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Old 04 July 2012, 07:51   #41
SR4
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Anyway I as of now I use neither, just bought a bargain shiny stainless steel folding one, I will keep my grapple one until I have tried and tested this, at less than half price it is worth a go, shame they don't do it in orange

Just need to source some stainless steel chain for it, I have a stainless 8mm shackle to attach it with but can't be having rough old galvanised chain now can I

Holt Stainless Steel Folding Anchor - Only 49.95 - Force 4 Chandlery
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Old 04 July 2012, 08:21   #42
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anchor

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Originally Posted by tonto View Post
Not exactly, although it does help.

The wieght of the chain causes the anchor shank to lie horizontaly on the seabed, (perticularly with an AC14, Danforth, Admiralty Stockless anchor etc, which then allows the anchor to hold at it's full power, which for a high holding power anchor is typically 1.7 times it's mass. (if i remeber correctly)

If the shank is lifted up from the horizontal, this causes the flukes (pointy bits) to pull out of the sea bed, and cause the anchor to drag.

So yes the chain is important, and is helping, but it is primarily to ensure the anchor is acting horizontally.
true - but interestingly if you take most merchant ships (i was on tankers upto vlcc's and production rigs/vessels) we used to drop the anchor from the waterline. The cable goes out so fast you end up with the anchor buried under a small pile of cable followed by a long length of cable laid along the sea bed with piles of cable every so often. The anchor didn't even have a chance to dig in let alone do anything. Latter it became the norm to lower the anchor to the sea bed then pay out the cable as the vessel went astern more often than not laid in a curve across the sea bed as the ship drifted/went astern slowly whilst 'laying' the anchor, if it ever got to the stage that the anchor was holding you, you haven't got enough cable out - you'd probably be dragging at this stage. In busy anchorages it wasn't uncommon for anchors and cable to be left behind (not ours) because they had got hooked up on something on the sea bed. As i used to be a ships diver, i occasionally helped on a friends salvage vessel recovering anchors and cable (amongst other things). Once we had dived down, you would normally find the cable had either hooked up on something or the anchor was buried under a pile of cable and had somehow picked up a loop around the anchor shank/fluke putting so much weight on it that the ships anchor winch couldn't lift the weight. Sometimes the shank was detached from the flukes. Unless you are at anchor for a long period, or anchoring in a strong tide or bad weather, i doubt that the cable ever stretched out straight. After you had turned at the first turn of tide it was probably laid in a circle anyway. In theory what you say is correct but in practice it is the weight of the cable and the friction from it on the sea bed that does the work. In most ship anchorages space/depth is restricted so you don't have the luxury of paying out the cable in a nice neat line from the anchor, it's normally a case of letting it go and put out enough to hold you (about 4 to 6 shackles depending on weather and depth) and hoping that no-one else anchored in your turning circle! Fortunately i don't have this problem on the rib

see this:



although i prefer the spoon type folding grapnel and i know it's not always a nice sandy bottom

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Old 04 July 2012, 09:07   #43
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Quote:
Originally Posted by wellhouse View Post
true - but interestingly if you take most merchant ships (i was on tankers upto vlcc's and production rigs/vessels) we used to drop the anchor from the waterline. The cable goes out so fast you end up with the anchor buried under a small pile of cable followed by a long length of cable laid along the sea bed with piles of cable every so often. The anchor didn't even have a chance to dig in let alone do anything. Latter it became the norm to lower the anchor to the sea bed then pay out the cable as the vessel went astern more often than not laid in a curve across the sea bed as the ship drifted/went astern slowly whilst 'laying' the anchor, if it ever got to the stage that the anchor was holding you, you haven't got enough cable out -
I still am currently working on large ships!
hve recently been on VLCC's, and am currently on a 300M Loa LNG ship, and can see what you are saying, and agree to some extent.

VLCC's stopped dropping their anchors about 25 years ago as they kept losing them. the inertia was just too much for the brakes, and they would be unable to stop them running out, and hence they would loose the whole lot, and parts of the chain locker as well. They were also anchoring in deeper waters, consider this a VLCC is at least 20M draught loaded, so would be in 30+M of water, and that is a long way to drop 20 tonnes of anchor, plus about 10MT per shackle of cable.

We started walking it out in gear to prevent the uncontrolled running away, and still do, however....

