I have recently been researching the issue of what anchor to choose.
In the course of my web searches I came across The UK Divers.NET site and the West Marine Sand Anchor Test by Chuck Hawley and Tony Gasparich(1994). Although that is a pretty old link it still gives a lot of interesting insights into the manufacture and design of anchors.
When I bought Enterprise she came with a 22lb Danforth type anchor that is stowed in the anchor locker. Although this is neat and tidy in most circumstances it is quite tricky to lift it out of the locker on a pitching foredeck, without drawing blood . Because it is hinged and the flukes are so large it is impossible to stow it on the bow roller without it taking a chunk out of the hull. Hence, the search for something more suitable.
After much searching of the web and various blog opinions I felt that the choice for my 32ft boat would lie between the old favourite the CQR and the newer Delta – both from Lewmar. Although the Rocna anchor and web site is very impressive.
Clyde Quick Release Plough (CQR)
So named due to its resemblance to a traditional agricultural plough (or more specifically two ploughshares), many manufacturers produce a plough-style design, all based on or direct copies of the original CQR (Secure), a 1933 design by mathematician Geoffrey Ingram Taylor.
Owing to a now well established history, ploughs are particularly popular with cruising sailors and other private boaters. They are generally good in all bottoms, but not exceptional in any. The CQR design has a hinged shank, allowing the anchor to turn with direction changes rather than breaking out, and also arranged to force the point of the plough into the bottom if the anchor lands on its side.
Another more recent commercial design, the Delta uses an unhinged shank and a plough with specific angles to develop slightly superior performance. Both can be stored in most regular anchor roller systems.
Owing to the use of lead or other dedicated tip-weight, the plough is heavier than average for the amount of resistance developed, and may take a slightly longer pull to set thoroughly.
The genuine CQR and Delta brands are now owned by Lewmar, although they have both been on-sold several times during their lifetimes.
The Delta was developed in the 1980's for commercialisation by British marine manufacturer Simpson-Lawrence. The Delta is a fixed shank plow, as opposed to the articulating variant of the plow concept (i.e. the CQR) of decades earlier. The need for articulation was avoided with more careful balancing of the anchor's weight and shaping of the rear end of the fluke in order to better guide the fluke through the setting process. The basic shape nonetheless remains a plow, with a brake-pressed plate heel and solid steel cast tip (welded together to form the only joint attaching the tip to the rest of the anchor) which comprises the fluke. Like other plows, this design relies on tip-weight for ballast and setting, an inefficiency which detracts from fluke surface area and ultimate holding power.
The genuine Delta brand is now owned by Lewmar. The anchor has been out of patent for a few years now, and poor copies abound, most of worse performance and questionable construction quality.
The Delta utilizes a high tensile steel shank, an element which is typically the first to be sacrificed in the pursuit of cost savings by knock-off producers.
From all the reading I think the Rocna is probably the best. The New Zealand designed Rocna has been produced since 2004. It too features a sharp toe like the Bügel for penetrating weed and grass, sets quickly, and has a particularly large fluke area. Its roll-bar is also similar to that of the Bügel. The Rocna obtained the highest averaged holding power in SAIL magazine's comparison testing in 2006.
In the end I chose the Delta from Lewmar. If I had a bigger boat say 40ft upwards, I would have chosen the Rocna.
It is actually quite large and difficult to mount permanently on the bow roller since it is rigid unlike the CQR which has a hinged head. Also if you drill the anchor in order to fasten it to the bow roller you invalidate the 5 year guarantee. Anyway it does look the business and all the technical assessments appear positive – and its is from Lewmar – who should know about these things :-).
Now all that remain is to try it out – which I plan to do when we sail to Alderney on Sept 14th.