Formed parts of a boat that have been damaged lap for mechanical fastenings. The unit can then be
must not be re-formed using heat. When possible, it is bolted to the aluminum hull with insulation between
suggested that the damaged part be replaced by new them. Splices can be made across the structural mem-
material formed for the job. bers. If tapes or neoprene are not available for insulating
Distorted plates, whether caused by damage or the the steel and the aluminum, material such as Butyl
heat of welding, must not be straightened by flame- rubber, polysulfide, or any heavy-bodied flexible coat-
quenching (torch heating followed by spray cooling). ing will do. Avoid wicking materials, such as flax or
The method does not work well and can result in over- canvas, and the use of lead-pigmented compounds, such
heating or melting as previously described. If the dis- as red lead. The steel temporary repair should be re-
tortion does nothing more harmful than detract from placed with the proper aluminum repair as soon as
appearance, it should be left alone. Otherwise, distorted possible.
shapes should be straightened cold, using jacks as nec-
essary, while distortion in plate panels may be relieved STEEL BOAT REPAIR
either cold or by making a saw cut in the center of the
panel and rewelding it. When you weld a saw cut, ensure
Permanent repairs of steel boats must be
that the correct alloy is used. Cracking of the weld will
accomplished by qualified welders and nondestructive
result if the alloy of the filler metal or authorized alter-
test personnel. Fabrication, welding, and inspections
nate is not used. The normal shrinkage associated with
must be accomplished as required by the BoatAlt or
aluminum welding will tend to remove the distortion.
applicable alteration or repair drawing. NAVSEA
The light weight of aluminum will facilitate repair
0900-060-4010 and NSTM, chapter 074 (9920),
by making handling easier. In addition, the preparation
should be used as guides.
of subassemblies or repair sections in the shop is greatly
facilitated.
If welding is impractical or impossible, use bolted
UTILITY BOATS
aluminum alloy patches. For this type of repair, the
following is needed: an electric circular saw for cutting
In the following sections, the discussion will deal
plate to size and for fairing out any jagged edges in the
primarily with typical repairs made to utility boats.
hull penetration, and a good metal-cutting saw blade.
When a boat is damaged, the HT is responsible for
After the patch plate is cut to size, connect it to the hull
making the required repairs. As an HT, you must know
with aluminum or stainless steel bolts or other fasteners.
the procedures for renewing a stem, stem frame, and
In an emergency, any type of bolt will do. However, this
engine foundation in a small boat.
must be considered a temporary repair since dissimilar
In general, the procedures described for repairing
metals cause galvanic corrosion. For bolting the patch
utility boats are similar to those required for repairing
to the hull, insert a sealing material around the perime-
motor boats, motor whale boats, and ships’ boats for
ter. If a number of repairs of this type are anticipated,
other types.
then it might be wise to provide several rolls of the
sealing tapes used by aluminum small boat manufactur-
CHOCKING THE BOAT
ers. Most major tape manufacturers supply these tapes
in various thicknesses and widths. These are the tapes
Before beginning to work on a boat, you must get
used on modem day aluminum small boats and they do
it into a safe position, retain its true form, and prevent
a good job, not only in sealing the seam, but also in
further damage, Figure 4-25 shows a type of boat
keeping the rivets and bolts from leaking. The holes for
chock that you can construct aboard ship. It is simply
the rivets or bolts will, of course, be made by a rotary
a framework made from 4 by 4’s and braced with 2 by
drill.
6 lumber. The number of chocks and other bracing
If the boat incurs damage in a remote area where
should be determined so that the craft can be held
there are no facilities for welding, and aluminum is not
reasonably rigid to a fixed position.
available, temporary repairs can be made with steel
NOTE: When positioning chocks, ensure that they
patches. Some type of insulation, such as neoprene,
bear on the hull at structurally reinforced areas.
should be used between the aluminum and steel, if
possible. Large, temporary hull repairs can be made in
REMOVING DAMAGED PARTS
this manner. The damaged area can be cropped out. The
steel repair plate, including structural framing mem- Remove damaged parts carefully since you will
bers, can be prefabricated by welding, leaving sufficient probably have to use them as patterns in making the new
4-22
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