Neeves
Well-known member
Most yachts have an engine sized according to the size of yacht. Big yachts have big engines, small yachts small engines. Consequently it is possible crudely equate engine power to revs to windage and the tension in the rode. Undoubtedly its crude, desperately so - but its all we have
. Even two engines of the same size will generate different rode tension - because they have different props. Similarly 2 yachts of the same length can have a different windage (and different engines)Most of the yachting magazines at some stage have made investigations into prop designs, I have actually conducted tension tests on our 2 x 20hp engines with 3 bladed folding Volvo props. The idea that 2,500revs, say cruising revs, generates a rode tension of that developed in 30 knots of wind is as good as you will get.
If you power set your anchor at 2,500 revs it matters not if this is the tension in your rode at 25 knots or 35 knots of wind - you have deep or well set your anchor, it will not move until the wind is greater than 25 or 35 knots and unless you are unlucky - if the wind is stronger (you might be in the wrong place
) but commonly a well set modern anchor, if subject to a higher tension than the set tension, will simply set more deeply. It will set more deeply till it reaches its ultimate hold in that seabed at that scope and then drag in the seabed. It will eventually clog, due to dragging and then surface - but the tension needed to commence a well set modern anchor to drag is 'unnaturally' huge.Power setting is not a panacea - there maybe a discarded beach towel 10mm just downwind of your anchor that will foul your anchor if the wind increases - but such issues are not common.
Live dangerously, be cautious, but enjoy the security of a good well set anchor. Simply consider how many 'dragging' events there have been mentioned on YBW in the last 12 months - dragging, or reported dragging is now so unremarkable - as to be remarkable. We are a simple example - we discarded a poor CQR copy that dragged reliably - we simply don't drag now that we use a modern anchor.
There is a current discussion on anchor alarms (we don't use one) - it would be interesting to learn how many alarms go off because of dragging (if its a large number - people don't report same) and how many go off because the alarm was not set correctly. In addition to not using an anchor alarm we similarly do not use a depth alarm, strong wind alarm - all of which are families on our electronics.
Most of us now have better anchors, we know how to use them (for example - power setting), an increasing number now use snubbers (which will make a poor anchor better and a good anchor excellent)......
Jonathan
