Quote:
Originally Posted by conachair
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Yes. And for the
record, I use a long snubber all the time (on a cat it is a bridle). That said...
The force probably requires a sustained 25 knots of
wind, but it depends on the
boat. Gust will be greater, but much or that is damped out by the
keel. Brianlara was talking about a Triton, which probably does not see 250 pounds of
wind load until 42 knots. Additionally, he was talking >6:1
scope.
It has been shown (on the water testing)that occasional lifting does not really disturb the
anchor.
There is nothing magic about the chain just coming off the bottom (unless you are using an in-line tandem on rocks or cobbles). There is still a lot of curve left at that point.
Another interesting number is the sustained wind at which the chain becomes effectively straight. At that point the cable only has about 23' of "stretch" in it, and by 500 pounds (60 knots for a Triton), only about 6 inches. At 42 knots, that 3' plus the motion of the chin through the water is plenty to damp out waves. However by 60 knots the chain is pretty straight and damping will become minimal. Also, the chain will be giving a lot of
lift.
Thus chain can help a lot in most
weather in deep water (25 knots sustained is pretty brisk), but in really strong conditions, you still should have some scope 5:1 in 30' is only 150'.
So Brian was telling the whole truth, for his situation, using the same "simple maths" we have been discussing. For a larger
boat... well then the math changes. But he didn't claim knowledge beyond his experience.
How many folks here know the wind load for their boat (no fair looking it up just now)? I've measured mine in a range of conditions with many
rode and snubber types. It's a pretty important number. How about reverse thrust for testing that anchor? Do you know what windspeed that equates to?