Subject: Re: [baidarka] Frame flex.
From: Peter Chopelas (pac@premier1.net)
Date: Sat Oct 13 2001 - 18:48:22 EDT
Vaya Con Dios,
The skin will make a big difference, but also the way you are loading it is
far more severe than what happens in the water. The water supports the hull
distributed among all the frame members.
Also consider that the support the water gives is distributed according to the
water displaced. so the widest and deepest part of the hull, right where the
seat is, is what provides most of the support. Which is also right where
most of the weight is concentrated. The ends, where you put your blocks, do
contribute some support when in the water, but it is a very small contribution
compared to the central part of the hull.
There is no easy way to make this comparison unless you have a frame
only(without the skin) of a hull that you know has the right amount of
stiffness. Your method of 'testing' the flex is not even remotely similar to
what happens in the water.
You can skin it with sheet plastic and packing tape and give it a quick try
out. After a test like this making the frame a bit stiffer would be easy at
that point by adding a few heavier members on either side of the keelson for
2/3rds the length of the keel. Or if the boat is too unstable for you, it is
better to modify it at that point than waste a lot of effort and good skin
material to find you have something you do not like.
I highly recommend the plastic skin, or "seran wrap" test before you do
anything else. It will give you piece of mind if nothing else, and it
motivates you go get it done since you had a taste of what it will look and
behave like. It is also fun.
It only takes a few hours to wrap it with plastic and try it out. You can use
3M spray adhesive at the overlap if you like (I did not and it worked but
there was a lot of seepage) and clear packing tape to make it seal ( water
will still find its way in but it is slow enough you will have enough time to
see what it is like). I also wrapped the packing tape in a big spiral from
stem to stern for extra strength so a large tear could not get started. all
you need is a lake or calm bay to try it out (without spray skirt of course)
and a few hours. Do not get too far from shore however!
Give it a try and report back to us.
Peter Chopelas
-
Baidarka Mailing List - All postings copyright the author and not to be
reproduced outside Baidarka or Baidarka archives without author's permission
Submissions: baidarka@paddlewise.net
Subscriptions: baidarka-request@paddlewise.net
Searchable archive: http://rtpnet.org/robroy/baidarka
This archive was generated by hypermail 2b27 : Thu Nov 01 2001 - 01:30:02 EST