MC,

If you fo to all tht trouble of figuring things out every time you sail, do
you ever get to relax? You should have a hibernate setting on the right
side of your brain.
"Scout" wrote in message
...
Gee whiz Nav,
how long have you been waiting to work that one into a conversation?
Scout

"Nav" wrote in message
...
Just for fun why not do a simple engineering calculation for us Doug?

For simplicity let's say the rig has mast without any stays.

Mast 20' vertical Boom 10' horizontal. Gooseneck 3' from base of mast
Vang attched to point 3' from goosneck. 200 lbs to be lifted.

What is the bending moment on the boom at the vang if the load is held
by the vang?
What is the shear stress on the boom the load is held by the vang?
What is the compression force of the boom at the vang attachment?

Now let me quickly solve for the topping lift case:

If a topping lift is used, the bending moment at the vang is 0.
If a topping lift is used, the shear stress is 0
If a topping lift is used, the boom compression is 200 x 10 /17 = 118
lbs.

What is the maximum stress at the vang attachment point in each case?

Cheers