V-struts, the backing block should span the
width between its twin bases. The backing
plate should have a footprint that is about
10 percent greater than the strut’s base foot-
print outside. Don’t forget to bevel the back-
ing block edges and radius the corners as
well. Cutting them off vertical and square
can leave hard spots that aggravate stresses
in the hull. If the backing block is wood, it
must be very thoroughly saturated with
epoxy—three coats minimum—with extra
attention paid to sealing the end grain and
bolt holes. Wooden hulls need similar care-
ful attention to backing blocks and plates.
Strut Construction
for Metal Hulls
For steel and aluminum boats, struts are usu-
ally best when fabricated of the same material
as the hull itself. One method of fastening is
to insert the strut legs through slots in the
hull bottom and weld them to longitudinal
girders inside the hull (Figure 2-5). Some-
times these girders are the same girders
as the engine beds, but not always. The slot
in the hull should be just a little bit long fore-
and-aft. In this way the strut assembly can be
inserted into the slots and slid around to get
proper alignment before being tack welded
in place. The doubler plates outside are in-
stalled as split plates around both sides of
the strut legs and tack welded. Alignment is
rechecked, and then the entire assembly is
structurally welded in place.
An alternative method is to fasten the
strut legs to a transverse floor or deep frame
(Figure 2-6). In this case not only is the hull
bottom slotted to accept the strut legs, but
the floor or frame is notched as well.Chapter 2:Struts, Propeller Apertures, and Shaft Angle
Figure 2-4. Strut
fastening