Subject: Re: [baidarka] Bending ribs on Greenland
From: kschmidt (kschmidt@akutan.aesd.schoolaccess.net)
Date: Sun Feb 29 2004 - 17:48:19 EST
Steve I am at this step right now.... however i am cutting hickory
into square 3/8 inch strips and then shaving them down to a rounded
shape with a block plane.... obviously they are not symmetrical. So
they do not bend the same every time.
To fix that fact.... I made a jig separate from the boat and just
steam bend the ribs to a pre measured size (the jig) You will need
four or five separate jigs for each section of the boat. all of my
ribs are planed and then centered on the jig and bent..they are all
oversize (too tall) about 2 inches. When all the ribs are done for a
section I will then cut them to size (the piece that inserts into the
mortise hole) so they will be symmetrical in height and shape. I
think the subtle curvature of the boat will be compensated for
between jigs stations by the shortening of the ribs as the taper
between the gun whales converges.
Kurt
(Making my first boats)
>I'm about ready to start bending some ribs on a Greenland style kayak.
>I've been using various books and information resources for
>techniques and procedures.
>One thing that puzzles me is the way that the ribs are bent free
>hand to the desired
>shape and then the longitudinals are lashed in and faired.
>Doesn't it make more sense to set the longitudinals in place using
>section molds with notches cut to
>receive the keel and chines and then bend the ribs by steaming and
>springing the rib to the points
>established by the longitudinals? This would follow traditional
>bent frame carvel planked boatbuilding
>methods and would eliminate the novice having to try to "eyeball"
>the correct shape of the rib. It would
>also eliminate having to calculate the length of the rib prior to
>bending. Just bend the rib roughly so it fits
>between the gunnels and clamp it to the keel and chines. When dry,
>mark and cut the ends by adding the depth of the mortises. Remove
>the keel and chines which are temporarily lashed in place and
>install the ribs in the usual manner. Although the bend would be a
>bit tighter than the real distance between gunnels, it seems like
>it wouldn't matter and the ribs would have some spring back and fit
>in the mortises anyway What am I missing?
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