Anchor design and misnomers

[Kettlewell]

This discussion of Mirabella is a bit OT, but what it does tell us is that anchor design, selection, and use still has a lot of "art" in it. You can't just look up some figures in a table and believe you're good to go.

[noelex 77]

re : Mirabella V

The principals of Anchoring large ships does not scale up well from the size of vessels CF members are likely to own.

However, the message is clear, despite a professional crew in relatively benign conditions they managed to drag and do significant damage.

For an extra 10-20kg and few hundred dollars, a cruising boat can equip itself with a primary anchor that makes a similar accident much less likely.

This seems like a sensible precaution to me.

[Kettlewell]

For an extra 10-20kg and few hundred dollars a cruising boat can equip itself with the sort of ground tackle that makes a similar accident much less likely.

I have a feeling that the Mirabella V folks weren't trying to save a few bucks by cheaping out on their anchoring gear, so I guess I don't get that message from the incident. In fact, the message seems to be that despite spending a lot of $$ and having stuff that was way beyond spec. something went wrong. In other words, just throwing money at your anchoring gear doesn't mean it is better.

[noelex 77]

Most of the super yachts spend little time at anchor.
They are expected, on the occasions they do anchor, to have personal on a 24hr anchor watch.

The largest sailing yacht in history chose a Bruce copy.
Don't they read Cruising Forum

I am sure the cost of a better quality, larger, anchor was not a major factor in the decision process, but I suspect aesthetics, weight, etc was the determining factor that led to an anchor selection that contributed to major damage.

CF members can learn some lessons from this accident.

[Kettlewell]

Mirabella V was launched in 2003. I suspect she was designed and specifications made a few years prior to that. Not sure what anchors were available then that met appropriate standards organization certificates in the sizes needed.

[noelex 77]

A 600kg anchor sounds enormous. I have no idea how appropriate this sized anchor is, but it is about 11x the size of my own anchor, but Mirabella's beam is bit greater than my LOA! So this makes it sound rather puny.

I believe there has been some suggestion that the windage was under calculated and the anchor/s were too small.

If the designer had read CF and had a BIB philosophy it may never have made the headlines for the wrong reasons.

[Cotemar]

Here are a few pictures of my current Rocna 45 lbs and the New Mantus 45 lbs side by side.

The Mantus has more surface area and a sharper tip.

I was so excited to try the Mantus out, but it turns out that the wider eye on the shank end hits on my rectangular anchor slot. I tried a couple of adjustments and it was still a no go.

If someone is looking for a great deal on a new Mantus 45lbs just PM me for the details.

[Andrew Troup]

Yes, Noelex, they weren't attuned to BiB when they specified the anchors on Mirabella V, but it seems the executive officers did read the "One Anchor" philosophy which has been popular on CF of late (or at least, they clearly adhered to it)

I agree that big boats have different issues, but one reason that they regularly lie to two anchors is to cut down on yawing and sheering.

I acknowledge the issues with multiple anchors, but there are advantages to safety as well as peace and comfort from what used to be called a "fork moor", in which (provided the wind direction does not veer by more than the angle of the fork) the shank of each anchor is always pulled from the same direction.

It's interesting that, while we seem to have decided that bigger cruising boats are better served by a "single anchor" solution than smaller ones ....

bigger boats still, notably ships, appear to rely on a "two anchor" solution when conditions are challenging.

Incidentally, I think Nigel mentioned that anchor handling tugs used to routinely use two anchors when mooring themselves to a rig (and two sternlines), despite the fact that they are hung like a hedgehog.

[Delfin]

Originally Posted by noelex 77

A 600kg anchor sounds enormous. I have no idea how appropriate this sized anchor is, but it is about 11x the size of my own anchor, but Mirabella's beam is bit greater than my LOA! So this makes it sound rather puny.

I believe there has been some suggestion that the windage was under calculated and the anchor/s were too small.

If the designer had read CF and had a BIB philosophy it may never have made the headlines for the wrong reasons.

I think it's kind of interesting that using Snow Petrel's formula with a target anchor size proportionally equal to what Cotemar carries on his cat, the Mirabelle would need an 1100 kg anchor. The 600 kg that they did carry translates to a 28# hook for Cotemar, which I suspect everyone would think was bit on the thin side.

[Snowpetrel]

We used two anchors occasionally on bigger ships and fairly often on the square riggers. Always with a anchor watch. And we always layed and retreived if the wind shifted sigificantly to prevent the possibility of a foul hawse (crossed rodes). With the second anchor deployed correctly sheering was almost completly eliminated and the loads on both anchors seemed considerably reduced.

[downunder]

Originally Posted by Delfin

I think it's kind of interesting that using Snow Petrel's formula with a target anchor size proportionally equal to what Cotemar carries on his cat, the Mirabelle would need an 1100 kg anchor. The 600 kg that they did carry translates to a 28# hook for Cotemar, which I suspect everyone would think was bit on the thin side.

Perhaps with an Excel Cotemar would only need a 28lb.

[Delfin]

Originally Posted by downunder

Perhaps with an Excel Cotemar would only need a 28lb.

Troublemaker.

[JonJo]

I posted this on the BIB thread but it seems apt. I did not dig it out, someone generously sent it to me:

Anchoring Info

Jonathan

[goelze]

After 8 years of dragging around with our CQR type anchor we've purchased a fabulous anchor from Australia - the Sarca Excel. I purchased it based upon the way it hooks up to our Seawind 1000 boat and it's overal design. In the 5 months we have used it - on a daily basis - we have never dragged at all. We are in the West Indies in average 20k and up to 35k. We never stay at a marina.

The anchor penetrates thick grass, sand, marl and sticks as soon as it's facing the right way. Typically it's less than a foot from the drop.

I am a mechanical engineer, for what that is worth, and the things I appreciate about this anchor is: the amount of weight in the tip, the tip is also curved down to bite in quick. There is no big roll bar to contend with - an issue on a Seawind unless you want to mount an anchor on top of the cross beam of the Cat - which we don't want to do. The anchor shank has a curve to match our roller and this prevents the anchor from ever rocking around. It also has a way of cleaning itself due to some openings in the blades. So when you pull up the anchor - it's clean.

The folks at Sarca are EXTREMELY great to deal with. I purchased this anchor from Australia and they had it shipped to Grenada for me. paid more for the shipping of course than the anchor, but I now I have an awesome anchor. I know I sound like a paid advertisement but I am so pleased with this anchor and especially with the amazing support I got from Joy and Rex.

[sailsw00]

Originally Posted by downunder

I just imagining you underwater digging up a big heap of bottom.
Know anybody thats tried it.

I confess that I did just that in the Bahamas some years back, for a stern anchor, in an anchorage that had only a few inches of sand over the bottom off the stern: Wardrick Wells? Anyway, the bow anchor was secure, but the stern was swinging and I wanted to secure it, in very little sand. Using snorkeling gear I just piled up sand on top of my Fortress after wedging a fluke into a small crack in the bottom rock. It didn't have to hold a lot - there was no current. But it worked.
Anyone have comments on the differences on anchors for cats vs. monos? I've just bought a 43' cat and will be replacing the anchors.
Thanks.
-Steve, in Vriginia