T&T: Anchor,chain,rope specs and use

[Robin]

What's what's a reasonable relationship between anchor holding specs, chain
working load, and nylon breaking strength? These are the way the three are
routinely rated in marine catelogues.

For example, Danforth  says for a  boat size 44 to 54 ft, 5300 lbs holding is
required for  winds to 60 knots. That sounds to me like it would hold to 100
knots!

For my heavy 48 Hatt YF, I've used a Danforth T4000, 4000 lbs holding with
5/16" ACCO G4 chain rated at 3900 lbs working load. I tried to roughly match
the two figures when making my purchases. Is that the conceptual way to go?
(I can't imagine that force on my anchor rode unless in hurricane winds and
surging seas.)


I trust the chain limit a lot more than holding rating of the anchor due to
varying bottom conditions. I do know my rig has held  for brief periods in 75
mph winds without any problem.

And what's a guide for rope strength: unfortunately rope seems to be listed by
breaking strength rather than working load. 5/8" inch three strand nylon that
I use is usually rated about 9,500 to 10,500 lbs breaking strength. That SEEMS
like plenty for use with a working load of about 4,000 lbs....but whats a
recommended working vs breaking load for three strand nylon?

All these years I've been going by experience rather than trying to match
specs....

Tied in with all the above, does anybody have wind force per square foot at a
few different wind speeds? say 50 and 100 MPH? I think I remember wind force
varies as square of wind speed, so 100 MPH has four times the force of 50 MPH.
Is that right?

Rob Brueckner
Hatteras YF