Anchor chum

wizard

wizard

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Having a 31ft yacht I wondered what amount of weight should I use for the chum to help with the jumping about.

Hopefully you will have experiences to share about this
 
Previous threads discussing this concluded that, to make a significant difference, the chum has to be inconveniently heavy. Alain Fraysse's web page explains this, and offers a spreadsheet to calculate the difference it makes to the critical tension (the tension required to lift the whole rode off the sea bed). He concludes that the combination of a long chain and short nylon line is the winner.

Putting it in more intuitive terms, think of the chain itself as a long kellet. 30 metres of 10mm chain weighs around 70 kg. To make much difference to that you'll need 10 - 20 kg (say between 28 and 56 lbs).

Mark
 
Hi. Our boat is a 36ft Beneteau Oceanis cc which weighs in at about 6.5 tons when cruising. For our boat the standard anchor of 28lbs was replaced with a pair of anchors of 20kg each ( CQR and Delta ) for various sea-bed conditions in the Med. We usually use the Delta as our primary anchor to cut through the weed and lower our 20kg chum ( same weight as the anchor ) on a separate line 2/3rds of the way down the main anchor rode to the sea bed. Although the chum may move/drag/even jump about a bit in a large swell, the anchor stays where it is as it is the chum and the chain which are moving about on the sea bed. Before we went to the Med last year I did a lot of research in this subject and found that the English in the main were more likely to use two anchors at an angle of about 30 degrees in extreme conditions whereas the Americans relied heavily on a chum, usually the same weight as the anchor, as long as the anchor was the next one up from that recommended by the manufacturers. There are many books available on the subject, each with their own ideas but the general understanding is that a weight the same as the primary anchor is required to keep the chain from dragging on the sea bed so as not to disturb the anchor to much. I hope this is of some help.
 
[ QUOTE ]
Having a 31ft yacht I wondered what amount of weight should I use for the chum to help with the jumping about.

Hopefully you will have experiences to share about this

[/ QUOTE ]Freestyle's post is correct in that a kellet is completely pointless, at least at practical sizes, in terms of performance. They will not help prevent your anchor dragging.

However, they can be useful in reducing sailing on the anchor, and minimizing swing radii in light wind conditions. But, they have drawbacks, and they are really a band-aid fix rather than a true solution. Their effectiveness even for your desired application will also disappear in stronger conditions. You should rather consider your overall rode and your boat - what is making it sail around?

For example, if you are using nylon rope and have a boat with windage relatively far forward, you will eliminate a great deal of the problem by switching to all-chain and using a riding-sail.

Alandee's set-up should be condemned to be honest, as it implies dragging the kellet around on the bottom a great deal. This is no way to treat the marine environment, especially in the Med.
 
I use a Broads style mud weight [a left over from a previous boat kept on the Broads]. This has certainly damped the movement on the occasions that I have used it. I did let it down until it touched the sea floor, which damped the hunting, but its main use in helping the anchor is when it is lifted on the chain catanery reducing the snatching felt by the anchor.
 
On the basis of my own experiences, I feel that I must disagree

Let me be specific: my boat is a 10 tons displacement long keel type. The bower anchor is a 45lbs CQR on 12mm short link chain; I use a 10ft length of 12mm three strand nylon, shackled to the bobstay plate on the stem at the waterline, as an additional snubber - an idea that I got from Don Street's books. The use of a short length of nylon rope with a breaking strain less than that of the chain is entirely deliberate; I want it to stretch, and to fail before the chain does.

I have found that using a chain slider with 3 x 28lbs pigs of ballast attached to it with short lengths of rope, as recommended by Claud Worth, is rather effective. This of course is about double the weight of the anchor, but it is fairly easy to handle as three separate weights. It is surprisingly easy to pull the slider back up the chain to the stemhead roller, pick each rope up and drop the pig of ballast on deck then remove the slider.

If your point is that there is no point in using a silly little weight, then I agree.

However, I have found the above set up very effective in strong winds.

I also disagree with the use of a riding sail aft. One sees ketches and yawls trying this and sailing all over the place:

To do any good, the riding sail must be full of wind, i.e. the boat must have sheered to at least the close hauled position. The sail is now providing drive so she sheers as far as she will go and snaps back. She will come round and the riding sail will flog until it fills on the other tack and she tries to sail the anchor out on that tack instead.

The theory of the riding sail assumes that the boat will pivot around her notional CLR; she won't, of course, because she is tethered by the bow to her anchor cable.

The upshot is that the boat sails around her anchor with the mizzen flogging itself to bits until the skipper comes to his senses or she sails her anchor out or hits another boat inside her swinging range.
 
In defense of the statement by Craig Smith of Rocna Anchors that the way I anchor should be condemned, I was purely answering Wizards question about the experiences I have had using a chum weight. In an ideal world we would all have the newest proven design of anchor at least one size up from that recommended by the manufacterer on a minimum of 200m of chain to give sufficient holding when anchored at 7:1 or more in bad conditions. Using Freestyles calculations we would then have approx. 480kg of weight on the bow of the boat. Not good on a small boat. We had to compromise in order to keep the weight down by using 1/3rd chain and 2/3rd multiplait rode. The chum is kept at the back of the boat for use when necessary. I am not an expert on anchoring techniques, just passing on what experiences i've had to another forum member based on his question.
 
Re: On the basis of my own experiences, I feel that I must disagree

Good to see that someone else is living in the real world when it comes to anchoring techniques and not just using this forum to advertise his own company during LIBS week!
 
At the moment I have a 35lb CQR plus 45m of chain and 45m of Octoplait. I dont mind carrying the extra weight for the chum as for the one time you really needed it you would be eternally grateful.

