failure later on. For example, if failure is in the bond,
liquid resin systems and glass reinforcements, and for
is it the result of insufficient bond area, peeling action,
repairing minor damage to other materials such as
or poor bonding technique? Examine the bonded area
wood and metals. Clean and abrade around the
to ascertain if a uniform and sufficient amount of
damaged area. Then, squeeze out the required length
adhesive was applied. Compare the amount of the area
of paste resin from the tube. Parallel to the resin,
that failed within the laminated part with the area that
squeeze out an equal length of hardener. This may be
failed in adhesion at the laminate surface to see if the
done on a flat surface that is covered with a piece of
surfaces were improperly prepared. Surfaces should
separating film. Mix the two materials with the small
be carefully sanded and cleaned before bonding. Any
mixing stick. The resin is white and the hardener is
repair should be aimed at preventing future failures.
black; when properly mixed the blend will have a
uniform gray color. Spread the mixture over the
If a stiffener has broken and must be replaced, the
damaged area with the mixing stick or a putty knife.
method of repair will depend on whether it has been
Cover the repair with a piece of separating film and,
integrally molded as shown in view A of figure 4-17
with a clean mixing stick or spreading tool, smooth the
or bonded in place as shown in views B and C. In the
resin from the center outward to obtain the desired
latter cases, the entire stiffener may be completely
contour. Finish the patch as previously described.
removed by delaminating the bond, and a new
stiffener fabricated by the WET LAYUP technique
Bolthole Repair
shown in view B of figure 4-17, or molded separately
and bonded to the plating. The use of positive
To repair a slightly elongated or oval bolthole
fasteners, at least at the ends and center of the stiffener,
where the washer or bolthole still bears on the
is often desirable where service loads are such that a
laminate, slightly abrade the enlarged portion of the
possibility of peeling exists.
hole with a file or sandpaper. Then fill the area of
In the case of integral stiffeners, the damaged
clearance around the fastener with the paste resin mix.
portion should be cut away to the extent necessary to
To repair a badly damaged bolthole, perhaps
assure stiffeners a satisfactory repair, and this area
caused by a bolt pulling through the laminate, remove
replaced, taking care that a good bond to the plating
the bolts and separate the primary structure from any
and adjacent members is obtained.
secondary member where necessary. Cut away the
Repairs to stiffeners may be accomplished with
damaged surrounding area with a metal-cutting saw as
the materials provided in the repair kit and simple
before. From this point, follow the same plastic boat
wooden forms, using the repair techniques previously
repair procedures described earlier in this chapter. Put
described. All surfaces to be bonded must be sanded
extra plies of reinforcement in this area to provide
and cleaned to assure good adhesion. The cross section
additional strength. After the repair is completed, drill
and size of the replacement stiffener should be
new boltholes-this time with proper clearance and
increased where necessary to provide additional
bearing area. To prevent recurrence of such a failure,
bonding area or strength.
replace the bolts and washers with a larger size or a
reinforcing plate.
Repairing Glass-Reinforced Plastic Coatings
Repairing a Damaged Reinforcing
Member or Stiffener
Damaged portions of glass fiber-reinforced resin
coatings on wooden boats and other structures can be
The stiffeners used in reinforced plastic structures
repaired with the resin and glass reinforcement
may be of various shapes that are either integrally
supplied in the repair kit. The steps for this repair
molded with the plating or secondarily bonded to the
procedure are outlined as follows:
plating. Figure 4-17 shows some typical stiffened
panel constructions. Failure may be the result of poor
1. Cut away any loose or damaged sections of the
bonding (in the case of secondarily bonded stiffeners),
glass-resin coating.
inadequate design, or unusual service loads. It is
2. Repair or replace any of the wood that has been
necessary that such failures be repaired as soon as
damaged. Fill seams and cracks with water-mixed wood
possible to avoid further damage to the structure.
putty or plastic wood. The resin and hardener or epoxy
When you begin the repair, keep in mind the cause
paste supplied in the kit may be used for filling. DO
NOT use oil-base putty.
of the failure and correct any defects to prevent similar
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