The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 14 – Hardware Bonding 143
When you set the hardware in final position, excess
epoxy mixture will flow out from the hardware
perimeter. You will need to clean it away. This may
require a bit of sculpting, especially if the cast portion
is large. We usually make up a wood paddle to the
shape desired so that we can get the best effect when
making a final pass across the uncured epoxy surface.
If you don’t get the results that you’d like, don’t worry.
You can sand, file, or refill the surface to develop the
final desired shape.
When the casting has cured, you can drill the holes for
the fasteners and install the fasteners themselves in the
appropriate manner. We caution you to remember to
adjust the fastener lengths for the angle change of the
hardware so that you get the same amount of fastener
penetration into the wood fiber.
Removing Bonded Fasteners
and Hardware
<strong>The</strong> bond between a fastener and WEST SYSTEM epoxy is
strong, but, with the right procedures, you can break it
to remove the fastener from the wood. If you know you
will want to extract a fastener at some point in the
future, coat it with wax, spray cooking oil, or a mold
release before installing it. Although the wax will interfere
with the metal/epoxy bond, it will not compromise the
mechanical keying around the threads which provides
the major load-transfer capability.
Bonded fasteners can often be removed with reasonable
force. If you have trouble loosening them, heat fasteners
with a soldering gun or iron until the surrounding
Figure 14-18 Soldering tips for heating small fasteners for
removal from epoxy.
epoxy softens. Attach a cutting tip to a soldering gun
and insert it in the slot at the top of smaller screws to
free them. Larger fasteners with more root diameter
can frequently be forced without breaking. However,
heating them to around 250°F (121°C) softens the
epoxy and makes the job much easier.
When you heat WEST SYSTEM epoxy to remove a fastener,
you may destroy some of its physical properties. Drill
out the hole completely and start afresh when you
replace the fastener.
To remove, hardware that has been bonded or cast in
position, use heat. At temperatures above 250°F
(121°C), cured epoxy becomes considerably weaker
than at room temperature. <strong>The</strong> epoxy softens and its
bonding capability reduces considerably. Begin by
removing any fasteners. <strong>The</strong>n heat the fitting itself with
a propane torch. A sharp rap with a mallet will usually
dislodge the hardware at this point. If the fitting doesn’t
break loose easily, don’t force it. Heat it a second time
and try again.
Drill out all cured epoxy before reattaching the fitting to
the deck surface.
Bonding Ballast Keels to Wood Hulls
Heavy ballast keels, especially fin keels, can produce
extreme high point loading. <strong>The</strong> problem is so difficult
with some designs that even fiberglass boats using
much higher density glass fiber have had difficulties
at the keel/hull connection point. By applying our
hardware bonding techniques to the process of keel
installation, however, we have found a very successful
solution to the problem of attaching keels.
<strong>The</strong> standard procedure for attaching a keel has been
to use two rows of bolts installed as close to the outer
edges of the keel as possible. <strong>The</strong>se run from the keel
into the hull and usually through laminated floors,
which distribute load throughout the hull skin. <strong>The</strong>
keel bolts are tightened with nuts inside the hull to
snug the keel up against it. Large washers or plates
distribute compression loads through the floors.
When a boat with a standard, unbonded keel installation
heels, tension loads are transmitted through the
bolts to the upper outboard edge, and compression
loads are transmitted directly from the keel to the wood