We will lay the cable out, more as a consequence of how we anchor, rather than thrying to achieve a neat line of cable. I have been doing this job over 27 years and I have not lost an anchor yet, or been on a vessel that has, baybe we were lucky. We have brought it up with flukes bent, and also with the cable looped round the shank, but never lost one yet. We anchor in upto 80M of water, and 4 or 5 shackles would not hold you there at all.

It is still the holding power of the anchor ultimately that hold you, as the cable will just slide easily over the soft muddy bottom. The catenery (bow ) in the cable ensures that the cable is pulling horizontally on the anchor. If it was just the wieght of cable you can be sure the shipowner would save the 1/4 million bucks a pair of anchors cost, and just put smaller ones on.
If you dont have enough cable out, this will cause the anchor stock to be raised at an angle to the seabed, thus breaking it out, as most crowns and flukes only move up to 30 degrees, so if the shank is raised off the horizontal by more than that, the flukes are not even digging in.

I have dragged a number of times, and each time was during heavy swell/seas, and winds, which cause the cable to be pulled tight, lifting the stock off the sea bed, thus breaking it out.

I have anchored in areas of rock covered by sand, and this has resulted in dragging, no matter how much we put out, as the flukes cannot dig in, and thus are innefective, irrespective of the wieght odf the cable.
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Old 04 July 2012, 09:16   #44
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I would say user error with the grapnel rather than no good, I wonder why so many are used and sold, does make you wonder doesn't it

In all the 40yrs of my boating I have never lost a boat yet, maybe it's just luck
Couldn't agree more, do yours not have the age old simple slide twist and lock... it can't close itself... user error 100%.

If you are swayed into going for a bruce I would recommend getting and anchor bag and seperate chain bag, saves you have 20 metres of chain rope and anchor tangled, and installing some little plastic hooks and bungey chord to hold it down, or alternatively put all your heaving lines on top, holes in the fibreglass don't bear thinking about...
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Old 04 July 2012, 09:46   #45
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Maybe a little unfair, I use a grapnels mostly as they are easy to stow and carry on and off the boats and will easily take a 6.5m RIB or a 3.8 and 6 dinghies...

We use a slightly different type of grapnel than sold by Force 4, it was bigger flukes on it for gripping mud and is truly versatile, however we do have 2 metal split/holding pins attached to hold the casing open especially on some of the cheaper anchors available.

Danforths and Brittanys with their hinges around heavy plates and sharp edges are a liability for getting fingers trapped and opening inside the locker making getting them out a pain... Similarly fixed design anchors like the Delta or Bruce are cumbersome and a pain as they often swing under the tubes as you lift them out of the water.

For all round ease of use, stowage and general performance I would have to vote grapnel with decent flukes and a decent design... Especially for the mix of anchorages we have in the UK and the storage space available to you in a small RIB...
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Old 04 July 2012, 10:07   #46
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anchors

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Originally Posted by tonto View Post
I still am currently working on large ships!
hve recently been on VLCC's, and am currently on a 300M Loa LNG ship, and can see what you are saying, and agree to some extent.

VLCC's stopped dropping their anchors about 25 years ago as they kept losing them. the inertia was just too much for the brakes, and they would be unable to stop them running out, and hence they would loose the whole lot, and parts of the chain locker as well. They were also anchoring in deeper waters, consider this a VLCC is at least 20M draught loaded, so would be in 30+M of water, and that is a long way to drop 20 tonnes of anchor, plus about 10MT per shackle of cable.

We started walking it out in gear to prevent the uncontrolled running away, and still do, however....

We will lay the cable out, more as a consequence of how we anchor, rather than thrying to achieve a neat line of cable. I have been doing this job over 27 years and I have not lost an anchor yet, or been on a vessel that has, baybe we were lucky. We have brought it up with flukes bent, and also with the cable looped round the shank, but never lost one yet. We anchor in upto 80M of water, and 4 or 5 shackles would not hold you there at all.

It is still the holding power of the anchor ultimately that hold you, as the cable will just slide easily over the soft muddy bottom. The catenery (bow ) in the cable ensures that the cable is pulling horizontally on the anchor. If it was just the wieght of cable you can be sure the shipowner would save the 1/4 million bucks a pair of anchors cost, and just put smaller ones on.
If you dont have enough cable out, this will cause the anchor stock to be raised at an angle to the seabed, thus breaking it out, as most crowns and flukes only move up to 30 degrees, so if the shank is raised off the horizontal by more than that, the flukes are not even digging in.

