external support for first 8' keelson removal

Comment

Comment by bob mitchell on June 22, 2010 at 10:02pm

Now that I look at it, I realize that just because the ribs are suported from underneath doesn't mean that the frame, without the floor timber, won't collaspe upwards. So tomorrows project will be to make the side frame members (ribs) rigid by bracing them inside to the cabin top and sides. Wew, just about missed that one, assuming they were a rigid structure, which they are until you take the floor timber away!

Comment by bob mitchell on June 22, 2010 at 9:50pm

What one has to consider when removing the floor timbers (bottom frame members that rest on and are bolted to keelson) is that when a floor timber is removed the section of the boat above it no longer will be supported by the keel. If you are going to rebuild the keelson you have to remove the floor timbers a section at a time, which requires the structure above to be supported by a lot more than screw jacks. Not only do you have to consider the vertical weight, but also, since the botton of the boat is angled, the vertical weight will tend to thrust your supports outward, so lots of diagonals are necessary, as well as inside bracing. Basically you try to imagine what forces the floor timber provides, and mimic them in whatever way you can. Later in the week, after I cut out the first eight feet of the keelson, I'll let everyone know if it worked. Except for the anxiety the work itself is really pleasurable.