too, which will keep moisture
away from the glue.
Now you see, there I have the advantage of you because I have learned in the
real world that (a) paint, varnish, etc, canot be counted on to keep the
underlying surface dry when it is covered by standing water and (b) even
the very expensive multipart coatings have a limited service life in a
marine environment. If the "varnish or other protective coating" will keep
moisture away from the glue" then why did the wood rot out in the first
place? Or will it just magically keep moisture away from the glue and not
from the surrounding wood?
Do you know of a stressed PVA glue joint that "let
go at sea"?
I don't know anyone who was stupid enough to use PVA glue in a stressed
joint on a boat. However I do remember a laminated tiller, nicely carved
by a local artisan and glued together with what he assured us was
"waterproof glue", lying on the sole of the cockpit completely delaminated.
And that tiller was under no stress to speak of and was subject to less
water exposure than a canoe gunwale when it came apart.
Look, if you want to stick your neck out that's fine, but when you start
advising other people to do dangerous things while pretending they are not
dangerous you're behaving irresponsibly. Grok the concept--bad advice
about how to use a table saw may cost somebody a finger. Bad advice about
how to fix a boat can cost several people their lives.
Hey Ron, you're the resident boatbuilding expert, what's your
opinion?
If you're _not_ a "boatbuilding expert" then perhaps you should not be quite
so quick to criticize the opinions of others who have relevant experience.
I doubt that the Titebond folks are paying you to advocate the use of their
product in boatbuilding, so why are you so upset about the notion that it
is not suited to that purpose?
JOAT
We've got a lot of experience of not having any experience.
- Nanny Ogg
--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)