Anchor question,

[Neeves]

Duster

You have a way with words, with which I cannot compete

We carry a couple of short lengths of chain to wrap round rocks (and some long lines). Many or much of our cruising ground is World Heritage listed or National Park - I have this fear the bureaucrats would not take kindly to my hammering pitons into rocks

I thought I'd replied to this as well - I'm hitting the cancel button too easily.

Jonathan

 

[noelex]

I have seen no evidence that a bigger anchor of the same design is any 'safer' than a smaller one.

I doubt anyone will ever tell the difference between a 20kg anchor and a 25kg anchor.

In this thread I have shown two photos of dragging anchors (a Kobra and Ultra). In both of these cases the anchors were only dragging in the stronger gusts. I think it would be reasonable to say that increasing the anchor size by even the small amount you have suggested in the second quote (5kg or 25%), may well have been enough to successfully hold the boat.

why buy a 35kg anchor when we have had no problems with a 15kg steel anchor

In your own case using 15kg steel anchors on a 38 foot cat I think a modest increase in size (it needn't be another 20kg ) would reduce or eliminate your need for your current practice which I understand is to always deploy two 15 kg sized anchors when the forecast is 30 knots, or above.

While longer scopes are always desirable, I suspect you would also become more confident using shorter scopes in modest winds in anchorages where longer scopes are not possible. (3:1 in 20 knots should not be out of the question in my view).

There are of course drawbacks to larger anchors well. The extra bow weight, particularly on a catamaran needs to be considered. An oversized anchor will not be the right choice for everyone. It is an interesting debate, let's keep it sensible. Suggesting increasing the size of an anchor has no effect on the holding power is not realistic.

 

[charles_reed]

Thanks Charles, I thought it was long dead and buried (and so deeply buried it never occurred to look in Wikipedia!).

So did I, except for a trace memory of the use of the "Access" title on one of my Mastercard Credit cards. So I bothered to look it up and widen my knowledge-base with more irrelevancies.

 

[Neeves]

If the seabed is such to allow an anchor to 'set' 100cmsq of its fluke I fail to see why an anchor of the identical design will set further. The seabed is resistant to more than 100cmsq of the smaller anchor (that might have a fluke area of 500cmsq) - what magic is it that allows the bigger anchor to overcome that resistance.

Setting 2 anchors reduces veering - it makes for a more comfortable anchoring state, reducing veering reduces snatch loads, snatch loads can result in dragging.

I think JD will point out to you that a 25% increase in weight, sadly, does not equate to a 25% increase in area. Equally anchors do not scale efficiently. You might want to re-think this

Jonathan

 

[Neeves]

So did I, except for a trace memory of the use of the "Access" title on one of my Mastercard Credit cards. So I bothered to look it up and widen my knowledge-base with more irrelevancies.

Charles - you must be as young as me , I don't have your enquiring mind.

Jonathan

 

[NormanS]

NormanS - you mention your use of a riding sail, often - how would one make, use, a riding sail on a multi that has no back stay? The only 'idea' I have is to launch up the topping lift and have a little boom off the main boom, tensioned to each transom - does this sound sensible? Any idea of size vs yacht length. I'm assuming your riding sail if off the aft mast (or aft mast topping lift?) and you use the existing boom. You obviously are smitten - I've never, ever, seen one in use in Oz.

Jonathan

Hi Jonathan,
My boat is a 36ft ketch, although I think that must be measured from the outside of the taffrail to the forward extended bow roller. The hull is probably about 34ft. With a ketch, the obvious anchor sail is the mizzen or reefed mizzen. Here, you quite often see ketches anchored like that. I found that to be noisy, and unless the sail is extremely flat cut, it won't have any effect until the boat is 20 or 30° away from the wind.

As a result, I experimented with a twin sail with the luff attached with slides to the mizzen mast, the two clews held apart by a short pole, and sheeted down to the corners of the taffrail. The finished article sizes are:-
Luff. 3250mm
Foot. 1830mm
Leach 3900mm

When rigged, the spreader tube is just above the furled mizzen on the boom. (The spreader tube, is also a slightly modified boathook). The sail material is what would be suitable for storm sails, as it has to be able to be used in extreme conditions. It's not a big sail, and when folded away and stowed, doesn't take up much space.

I find the anchor sail, or riding sail works well, is rigged in moments, and cuts down yawing at anchor (and its associated problems) greatly. I have very little experience of cruising catamarans, so cannot advise how such a sail could conveniently be rigged. I'm sure some experimentation would be worthwhile. I tried mine out using light poly tarp material, to get some idea of the dimensions.

