Anchor Chain Length

[Scubadoo]

Last weekend at the Bournmouth airshow, I spent both Saturday and Sunday there and had real problems anchoring. Saturday I had no problem, but Sunday I just couldn't get it to hold. Everyone else seem to do a better job than me from very small to large boats. So what do you think I was getting wrong. I guessing I probably didn't have enough line for the 12metres depth. I only had about 26metres of line including 5metres of chain.

Should I get more chain and at what length, what is the length of your line.

 

[lisilou]

We were at 10m depth on sat with 20m (i believe) line and having watched carefully for a bit, we held fine.

 

[BartW]

only chain I put min. 3 times depth
and with warp I put min 5 times depth,
(YM course teaches 4x and 6x)

when diving, when the anker securily holds on a wreck,
then we use warp length, two times the depth.
and check / secure it when we reach the wreck,


so I guess you need a longer warp,
5m chain might be OK,
how long / heavy is the boat and the anker ?

 

[[2068]]

I was at the SW corner in 40ft of water.
I deployed all 40m of chain, and this worked fine.
Several others were having problems due to not enough chain/line.

When I had a boat without a windlass and mixed line/chain, I found 10m chain and 30m line was a good compromise: it wasn't so heavy that you needed to be a russian weightlifter to pull it up, but it held well in most sensible conditions.

 

[longjohnsilver]

I was at the SW corner in 40ft of water.
I deployed all 40m of chain, and this worked fine.
Several others were having problems due to not enough chain/line.

When I had a boat without a windlass and mixed line/chain, I found 10m chain and 30m line was a good compromise: it wasn't so heavy that you needed to be a russian weightlifter to pull it up, but it held well in most sensible conditions.

Had much the same on my previous boat, 32' mobo, worked well.
So in answer to OP more chain and more line needed, with 10m of chain I'd be looking at min of 4 x depth.

 

[Philiz]

You didn't have enough anchor warp out. Personally I'd put a lot more chain on if you have a decent windlass to pull it up and it wont make you bow too heavy.

 

[fireball]

on our previous boat (30' fin keel yacht) it had 3m of 8mm chain spliced to 50m of warp. I replaced the 3m of chain with 10m of 8mm chain and that made a big difference to holding.
In the new boat we now have 50m of 8mm chain ... that works!

 

[duncan]

Had much the same on my previous boat, 32' mobo, worked well.
So in answer to OP more chain and more line needed, with 10m of chain I'd be looking at min of 4 x depth.

does it for me - on a boat that size 10m 8mm chain and enough warp to make a rode for 4 x your normal anchoring depth, although you will fine with a well set anchor and 3x in that sort of depth.

7.5 or 10kg hook on the end.

but lets not get into a full blown anchoring thread! suffice to say the original poster wasn't just 'unlucky', it was definitely a little on the short side for the depth etc

 

[Scubadoo]

Thanks everyone, I now have a better idea of what I need to do i.e. get more chain.

I don't have a windlass so it is really a down to how much weight I can lift if I put more chain on.

I realised anchoring in 12m with just 26m available was not good, but worked fine the day before which was a calm day compared to Sunday.

 

[strakeryrius]

You would have been Ok if it had been 26m of all chain, but the length of warp involved is just not heavy enough.

I was there Sat and Sunday in 14m with just 25m of all chain out and didn't move an inch either day. Don't worry though, you weren't alone with anchor problems. We were there early and witnessed quite a lot of anchoring antics during the course of both days. It sometimes makes me wonder if the air show is the only time that some people put down their anchors and the rest of the time they are marina-hopping or picking up buoys, so don't get enough practice.

 

[duncan]

You would have been Ok if it had been 26m of all chain, but the length of warp involved is just not heavy enough.

I was there Sat and Sunday in 14m with just 25m of all chain out and didn't move an inch either day. Don't worry though, you weren't alone with anchor problems. We were there early and witnessed quite a lot of anchoring antics during the course of both days. It sometimes makes me wonder if the air show is the only time that some people put down their anchors and the rest of the time they are marina-hopping or picking up buoys, so don't get enough practice.

whilst your first part could be debated for at least 20 pages (50 on PBO) I have to agree the second; the same thing happens at firework displays as well.

many Poole and Solent boats only seem equipped to anchor in Poole Harbour, Studland, Newtown Creek and Osbourne Bay!

mind you many don't seem much better equipped to raft up in marinas, or town quays, either.

 

[hlb]

Amased at how many folk scrimp on chain. With 60 metres available to me. It's like putting the hand brake on.

5 M of chain is like a chocolate fire guard.

 

[[2068]]

Amased at how many folk scrimp on chain. With 60 metres available to me. It's like putting the hand brake on.

5 M of chain is like a chocolate fire guard.

5m of chain is like pulling up the handbrake only three clicks. It does slow you down a bit, and there is a funny smell.

