fixing screw heads pulled though surface ply

A daggerboard trunk was installed in a lauan underlayment boat
last summer, close to one side of the boat, and fastned with PL
Premium glue and screws through the hull from underneath. The boat
hasn't been sailed vary often but the stresses on the trunk
started pulling the screw heads through the thin face veneer. Two
of the six screw heads had been pulled through the face veneer.
Water got under the face veneer and started lifiting it. Water was
seeping into the boat near the trunk. All the glue lines at the
bottom of the trunk are sealed with a line of epoxy resin. Epoxy
is built up on the inside join where the board rubs on the
plywood. The slot itself is no problem. The outside of the boat is
painted. The inside has several coats of linseed oil built up from
annual applications.

A repair was made by removing all the screws; cutting out any
delaminated surface ply with a jacknife, gluing the delaminated
surface pieces back on when dry with a bit of epoxy thickened with
powdered talc (baby powder), taping with cellophane, weighing with
bricks until set, and sanding for a smooth surface; making a
cardboard template; cutting and bevelling a piece of 1/4 inch 3-
ply scrap spruce plywood (no longer manufactured AFAIK), gluing
(PL Premium) and screwing (longer screws) the piece of spruce ply
to the outside of the hull over the daggerboard slot after fist
lining the old screw holes with epoxy applied with a toothpick and
lettign it harden; sealing the bevelled edges with two
applications of polyester resin; sealing the glue line with a bit
of epoxy resin; and painting. The new screws were slightly
countersunk and the heads puttied with a mix of latex paint and
powdered talc so they could be removed at some time if necessary.

Thnking back its odd I did not anticipate the screw heads pulling
though the thin face ply of the underlayment plywood. I had used
double thick plywood for screwing underlayment before but not this
time.

This is the boat's fourth season. It not expected to last a long time but
is showing no signs of deterioration so far. I expect to get a few more
years out of it. A backrest was added this year. The roughest conditions
so far was 1 foot breaking waves on the Ottawa River this summer. Its the
Dogskiff on my website.

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William R Watt National Capital FreeNet Ottawa's free community network
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ag384.DeleteThis@FreeNet.Carleton.CA (William R. Watt) wrote in message news:<bk27gd$gll$1@freenet9.carleton.ca>...
 > A daggerboard trunk was installed in a lauan underlayment boat
 > last summer, close to one side of the boat, and fastned with PL
 > Premium glue and screws through the hull from underneath. The boat
 > hasn't been sailed vary often but the stresses on the trunk
 > started pulling the screw heads through the thin face veneer. Two
 > of the six screw heads had been pulled through the face veneer.
 > Water got under the face veneer and started lifiting it. Water was
 > seeping into the boat near the trunk. All the glue lines at the
 > bottom of the trunk are sealed with a line of epoxy resin. Epoxy
 > is built up on the inside join where the board rubs on the
 > plywood. The slot itself is no problem. The outside of the boat is
 > painted. The inside has several coats of linseed oil built up from
 > annual applications.
 >
 > A repair was made by removing all the screws; cutting out any
 > delaminated surface ply with a jacknife, gluing the delaminated
 > surface pieces back on when dry with a bit of epoxy thickened with
 > powdered talc (baby powder), taping with cellophane, weighing with
 > bricks until set, and sanding for a smooth surface; making a
 > cardboard template; cutting and bevelling a piece of 1/4 inch 3-
 > ply scrap spruce plywood (no longer manufactured AFAIK), gluing
 > (PL Premium) and screwing (longer screws) the piece of spruce ply
 > to the outside of the hull over the daggerboard slot after fist
 > lining the old screw holes with epoxy applied with a toothpick and
 > lettign it harden; sealing the bevelled edges with two
 > applications of polyester resin; sealing the glue line with a bit
 > of epoxy resin; and painting. The new screws were slightly
 > countersunk and the heads puttied with a mix of latex paint and
 > powdered talc so they could be removed at some time if necessary.
 >
 > Thnking back its odd I did not anticipate the screw heads pulling
 > though the thin face ply of the underlayment plywood. I had used
 > double thick plywood for screwing underlayment before but not this
 > time.
 >
 > This is the boat's fourth season. It not expected to last a long time but
 > is showing no signs of deterioration so far. I expect to get a few more
 > years out of it. A backrest was added this year. The roughest conditions
 > so far was 1 foot breaking waves on the Ottawa River this summer. Its the
 > Dogskiff on my website.


Looks like a fun boat Will. The materials used and glue choice in
areas are your choice and we have addressed that with each other in
other threads, always in a calm manner I must add... Anyway, now it's
time for the big guns... get with me off list and I will send you some
of that 3.8oz tight weave glass I sent that other guy (it is paper
thin, and strong as hell) and you pry out your wallet and get some
real epoxy and paste this thing together so you can get a few more
years out of it... It don't need to be pretty, or expensive... unless
of course you are on that other news group :-0
Scotty... Hey Will, seen the pics on the site, still flyin' that freak
flag?<!-- ~MESSAGE_AFTER~ -->