Anchors - Bigger is Better ?

[JonJo]

If I can find more info on Granny Smith and the conditions - I'll post.

But they do seem to have survived on the one small anchor, I wonder if they had a fall back plan?

A suggestion was made to me that Bigger is Better works for larger yachts, or those with unmanageable anchors (this is not to be disrespectful of any particular design, I'm thinking sheer weight).

If you have a smaller anchor, one of the recommended size it is quite easy to bring another on deck and deploy it. It is possible to take, say, a 25kg anchor out of a lazerette carry it up the deck pick up a rode, 10m of chain and 50m of nylon carry it up the deck, fix it all together and then lower the 25kg anchor and say 10-15 kg of chain over the lifelines near the bow. I depends on the conditions, but it is possible. It is equally possible to row the assembly out in a dinghy.

Conversely once you get to 40kg this all becomes impossible. Or I'm not sure I could safely carry a 40kg anchor along the deck. Lowering it gently over the the lifelines would be a disaster. At some point between 25kg and 40kg it simply is not sensible to think of deploying a second anchor at all (unless you have 2 bow rollers).

This obviously, and suddenly, becomes a very strong case for a Fortress.

But maybe the recommended size anchor works less well for big yachts (or ones with heavy anchors, simply because there is no option but smaller yachts have considerably more flexibility).

Basically everyone is correct - just discussing from too narrow a perspective?

But I note no-one has professed to have had a new gen correctly sized (as per sizing charts) anchor drag (excepting weed) - at all. Which begs the question - do they drag?

[Kettlewell]

My second anchor (FX-23) is kept in a bow locker just aft of the windlass, with its rode in a sailbag (10' of chain, 200' of nylon). I can and have had that anchor over the side in less than 2 minutes. Sometimes if caught off guard I simply drop it to the bottom as far out and to one side as I can from the mother ship, and I know if I started to drag for some reason it is already there, on the bottom ready to help hold me once I get back far enough for it to have decent scope.

Frankly, I think any anchor can drag under the right (or wrong) conditions. I am reminded of an old-timer friend of mine who was holding the bar up with Don Street down in the Caribbean, back in the day. Don was a proponent of old-style Herreshoff anchors on nylon only, with no chain, and was bending my friend's ear off tiresomely about the "proper way to anchor." Then my friend looked out the bar window and asked Don, "Is that Iolaire drifting by now?" Don was last seen rowing madly after Iolaire as she drifted away.

[estarzinger]

Originally Posted by JonJo

But I note no-one has professed to have had a new gen correctly sized (as per sizing charts) anchor drag (excepting weed) - at all. Which begs the question - do they drag?

Incorrect, my rocna dragged several times, enough that I have taken if off the bow and off the boat and stuck it in a shed. They certainly can drag.

[Kettlewell]

Evans, remind us again what size Ray you are using. Do you think it is the best of the current Bruce-type designs available?

[estarzinger]

Originally Posted by Kettlewell

Evans, remind us again what size Ray you are using. Do you think it is the best of the current Bruce-type designs available?

50kg, as was our Bruce and rocna. I tried a 40 kg anchor (a supreme copy) while waiting for the new anchors to get shipped in, and decided that 50 was a much better size to deal with uncertain bottoms in strong winds.

We had a 20kg Bruce on Silk, in the tropics.

I have not done an exhaustive comparison test of all available Bruce types, so can't honestly say it is "best", but I can say it is quite good, both in construction, shape, and service. One of my big requirements was someone who could and would ship the damn thing to puerto Williams chile (nearly the end of the earth), and Manson pulled that off beautifully.

[Cotemar]

Bruce anchors are great anchors. I think if I ever went with one again, I would make sure it was a genuine Bruce.
Either of these pictures would be the approximate size I would get.

I think we would really sleep well and a storm anchor really would not be needed.
With a Bruce, bigger has always proven to be better. And then size up 1000%

[Kettlewell]

50kg, as was our Bruce and rocna.

Wow! 110 lbs. on a 47-foot boat. I guess you are a BIB fan.

[DumnMad]

Evans; roughly what wind, wave and bottom conditions were you in to drag 50kg?

[noelex 77]

Originally Posted by Factor

which ones? apart from survey vessels?

For those not familiar with Australian law many vessels in Australia are built and or operated under survey. For example all bareboat charter yachts.

