Neeves
Well-Known Member
Jonathan, you say that so-called NG anchors have double the holding capacity of older anchors. Compared not just by weight, but by size. Specifically, I replaced a 20kg genuine Danforth with a FX23 Fortress, which is about one third of the weight, but is of practically identical dimensions and design. Should I expect twice the holding capacity, and if so, why?
For the avoidance of doubt, the change to the Fortress wasn't to achieve any greater holding, but merely for easier handling..
Excellent point
The Fortress is an unusual beast as though it is ostensibly similar to a Danforth it does have differences, one being that one is made from steel and one from alloy. The Fortress is also, arguably, better engineered as it has a tapered and machined shank and bevelled flukes - so I would expect it to be better than a Danforth, for the same size but I cannot conjure any reason for it to be twice as good, but see below. However if ABS rate it as an SHHP anchor, as Lloyds rate Supreme a SHHP and ABS, again, rate a Ultra as SHHP then I'm not going to argue. I don't know where Danforth falls in the rating, it may be close to SHHP, I don't know.
The ratings are pretty broad, historically an anchor better than CQR was simply an HHP anchor. I believe Supreme was the first SHHP leisure anchor as it satisfied Lloyds it was twice as good as the standard anchor against which the Supreme was tested, the standard might have been CQR and or Delta both of which were HHP. Basically SHHP is a recent designation. Any anchor tested subsequently if equal to, or better, than a Supreme is, or was, rated as an SHHP anchor (even if it had twice the hold of a Supreme it was still an SHHP anchor (as there is no better/higher classification) - not that I have heard that that any anchor has been factorially better than a Supreme). Basically an anchor with capacity 10% less than a Supreme would be HHP, not a SHHP. Rocna was tested by RINA, though their (Rocna/CMP) certification may have lapsed it was rated SHHP.
Supreme was the SHHP standard against which all other anchors have been 'measured' - but they had to be 'better' than a Supreme - and as every more recently classified anchor is thus 'better' then logically you would choose a Supreme against which to be judged if you have a new design.
It is sad but an anchor just not meeting the requirement of a Supreme would be an HHP anchor - which may answer your question.
How the ABS conjure with equating a Fortress (at half the weight) against a Supreme - I don't know.
When Fortress tested their anchor against a similarly sized, but heavier, Danforth in soft mud - their anchor had approximately twice the hold. This illustrate 2 factors - no anchor is perfect in every seabed and that care must be taken when testing anchors as it is possible to skew results. Similarly if you are looking at 'holding capacity' results it merits looking at a cross section of tests. I am sure that if a Danforth were tested with the fluke angle set at 45 degree, this would need the anchor to be severely modified (or specially made), then the Danforth would perform better (and maybe as good as a Fortress) in thin mud. Advantageously the Fortress fluke angle can be relatively easily changed. Changing fluke angle is not rocket science and i well known internationally - river barge on the Mekong have their fluke et at around 40 degree - reflecting the muddy bottom of the river.
So - I can actually conjure with the concept of Fortress being twice as good as a Danforth, in thin mud, with the Fortress fluke set at 45 degrees. We now carry an FX 16 set at 32 degrees for sand and an FX 23 set at 45 degree for use in thin mud - noting many of the anchorages on Australia's east coast navigable rivers have a mud bed (and I cannot be bothered with faffing about with a spanner at 2am).
Danforth, the genuine model, is made in America by the Tie Down Engineering company and they may have decided not to go to the expense to test or re-test Danforth - it may be HHP, it may be SHHP.
We are like you - we chose a Fortress for its handling characteristic and I doubt we would ever have considered a Danforth. The latter, of the size necessary for us would have been incredibly combersome, heavy and a very real danger to fingers. The Fortress with its variable fluke angle, from 32 to 45 degree makes it outstanding against any other anchor, at all, in thin mud, and at leat as good in sand comparing 2 anchor of a similar size (but the Fortress half the weight).
Jonathan