ANCHORWATCH is an entirely new instrument designed to improve the safety of anchoring for pleasure yachts (7 to 12 metres LOA). If you anchor regularly, and have ever dragged your anchor, you will be aware of how difficult it is to be sure that you are safe under anything but mild weather conditions. Any regular cruising yachtsman will have spent anxious nights wondering if his anchor will hold. ANCHORWATCH is designed to relieve this anxiety.
Although there are many ways of detecting dragging, such as setting deep and shallow alarms on your echo sounder, or setting a circle of uncertainty on your SATnav, the fact remains that once you have dragged it may be too late, especially if the anchorage is crowded or you are close to rocks. ANCHORWATCH is intended to prevent dragging. It sounds an audible alarm, to warn that dragging may occur.
ANCHORWATCH, shown above, consists a Load Cell and Control Box, and is powered by the ships 12 volt battery. It takes about 80 mA. ANCHORWATCH measures the load or tension on your anchor cable. One end of the LOAD CELL is connected to the anchor cable, and the other to a strong point on the deck so that the Load Cell takes the full load when it comes on the cable. The connections to the cable and strong point are made with 14 or 16 mm nylon Anchorplait. Alternative ways of doing this are shown in Illustration 2. For the "Foredeck configuration" one might use a 3 metre length of Anchorplait, while for the "Cockpit configuration" an 8 or 10 metre length would be used. The Control Box would normally be kept in the cockpit or below." Basically ANCHORWATCH measures the load or tension on your anchor cable. It uses a LOAD CELL electrically connected to a CONTROL BOX. One end of the LOAD CELL is attached to the anchor cable and the other end to a strong point on the deck so that the LOAD CELL takes the full load when it comes on the cable. The LOAD CELL is normally connected using a length of 14 or 16 mm Anchorplait as shown. For the "Foredeck Configuration" a 3 metre length would be used, and for the "Cockpit Configuration" 8 to 10 metres. The CONTROL BOX would normally be positioned in the cockpit for easy viewing.
"ANCHORWATCH is normally kept permanently connected to the yacht's battery; the Load Cell is connected to the anchor cable each time the yacht is anchored. Once the Load Cell is attached, the anchor is pulled gently at first, and then with full revs of the engine noting the anchor cable tension. The Peak Load facility enables the maximum loading to be recorded. If a large tension is required, the yacht is motored forward to give some slack cable and then in reverse at 1 to 2 knots to bring the yacht to a jerk stop. This normally gives a pull in the range of 100 to 300 kg, enough to withstand significant wind and sea. At this stage, the Alarm Load is set for a load below the Peak Load achieved during anchoring, and the Peak Load is reset to a low value. Unless there are major changes in wind direction an anchor should hold up to the Test Load. Indeed, it may well hold to a higher load, but one has no way of being sure of this without a direct test. The Test Load should therefore be above the maximum load which is anticipated when at anchor. Once the Peak Load has been reset the new Peak Load will be that achieved when at anchor.
Use of, ANCHORWATCH can greatly improve a skipper's confidence while at anchor as well as warning him when he is stressing his anchor beyond the Test Load. The use of ANCHORWATCH does not, of course, relieve the skipper from making decisions on the basis of the prevailing conditions and the data that is provided by ANCHORWATCH."