Spiling and fitting planks is perhaps one of the most daunting tasks
in model ship building. Spiling is the process by which the devel-
oped plank shapes are obtained so that they fit the hull properly in
their designated position. The process is begun by belting and lin-
ing off the hull as shown on plan sheet 2. For this model, the lining
off was done in CAD and the plank seam lines are laser engraved on
the molds. The planks were developed for the prototype by spiling
and then traced and digitized so they could be laser cut. This is an
innovation in model ship building.
It is important to note that the laser cut planks are a little oversize
and must be further shaped and fitted so as to conform to the laser
engraved line off marks on the molds. It is also important to note
that the laser engraved marks need to be projected to the outside of
the frames ( inside of the planking) as that is how the lines on sheet
2 are drawn. It is a good idea to use a straight edge and pencil to
project these lines to the frame surface so that parallax does not
cause errors to creep in. If your pre-cut planks are properly finish
shaped to conform to the line off marks, they should fit nicely.
It is a good idea to lightly pencil the plank numbers on the planks
before removing them from the basswood sheet. Some of the
planks are very similar in shape and can possibly be misidentified
when installing. All planks must be pre-bent and completely dry
and fitted to the marks before installation. The plank ends that
meet the rabbet at the stem are called hood ends. The hood ends
are shaped and positioned by using the patterns provided on sheet
2. It is important to note that it is the inside edge of the plank that
is positioned such that its projection forward would flow nicely
into the marks on the pattern. Study the illustration on sheet 2.
This projection distance ranges from the most at the garboard to
practically none at the sheer plank. Remove the keel alignment
tabs from one side of the keel. When the garboard is fitted and
glued to the frames and keel on that side the tabs on the other side
may be removed.
We will apply the sheer and garboard planks first and then work
downward from the garboard and upwards from the sheer plank
until we meet at the turn of the bilge at plank 6. This last plank is
called the shutter plank and/or sometimes the whiskey plank. You
may as an option start at the sheer plank and work upward. The
method of bending the planks for the prototype model was a coffee
can of boiling water on the stove. Place the hood end of the plank
11
bending to a mold, i.e., a pre-bend. This, of course, is after you
have hot soaked the frame. As you bend a frame in your fingers you
will develop a sense of how much the wood can take and where to
apply pressure on the frame to achieve the desired bend. You may
break a few frames as you go, but there is plenty of frame stock in
the kit.
Cut a supply of 3/32 square frame stock to about 4-1/2 inches
length. This length is suitable for all frames except molds 15 and
14 which require a slightly shorter length. Frames are bent by
hooking the keel end under the keel in the sockets about halfway
through and then wrapping the frames down over the mold and
clamping them below the sheer tabs. Refer to sheet 2, hull con-
struction. The most severe bends are at the turn of the bilge near
midships. Begin your frame bending elsewhere; say around molds 4
and 5 where the bends are not so severe. This will give you a feel
for the process. The hot, wet frames must dry completely before
any futher work as the wood swells when wet and shrinks as it dries
out. Clamp the frames to the molds below the sheer tabs and let
them dry overnight. Also clamp them anywhere along the mold
where the frame may tend to lift away from the mold. Photo 10
shows a variety of clamps that can be used for this.
The frames must not only bend but twist as they wrap around the
molds due to the fairing of the mold edges. There is very little twist
near midships but quite a bit near the ends. You may have to “help”
your frame take this twist by twisting it with your fingers. Frames
may also twist naturally as they are bent due to the peculiarities of
the wood grain. This may have to be “wrestled” with to make your
frame conform and lay as you want it. If you encounter a particular-
ly stubborn frame, throw it out and try another. The goal here is to
have the frames make intimate contact with the mold conforming to
both bend and twist while in the wet state. When they dry they will
retain this shape and become quite stiff and strong. When your
frames have completely dried (preferably overnight) they are ready to
install. The wetting of the frame stock will raise the grain and make
the wood feel rough. There is little chance of sanding the frames
after the planking stage so now is a good time to sand the interior
surfaces of the frames before gluing them down. The frames are
SPOT glued to the molds below the sheer tabs as indicated on sheet
2. This spot glue is easily popped off after planking is completed
and the hull is ready to be removed from the building jig.
When all frames have been installed is the time to fair in the tran-
som. Use a batten and fair the edge of the transom to receive the
planking. Also use a batten to check the fairness of the frames.
Some slight sanding may be in order if some frames seem to be out
of fair. Since the frames are only attached where we glued them to
the molds they will seem a bit flimsy for this operation. Sand along
the frame vertically and/or clamp the frame to assist in the fairing. If
you should discover a frame that just does not satisfy you as to its fit
and shape, throw it out and bend on another.
Now we can check the rabbet by using a strip of 1/16" material to
see how it flows into the rabbet. Make any final adjustments to the
rabbet you deem necessary. We are now ready for the planking.
STAGE 3:
PLANKING THE HULL
Photo 11, garboard and sheer planks bent and clamped in place to dry
