Manufacturing Knox Anchors is a precision business.
When reliability of a safety device like an anchor is required, then not only top materials, but also expert assembly and welding is required, followed by galvanizing to the latest International standard is necessary.
We use two special grades of steel in Knox Anchors. The shank for example uses 900 MPa steel a very high strength rolled quenched and tempered steel. This is necessary so that when your Knox Anchor resets after a wind-change while you are at anchor, the shank will not bend.
Next are the flanges and other parts. Using high tensile steel, these are all assembled according to the CAD drawings, and fully welded by very experienced welders using MIG welding technology.
The flanges are cut and bent to precise angles to obtain the high holding power than only a Knox Anchor can achieve.
The anchor is now fully welded, and only requires to be hot dip galvanized. This specialist process creates a layer of zinc and iron alloys on the surface that give corrosion protection. There are nine stages to this process resulting in a protective layer about 100 microns (0.1mm) thick, which should give many years corrosion free service in saltwater conditions.
Some conditions will wear your anchor's galvanizing faster than others. For example coral is more abrasive than most rock, with sand and mud the least abrasive.
If your Knox Anchor's galvanizing starts to show wear after many years use and you wish it, we can arrange refurbishment and re-galvanizing of your anchor. Contact us for details.
Companies that help make a Knox Anchor:
Steel fabrication: David Ritchie (Implements) Ltd, Forfar http://www.ritchie-uk.com/
Hot Dip Galvanizing (ISO1461): Highland Colour Coaters Ltd, Cumbernauld http://www.higalv.co.uk/
Why not Stainless Steel?
We often get asked why we don't make a stainless steel anchor. The answer is simple - ordinary stainless (like 316 grade) is not strong enough. While stainless has many advantages, and looks nice forever, (despite costing several times the cost of carbon steel), it is not particularly strong. An anchor requires to be strong enough to take the loads your boat might exert on the anchor rode. Ordinary stainless steel isn't suitable for this design of anchor. The same applies to aluminium. Such an anchor might seem nice and light, but that's exactly what it is - a lightweight in the anchor stakes. If you want your anchor for its intended purpose - to hold your boat, then you need one designed for just that.
An anchor could be made strong enough in duplex steel, or high grade aluminium, but the cost would be unattractive to most leisure boat owners.