been cleaned and dried, you should make a careful
necessary. All frame member sections should be
inspection to determine the extent of damage.
joined with a scarfjoint if at all possible. A scarf with
a 12:1 pitch is best. A scarf with this pitch, glued with
Physical damage may extend far from the
epoxy and secured by boat nails, bolts, or rivets, will
obviously stove-in areas. A boat may have been
be nearly as strong as the original member. If you use
squeezed in a collision situation, and although there is
epoxy glue, you can allow some gap in the joint since
obvious damage on one side, equal stresses have been
epoxy has better strength in tension than regular
suffered on the other side. By calculating the direction
marine glues. A good scarf can be made by
that forces were exerted on the hull, you can estimate
overlapping the members to be joined and shaping
the points where stresses were transmitted. Look in
both ends with one cut of a saw at a steep angle. Heavy
those areas for loosened fastenings or cracks in the
timbers must be sawed and carefully planed to shape.
wood.
When a rib or strake cannot be easily reached, the scarf
If decay is present, either as the cause of failure or
angle will probably have to be chiseled into it. The end
incidental to it, you must plan to remove not only the
of the new section then is carefully fitted to this angle.
rotted wood, but also the wood into which the decay
Since epoxy has strength in tension, rougher faces of
organisms are assumed to have spread. The rule in
joints can be used than was possible with older glues.
doing this is to remove sound wood for 2 feet along
The easiest way to lay out a replacement part is to
the grain from the soft wood and for 2 inches across
use the old part as a template. If the old part is too
the grain from the soft wood. Plywood should be
badly damaged, you may be able to construct a
removed for a 2-foot radius from the rotten area. If this
template of scrap materials or lay out the new part by
is not done, decay can spread back into the repaired
careful measurements. Experienced boatwrights have
area.
a number of techniques to form duplicate replacement
When you remove a damaged plank, plan to take
parts, but for emergency repairs you can probably
out a generous length. The new plank should butt to
settle for any method that will fill the hole or provide
the end of the old one between frames, using a butt
adequate reinforcement. Plastic patch materials
block; you should saw the ends to meet that
permit simple, quick repairs that formerly were not
requirement. If the plank is fastened with screws,
possible.
chisel away the putty or the bung plugs and remove
the screws. If boat nails are used, cut off the heads with
a cold chisel. When the plank is pulled off, either pull
FERROCEMENT BOATS
the nail or drive it into the frame. To remove rivets,
cut off the upset head and punch them out. (Rivets are
Ferrocement is a material finding increased use as
usually found in lap stroke hulls, which are best sent
a low-cost material for hull construction. It is a
to an expert for repair.) If the plank is fastened with
combination of steel-reinforced mesh and portland
drifts, pry them out by leverage on the plank, or allow
cement binding. The reinforcement material ranges
the plank to break at the rib, then pull the drift or drive
from several layers of chicken wire to a few layers of
it flush.
specially woven steel wire. Ferrocement hulls may
To repair a sprung frame or rib where the exterior
also have some structural steel or steel pipe
planking is sound, construct a sister frame and fasten
it along the old frame. The sister frame should extend
Repairable damage to ferrocement hulls probably
well to either side of the damaged area. Planks may be
will be in the form of punctures or structural damage
refastened to the sister frame.
from collisions or groundings. Other failure of these
If a frame has rotted, or is badly damaged, it must
hulls will be caused by poor design, materials, or
be replaced. To replace a curved frame section, it is
workmanship. Hull failure from these causes is not
easiest and best to laminate the replacement part on a
economically repairable since the seaworthiness of the
template; or, if the exterior of the boat is sound, the
entire craft is questionable.
section could be built up in place. On Vee hulls, the
To repair punctured areas not over about 1 foot in
lower ribs should go from keel to chine, and the side
ribs from the chine to the sheer strake. The ends should
greatest diameter, use the plastic patching kit and
be joined as were the original members. Curved rib
basically the same techniques described later in this
sections can be joined to the ends of the old rib if
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