So it looks like the weight has to be close to or more than the existing weight of the anchor to be useful ?

As for the riding sail I have never found this useful on a modern lightweight (relatively) hull form. This coming year I am going to try different bucket shaped articles to increase drag from the stern to attempt to slow the shearing about and will report back on the results.
 
Yes, I would say so. I've found a couple of lead ballast pigs with a hole drilled through one end to be easy to handle and easy to stow under the floorboards.

On the sheering about, this is a suggestion, and I don't guarantee that it will work, as our boats are different, but you might try an experiment in cutting down the sheering about by giving the boat a deliberate sheer by bending a warp onto the anchor chain and taking it back to one of the winches in the cockpit, so that she sits about 20 degrees off the wind/tide.
 
Yes, I have tried that and it does work to an extent but as I say I will try the bucket drag method this year as in theory it should provide a real brake (fingers crossed)
 
[ QUOTE ]
The chum is kept at the back of the boat for use when necessary

[/ QUOTE ]

This is the best justification for a chum that I've seen. I haven't been happy with only 35 m of chain in the anchor locker (plus 35 m of eight strand nylon), the chain is in need of sending away for regalvanizing, and I need some chain for the second anchor. So I took the plunge and ordered a longer chain. I asked for 50 m, but was persuaded to take the full 60 m length that comes in a drum from China. The delivery driver grumbled. The drum says 141kg net. I lie in bed at 0400 considering the effect of 141 kg on my trim, alternately designing a tube system to get the chain further aft and choosing how much to cut off the 60 m.

Now, going down the chum route, if I were to take up bilbobaggins offer of a couple of 56lb/25kg weights (which I could carry aft to the cockpit locker), I could counteract the effect on the trim of an extra 15m of chain in the anchor locker. (Although it would exacerbate its effect on the moment of inertia of the yacht's pitching.)

Mark
 
at the risk of raising another issue - surely the answer is 8mm chain in your case rather than shorter chain and a 'chum'.

if the boats not big enough and ugly enough (and that's hugely tounge in cheek in your case!) to carry the weight of the chain it's probably too big - assume 10mm from your figs.

what size anchor do you have on the end of such a rode?
 
A 31fter on 45lber with 45mts of chain and a 10tonner on 12mm chain and both using or looking at chums.

I really am not trying to be rude but have we had a closer look at our anchoring technique rather than the gear?

From a 32fter on 15mts of 7mm chain, 12mm warp and a 22lb anchor who has no problems at all. I do sail around a bit but that is good, it burys the anchor further.

Opps forgot. Riding sails are good, sometimes, if you can put up with the bloody awful noise all the time.
 
wondered if it might even be 12 at that weight............

exactly the point I was aiming towards but you got there somewhat quicker! I thought to explore the balanced nature of the overall rode first............ /forums/images/graemlins/smile.gif
 
The more I think about the separate weights the more I like the idea, especially as they can also be kept in the centre of the boat in the bilge just behind the keel.
 
Thank you for the thought! /forums/images/graemlins/wink.gif

"Normally" I do what most Thames Estuary amateur sailors do - drop a CQR on three times the depth at HW of chain. The short scope is because most anchorages are either on the edge of a ship channel or are crowded with other boats or both. We don't have the luxury of wandering about on half a mile of rope. /forums/images/graemlins/smirk.gif

In the past 22 years of sailing my boat in the southern North Sea and the English Channel, I have used a "chum" four or five times, and been very glad of it each time. It is not an everyday measure, but it can be very handy. Three situations in which I've used it were:

Singlehanding coastwise - anchoring offshore in moderate weather to get a decent sleep during a foul tide. It may not have been "necessary" but it allowed me to sleep soundly. This was the application for which Worth invented it. She was snatching slightly at the chain every few minutes, enough to keep me awake, until I used it - not afterwards. I now routinely use it when anchoring offshore.

At anchor in shelter sitting out a severe gale, in a fairly confined space where we might have dragged ashore - not dangerous, just annoying. It might not have been necessary, but we certainly stayed put.

Anchoring in a tearing hurry on shingle in a narrow channel - rope round prop, dead header, too narrow to tack (moored boats each side), three knot tide...to wait until I could sort things out. On this occasion we were dragging until I used it, so I can specifically say - it works. I don't, of course, anchor in such spots from choice! This was an odd one, because, unlike the other two cases there was no sea running, but it stopped us dragging due to the CQR slithering through the shingle.
 
[ QUOTE ]
Alandee's set-up should be condemned to be honest, as it implies dragging the kellet around on the bottom a great deal. This is no way to treat the marine environment, especially in the Med.

[/ QUOTE ]
Whilst we should all be aware of the potential damage our anchoring does to sensitive marine environments, alandee’s post also says that the chum probably reduces the amount of chain that is dragged along the seabed.

[ QUOTE ]
….the general understanding is that a weight the same as the primary anchor is required to keep the chain from dragging on the sea bed so as not to disturb the anchor to much.

[/ QUOTE ]

I would have thought that lengths of chain dragged around and dropped in different positions with every wind shift and wave would damage a greater area of the seabed than a single chum (although of course there is also some chain movement with this as well). I don’t know whether you (Craig) are right or not but I think you have been a bit unfair condemning alandee so roundly.
 
[ QUOTE ]
This coming year I am going to try different bucket shaped articles to increase drag from the stern to attempt to slow the shearing about and will report back on the results.

[/ QUOTE ]

I'd be interested to hear of anyone having used a 'chum' or somesuch lowered from the stern onto the bottom, and acting as a 'drudge' in reducing sheering about.

/forums/images/graemlins/wink.gif
 
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