Visit our Popular Forums

**minaret** · 26-03-2013, 10:47

Quote:

Originally Posted by Cheechako

It's not flexing the hull before bending the lead alloy? surprising and interesting....

In theory, the ballast keel has been totally immobilized in relation to the hull. There should be little or no load imparted to the hull here. In theory.

Richard5 · 26-03-2013, 21:44

Quote:

Originally Posted by minaret

In theory, the ballast keel has been totally immobilized in relation to the hull. There should be little or no load imparted to the hull here. In theory.

I am trying to align this comment with your earlier comment of how tricky this operation, that it potentially could lift the hull off the jacks.

Practically speaking, the hull is stabilized by the jacks and the boat weight is supported at the base of the keel. Sure, the jacks do take up some of the weight. So...how, if you are applying a downward force (torque) on the wing would there be a potential to lift the boat off the jacks? The only thing I can think of is as expressed by Newton's 3rd Law of Motion where the force applied at the wing results in a shift of the boat's CG moment. But this would tend to be cancelled by the 1) malleability of the lead; 2) the fact that you probably are not applying circa 40,000 lbs of force. Too, given the slow creep over time you are avoiding "acceleration" resulting from the force applied to the wing.

**minaret** · 29-03-2013, 17:46

Quote:

Originally Posted by Richard5

I am trying to align this comment with your earlier comment of how tricky this operation, that it potentially could lift the hull off the jacks.

Practically speaking, the hull is stabilized by the jacks and the boat weight is supported at the base of the keel. Sure, the jacks do take up some of the weight. So...how, if you are applying a downward force (torque) on the wing would there be a potential to lift the boat off the jacks? The only thing I can think of is as expressed by Newton's 3rd Law of Motion where the force applied at the wing results in a shift of the boat's CG moment. But this would tend to be cancelled by the 1) malleability of the lead; 2) the fact that you probably are not applying circa 40,000 lbs of force. Too, given the slow creep over time you are avoiding "acceleration" resulting from the force applied to the wing.

Yep, you got it with 3rd law. We finished this job by cutting a few feet off the lever arm (it was bottoming out) and going up to a 2 ton block. Came out nice, but I lost my phone about this time and there's a resulting blank in the photo record. Too bad, it was a pretty hairy setup! 2 tons on about five foot of lever arm is a lot of force, I'm sure some of the engineers around here could easily tell us just how much.

Richard5 · 29-03-2013, 21:48

Weight multiplied by arm equals moment. A 4,000 lbs weight on a 60 inch arm equals 240,000 inch pounds. In lbs/12 = foot pounds. In your case, assuming the arm is 5 feet (60 inches), you exerted 10 tons of torque. The disclaimer is the assumption of the length of arm.

mrm · 30-03-2013, 09:46

Well, I am 'imperial impaired'

but it seems to amount to ~20000[N] x (5 x 0.3048[m]) = ~30480 Nm.

Quite a substantial torque. Rougly equivalent to a 100 diesel car engines.

Richard5 · 05-04-2013, 05:25

Did Minaret take a vacation? This is completely unacceptable. <goofy grin>

**minaret** · 05-04-2013, 15:20

Nope, just waiting for some activity on the thread! Closest I've come to a vacation is one day "off" to sail my new tender. I showed up in this baby on a perfect spring Saturday afternoon at the marina. I could have sold tickets so many people wanted a ride or just to check it out!

**minaret** · 05-04-2013, 16:04

Her big sister.

**minaret** · 19-04-2013, 22:49

New sails are works of art.

**minaret** · 19-04-2013, 22:51

No stops and starts anywhere in any of the stitching, zero loose ends or backstitching.

**minaret** · 19-04-2013, 22:55

Legendary quality worth paying through the nose for. Franks designs are prescient and Axel's work is superlative. Can't recommend them enough.

Schattauer Sails Inc.