Sunday, April 5, 2020

Catboat Math 05 Apr 20

05 Apr 20:

There's the plan and then there's actually what happens. We have Chapelle's line drawing for a 17 foot diamond bottom catboat, and we planned to scale that plan down to 16 feet. Let's see that's .941176 smaller. So I did a bunch of measurements and scribbled all over a copy of the plans and headed out to the Carriage House to transfer those numbers onto a lofting on the Carriage House floor. But first I had to correct my highly calibrated blue tape baseline, and mark off 1 foot increments out to 16 feet. Then I used the square to find a perpendicular at each foot mark, took the steel tape to find the Feet-Inches-Eighths point, make a mark and put in a deck screw.



Somewhere along the way I remembered that I wanted to scale the beam of this boat down from 8'6" inside of plank to 8 feet outside of plank. I thought I could just reduce everything by 10 percent but instead discovered I needed to draw a new sheer line, and get those new measurements off of the new line. Fiddled with the fair curve and came up with a sheer that looks okay, pending Skipper's approval.




If Skipper is happy with it then we can pull new measurements off of the lofting at a few points to get the measurements we need for building molds and bulkheads.


Placed the rough keel batten down to start thinking about keel shape.


Log of MARGARET ROSE.

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