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How much chain is enough chain?


tuffyluffy

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Im planning on heading up to the islands next year and I’ll need a full chain anchoring set-up.

 

Weight is an issue and I don’t want to carry to much of the stuff, but still have enough to anchor comfortably in most places without worrying about chaff, therefore, can someone with experience tell me how much I should carry?

 

I was thinking, based on a 5:1 scope, that 50 metres should do it (10 meter deep anchoring), with another 20-30 of rope as backup in a blow. Is this too much/too little?

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I always got away with using 100ft of chain.I didnt piss around with chain markers and 100ft made the arithmetic easy.It wasnt the best in water deeper than 30ft but I mostly managed to avoid deeper anchorages.Of course I could let out some rope after the chain as long as I didnt put enough to contact the coral.But this was with smaller/lighter boats without an electric windlass.The manual windlass was a bit slow and I liked to pull up by hand .

You should probably say how big/heavy your rig is to get more better advice.

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I also kept a 2nd anchor with 100ft of chain.Thats the thing with the smaller boats.You cant carry hundreds of meters of chain but you still need a 2nd anchor as good as your primary.

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Ta for the feedback guys. Sounds like 30 metres might be the goer. As i said, I want weight kept to a min

 

The boat is 5.5 ton (lightship) 42 ft sloop, anchor is a 25kg Rocna on a Maxwell VWC2200 winch. The anchor will be staying on the roller, but the winch and chain locker is 3 metres back from the bow in an effort to keep the weight back

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Don't forget it is now a lot more common to get full anchorages so later arrivals are out further in deeper water.

 

Had 3 boats go up last season (Fiji) with between 50 and 65mts of chain backed by warp. 2 rang and 'send another 30-40mts and fast' within 10 days of arrival. The other boat got very selective at where it anchored and is going longer chain for next trip.

 

From what we see and hear 30mts is highly likely to limit your options as to where you park.

 

The average lengths usually fitted are between 80 and 110mts. You can go a lot shorter for the secondary as if you've lost your primary the love and care transferred to the 2nd suddenly and dramatically increases. Fingers crossed you aren't parked behind MotoMiddleOfNoWhere at the time though.

 

All depends on how long you're up there, whether it's a pop-up and then back or the start of a longer tour, just how much you want to buggerise around come anchor spot finding time. If it's a short term maybe you can handle some buggerising around but if it's a long one you probably would get over that quite quick.

 

It is knot uncommon for boats to move their chain aft to on top of the keel area, just for the trip from here to there or the week plus long passages. Once there, up the front she goes and there she stays until the next long passage. Something I did myself one one trip, worked OK and was pretty effortless really.

 

As usual it's all a trade-off one way or the other, bloody boats.

 

FYI - Chain weights,

10mm = 2.3kg/mt

9mm = 1.8

8mm = 1.4

Even though you really don't want to work it out sometimes :)

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Friends of mine were often anchored in deeper waters than 10 metres. you may want to allow for deeper water and it can often be windy. You don't want to be dragging onto bommies now do you?

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We have 50m chain + 100 m warp but wish we had 75m chain as the deeper anchorages where we have to lay on the warp make me a little nervous (we are only 9m long). Tonga isn't too bad but Fiji has some deeper anchorages (15m+ is the norm).

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Our steel cutter is also 42ft but just over twice the weight. We have 75m of 10mm chain and backup of 75m of 8mm stored in bilge, same windlass as you. Anchor is Rocna 33. I think you'll find with the Rocna that a more typical scope for good holding in the islands is 3:1, not 5:1. As you get further west (Solomons and PNG) there are many places where you must anchor in 15 to 20 metres depth or not at all. We never used a rope rode on the end of the chain. We're now in Alaska where 20m depths are also common.

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It depends on the chain dia., with a 7 tonne boat 8mm would be quite acceptable. I have seen 8mm used up to 12 tonnes though for me that would be the limit. You could consider going lighter if you went to HT chain, though I would be advised by Knot Me and go with his recommendation. Also it will depend as to where your chain locker is, further back into the body of the boat the less effect it will have on your trim, if it is like my boat (7 tonne) and is right in the bow then every extra kg has a negative effect on the fore/aft trim, I have 55m of 10mm on a rocna 20 for anchoring here in NZ but would go to at least 100m when heading north. (probably 8mm)

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The HT (as in High Tensile knot High Test, 2 differing animals there) isn't needed in most cases people buy it for, often it's just a feel good purchase. That's like having a Ferrari in NZ, where do you use all it's fastness? Grade 40 is more than enough when you consider a Rocna and ever other good anchor of that size will only hold 3/4's of the chains bust load, and that's on a good day. Also if you have 4 tonnes on your anchor rode, assuming 8mm G40, I'd hate to be the winch and other gear around it or even aboard being honest. To put 2 tonnes on the rode of a 40fter is hard to do. So getting a high tensile chain (8mm again) with a 7t bust does seem a waste of money don't you think.

