Anchor Chain

[scruff]

Hi,

I'm needing to replace my anchor chain rode this winter; new boat (to me) has 5m chain and about 20m of blue poly (floating!) anchor rode.

This, obviously is not sufficient.

For the avoidance of starting an anchor debate, the pick on the end is irrelevant.

The boat; a Folksong does not have a hawse pipe so all the rode will be in the bow locker. As such, weight is a bit of an issue so unable to go for full chain.

I have looked at various sites and it looks like I could go for either 6mm or 8mm chain. For the same weight overall (and cost) I could have;

i) 50m of 6mm chain which weighs in at 40kg
ii) 30m of 8mm chain which is near as damnit 40kgs again.

Spliced on to the chain will be x meters of rope to make up the suitable length required for the west coast. It is quite likely that I will find myself anchoring in 10m depths so a long rode will be required and often swinging room is not an issue.

So my question is, what is more effective; a longer catenary curve with a lower p/m weight or a shorter catenary curve with a higher p/m weight?

Your thoughts please?

Many thanks,

Scruff.

 

[LittleSister]

You could compromise and get 7mm chain!

I would imagine that 6mm is rather light for your boat. I faced the same dilemna. Almost all the recommendations for my boat - 23ft, 5,000lb, long keel - said 6mm was too low. Though it might well be strong/heavy enough in real life, if I ever did have to make an insurance claim, I didn't want an argument about it. 8mm is more than strong/heavy enough (and is recommended for much bigger boats), but I wanted to keep the weight down and increase the length (and also the 8mm I started with often stuck in the hawse pipe). I went with 7mm and I'm now sure I made the right decision. It's much more substantial than 6mm, but not over the top, which is what the 8mm felt like on our little boat.

If I remember correctly 6mm is about 0.75kg per metre, 7mm is about a kilo a metre, and 8mm about 1.4kg per metre.

 

[Roberto]

Hi,


So my question is, what is more effective; a longer catenary curve with a lower p/m weight or a shorter catenary curve with a higher p/m weight?

Your thoughts please?

Many thanks,

Scruff.

If you define "effective" as the type of setup which will maximize the pull necessary to lift the last chain link, the one at the anchor -that is bring the catenary tangent to the bottom- then for a given weight, a longer and lighter chain will need a higher pull (ie will be better) than a shorter and heavier chain

 

[ukmctc]

Hi,

I'm needing to replace my anchor chain rode this winter; new boat (to me) has 5m chain and about 20m of blue poly (floating!) anchor rode.

This, obviously is not sufficient.

For the avoidance of starting an anchor debate, the pick on the end is irrelevant.

The boat; a Folksong does not have a hawse pipe so all the rode will be in the bow locker. As such, weight is a bit of an issue so unable to go for full chain.

I have looked at various sites and it looks like I could go for either 6mm or 8mm chain. For the same weight overall (and cost) I could have;

i) 50m of 6mm chain which weighs in at 40kg
ii) 30m of 8mm chain which is near as damnit 40kgs again.

Spliced on to the chain will be x meters of rope to make up the suitable length required for the west coast. It is quite likely that I will find myself anchoring in 10m depths so a long rode will be required and often swinging room is not an issue.

So my question is, what is more effective; a longer catenary curve with a lower p/m weight or a shorter catenary curve with a higher p/m weight?

Your thoughts please?

Many thanks,

Scruff.

I had 8mm chain 30 mtrs + 30 mtrs 14mm rope multiplad on same style boat.

 

[doug748]

I would go for the 6mm.
The other stuff takes a lot of lugging to fetch up from 10/15 mtrs.

 

[john_morris_uk]

Despite the very strong opinions that are potentially about to be expressed, I really do think you have to have some consideration about where you are going to anchor. The only hint that you give is that it is going to be in serious depths.

If you are going to anchor on a rocky bottom - or near coral etc then the durability of chain is highly desirable.

Without a windlass the weight of chain from depth is also going to be a serious consideration. (We have 40 metres plus of 10mm chain and without a windlass, I would need to rig a rolling hitch and use a winch to lift the chain and anchor if it ended up hanging from the bow in deep water)

You also need to consider the sort of sailing you do. If you are setting off round the world, then most people tend to oversize their anchor and chain as they are potentially going to be using it in more extreme conditions than on a summer cruise round the coast of Brittany. (No disrespect to the sailing off Brittany and the UK, but I ended up anchoring in a hurricane once)

Most people anchor most of the time in only a few metres of water. Think about how much cable you really need - perhaps 30 metres of chain and 30 metres of multiplait might be a good compromise?