(My understanding was it was limited to class vessels, but the Australian laws are a bit of bureaucratic nightmare)

No matter what the exact requirements (and knowing Australia they will vary from state to state) the lack of a proof loading certificate will restrict the number of anchors, particularly larger anchors that can be sold.

As always the consumer bears the cost of this red tape.

Originally Posted by Factor

Oh and one other thing, every time I mention the importance of an anchors ability to reset Noelex suggests that I am sadly mistaken, anchors dont need to rest - they don't unset if a good proper anchor. I respectfully disagree with him, and so does one of the worlds biggest anchor manufacturers - Manson.
Manson's words - not mine

Quote:
During a 180 degree instant wind shift ALL anchors can pull out. It's what can happen.

Manson also say this:

When you're using the short slot the anchor will remain buried even with major windshifts

So I think they are more confused than most of us on anchoring topics

The Manson quotes ( both Factors and mine) are here:
http://www.manson-marine.co.nz/SiteP...sDualShank.htm

I think with Factors quote the emphasis is on the "can break out" (not will break out) and they are trying to justify and deflect criticism the slot (which will make the anchor likely to break out with a 180 degree wind shift). Read the full quotes for yourself and make up your own mind.

Even better snorkel and watch anchors rotate in a 180 wind shift.

[Jim Cate]

Originally Posted by JonJo

But I note no-one has professed to have had a new gen correctly sized (as per sizing charts) anchor drag (excepting weed) - at all. Which begs the question - do they drag?

G'Day all,

Earlier in this thread (at least I think it was this one!) I mentioned two dragging incidents with our nominally correct size Supreme. PErhaps you missed them... But now I can add a new instance:

We just returned from a stay in Port Davey in the southwest of Tasmania. While there we experienced the passage of a deep low, nearly over the top of us. This system generated storm force winds from the W to NW for a period of around six hours. We recorded sustained winds in the low 50's and gusts in the high 60's. The gusts came from two directions, apparently due to local topography (for those who know the place, we were in the middle of Ila Bay). The two directions were nearly orthogonal to each other, which often meant that we experienced very strong gusts beam on. We were anchored in about 25 feet of water using a 60 lb Supreme on about 175 feet of 10 mm chain. There was no significant sea running.

As the wind speed increased, several other boats in the anchorage dragged and departed for some other spot. We held for a few hours but eventually we too slowly moved astern. We picked up and reset the anchor twice, and each time the anchor was essentially clean when it broke the surface. When we began to move the third time I set a second anchor, an old Hi-Tensile Danforth of 20 lbs on 20 ft of 10 mm chain and then nylon. Did this by motoring up to a spot estimated to be 50 feet or so to the side of the main anchor, dropping and falling back until both rodes were taught.

This was completely successful, and we did not move further. Later when I recovered the anchors I found that both had been deeply buried in the mud. The Danforth brought up a large wad of very thick and sticky mud, but the Manson came up with a small amount of thin, soupy mud. I conclude from this that the likely cause of the Manson dragging was low shear strength seabed, and the success of the Danforth was it fortuitously finding some better holding ground.

Since the Manson never broke out, but was slowly moving through the bottom, I venture to believe that a larger one with more fluke area would have fared better, so count me in the bigger is better group of fanatics.

Cheers,

Jim

[JonJo]

Originally Posted by estarzinger

The table on page 16 is interesting for the OP. it says (for example) for a vessel (class a or b) that is 15 m long and 2 m high, the required anchor mass is 50kg. That's is exactly what we have decided by experience, but most "yachtsmen" consider that much bigger than necessary. And if you were somehow oing to take our rig wind age into account, it would demand even bigger. So, this suggests practically speaking they think bigger is not only better but necessary.

I might have misread the document but it seems to say the 'tables' relate to 'standard' anchors and standard anchors are given a performance factor of 1. High Holding Power anchors, viz CQR and Delta are given performance factors of 0.7 and Super High Holding Power anchors (Supreme, Fortress) a performance factor of .55. So a 50kg standard anchor (for the nominal 15m x 2m yacht) becomes 35kg if a HHP (CQR) and 27.5kg if a SHHP, (Fortress etc). However they do seem to suggest that 2 anchors of the specified weight are carried and the second anchor be available for deployment within 15 minutes. I suspect that there would be some querying of a 27.5kg anchor for a 15m yacht, but one might want to include a factor for furled sails and mast etc., which is part of Evan's post.

