Anchor chain length

Medium weight 44ft cutter. Year round liveaboard in the Caribbean amost always on the hook.

60 lb CQR 210 feet 3/8th chain with 200 feet of rope rode attached. Times 2. 37lb Fortress on rope as a kedge.

Things that nobody says.

It is the middle of the night, it is raining and blowing 40 knots. " Hmm wish I had a smaller anchor and a bit less chain. "
 
As has been said, so much depends on draft and where you normally choose to anchor.
My boat is a 25' twin keel which is normally found around Solent and Poole; in the latter, especially, tidal range is small. Quite often the boat will remain afloat, sometimes it will take ground at low tide.

So, some sums. Tidal range for the day is 2 m. Stemhead is roughly 1 m above water. Draft is 1 m. Let's say I want at least 1 m beneath the keels at low tide. That gives 5 m between sea bed and stemhead at HW. On the basis that I might want length of chain = 4 x depth of water, that's 20 m. In practice, I found that if I had 25 m of chain available, I rarely used it all. There is, of course, plenty of warp available if I need it, which I very rarely do.

Consider also that the chain which most helps the anchor to set is near the anchor. More chain than that will help to stop the boat wandering about around the anchor; but the last few metres hanging from the stemhead don't do a lot, apart from weigh the front of the boat down. Also, if it started to blow old boots and I wanted more scope, octoplait would do nicely and would absorb shock loads better than chain, and with that much wind the boat isn't going to dance circles around the anchor.

I accept that if I wished to anchor and remain afloat in, say, the Channel islands or Bristol Channel, the calculation could look different.

More. The boat is, as I say, 25 feet long, and 25 m of 8 mm chain and a 10 kg anchor gives about a hundredweight of anyoldiron right in the bows, which is where I don't want weight, especially in a small boat. Of course I could use 6 mm chain but that wouldn't be as effective, either in helping the anchor to set or in restricting the dance around the anchor.

So, I will continue to carry rather less length of chain than many would consider necessary.

Incidentally - horror of horrors - I understand the boat as equipped by the builder had 7 m of 6 mm chain, plus a 7.5 kg anchor ...
 
Thank you every one, really good idea"s.
Okay my yacht 39ft has 8m anchor chain 47 m / Kobra 20 kg anchor with no rode.

Kedge is a new fortress / 10 metres of 8m chain & 40 m rode , please what would the best set up be.

We are travelling all over the Med and hopefully further afield.
Really appreciate advice.
 
Tranona said:
Depends entirely on your method of anchoring and where you anchor. Some people prefer a rope/chain rode, others an all chain, but commonly mainly chain with rope backup. I have 50m chain and 50m rope spliced to the chain in a 37', and think that combination is quite common. Rarely need to use the rope where I sail now, but often used to when I had the boat in the Med. Your 47m on its own would not be enough if you cruised big tidal ranges such as Brittany or Channel Islands, but adequate in the Solent.
Click to expand...

and of course what type of anchor you use. Sadly this is going to bring on another anchor debate.


imho and in my limited experience the modern generation anchors probably require less chain to do a reasonable job in holding in perfect conditions, because they

are probably less dependant upon the weight and resistance of the chain on the seabed. Using other than modern generation often requires a certain skill to set

them and they are said to not be reliable in resetting themselves given a change of tide. Not very reassuring to sleep on!

I still have 70m of chain on a 15kg Rocna (boat weight 9.4T) as I anchored and slept on it many times during our 5 month cruise last summer. I often use more

than recommended chain where possible, i.e. 6:1 and this enables me to drop an anchor chum a few metres down the chain to supress the actions of swell if

required. I also run a container of water down a long rode to a buoy where required to have the same effect of dampening the effects of swell.

My experience of the anchor type had been good on a smaller boat with 10kg Rocna with only 30m chain. My thinking was that with a heavier boat the minimum

size Rocna would be the 15kg. (My friend with a Moody 38 uses a 20kg Rocna.)

We did anchor in some fairly severe winds...(F8 in Fishguard for 2 days with no swell). I believe it's the swell that really can give greatest difficulty at anchor as the

chain is tugged at and snubbers may be useless if swell is severe.
 
Just mailed myself my very old 2kg danforth, from France. Wasn't as costly as I expected. I'm thinking that 20ft of 6mm chain should keep the pull nicely horizontal...

...with a long, light nylon warp as well. Not that I'm thinking particularly of the Solent, but I reckon 10mm anchorplait would be a bit hefty for a big dinghy. I've used three-ply line before and I hated its twisty tendencies...is there any type of durable, stretchy braided rope I should go for?

Crazy, sending an anchor through the post. All that bubble wrap, just to protect other items being mailed...:rolleyes:

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