 

[hlb]

5m of chain is like pulling up the handbrake only three clicks. It does slow you down a bit, and there is a funny smell.

Bit like the bloke on here a good few months ago.

I put the anchor down but it does not "hook up".

When questioned he said aggressively. "It dont hook up".

AS if it was some sort of grappling hook, trying to grab a passing rock.

Turned out he was dropping about 10 meters of chain in 20 metres of water.

You could not make it up.

 

[epervier]

You would have been Ok if it had been 26m of all chain, but the length of warp involved is just not heavy enough.

I was there Sat and Sunday in 14m with just 25m of all chain out and didn't move an inch either day. Don't worry though, you weren't alone with anchor problems. We were there early and witnessed quite a lot of anchoring antics during the course of both days. It sometimes makes me wonder if the air show is the only time that some people put down their anchors and the rest of the time they are marina-hopping or picking up buoys, so don't get enough practice.

Guilty as charged, my new boat hasn't got up and down buttons on it, like the old boat did, and with a bloody great Clyde and fifty metres of chain, I tend to look for buoys or pontoons, rather than give myself another heart attack hauling that lot back up by hand

 

[Scubadoo]

Amased at how many folk scrimp on chain. With 60 metres available to me. It's like putting the hand brake on.

5 M of chain is like a chocolate fire guard.

Yep I hear you HLB, the problem is on a small boat carry large amounts of chain is simply too heavy and of course no windlass makes things worse. It is a case of trying to find a happy medium really.

 

[Scubadoo]

You would have been Ok if it had been 26m of all chain, but the length of warp involved is just not heavy enough.

I was there Sat and Sunday in 14m with just 25m of all chain out and didn't move an inch either day. Don't worry though, you weren't alone with anchor problems. We were there early and witnessed quite a lot of anchoring antics during the course of both days. It sometimes makes me wonder if the air show is the only time that some people put down their anchors and the rest of the time they are marina-hopping or picking up buoys, so don't get enough practice.

Well I am not one of them, I do anchor a lot and generally have no issues, however I am anchoring in 4 to 6 metres of water usually. Unforunately at Bournemouth I didn't have the choice of finding that depth. Still, next time I hope it won't be a problem when I get more chain.

If I had 26m of chain I think my next problem would be weight and lifting it, like I said in my post to HLB.

 

[fireball]

I think you'll find 10m of chain will make a big difference - but you need plenty of warp too ...

 

[duncan]

Yep I hear you HLB, the problem is on a small boat carry large amounts of chain is simply too heavy and of course no windlass makes things worse. It is a case of trying to find a happy medium really.

You don't need a happy medium, anything over 1.5x boats length isn't going to make any difference to the ultimate holding of your rode (and even that can be argued - it's primarily there to avoid chafe with the bottom and to assist both setting and short scope anchoring). As you point out you really don't want another 60kg sat in the anchor locker on your craft either!

The other advantage of chain is with a windlass where it makes things a lot easier overall - which is a good think 'cos the windlass is required when anchoring deeper water with chain (it's only the chain hanging that has weight so, with 8mm chain, your maximum 'lift' in 20m will be about 25kg + anchor weight - far more than can be handled safely on a foredeck of most smaller boats) At 10m it's about 12kg + anchor - say 20 to 25kg all up which still requires a safe platform to work from and a strong back etc!

My normal rode is 200m 14mm anchorplait + 12m 8mm chain + 10kg delta. This enables me to anchor just about anywhere in the English channel, and did have an additional 200m for the occasional trip to wrecks in the Hurd Deep but it's not only a pain to set and recover in that depth (even windlass assisted) that I probably won't do it again). 3 x holds fine once the depth is up over 30m, 4x is often required in shallower water and I would use at least 6x in an emergency, or overnight in anything but a sheltered anchorage, because it's the angle of pull on the anchor stock, combined with the geometry and holding power of the anchor, that dictate the holding once serious loads go on.

Put another way, your 5m chain (any diameter) would have been fine if you had had 40m of warp....

 

[strakeryrius]

Put another way, your 5m chain (any diameter) would have been fine if you had had 40m of warp....

This would be right under normal circumstances, but at the airshow peeps were coming up and anchoring far too close to be able to have that much rode out. I arrived early (11:15) both days, and by 1pm had at least three other vessels anchored within 10m of me both days. On the second day a 40ft yacht anchored right in front of me and was only some 5m off my bow most of the time. Hence the need for as short a rode as possible and only 25m out in 14m of water.

I was fine with all chain, but its a conundrum for smaller boats, as I appreciate that the weight of the chain required with no windlass would be prohibitive unless you had the muscle mass of the incredible hulk! Maybe two anchors, fore and aft? Or consider moving to the west of the pier into shallower water, but the density of boats there looked to be even worse than where I was.