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BRUCE ANCHOR SELECTION GUIDE Anchor weight Storm Anchor weight working Boat lenght Beam Sail Beam Power Rods Dia. Chain Dia. Chain Lenght kg----lb kg----lb m----ft m----ft m----ft mm---ins m----ft m----ft 2.....4.4 2......4.4 5.....16 2.0....6.6 2.2....7.2 9.....0.31 5....0.20 2.0....6.6 5......11 2......4.4 7.....23 2.7....8.9 2.9....9.5 10....0.39 6....0.24 2.6....8.5 7.5...16.5 5......11 9......29 3.1...10.2 3.4...11.2 12...0.47 7....0.28 3.0....9.8 10....22 5......11 10....33 3.4...11.2 3.7...12.1 14...0.55 8....0.31 3.2...10.5 15....33 7.5...16.5 12....39 3.8...12.5 4.2...13.8 16...0.63 9....0.35 3.7...12.1 20....44 10....22 14....46 4.2...13.8 4.6...15.1 18...0.71 10...0.39 4.0...13.1 30....66 15....33 18....59 4.9...16.1 5.4....17.7 22...0.87 12...0.47 4.5...14.8 50...110 20....44 25....82 5.8...19.0 6.7...22.0 26...1.02 16...0.63 5.0...16.4
The anchor size given above assume winds up to 60 mph, some protection from seas, fair holding ground, and operation at scope adaquate to develop full holging power. Where a vessel has unusually large supperstructure or heavy displacement, use a size heavier. Vessels built to classification society requirements have anchor weights stipulated by the societies. For optimum performance a close fitting shackle should be used, otherwise the shackle should be centralised by means of galvanised washers. The mooring lines should have sufficient elasticity to minimise shock loading on the anchor and on the boat fittings due to wind and wave surges. Chain of sufficient lenght to provide an adequate catenary, or nylon rope of sufficient lenght to provide an equivalent effect under load is recommended. Where nylon rope is used, a short lenght of chain should be included at anchor end to resist chafing of the sea bed as recommended in table above.
MANUFACTURED OF HEAT-TREATED CAST STEEL to B.S. 3100AG
Type approved by Classification Societies as a general purpose high holding power anchor
| Normal Weight | A | A | B | B | C | C | D | D | kg----lb | mm | ins | mm | ins | mm | ins | mm | ins | 2.....4.4 | 189 | 7.4 | 349 | 13.7 | 246 | 9.7 | 7.8 | 0.31 | 5......11 | 258 | 10.1 | 467 | 18.4 | 315 | 12.4 | 10.8 | 0.43 |
|---|---|---|---|---|---|---|---|---|
| 7.5...16.5 | 284 | 11.2 | 519 | 20.4 | 361 | 14.2 | 12 | 0.47 |
| 10....22 | 321 | 12.7 | 570 | 22.4 | 385 | 15.2 | 12 | 0.47 |
| 15....33 | 335 | 13.2 | 669 | 26.3 | 441 | 17.4 | 12.7 | 0.50 |
| 20....44 | 363 | 14.3 | 725 | 28.5 | 478 | 18.8 | 13.8 | 0.54 |
| 30....66 | 416 | 16.4 | 830 | 32.7 | 547 | 21.5 | 15.8 | 0.62 |
| 50...110 | 493 | 19.4 | 984 | 38.7 | 649 | 25.6 | 18.7 | 0.74 |
For all drag anchors, maximum holding power is developed when the cable angle at the anchor shackle is 0 degr. to the horizontal. At a cable angle of 30 degr. the Bruce anchor is capable of producing up to 50 % of its holding power comparerd to less than 10 % for other anchors. Thus the high holding power of the Bruce anchor at long or short scope allows reduced anchor weight or greater safety. High holding power at short scope interference free mooring in crowded anchorages by virtue of a great reduced swinging circle while a combination of low breakout force and short chain lenght out, greatly reduces the labour of weighing anchor.
When using a conventional anchor at an anchorage where foul mooring ground is present, it is advisable to attach a trip line to the rear of the anchor to allow it to be brocken out backwards if it fouls a cable or snags badly on a rock. With the Bruce anchor a trip line my be omitted. If subsequently, the fluke of the anchor fouls a cable or snags on a rock, a trip line can then be attached to a convenient loop of chain passed around the mooring cable and slid down th cable until it isstopped ot the bendof the anchor's shank. The anchor can then be broken out backwards as if a trip line has been attached befor anchor placement. This method of retrieving a fouled anchor can be difficult, if not impossible with any other design of anchor.
If the Bruce Anchor is loaded in excess of its maximum holding power, it will drag. The dragging pull exceeds the maximum holding pull and increases progressively with speed of dragging. Owing to its absolute roll stability, the Bruce anchor will not roll out of the sea bed as other anchors do when dragging. Thus the hazardous sudden loss of anchor pull associated with other anchors in extreme conditions is avoided.