I have dragged a number of times, and each time was during heavy swell/seas, and winds, which cause the cable to be pulled tight, lifting the stock off the sea bed, thus breaking it out.

I have anchored in areas of rock covered by sand, and this has resulted in dragging, no matter how much we put out, as the flukes cannot dig in, and thus are innefective, irrespective of the wieght odf the cable.
nice to see there are still some employed at sea! i came ashore about 20 years ago as the british vlcc's started to flag out or go to scrap. Glad we agree on some things ref anchoring. Most of the vlcc's i was on were 22m loaded draft and most of the anchorages in europe/persian gulf/singapore occasionally mexican gulf around 40m. 1 shackle is 90ft (about 28m) and depending on weather/tide it used to be about 3 to 4 times depth of water (sometimes more) for cable length, don't know about now but most ships only carried about 12 shackles due to the space required to carry more, this restricted anchorage depth to a max of about 60m in reality to get required cable out (plus contingency). Also if you had 8 shackles out plus the length of ship in singapore you would have a swinging circle of nearly a mile across, (our ships were about 384m) and you would quickly run out of space in the anchorage at that rate. I'm not saying that on some occasions anchors don't dig in (they obviously do if the ground is right and you get the right circumstances when going astern or you haven't got enough cable out and you get to the stage that you are about to drag - i would have let more cable out or left the anchorage before then) but you would have to 'set' the anchor and in most anchorages ships don't have the space or time to mess around going backwards and forwards to set the anchor. it's lay it and hope - or try again (rarely). Most of the anchors that i've been involved in recovering have not been 'set' (flukes in) and that's the point i make (an observation) not that anchors don't do anything. I wouldn't recommend only carrying cable and no anchor for instance. Certainly for ribs with virtually no chain and require a quick hold you need a decent anchor (see you tube dems
i put up earlier) After 20 years at sea, i never ran aground as a result of anchor dragging so must have got it right. It was interesting to see what the cable and anchor was doing underwater on those that we recovered because as a seafarer you just assume the anchor is set, from a divers perspective they rarely were.
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Old 04 July 2012, 13:02   #47
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For all round ease of use, stowage and general performance I would have to vote grapnel with decent flukes and a decent design... Especially for the mix of anchorages we have in the UK and the storage space available to you in a small RIB...
I know grapnels don't work in sand (which we have a lot of here), the flukes don't dig deep enough nor present enough surface area to keep the anchor from dragging along the bottom. That's from experience, having seen my anchor pass me while diving for halibut.

In uneven rock, they tend to lodge themselves in a manner that needs to either be pulled out backwards (which is what the little hole on the nose is for), or dove on to free it.

A small Bruce or Bruce knockoff (like 4 to 6 lbs), or a 3 -5 pound Danforth should suit well with a decent length of chain (I'd suggest 10 -12 feet or so of fairly heavy hot dip galvanised chain, about 1/4" mininum size.)

Then again, I'm not familiar with the bottom compositions you have in the UK, so this is guesswork based on my experience on the US west coast.


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Old 09 July 2012, 18:02   #48
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I lost my 2kg Bruce this weekend, first outing with it!

They're not very giving if you get a bit unlucky with rocks it seems.
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Old 10 July 2012, 23:07   #49
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I lost my 2kg Bruce this weekend, first outing with it!

They're not very giving if you get a bit unlucky with rocks it seems.
Sorry to hear that, but you certainly can't blame the anchor for that! Sounds like it was doing exactly what an anchor should do. Now whether the chain, rope, splicing, or shackles were sufficient is another question. At least one of them obviously failed on you.
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Old 10 July 2012, 23:08   #50
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Anyway I as of now I use neither, just bought a bargain shiny stainless steel folding one, I will keep my grapple one until I have tried and tested this, at less than half price it is worth a go, shame they don't do it in orange

Just need to source some stainless steel chain for it, I have a stainless 8mm shackle to attach it with but can't be having rough old galvanised chain now can I

Holt Stainless Steel Folding Anchor - Only 49.95 - Force 4 Chandlery
Very interesting. I haven't seen that design before. Looking forward to your field reports on it.
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