birds mouth boom for bolger bobcat
- i was wondering if any of the folks here who have built birdsmouth
spars could help me figure out the diameter of my boom for my bolger
bobcat......the gaff is easy, it's a square...the boom is another
matter. It is specified as a 1-1/2" x 2-1/2" 13'-6" boom with
stiffeners on it's sides. i would like to build it round by the
birdsmouth method. how to calculate??? any idea's would be helpful
- Hi Bob
Jim Michalak has a good essay on hollow spars, including calculations for
comparing round and rectangular spars. (Feb'00).
John O'Neill wrote a two part article on birdsmouth spars for Boatbuilder
magazine. The Jul/Aug '01 issue has the calculations for elliptical section
Gregg Carlson has a neat program (available at www.carlsondesign.com) for
calculating strip sizes for round birdsmouths.
Although a birdsmouth enthusiast, I'm curious as to why you would build the
boom this way.