| | | MY experiments show a number of interesting and, in some cases, quite unpalatable results. My overall winner is the SPADE because it never rolled out and also gave the best hold, with very little change when the scope was decreased. On the other hand, the Brittany rolled out whatever the situation, even when veered. The plough wasn't much better. As for the Danforth and its copy, even they were a little dubious in terms of roll out and shouldn't be relied upon completely. The HiBlade, Delta and claw all did well but their holding power was less than the SPADE'S. | | |
| | | How much cable should I deploy, and should it be chain or warp? The answer has been given in my earlier articles dealing with wind forces. Briefly, there are two very simple rules. First, if you anchor with all chain, the length (in metres) required for safe anchoring is equal to the wind strength (in knots) multiplied by a factor which depends upon the water depth and chain weight, but is typically about VA. If you can't deploy this amount of chain, snatching will occur and you should add 10 or 20 metres of nylon multjplait to the rode to act as an energy absorbing spring. Will my anchor come out il I pull it too hard? No, not if it's properly set. You can pull your main anchor much harder than you would ever want to and it will not come out. It will simply plough slowly through the seabed. However, some anchors are unstable when dragged and may roll out. They should be avoided in my judgement - see my answer to the next question! Do all anchors perform similarly or are some better than others? Some anchors roll out when forced to plough through the seabed. This was certainly true with the plough | | and Brittany, but there may be others. Anchors which are stable to rolling and will plough indefinitely through the seabed are the SPADE, HiBlade, Delta and claw, and again there may be others which I've not tested. The Danforth is somewhere between and shows some indications of instability. Some anchors, like the Danforth and plough, don't set well initially, especially if the seabed is hard. What happens when the wind direction or tide changes? Will my anchor still hold? Yes and No! The roll-stable anchors can be veered without pulling out. The plough and Brittany roll out: the Danforth sometimes comes out. Roll-out is dangerous since there's no guarantee that these anchors will reset. What's the eltect ol scope on the holding of an anchor? As the scope decreases, the holding power decreases. Some anchors are better than others. The SPADE shows the least effect of decreasing scope, the HiBlade and claw show the most, but even these lose only about 30% of their holding going from infinite scope to scope five, although they lose up to 50% of their holding power going from infinite scope to scope three. | | |
| | | will slowly plough through the seabed. In a Force 8, such an anchor, buried in medium-hard sand, will plough under peak loads at about three centimetres per second. Which anchor should I choose? You should always choose a roll-stable anchor. Of these, the SPADE performed the best for its weight. It gave the highest hold, the least reduction of hold with scope, the highest static hold (SHF), and the lowest rate of ploughing when the SHF was exceeded. It was closely followed by the HiBlade, Delta and claw in that order. | | |
| | | How heavy an anchor do I need? The recommended weight in kg for a yacht is roughly [%) of its (LOA in metres) squared. If an anchor is lorced to plough through the seabed, how does the speed at which it drags depend upon the force applied? The force up to which a well buried anchor will hold in medium hard sand without moving, called its SHF, is around 11 times the anchor weight. An anchor of the recommended weight buried in medium-hard sand will hold without moving up to about Force 6. When a larger force is applied, an anchor | | |