Anchoring debate
Christopher Smith’s article ‘How much anchor chain?’ (YM, Summer 2019) makes some excellent, well-researched points. But I fear they are based on a false premise, that an anchor will only hold effectively if the ‘catenary’ shape of the anchor chain applies a horizontal pull on the anchor. It would seem that an anchor will continue to dig in so long as the tip is pointing below the horizontal. Hence the critical parameters are the angle of the flukes to the shank and the angle at which the chain pulls on it: even if the length of chain is such that the load pulls it almost straight, so long as this angle is not exceeded, the anchor will hold. Of course, the motion will not be as comfortable, as the chain will tend to snatch. I have no research to support this, but when anchored in 4m of water with 20m of chain our chartplotter displayed a perfect circle as a 20-25 knot weather system passed over us. Simon Glover Christopher Smith responds:
How right you are, Simon. Anchors hold and slip under lots of conditions. What is undeniable is the more the wind, the more the force on anchor and chain. I was simply stating in my article that wind and tide are vital considerations.
Snatch, as you say, is uncomfortable but obviously a factor for dragging an anchor. The idea of a boat length of chain on the seabed is entirely my choice but has a rationale in terms of swinging at anchor.
Choose whatever angle of chain to anchor you want but please allow for the maximum wind force you expect during the night.