chainplate calculations for a jordan drogue

[asdf777]

If somebody could verify my calculations for jordan drogue chainplates, it would be really great!

The boat is 30' sloop, 8600 lbs official displacement, but probably around 9,500-10,000 lbs fully loaded.

I'm thinking of the following:

1.5" x 0.25" x 12" with a 1/2" hole and 4-5 bolts. Crosby 7/16 209a shackle - the pin is 1/2". WLL ~= 6000lbs. The chainplate strength should be:

(1.5" - 1/2") * 0.25" * 30,000 lbs/in^2 (tensile strength for 316 without yielding) = 7,500 lbs.

Does it look right?

Many thanks!
Gleb