Previously: “That Will Buff Right Out”
Via Daniel Hearn, Spaight Street Syndicate
Trust The Engineer…Or Else!
Since it was determined last weekend at Lake Pepin that I have a weak spine, this weekend it was time to man up. First I removed the ragged skin to the closest bulkheads, sideboard or stringer. Then I cut out the what remained of the old spine. The original T-beam was constructed of 5/8” Sitka, 2-1/2” wide with triangles underneath. I made the new T-beam out of 1” x 3” White Oak with two verticals on the bottom, triangles underneath and horizontally at the bulkhead joints. For additional peace of mind, I added a layer of 45 degree carbon and a layer of biaxial carbon around the entire beam, plus one more layer of carbon on the top. And finally, carbon gussets at each of the corners were the beam and bulkheads meet. This construction should be dramatically stronger than the previous, which would have been fine, had I just followed Pat’s plans.
Rather than using a traditional top-mounted mast ball track, which would have spread the load out across 14” or so, I used a 6” countersunk style. This required the removal of a fair amount of material directly under the mast ball, when the shorter length was already concentrating the load in a smaller area. The mistake I made was not accounting for these impacts. But the countersunk style looked cooler. (That’s what we call “solid” marketing thinking!)
The spine didn’t actually collapse, rather, the track twisted, blowing out the side of the original beam. It was breezy that day on Lake Pepin, so in addition to carrying a bunch of lead, the stays were slacked off, which caused more side load on the mast ball, hence, the twist.
Hopefully the Northwest will be “On” for the coming weekend, so I can give Lorem Ipsum another shakedown, and try to catch Pat!