You say you've never seen one in Oz, but then you'd never seen a "boomerang" either

 

[Neeves]

Thanks NormanS,

So that I am clear. This is a twin sail, each sail is the same size, to the dimensions you quote. Its presumably one piece of fabric with the slides up the middle. Might I guess that the sails are each held apart 20-30 degrees from the boom (or centre line) - so one of them is always opposing the wind - but the sails are 40-60 degrees apart to each other. I assume there is no need for shape 'flat' is ideal. You mention noise - so I assume they are hoisted and sheeted in tight.

Why the spreader tube - why not tie out and down the 2 clews - does it serve any purpose or to put it another way - what happens without the spreader.

You mention their use on ketches - do you see them on single masted yachts or are these 'ketch things' and if used on single masted vessels how, where do they hoist - mast, backstay?

Why not more popular - or is it a bit like snubbers - only used by the few who stray outside comfort zones.

It does not seem an impossible task. I cannot attach with slides, as you do, I assume use of the mast moves the centre of effort too far forward but I could hoist up the topping lift (maybe a velcro pocket to house the topping lift). A pole is not an issue - I have 1 and a half windsurfer masts. We have an old heavy fabric dacron sail someone gave us and a decent sewing machine

But Boomerangs are now popular - I learnt today 20 are being sent to a galvaniser from a consortium of boat owners from around Melbourne 10 for 8mm and 10 for 12mm chain. You are just another unsung hero Mind you - I'm just unsung . Interestingly not long after you introduced me to yours we had a new Catana moor near us (with the unusual name of 'Skye') - it was commissioned with an Oscaluti bent link - so I saw the more complex version - in the flesh. Your idea - the simple bent link, so much better and cheaper.

Jonathan

 

[GHA]

But, and with all due respect, you start about a thread a week in order to tell us we all need to have much more effective anchors.

And have a go at noelex at the slightest opportunity.
Another waste of bandwidth for the ignore club

 

[NormanS]

Thanks NormanS,

So that I am clear. This is a twin sail, each sail is the same size, to the dimensions you quote. Its presumably one piece of fabric with the slides up the middle. Might I guess that the sails are each held apart 20-30 degrees from the boom (or centre line) - so one of them is always opposing the wind - but the sails are 40-60 degrees apart to each other. I assume there is no need for shape 'flat' is ideal. You mention noise - so I assume they are hoisted and sheeted in tight.

Yes to all that.

Why the spreader tube - why not tie out and down the 2 clews - does it serve any purpose or to put it another way - what happens without the spreader.

I simply found that the outboard corners of the taffrail weren't far enough apart to get the desired angle between the two parts of the sail. You don't have that problem.

You mention their use on ketches - do you see them on single masted yachts or are these 'ketch things' and if used on single masted vessels how, where do they hoist - mast, backstay?

A few boats do use them. Paul McNeil, who runs "Westbound Adventures" uses a single triangle hoisted on the backstay, and says it works well. What you're looking for is lateral resistance to the wind, placed as far aft as possible. The further aft it is, the less area required. Quite how you could arrange that on a cat, I leave to your own ingenuity.

Why not more popular - or is it a bit like snubbers - only used by the few who stray outside comfort zones.

Mmm. Could be.

It does not seem an impossible task. I cannot attach with slides, as you do, I assume use of the mast moves the centre of effort too far forward but I could hoist up the topping lift (maybe a velcro pocket to house the topping lift). A pole is not an issue - I have 1 and a half windsurfer masts. We have an old heavy fabric dacron sail someone gave us and a decent sewing machine

But Boomerangs are now popular - I learnt today 20 are being sent to a galvaniser from a consortium of boat owners from around Melbourne 10 for 8mm and 10 for 12mm chain. You are just another unsung hero Mind you - I'm just unsung . Interestingly not long after you introduced me to yours we had a new Catana moor near us (with the unusual name of 'Skye') - it was commissioned with an Oscaluti bent link - so I saw the more complex version - in the flesh. Your idea - the simple bent link, so much better and cheaper.

Aw, shucks.

Jonathan

 

[Neeves]

Thanks Norman,

I've got all that

I'll report in later, something else for GHA and JD to read but ignore

Jonathan

 

[snowleopard]

....top in the majority of anchor tests, which usually only compare ultimate holding...

The thing I notice about almost every anchor test article I read is that they make great play of the highest reading. That doesn't make sense to me. What you should look for is the lowest reading. You don't want an anchor that will hold really well once in a while but one that holds reasonably well every single time.

My boat is 5 tonnes and I use a 16kg anchor which I consider a minimum. Even so, I have a humungous Fortress at the bottom of a locker that I can deploy if things get really hairy. 10kg/4 tonnes leaves little margin for bad situations.

I know the OP has made up his mind but I'd go for the 16 kg Delta, have more security and save a shed load of dosh.

