What to do with
those long pieces? These are also known as
keel, chines, sheers and battens. The placement, fitting and
clamping of these unwieldy objects can be difficult. In addition,
cutting the scarf joints is tedious and needs to be precise. Here is a jig
for cutting scarf joints.
Fitting these long pieces is difficult due to
their length and the fact that very little of their length is
straight when they are finally in place. It is strongly
recommended that you find at least one helper for the cutting and
installation of these pieces. It turns out that due to limited
width of my shop area that fitting completed pieces in places is
sometimes impossible. This was particularly true for the sheers
and side battens.
Glue-up of the scarf joints while assembling to
the frames for these pieces runs exactly counter to the
instructions provided with the plans and other books. I did the
in place glue up as there was no other way to handle the pieces
and I am quite satisfied with the results. Be careful to place
the joints in areas with mild curves. If they are in an area with
sharp bend the curve will not be fair. This MAY be correctable
in final fairing.
The first long piece to be installed is the
keel. This is also the simplest of the "long pieces" to
fit into place. It is assembled in place with scarf joints. Start
installation at the stem. The initial bend requires quite a bit
of pressure. Use several clamps to hold the keel in place as you
bend it downwards.
The first keel layer should be able to
glued in place without requiring any permanent fasteners. Clamp
firmly to the frames. This will set the positions of the pieces
and then clamp the scarf joint(s). The clamp pressure on the
scarf joints will cause them to slide apart if the pieces are not
already clamped to the frames. Allow the epoxy to harden. Next
apply the second layer of the keel. I found that many (35) clamps
were needed to keep the two layers in good contact.
In order to fit the complex angles of the
chines at the stem, several passes were made in a successive
approximation to the final joint. For the final trimming, I found
that holding the chine piece clamped loosely against the stem I
could the use a saw to trim the end of the chine piece with the
saw blade laid against the stem. Again a saw with no set will
give the nicest results and not chew into the side of the stem.
For the chines I glued up the pieces in to long
strips prior to mounting on the frames. The chine curves near the
bow extend for quite a distance and even past the first scarf
joint. Again start applying the chine at the bow and in the test
fitting, clamp it in place over its entire length to the frames.
Measure the distances between frames at the chine to make sure
that they have remained square. Adjust and re-clamp as necessary.
At this point drill the pilot and countersink
holes for any screws that may be needed. To apply the glue,
remove the front 4 clamps and then apply the glue to the joints
and then re-clamp. Next remove the balance of the clamps, apply
glue and re-clamp. Doing it in this manner preserved the fit at
the stem and allowed glue up to proceed with only one helper.
Pre-drilling the pilot holes for the screws
makes clean-up of the glue fillets much easier as there is not
fresh sawdust in the glue. It also means less glue will be coating
the power tools when you are finished.
Battens are fitted in the same manner as the
chines and the scarf joints are glued up prior to assembly to the
frames. I used the boat frame as the work table while gluing the
scarf joints. It allows clamping of these long pieces while
keeping them straight. After clamping sight down the length of
the batten to see that it is straight and fair. Correct as
necessary before the glue hardens.
Here David is holding the free
end of the batten during glue up.
Here is Elyse providing clamping pressure. Only
3 more hours to go...
Notches for battens
cutting of the bottom batten notches see the router jig for battens. The router jig provided consistent notches with
minimal hand fitting required other than at the bow. Most of the
side frames are too curved to use the router jig. For the sides,
now is the time to go back to hand cutting. Make a marking jig
and mark each of the notches. For each notch cut 3-5 saw kerfs
with a hand saw. The kerfs should be to the depth and angle of
the required notch. Take a mortising chisel (3/4" to 1")
as shown and chop into the end notches with a strong mallet whack.
The pieces between the kerfs will snap off easily. Repeat from
the other end of the notch and most pieces will now fall out. Use
the chisel to clean up to the depth of the kerfs.
If the grain runs parallel to the bottom of the
notch, only 3 kerfs are needed. If the grain runs out with
respect to the kerfs, use 4, 5 or even 6 kerfs to control the
depth and even-ness of the bottom when snapping the waste pieces
Fitting of the sheers to the
notches is difficult due to the working position. Most of the
cutting and chiseling is done while laying or sitting on the
floor. The frames are very springy which makes fore-aft oriented
chisel cuts difficult for final fitting. Try to borrow a power
chisel (Foredom or AutoMach) from a wood carver. These devices
make this RADICALLY EASIER.
My dad lent me his AutoMach and
initially I was skeptical, but it was a huge help. Much of the
chisel work is cross end grain and these devices will pare off
beautiful thin curls. Sharpen the blades frequently as the silica
filler for the epoxy rapidly wears down the edges. I could not
justify buying one of these for this task alone, but it is
certainly worth searching out if you can borrow one for a day (offers
of beer and a couple of new sharpened chisel tips may help also).
||View of sheer from looking inwards through the transom.
This is the second layer being held in place. As you can see, once
again you cannot have too many clamps. In this case, I borrowed some
from a friend. Just be sure to wax the clamps to allow for easy removal
of epoxy drips and finger prints.
Sheer piece-wise glue-up
For the sheer, a different assembly method was
used than for the battens and chines. This was due to the
relatively narrow work space (12 feet), and the long (20-24 foot)
sheer pieces were unwieldy. In addition, the thinner members bent
much more easily, even though the curves are more extreme.
Fit up of the sheers is similar to that of the
chines, but at each scarf joint, use 2 clamps. I prefer wooden
hand-screw (Jorgensen) clamps for this task due to the large
clamping area. Drill a single pilot hole through the center of
each scarf joint for a temporary wood screw. The screw will
provide for the longitudinal alignment of scarf joint. Check
frame alignment again and drill pilot holes for one screw at each
frame and for 3 screws at the stem. After drilling the pilot
holes at each frame, remove the clamps and pieces and start glue-up
at the stem once more. Apply the first piece and then clamp the
first scarf joint securely prior to starting to fasten the second
piece to the frames. If you fasten the second piece to the frames
prior to clamping the scarf joint, it will be impossible to align
them properly and the pieces will be angled from each other and
provide an abrupt discontinuity in the curves, rather than
creating a continuous and fair curve.
|Next: Fairing the frame
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