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Knox Anchor – an affordable choice for a comfortable night on the hook

British designed and manufactured

The Knox anchor recently crossed our bow and we were very pleased to take it out for a cruise this summer. Over the course of a few weeks, we anchored in everything from soft mud to weed and hard sand and it set quickly and well in all instances. Even though the anchor we tested may be considered undersized for our boat (Bowman 57), we did not move in sustained winds of over 35 knots; mind you, the fluke area of the 27kg Knox looks equivalent to that of our 40kg Spade. So, surprising this is not.

The Knox anchor is a very interesting looking design by the late Professor John Knox of Edinburgh applying over 20 years of accumulated research. Prof. Knox developed a rigorous testing method to assess anchor performance and wrote the benchmark article published in PBO, August 2011, comparing nine different anchors.

On first glance, the Knox anchor would appear to be a cross between a fluke type anchor and a roll-bar scoop. However, the flukes are not hinged, and the overall design is very much a scoop.

The patented divided fluke is said to be responsible for the Knox anchor's high holding power. It also allows some of the substrate to pass through the anchor, reducing the possibility of a conical build-up which is thought to reduce the holding power or resetting ability of some other scoop type anchors. The Knox boasts a higher holding force per unit weight than any other comparable anchor design according to tests published on the manufacturer’s website. The side flanges ensure that the anchor does not roll out even when forced to plough through the seabed by excessive force.

As with other roll bar type anchors, the roll bar ensures that when the anchor is lowered to the seabed it always settles with the tip of one of the flukes bearing on the seabed, at the correct orientation for burial. Roll bar and shank design are also always potential limiting factors when it comes to fitting an anchor on a given boat’s bow roller, though the Knox is likely to fit on most modern sail and power boats.

Knox Anchors is based in Scotland and the anchors are manufactured in the UK. The flukes are constructed of high tensile steel, greater than 350MPa and reinforced by stiffener plates to provide high resistance to bending. The shank is made from 900 MPa steel; a very high strength rolled, quenched and tempered steel. This has been used to ensure that the shank will not bend in a wind or current shift – as has been seen to happen with some other anchors.

During each instance that we deployed the anchor, we noted that it started to bury itself immediately. Within two or three metres in most bottoms it was completely buried. In fact, as the chain extended fully and the anchor caught, the boat would come to a shuddering stop reminiscent of a parking brake being deployed. The Knox held without budging in sustained winds of more than 35 knots with higher gusts. Small wonder, really, that it held so well. Wher we later put it side by side to our 40kg Spade and 35kg Ultra, we noted that its flukes had about the same surface area as these two heavier anchors.

When it came time to lift the anchor, it came up without nearly as much bottom substrate in the flukes as is the case with many other scoop type anchors, although it wasn’t always completely clean. The Knox appears to be very well made, yet reasonably priced.

If you are thinking about replacing your older anchor with a modern scoop type anchor, gaining much greater holding power, you now have the choice of using a lighter Knox or a heavier anchor with the same holding power. Knox anchors are shipped by courier service from the UK to just about anywhere in the world. Details are provided online at




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