Constance's Seat

[catsittingstill]

Folks may remember last fall I was disappointed to find I had put Constance's seat in the wrong place. With a paddler in the seat, she was nose-heavy, which made her harder to steer and meant she tended to "weathervane" or turn into the wind, which is sometimes a good thing, but sometimes not.

I solved the problem temporarily by filling a couple of two-liter bottles with water and putting them in the far stern of the boat. You'll recall I mentioned this in the post with the pictures of Launch Day.

A few days ago I worked out where to move the seat. I wanted the front edge at the center of buoyancy. The problem is, I don't know where the center of buoyancy is, exactly, just that it is behind the current front edge of the seat.

So I set it up as a teeter-totter problem. The front edge of the seat is some unknown distance, call it n inches, ahead of the center of buoyancy. The two two-liter bottles of water are 61 inches behind the front edge of the seat or 61-n inches behind the center of buoyancy. And just like on a teeter totter, when Constance is trimmed level, my weight times my inches ahead of the center of buoyancy equals the bottles' weight times their distance behind the center of buoyancy.

So 180 x n (my weight times my distance) = 8.8 x (61 - n) (the two two liter bottles (2.2 lbs/liter x 4 liters total) times their distance)
Divide both sides by 8.8 to get 180/8.8 x n = 61 - n
add n to both sides to get ((180/8.8) +1) x n = 61
divide both sides by (180/8.8 + 1) to get n = 61 / ((180/8.8) +1) or n = about 2.84 inches. I went for 2 7/8 inches, which is 2.875 inches, because that seemed pretty close and my ruler isn't divided into tenths of an inch.

This means gluing on extensions to the rails the seat rests on, because they don't go that far behind the seat. It also means making a back thwart with considerably more curve to go almost three inches farther back than Constance's original back thwart. (The back thwart runs right behind the seat and the paddler leans back against it a little to support her lower back; if I don't move it back, the paddler will be bent like a very bent unhappy person. However the back thwart is screwed down to knees I epoxied into the boat, which would be a pain to remove in the time I have. Solution: move the *middle* of the back thwart three inches back; leave the ends where they are.  The boat is wide enough that I can get away with this.)

So I patterned and cut the new thwart yesterday. I fitted and shaped and sanded (and dampened and re-sanded with 120 grit and re-dampened and re-sanded with 220 grit) the thwart today, and I cut and shaped the seat rail extensions and cut the slots in them where the caning on the underside of the seat needs extra room. And just now I finally found the oomph to epoxy them in (let's hope they don't slip) and paint the back thwart with epoxy to seal the pores.

And tomorrow I shall cut the slots for the front cane, hopefully figure out some way to remove the extra four inches or so of seat rail that sticks out ahead of the seat in an unsightly way, drill the holes for seat and thwart installation and run a small patch test to see if I can varnish yet. Also there is some damage to the varnish on the gunwales where I slid her across the rack on the back porch, and I will fix that. Plus I need to think about carpeting or padding that rack when I have time or I will always be touching up the gunwales.

But today I got all the boat stuff done that I planned.  Not all the other stuff, mind you, but all the boat stuff.  Go me.