We successfully anchored our Bav 38 ( 2010 model) in winds gusting between 40kns and 75kns for 3 days in Pula, Croatia. We had 60m of chain out in 4 m of water using a Kobra 23kg anchor. ( Kobra 23 kg was largest anchor we could fit on our roller ) When the winds reached over 50kns we deployed our CQR ( The one that came with the boat) on about 20m of chain much closer to the boat. The second anchor reduced the yawing. Before deployment of the second anchor the wind gusts were lying the boat over so far I would be rolled over in bed. The chain was so straight, it did not touch the water for 2 to 3 boat lengths in front of the boat.
We were anchored in the bay near the colosseum and had no wave action. The additional loading on the chain in these conditions is not a shock loading when the boat changes directions but a loading that might approach 1 1/2 to 2 times the standard strain. (There is a web site produced by a french sailor with these calculations) . We divided the strain between the deck cleats using a short nylon snubber to protect the windlass and had lines from the cleats back to the main genoa winches as a precaution against the cleat being pulled out of the deck. If you need to anchor in strong winds, I recommend that it is more important to be away from wave action than away from the wind.
Most anchor tests show the concave shaped anchors hold greater loads than the plough type anchors. But, beware, if they have roll bars, they may collect a lot of weed. We have seen a number of these anchors fail to set as a ball of weed clogs the anchor. The plough shaped anchors tend to shed the weed more easily.This could be dangerous when the wind changes directions.
The beauty of laying 2 anchors, one behind the other is that, if one drags, then you can let out additional chain on the other to tension both anchors. Our 2nd anchor was not used to divide the load as such but to reduce yawing. By reducing the yawing and taking some of the load, it contributed as much holding as the main anchor.
A simple vector diagram will show that laying 2 anchors in a V pattern in strong winds will do nothing to reduce tension on the boat. It will mean that the load is merely transferred from one anchor to the other when yawing and will do little to reduce yawing. With 2 anchors in a V pattern you are more likely to tangle the anchors if one anchor drags or the wind changes direction, even a little.
Catenary is a myth in strong winds. Do not invest in heavier chain but invest in the largest anchor that will fit on your boat. Never buy a CQR, all the recent anchor tests show the problem that they take longer to set when pulled out and their holding is not as good as the Kobra or Delta designs.
I now have a fortress as a spare anchor. It suspect it would not be as good as even a CQR to stop yawing but it would be good as a kedge anchor to pull me off a sandbank. With a small fender, I can swim out with the fortress ( 7 kgs) and drop it in the water away from the boat. ( Nylon rode only). Beware of the Fortress or danforth type anchors, particularly in the med, as they are difficult to remove if they pick up a chain from the bottom. Took nearly 1 hour, and using a mallet, to bash a chain out of the gap between the flukes and the shank on a neighbours boat after they picked up my chain.
When attaching a snubber, always, if possible, attach to the chain between the roller and the water and lead back 2 lines, one to each cleat. I can't speak for most boats but one mine, I think I am more likely to pull the windlass out than wreck the bow roller.
Craig
"Shirley Valentine"
Gold Coast
Australia
