Sets quickly and reliably in most seabeds. Its unique design always engages the
bottom and digs in, so it stays buried as the boat swings.

Superior strength, cast, heat-treated high-tensile steel
No welds or moving parts
Lifetime warranty.

The Bruce anchor is of one-piece construction, resembling a single fluke A.M.1 2 mooring anchor with its stock removed and with curved extensions at each side of the fluke. The transverse median line of the extended fluke surface approximates to an inclined hyperbola lying athwart the plane containing the shank of the anchor and the fore-and-aft center-line of the fluke.

The anchor is self-orientating at the sea bed surface irrespective of drop attitude. It penetrates the sea bed surface while orientating and exhibits complete roll stability below the surface however far it is dragged. Ultra short scope may be used since the anchor will engage, orientate, and bury even with the cable inclined at angles of up to 30 degrees at the sea bed surface. Also, the anchor may be veered full circle without breaking out or losing its holding power.

The anchor operates during dragging by rolling to a burial attitude while engaging the sea bed surface by either fluke extension. This is due to the natural tendency of the center of resistance of the engaged portion of the fluke extension to move along the transverse median line of the extended fluke surface to maximize its separation from the cable attachment point on the shank. This migration of the resistance center is one principle of operation of the anchor.

Once it has rolled to a shank-uppermost attitude, further dragging causes the anchor to bury in the usual manner. During burial and any subsequent dragging, the anchor is maintained roll-stable due to the fluke extensions producing stabilizing forces . These stabilizing forces may be considered conveniently as resultant force vectors which intersect the vertical plane of symmetry of the anchor aft and above the roll axis of the anchor. Any roll disturbance of the anchor produces a relative skew movement of the sea bed material over the fluke extensions and unbalances the resultant force vectors so that a turning moment is established about the roll axis which opposes the original roll disturbance. This vector roll stabilization is another principle of operation of the anchor.

These principles have not been used hitherto in the design of anchors

The method of introducing the extended fluke into the sea bed allows a larger area of fluke to be used at a higher aspect ratio than with any other anchor design. This gives higher holding power and higher tolerable cable angles than previously possible.

The curved nature of the fluke and the small moments of area of the fluke about a transverse line through the center of the fluke area ensure that resistance of the fluke to vertical rotation is small. Hence, the breakout force is as low as 20-25% of the prior holding pull.

Bruce FFTS MK4 Anchor, the preferred anchor
For upgrading semi-submersible exploration rigs for deepwater drilling operations

Anchor Design

The Bruce anchor represents the most important advance in anchor design for more than 150 years. During this time, attention was focused on optimizing existing designs rather than on establishing a new design from consideration of the essential characteristics for an ideal anchor.

These characteristics were demonstrated when the Bruce anchor was shown on the television programs
"Tomorrow's World" and "Living Tomorrow".

Self Orientation: The anchor should en the sea bed rapidly and orientate into its burial attitude, irrespective of drop attitude or nature of mooring bed (e.g. sand or mud).

Short Scope Capability: The anchor should be capable of engaging, orientating, and burying at long or short scope. If the anchor can operate with a high cable angle at the sea bed, less cable is needed or, alternatively, mooring is possible at greater water depth for a given length of cable.

Deep Burial: Since holding power is a direct function of the depth of burial of the fluke of an anchor below the sea bed surface, the anchor should penetrate as deeply as possible to achieve the highest holding power.

Absolute Roll Stability: The anchor must remain absolutely stable in its normal burial attitude when dragged through the sea bed material in order to make deep burial possible.

Low Penetration Resistance: A roll-stable anchor must be streamlined to give low resistance to penetration of the sea bed if it is to be capable of deep burial.

Full Veering Capability: The anchor should maintain its burial capability and mooring line tension even if veered full circle.

Adjustment Free: The anchor should develop high holding pulls in varying sea bed conditions (e.g. sand or mud) without the need for any fluke angle adjustment.

Low Breakout Force: The anchor should have a breakout force which is as low as possible compared to its prior holding pull. The breakout force for conventional high holding power anchors is generally between 50% and 1 00% of prior holding pull.

No Moving Parts: Jamming of pivoting fluke anchors may result in failure to bury and develop high holding power.

No Stock: The stock is an easily damaged part of many high holding power anchors which may lead to fouling of mooring and pennant lines. It offers high resistance to sea bed penetration and may produce handling and stowage difficulties. 1f.the stock becomes damaged, it causes loss of stability at the sea bed surface resulting in loss of holding power.