 

And the chances are about 9:1 Tuffy will join the chain to the anchor with a non-tested chinese shitter commercial shackle (what's on 98% of boats today) of very wondering loads. He probably won't now but 9 out of 10 usually do.

 

Just thinking like Steve and if Tuffy's locker is 3mts aft, that's a fair way. So if he is running 8mm I really don't think the weight will be a big issue even if 100mts. Will be more if running 10mm though obviously.

 

Agree with Steve 8mm would do, bottom endish size wise but would, which is helped by having one of the good anchors, as Tuffy has. It all comes back to the most important part of anchoring your boat. 'The feel Good factor' i.e. do you feel happy going to sleep with a 8mm chain or do you need bigger to get a good snore off. Some are, some aren't.

 

Another thing worth mentioning if the idea of swapping sizes goes further, if it even needs too. A VWC2200 gypsy costs $480 RRP inc, often a bit less if you shop around.

 

I suppose we are assuming Tuffy has 10mm chain currently.

 

Another FYI moment - Chain bust loads, these are minimums it must to meet to conform with the appropriate Grades -

Grade 70 - 8mm = 7t, 10mm = 11t - Knot that common as it's bloody hard to galvanise.

Grade 40 - 4t and 6.5t respectively - In NZ that would only be the Maggi made chain and a few IPC made chains.

Grade 30 - 3.2t and 5t - this is the most common on the water today worldwide but is moving towards G40. All (99.9%) Aussie made anchor chains (PWB and Serifini) in NZ are this grade as are some IPC made.

Grade 20 - 2.4t and 4t - a huge amount of the chinese made is this even though it's commonly and usually unknowingly sold as a G30 sadly. Stretches real easy so stops fitting winches real easy.

 

G50 is available but exceptionally rare. G60 and/or 63 = nope.

 

Working Load limits are 25% of the above numbers. Proof Load is 50% of the above numbers and also a load the chain MUST get too without any sign of deformation. Generally the higher the grade the high the % of bust load it'll take to deform a chain. G70's for example don't deform much until just before they go SNAP. We've seen a Vindex 34 stretch a bit of 10mm chinese made during 25kt gusts while at anchor, that's just so wrong it's spooky. No way should a 34fter ever be able to make a good 8mm change shape let alone a 10mm, bar maybe in the heart of Hurricane Katrina if the anchor is jambed in rocks maybe.

 

And don't forget chain rusts, bless it's heart :), so will get a tad weaker as time ticks by.

 

General chain, in a anchor rode, rules -

Some is better than none.

Longer and smaller is better than shorter and heavier, given the same total weight of each and the required strengths are still there.

More is better than less. Add 25% of length and it doubles the help it gives the anchor. Round figures.

It must match the gypsy on your winch well or you'll need lots of weetbix and/or a new gypsy quicker than you should need to.

Using a all chain rode the standard scope is 3:1 plus a handful.

More scope is better than less, applies to all rodes equally.

Never leave you boat hanging off the anchor winch, they are knot a bollards. Use a snubber or something to take the load off the winch.

All persons, who know too much sh*t about chains, seen in any anchorage worldwide are thirsty, be nice and chuck them a cold beer every chance you get ;)

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Im planning on heading up to the islands next year and I’ll need a full chain anchoring set-up.

 

Weight is an issue and I don’t want to carry to much of the stuff, but still have enough to anchor comfortably in most places without worrying about chaff, therefore, can someone with experience tell me how much I should carry?

 

I was thinking, based on a 5:1 scope, that 50 metres should do it (10 meter deep anchoring), with another 20-30 of rope as backup in a blow. Is this too much/too little?

How far afield does "the islands" take you?

I'd guess your assumption above at 50 m is probably near the mark. Less could restrict your options if you're really wanting to avoid the chain leaving the gypsy.

