Subject: Re: [baidarka] Bending ribs on Greenland
From: steveJ (vtboat@VERIZON.NET)
Date: Sun Feb 29 2004 - 18:15:07 EST
The section molds are only temporary, Made of plywood. Notched to
receive chines and keelson.
Since the temporary spreaders need to be placed between the gunnels,
why hot just extend them up
to establish the chine locations and keel profile? Then bend in the
ribs. This would be a little more accurate to mantain the shape of the
hull at critical points like the depth at the back of the cockpit rim
and the water entry
section. It would also allow the positioning of the chines to be worked
out so that the skin does not touch the ribs.
steveJ wrote:
>The section molds would be removed with the method I am describing.
>How would the flexibility be effected? The finished structure is the
>same either way.
>
>James Mitchell wrote:
>
>
>
>>I have used station frames to approximate the shape of the chines, but
>>I remove them as soon as I can. I set a couple ribs on either side, and
>>then take them out. These hulls have much more flex than a carvel hull,
>>and I think the frames would interfere with that.
>>
>>On Mar 1, 2004, at 7:27 AM, steveJ wrote:
>>
>>
>>
>>
>>
>>>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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>>>
>>>
>>>
>>>
>>>
>>>
>>James Mitchell
>>Email: baidarka@earthlink.net
>>Japan: 090-4974-3874
>>Japan (from USA): 011-81-90-4974-3874
>>US Message Phone: 425-424-1325
>>-
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>>
>>
>-
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