Frankly I have no idea what a 'standard' anchor, in terms of leisure craft, looks like. I am also very comfortable with the idea, in terms of the tables, that Spade, Rocna, (probably Mantus and Boss) are equivalent in terms of performance (holding power) to a Super SARCA, EXCEL, Supreme, Fortress and that a Bruce is equal to a CQR, Bugel, Delta etc.

There does not seem to be an option for carrying one big anchor instead of 2 'smaller' ones.

[DumnMad]

Thanks Jim:
Very informative post, 60 to 70 knot gusts are not uncommon in our latitudes.

[JonJo]

[QUOTE=noelex 77;1192245]For those not familiar with Australian law many vessels in Australia are built and or operated under survey. For example all bareboat charter yachts.

(My understanding was it was limited to class vessels, but the Australian laws are a bit of bureaucratic nightmare)

No matter what the exact requirements (and knowing Australia they will vary from state to state) the lack of a proof loading certificate will restrict the number of anchors, particularly larger anchors that can be sold.

As always the consumer bears the cost of this red tape.


Hi John,

You will be relieved to hear that the responsibility for maritime safety laws have been centralised under AMSA. The States have given up their individual responsibilities. Its actually all happening 'now', it might have happened, but its all new. Its probably still a bureaucratic nightmare, the consumer still pays for the red tape but a vessel 'in survey' in NSW will now or will soon meet the identical requirements anywhere else in Oz. I'm not sure that the legislation has dropped down to the leisure level (ie vessels for private use only) (but I'd guess that's the intent) but it certainly covers anything 'in survey'.

Jonathan

[JonJo]

Granny Smith,

She is a 30' x 4.5t Currawong. She is quite 'old' and took part some years ago, with considerable success, in the Sydney Hobart. I'm not sure of the year.

I think the other vessel in the vid might be 'Somoya'

At the time, as I think Noelex mentioned, it was forecast for 15-20 knots. They had their 27lb Excel, (12kg), 48m of 8mm chain + 8m of 'rope'. The depth was 6m (not sure when the depth was taken I think the tides are 3m). From the vid they seem anchored quite far offshore, but I've only seen the place as a smudge on the horizon.

We once left Jamiesons Bay, not that far away from Trousers Point, to head north (to the mainland about 200nm away) with a forecast 20-25knots. It initially did gust to 30/35knots but eased slightly but by the time we cleared the northern end of Flinders is was averaging 30knots (and with a 20-25 knot forecast we thought they had it slightly wrong and we did not fancy beating back into a 30 knot wind). It slowly built and we then enjoyed 7 hours of winds of over 50 knots slightly behind the beam. The cat handled it well, we averaged 8 knots, the waves breaking over the cabin roof were a worry for the crew.

Later I looked at historic Buoy Weather and we had been running on the edge of a tiny low pressure system, simply too small to forecast, it travelled NE as we travelled NE. I spoke to our Bureau of Met when in Tasmania the following year (they have a walk in office in Launceston) and they said that these low pressure cells were quite common in Bass Strait and impossible to forecast (really encouraging).

[estarzinger]

Originally Posted by DumnMad

Evans; roughly what wind, wave and bottom conditions were you in to drag 50kg?

In South Georgia, lets say high 40's kts. The problem there (I think) was extremely heavy kelp (really really thick), which would tangle in the roll bar and degrade the ability to set deeply.

In Nova Scotia it was only 25kts gusting into the 30s. The problem there (again I think) is that the anchor was "set" into a narrow ridge (perhaps 2' wide) of mud over a rock substrate. It very slowly (unnoticable) pulled thru the ridge and then just let go . . . We were in "freefall" for about two boat lengths until it caught another ridge of mud. That's the locals later told me about the bottom.

There was a third situation, but it involved 2:1 scope, so I probably should not have been doing that with that anchor, as I knew it did not like short scope.

There was a fourth situation involving very soupy mud over rock, and I am not sure how well any anchor would have copped with that one, but I suspect the Bruce would have been better (with two point contact rather than one point).

My experience with the Bruce suggests it would have coped with all four of these situations better . . . No roll bar, multi point contact with the bottom, and better on short scope. I am not making any claims that it's the perfect anchor, as it certainly has its own flaws, but I personally have lost confidence in the roll bar anchors (which i think are absolutely terrific in good sand or mud but not so good in "difficult bottoms"). I am curious about the Boss.