 

Rocna advises 10 mm G40 chain with your Rocna 25. The obvious answer to your weight dilemma, which has been alluded to above, is to use G70 high tensile - 8 mm instead of 10 mm. That's a rated break load of 7000 kgf vs ~5100 kgf for the 10 mm G40, so heaps more margin in terms of strength, and you are saving a LOT of weight - 1.40 vs 2.35 kg/m...

 

Talk to G MacDuff (Knot Me) about Maggi Aqua7, which I believe is your only practical choice (?) in NZ, if he has it in stock or how soon he can get it. According to his website the 8 mm G70 is actually cheaper than the 10 mm G40, so go figure. 'Tis the obvious choice in your situation and is what I would go for without a doubt.

 

http://www.rocna.com/kb/Chain

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Looks like we have a lot of anchor experts here so time for a silly question, is displacement that important with anchor and chain sizing? I would have thought that windage would be the most important determining factor?

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Rocna advises 10 mm G40 chain with your Rocna 25.

What happened to the chain is evil use only rope theory you were heavily pushing? A rhetorical question by the way ;)

 

And surely you'd size the chain to the boat slash system being using, rather than just the anchor it's attached too, especially with some of the sizes of anchors some outfits are suggesting for some boats.

 

Yes displacement can be important when picking an anchoring system, as are windage, boat shape especially the front 1/2, where you are using the vessel and what for, what gear you have to handle the system, how twitchy the boat user is, how much they want to spend and a few other smaller things. It's very much a horses for courses sort of a thing, most of which is really only a judgement call at the end of the day.

 

 

Hey Craig, how's Dad? Nearly caught up with him the other day by just missed. He back in town for a while or back off adventuring again shortly?

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I am off the school of chain to suit vessel length/weight.

I would also being going for a really good 10mm over a superdude 8mm chain, purely because the weight is just as important as length of the rode in combination with weight of vessel. The inertia is all used up trying to lift the chain off the bottom. Although it happens, you don't really want the chain to completely lift free of the bottom and leave just the anchor connecting you to the world. The real strength of being held in place is from those last few metres of chain lying on the bottom and allowing all tension on the anchor to pull that anchor so it will at the least pull horiontally, or at best sink even deeper. I strongly believe that in all but very rarest and strongest weather events, if you are pulling that chain rode tight and straight out, then you don't have enough length nor/or weight (which can be a combination of both).

Another way to look at it is that a heavier chain can also mean less length payed out in a confined anchorage. If there are lots of boats all trying to find a hole to anchor in, no point having 100m of 8mm payed out when you could have just 50m of 10mm.

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ah but allan you have it so good down there you just pull up to a mooring , no anchoring to worry about :D :D :wink: :wink: When I come down I will have to join Mana Yacht club to be able to use the same moorings. I know with the depths there I would rather be pulling up 8mm chain (manual windlass) than 10mm if I have to anchor.

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Thanks for the great feedback guys.

 

KM, believe it or not, I don’t know what size the gypsy is as I’ve never used it. I’m currently using the old (came with boat) tackle and hurling it off the foredeck. It’s a new anchoring method Ive developed called the hurl’n’hope, its especially effective when combined with down-wind fizz-boats as a drift alarm. I’m assuming the gypsy is 10mm, but will need to check before I drop the coin. Despite the slight weight penalty, 10mm is what I’d prefer if the gypsy fits.

 

Another question for the panel, what are the pros and cons of stainless chain over galv (apart from price)? The plan is to head away for a few years (tropics then up to Med) and the last thing I want to be mucking around with is regalving chain after a few months in the tropics. A galv anchor isnt a major to touch up now and then, but chain is a different story. Is the price premium worth it?

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98% of people wanting SS do until they see the price at which point they suddenly find they can live with Galv.

 

I think that sums it it pretty much :D

 

Chain that is used a lot doesn't rust. Chain that sits in lockers, often in a inch or 2 of water, rusts real quick.

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To answer your original question tuffy.

 

Personally I would agree with your 50 metres - BUT only on the proviso of the following:-

 

Nobody so far has mention kellets - I would suggest you consider a NZ made 'Anchor Buddy'

(I have no connection with them) before you go off buying more heavy chain.

 

A 13.6kg model will increase your holding power by 50 to 80%, plus reduce your swing in crowded anchorages.

 

- do a 'Google' for full info

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Damn, I remembered Anchor Buddies last night and then promptly forgot. Indeed a very handy tool for the arsenal.

 

50-80% I think knot, especially in the size range of Tuffy. Smaller gear maybe but on 10mm, I doubt very much.

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