Wooden Boat Restoration Repair - WEST SYSTEM Epoxy

Repairing the Structural Framework 17
4 Repairing the Structural
Framework
Replace or reinforce in place framework that is too weak to carry its designed load.
Structural framework includes the keel, stems, hull frames, floors, stringers, deck
beams, sheer clamps, shelves, knees, carlins or thwarts. They vary widely in size, shape
and position, but have many problems and repair techniques in common.
Frames can be damaged from dry rot or from impact. Under impact, frames often
break in multiples. If you find a cracked frame, take the time to look for others,
especially adjacent to the broken one. Hull frames often break at stringer edges, the
turn of the bilge and at the reverse turn (especially in the stern). Examine the outside of
the hull for a knuckle or unfair spot in the planking in the area where the frames are
damaged. If you find planks that are out of position, temporarily force the affected
planks (and frames) back using whatever means are available. You may use bracing and
shims on the outside of the hull and/or rope and tackle on the inside. The frame repair
can begin once the shape of the hull is restored.
Frame repairs rely on replacing damaged frames or sections of frames with material
that is of equal or greater strength (see Appendix–Wood data, page 75). Laminating is
an efficient method of building frames and a basic technique for the frame repairs in
this Section.
4.1 Laminating beams, frames and stems
Frames can be cut from solid stock or steam bent if you plan to restore the structure
exactly. (If you steam bend frames, be sure to allow plenty of time for the frame to dry
out before bonding.) However, laminated frames have many advantages over steam
bent frames, both structurally and in ease of fabrication. Whole and partial frames are
made of multiple thin layers of wood to duplicate the shape and dimension of the
damaged frame (Sections 4.2, 4.3 and 4.4). There are no limitations to the size of frame
that can be laminated. Laminating may be the only practical or economical way to
duplicate large structural members as large timber becomes more scarce. The new
frame can be laminated in a simple jig made from a pattern or, in some cases, directly in
place in the hull.
Keep in mind the following when selecting wood for laminating frames:
1. Choose wood strips that are the same or similar species as the original frame.
2. Use wood strips thin enough to bend easily into the shape of the original frame. Be sure
all of the strips collectively can bend to shape. When fewer, thicker strips are used for a
given thickness of frame, more stress is induced resulting in less strength and more
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