Subject: Re: [baidarka] Bending ribs on Greenland
From: James Mitchell (baidarka@earthlink.net)
Date: Sun Feb 29 2004 - 18:15:42 EST
I still install the ribs hot. When the ribs are being installed, the
chines lift up off the section molds in order to fit into the mortises.
Then I lash the chines to the installed ribs, and remove the molds. I
also pin these ribs to the gunwales by drilling a 1/8" hole through the
gunwale and rib end as it rests in the mortise, and then inserting a
bamboo skewer into that hole. This locks the initial ribs in place, and
allows me to frame the rest of the ribs to that point. The objective is
to produce a final shape that does not have bumps and valleys.
On Mar 1, 2004, at 7:58 AM, 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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>
>
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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