 

[scruff]

Thanks for your feed back chaps.

Looks like if I put the full scope out, 6mm will be best but in shallower water then the 8mm has the edge.

Guess I will just have to spend an evening pouring over charts in front of the fire looking around all the possible anchorages.

As to the aim of my sailing, the boat was purchased for an Atlantic circuit or Azores jaunt but new "Proper" job has most likely put that on hold for the time being.

Most likely just be Clyde, West Coast, Ireland with hopefully Iceland / round Rockall if I can wangle a long holiday off this summer.

 

[Kelpie]

As to the aim of my sailing, the boat was purchased for an Atlantic circuit or Azores jaunt but new "Proper" job has most likely put that on hold for the time being.

Most likely just be Clyde, West Coast, Ireland with hopefully Iceland / round Rockall if I can wangle a long holiday off this summer.

I think I can hazard a guess about at least one of the books you have read recently



Good luck and give us a shout if you're passing Stornoway

 

[scruff]

I think I can hazard a guess about at least one of the books you have read recently



Good luck and give us a shout if you're passing Stornoway

I have a rather full bookshelf! What book are you alluding too?

 

[mixmaster]

I would go with the longer 6mm chain. Obviously the bigger the chain and anchor the better but given your limitation I would go with more chain. If you have weight to spare, then put it in the anchor. I would however make sure the chain is high tensile (grade 40 not 30) chain.
We put a lot of though into this when we went long distance cruising. Ended up with 60m of Grade 40 8mm chain on our 12,000 kg 45 foot racer cruiser with a 25kg Rocna (!!!) and another 50m of multi plait rope. It's the shock loads that are the problem and we always put a nice long and stretchy snubber line on.
There are some very experienced and progressive cruisers out there that are of the put spare weight in the anchor school (look up Morgans Cloud or the Dashews). For quality grade 40 chain made by Maggi in Italy, try these guys:http://www.boatgeardirect.co.uk/. They will provide test certificates on request.

 

[scruff]

Thanks for the link Mixmaster, BGD seem to have some pretty competitive prices.

 

[vyv_cox]

Thanks for your feed back chaps.

Looks like if I put the full scope out, 6mm will be best but in shallower water then the 8mm has the edge.

Guess I will just have to spend an evening pouring over charts in front of the fire looking around all the possible anchorages.

It's the tidal range that is important, not specific anchorages. Assume for a moment that you draw 1 metre and like to have at least 1 metre beneath the keel. At LWS you will want to be in 2 metres. If you are anchored to the west of Mull of Kintyre that will also be near enough the depth at HWS, whereas if you are anchored off Jersey it will be something like 14 metres.

If you are all chain you need an absolute minimum scope of 3:1. If you are on mixed rope and a relatively small amount of chain you need 5:1.

Personally I like to err slightly on the side of caution, so I would go for 7 mm chain. If your home waters have a relatively small range then I would buy enough chain so that you can lie to it alone on most occasions. All-chain has many advantages, such as lying more stably and not suffering rope wrapped around underwater parts. However, in a small boat the weight can be a problem, so I would go for a mixed rode, but don't skimp on the rope length.

 

[reeac]

anchor chains and warps

If you expect to anchor only where you have lots of space then that favours the long scope/lighter weight option [equal holding power being assumed]. More crowded surrounding will place a limit on your scope.

 

[Kelpie]

I have a rather full bookshelf! What book are you alluding too?

Ah, my mistake, I thought you'd said you had a Corribee but I see it's a Folksong.
Just reminded me of Roger Taylor and his 'round Rockall and Ireland' trip so I was wondering if his book had been a source of inspiration.

 

[Tidewaiter2]

An Anchor Chum?

If you expect to anchor only where you have lots of space then that favours the long scope/lighter weight option [equal holding power being assumed]. More crowded surrounding will place a limit on your scope.

Plus an anchor chum(could be a bight of old chain sewed in a bag?) stowed low down away from the ends, and deployed later, to improve cantenary, might be the solution, if bow locker weight a serious problem?
Could use it as a 'drudge' too if the engine fails/prop fouls?