: Here's a question for ya... when doing a folder with a lot of rocker to the
: sheerline, how do you keep the curvature of the sheer. It seems if you cut
: all the forms and snapped the stringers into the holes, then it would
: "self-level" into a straight sheerline. I did notice some of
: your boats use a fabricated wood sheerstrake. Is that a nescessity on
: boats with a lot of rocker?

: Thanks,

: Malcolm

Good question... There are several things going on with the frame.
The HDPE snap on connections do a good job of keeping things pretty
tight, hence the rocker, chines, sheer are held pretty much in check.
I mention the connections, as I've made aluminum tube /wood section
non-folders that were lashed/epoxied together, and they are
downright rigid, with zero "reflex" of the tubes.

Another factor, is where and how much rocker you apply.
Most folders have no rocker( keel), but it doesn't need to be that way.
I believe a folder can and should have the same design potential as
any other kayak.

My Aleut kayaks, have a flat sheer, thereby freeing up some rocker
to be used at the keel and chines. A couple of them have 5 inches rocker
at the keel/stem intersection front, and also a fair amount at the chines.
These boats will flatten out some when sitting on the ground, but will revert
to the designed rocker when loaded and in the water. Part of the flattening
is due to these being 4 or 5 section frames, and therefore less rigid.
I now build three section boats.

On the Sea Rider, an East Greenland profile, everything is in moderation,
there is under 2 inches rocker at the keel, a similar amount at the chines,
and the the sheer has 4" at the bow and 2.5 at the stern. It seems to retain
it's shape quite well, on the ground or on the water.. In addition, there
is an inwale that approximates the sheer curve. It ties into the gunwales.
This is to add rigidity to the shallow hull ( 6.5" at the aft coaming location)
\ both longitudinally and laterally. Overall, this is a pretty rigid frame. I
detected zero deflection in the water today.

The final factor is the skin. The skin is made while the kayak is held in it's
correct rocker position. The finished skin conforms to this profile, and later when
the kayak is assembled for use, the skin in effect helps the frame in assuming
the designed rocker. While upside down on a strongback, the Sea Rider frame
is connected at cross sections 3 and 5 to assume the correct rocker while
making the skin. When right side up, I position the frame at cross section 1 and 6, again
to keep the rocker in check. This is critical, as the skin must correctly
match the designed rocker.

Even while building the frame upright on the strongback, only two station
(1 and 6) are used. I used to make stations for every cross section, but found it
was unnecessary. Just a habit left over from my stripper days.

Maintaining the correct frame shape isn't a problem unless you try
to be extreme in your bends. If you look at a front view of the Sea Rider
cross section, the sheer and chine shape looks straight. They aren't of
course, but this shows that all curves are constant, and there is no
severity in the curves. I guess, on say a steep West Greenland sheer,
that the gunwale tubes could be bent, but I try to avoid mechanical bending
when possible. On Sea Rider, the only bent tubes are the stems and the
front deckridge. Unlike wood, aluminum tubes don't create a sheer curve based
on the angle and separation of the gunwales.

Fabricate wood sheerstrake - I've built one wooden folder...Is that
what you're referring to ? Otherwise, I'm not sure what boat you mean.

Thanks for asking. I look forward to hearing about your kayak. These are
unique little boats, with numerous problems to overcome. That's what
makes them fun to build and paddle.

Tom