New generation anchors and correct scope

[noelex 77]

Originally Posted by RichMac

The real challenge is knowing the anchor forces. The ABYC are very overstated, we don't know if they are peak loads, or how much safety margin.

Yes, the ABYC tables assume the worst case with some wave action etc. They are not representative of typical loads.

Originally Posted by RichMac

In 7m of water, 8.8m to the bow, I let out 30m of chain. The wind was maybe 15 - 20 kts, gusts to 23kts. At no time did the chain lift the anchor, even as the boat yawed and took up slack. The theoretical load for this chain is 95kg. If the chain had lifted, I would have put more out!

There is nothing wrong with using more scope if this is practical, but there is also no need to be concerned about the chain lifting. In 15-20 knots with 30m chain in 7m of water the chain will not be lifting as you observed, but if you want to anchor in strong winds there is really no choice, the chain will lift.

This is an image of a Rocna in similar depth of water and scope to your example. From memory this was 4:1 in about 8m of water. The photograph was taken while the skipper applied the setting force with his engine. You can see the chain lifting with almost no catenary visible, just as the theory predicts.

The anchor is holding fine, just as it should do, and just as would expect:

[dougweibel]

We met some lovely cruisers, Ben and Sylvia, last winter in the Exumas. They have been cruising winters full time on their Colvin Gazelle for more or less 41 years, if memory serves, and have endured numerous squalls and many storms while at anchor over those years. Ben is a big advocate of using 15' of chain and the rest nylon rode. That setup is more or less guaranteed to not have the last link of chain on the seafloor yet they have endured numerous blows and don't think twice about dragging as an issue with their setup.