The best high holding power anchor yet?

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Nick
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The best high holding power anchor yet?

Postby Nick » Thu May 17, 2012 1:30 am

.
There's a new kid on the block claiming to be better than the Spade, which I have always regarded as the ultimate anchor:

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I had the privilege of getting to play with a 7Kg prototype a couple of years ago, and it held a Sigma 33 in a F7 plus full astern (hard sand, Kilchattan Bay). I was very impressed . . . .

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- Nick 8)

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sahona
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Re: The best high holding power anchor yet?

Postby sahona » Thu May 17, 2012 10:09 am

It seems to me the more efficient they are, the harder they will be to stow, but still they come...
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Re: The best high holding power anchor yet?

Postby ash » Thu May 17, 2012 10:13 am

It's sort of Bruce shaped.

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Re: The best high holding power anchor yet?

Postby DaveS » Thu May 17, 2012 2:00 pm

Interesting site. I like his idea of using a nylon spring attached to a stern cleat to get sufficient length while keeping the chain attachment point above water. I might give that a go, or at least do some experimenting: avoiding chafe is the obvious problem, not just at the bow roller but everywhere the spring touches something on deck.
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Re: The best high holding power anchor yet?

Postby sahona » Thu May 17, 2012 2:39 pm

I'm not so impressed with the 'transom spring' idea as there will be a longer length of the rope in contact with the bow roller once it starts working - with associated noise if you sleep below it.
I don't worry about the chain-hook and its swivel going underwater and have a permanently fixed anti chafe towel wrapped round the rope at the right distance from the inboard spliced loop. The wrap wedges into the bow roller so doesn't shuffle from side to side as the boat ranges.
I think the published figures for the new anchor are impressive, but, as previously mentioned, storing would be a problem for us.
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Re: The best high holding power anchor yet?

Postby wully » Thu May 17, 2012 6:15 pm

Looks Rocna-ish....

I'll be sticking with the Spade though...One of my winter projects is to get built an extended,pivoting anchor roller/ holder that'll also have somewhere to fly the cruising chute from as the Spade is a pain in the hoop to have hanging over the bow if your boatie lives on a mooring..

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Re: The best high holding power anchor yet?

Postby Silkie » Thu May 17, 2012 7:45 pm

Interesting to compare the numbers for the Knox with those of the Spade (the benchmark NGA) and the unique Raya.

Spade and Raya would both recommend their 600sq.cm models weighing 10kg for the Spade and 4.75kg for the Raya for Silkie. If I'm reading the table correctly (what do the colours signify?) Knox would recommend their 4.5kg model but this has a fluke area of only 350sq.cm. Clearly the Knox is much stronger than the Raya since both have no significant tip weight and the Knox is smaller for the same weight but is the geometry so superior that it can produce the same holding power with only two thirds the fluke area?

For Fairwinds both Knox and Spade would recommend an anchor of similar size and weight so perhaps it's just a scaling anomaly.

I typically only use about 3 or 4m of snubber (although it's about 10m long) so maybe I should rethink that but when it's blowing I'll have all the chain out and be on at least 10m of octoplait anyway.
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Re: The best high holding power anchor yet?

Postby stevepick » Fri May 18, 2012 10:23 am

It looks good, and it would be nice to buy made in scotland. My only minor concern is the split fluke, you loose some strength doing that, and how would it affect anchoring in weed if you caught a stem of something in the slot. Would it inhibit the anchor digging in? Nick , when you tried out the prototype did you do any evaluation in weedy anchorages? ( I really think anyone doing anchor tests should run part of the test in Canna! )

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Re: The best high holding power anchor yet?

Postby Nick » Sat May 19, 2012 2:56 pm

stevepick wrote:Nick , when you tried out the prototype did you do any evaluation in weedy anchorages? ( I really think anyone doing anchor tests should run part of the test in Canna! )


Sorry no, I only tried it in sand. I know the Spade is good in weed as it tends to cut through it, and I agree withn your point about the split fluke, there is surely the potential for a stem to jam in it as it goes down.
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Re: The best high holding power anchor yet?

Postby Arghiro » Sat May 19, 2012 11:06 pm

Have you considered giving this wonderful news to our friends on YBW Scuffle-nuts, Nick?

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Re: The best high holding power anchor yet?

Postby Nick » Sun May 20, 2012 12:04 am

Arghiro wrote:Have you considered giving this wonderful news to our friends on YBW Scuffle-nuts, Nick?


feck 'em :shake:
- Nick 8)

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Re: The best high holding power anchor yet?

Postby ubergeekian » Sun May 20, 2012 10:12 pm

Nick wrote:
Arghiro wrote:Have you considered giving this wonderful news to our friends on YBW Scuffle-nuts, Nick?


feck 'em :shake:


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Re: The best high holding power anchor yet?

Postby mm5aho » Tue May 22, 2012 7:57 pm

Their website says its high tensile steel.
It appears to be hot dip galvanized.
If so, I wonder how they avoid hydrogen embrittlement.
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Re: The best high holding power anchor yet?

Postby ubergeekian » Wed May 23, 2012 6:11 am

mm5aho wrote:Their website says its high tensile steel.
It appears to be hot dip galvanized.
If so, I wonder how they avoid hydrogen embrittlement.


OK, I'll bite. I thought you only got hydrogen embrittlement when there was molecular hydrogen around, either directly or as a result of water breaking down in welding or electrolysis. Why would it be a problem with hot dip galvanizing?

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Re: The best high holding power anchor yet?

Postby mm5aho » Thu May 24, 2012 8:17 pm

ubergeekian wrote:
mm5aho wrote:Their website says its high tensile steel.
It appears to be hot dip galvanized.
If so, I wonder how they avoid hydrogen embrittlement.


OK, I'll bite. I thought you only got hydrogen embrittlement when there was molecular hydrogen around, either directly or as a result of water breaking down in welding or electrolysis. Why would it be a problem with hot dip galvanizing?

You don't ask, you don't learn.


Hot dip Galv is a zinc rich coating that's an alloy of iron and zinc, with a composition gradient that ranges from iron (well steel actually) at about 98% Fe, to 99% Zn on the surface, with main areas of composition of 90Zn/10Fe, 95/5, 98/2 99/0. (Zinc isn't 100% pure)
This alloying action only occurs where the steel is chemically clean. Dip unclean (oxidized ) steel into molten zinc and it gets hot, but not galvanized. (450C)

Now to the hydrogen embrittlement:
To get the steel clean it is immersed in hydrochloric acid. (usually preceeded by a degreaser which is alkaline), and remains in HCl for from 30 mins to sometimes 3 hours, depending on rustiness.
While it is "pickling" in acid, some H2 is formed.
High tensile steels in presence of gaseous H2 can become embrittled.

It is possible to "clean" the steel by blast cleaning, but the reprofiling that often results alters the coating characteristics. Sometimes positively, sometimes adversely depending on the other factors involved.
It could be that the anchors is galvanized that way.
Most steel is chemically cleaned, it's rare that steel is blasted before galvanizing, though many people wrongly think that blasting is a pre-requisite.
About 900 tonnes of steel in galvanized in Scotland per week, and that accounts for about 6% of the UK steel so processed. The industry grows at about 4% per annum year on year for the last 30 years.

ask another question...
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