 

[Neeves]

The thing I notice about almost every anchor test article I read is that they make great play of the highest reading. That doesn't make sense to me. What you should look for is the lowest reading. You don't want an anchor that will hold really well once in a while but one that holds reasonably well every single time.

My boat is 5 tonnes and I use a 16kg anchor which I consider a minimum. Even so, I have a humungous Fortress at the bottom of a locker that I can deploy if things get really hairy. 10kg/4 tonnes leaves little margin for bad situations.

I know the OP has made up his mind but I'd go for the 16 kg Delta, have more security and save a shed load of dosh.

You have considerably more windage than he does - might that not reflect the difference (or similarity) of choice? Your choice is not too dissimilar to ours, 15kg anchor, 38" cat but 7t in cruising mode (but we have the windage of a Bav 45 and the Bav might be 12/13t). But its not only anchor weight - but let's not go there again - people get really upset

Jonathan

 

[Sybarite]

I think you need to look at Noelex anchor and read through Dashew. Both are strong proponents of grossly oversized anchors - Noelex has a whole thread devoted to the excellence of his choice. Most proponents of oversize reference Dashew to substantiate their philosophy.

Jonathan

Michel Joubert has the same philosophy.

http://www.voilesetvoiliers.com/cha...marthe-46-voilier-exploration-joubert-nivelt/

@ 7:00

 

[vyv_cox]

Michel Joubert has the same philosophy.

http://www.voilesetvoiliers.com/cha...marthe-46-voilier-exploration-joubert-nivelt/

@ 7:00

I read an only half-joking comment about Dashew's anchor choice. Seems he gave up using Bruce, or the Manson Ray, when the distance across the flukes became wider than his boat!

 

[GHA]

Michel Joubert has the same philosophy.

http://www.voilesetvoiliers.com/cha...marthe-46-voilier-exploration-joubert-nivelt/

@ 7:00

Many, many full time cruisers are fans of going up a size or maybe even 2. Not grossly oversize. Dashew is a different situation.

Hard to reason why not? Minimal weight increase, not that much of a one off payment when fitting out.

 

[noelex]

I read an only half-joking comment about Dashew's anchor choice. Seems he gave up using Bruce, or the Manson Ray, when the distance across the flukes became wider than his boat!

As has been reported Dashew fits oversized anchors. To give you some idea his 64 foot power boat comes equipped, with a 240 pound (110kg) ROCNA.

Now that is big. especially considering the narrow and low windage design although the displacement with the large fuel and water tanks is high.

 

[doug748]

I have been taking it all in and if I do make the move it will be for the Rocna, I think. The main problem is the roll bar which makes it a tight fit in the locker, which will be an annoyance. I never stow my anchor on the bow roller.

I was a bit surprised that more people did not say: "Wow that's a good price for the Spade - go for it". I never fully trust an anchor in parts though and the construction is a bit complex for me but it would certainly fit the boat better.

As for size, I was pretty happy with a 10kg Bruce and expect the new anchor to be no worse. 15kg would be too heavy for me to bring up by hand in deep water, I rarely use the mechanical winch which I find too slow. Hidden in the folds of the Rocna site is some stuff on sizing which to some extent supports my ideas on the 10kg weight:

http://kb.rocna.com/kb/Rocna_sizing_recommendations

As noelex has pointed out, the boat has low windage and tends to be steady at anchor, which helps.

So thanks everyone. If I do it, it will be later in the spring/summer meantime I will be on the lookout for a used one

 

[dnickj]

The thing I notice about almost every anchor test article I read is that they make great play of the highest reading. That doesn't make sense to me. What you should look for is the lowest reading. You don't want an anchor that will hold really well once in a while but one that holds reasonably well every single time.

My boat is 5 tonnes and I use a 16kg anchor which I consider a minimum. Even so, I have a humungous Fortress at the bottom of a locker that I can deploy if things get really hairy. 10kg/4 tonnes leaves little margin for bad situations.

I know the OP has made up his mind but I'd go for the 16 kg Delta, have more security and save a shed load of dosh.

and as it happens I have a 16kg delta that needs a new home |||

 

[vyv_cox]

You are right doug748, it is rare to see a Spade and a Rocna for the same price. I believe you need have no fears about the disassembly properties of the Spade, there are very many of them out there and I have only heard of one that came apart, a very long time ago. It transpired that the cause was that it was assembled wrongly (was this the one that someone had put together as a convex anchor?) The nut and bolt were subsequently redesigned with a spilt pin, just in case.

 

[Neeves]

If you are disassembling the Spade regularly the nylox nut loses its locking capabilities. The split pins on mine are a bit loose. The split pins are like big 'kirby' grips. I'd suggest carrying replacement nuts, chuck the old ones away, and maybe look at buying more secure split pins. But the assembly and design are very safe - I would not worry.

Jonathan