Anchor Chain

[rnjpinz]

I am sure this subject has been discussed many times but I need a refresher. I have a Caliber 40 and have just purchased a 45 lb Manson Supreme. I am also getting ready to order my Lighthouse windlass. My question is this: What is the best size chain and how many feet should I have. My wife and I are preparing to cruise the Carrbean next year.


Bob

[dennisjay]

Size chain should be dictated by requirements of the windlass. I've carried 200 feet in cruising the Caribbean and feel that's adequate. Sure others will have other opinions.

[captain465]

Size of chain will be determined by the displacement of your boat. I would say that 3/8 BBB would be good. You will have to decide before you order the windlass, as they will need that in order to give you the proper gypsy. I carry all chain (375ft) on my primary anchor.

[chuckr]

I can only tell you what we did -- we sail a jeanneau ds40 at 22k pounds -- we redid our anchor rode and chain last year - i did a long write up on it after a bit of research and it is below --

Getting ground tackle is not a simple question. How much, what size and what type of chain, how much and what size rode and how the chain/rode interface should be made? The easy part of the analysis is the size of chain. The gypsy of the windlass is designed for only one chain size. Our Jeanneau DS40 came with a 5/16” gypsy so chain size was easy. But how much chain and rode do we need?
First, we looked at our current set up, our lifestyle and where we cruise. We are full time cruisers’ and our current cruising grounds are from the southern Bahamas to northern Maine. The current chain/rode combination is 70’ of 5/16” chain with 250’ of 5/8” rode on the primary anchor with 70’ of chain and 200’ of rode on the backup anchor. Anchoring in water as shallow as 6’ and as deep as 30’we use a standard 7 to 1 ratio but have on occasion used shorter ratio, in tight anchorages, and as much as 10 or 12 to 1 for a pending blow. Anchoring in and around coral and rocks has always been a concern when exceeding 15’ of water due to chafing. It would seem simple to choose an all chain anchor. However, the cost would be beyond our budget and the weight of all that chain, at approximately one pound per foot, in the boats bow would certainly compromise the sailing performance of SoulMates. So what is the proper chain and what compromise between chain and rode?
Before deciding on the type of chain or rode we needed to understand the load that would be placed on the anchoring system under various wind speeds. Using an article by Nigel Calder in a September 2000 Sail magazine, Nigel referenced work done by the American Boat and Yacht Council (ABYC) listing loads on ground tackle in pounds at various wind speeds based on boat length and beam. While not specific to SoulMates, which has a 40’ LOA and 13’ beam, it was sufficient to provide some guidelines. For a 40’ boat with an 11’beam the load would be 1,200 pounds at 30 knots of wind, and 2,400 pounds at 42 knots of wind. For a boat with 50’ LOA and a 13’ beam the loads would be 1,600 pounds at 30 knots and 3,200 pounds at 42knots. So what does all that mean? Well, first we will rarely anchor out in winds in excess of 40 knots. We have been in 30 knots more than once but when the forecast call for bigger winds we either look for a better wind protected anchorage or head for a marina. Have we seen bigger winds; can you say hurricane Katrina or Wilma. Yes we have.
With The deepest anchorage we have been in so far, 30’ and a 7 to 1 scope would mean at total chain/rode of 210 feet. But knowing that all the chain does not lie on the bottom and gradually slope upward toward the bow of the boat and not right angles we knew we could use less than 200’ of chain to protect from chafing but gives us the holding we wanted. Our decision was to use 150 feet of chain. This gave us more than sufficient weight to hold our primary anchor, a 44 pound delta, in place while giving sufficient chafing protection.
Once the decision was made on the length of chain our next decision was the type of chain. The choices here can vary a lot depending on the quality of the chain. Back to the Nigel Calder article and we estimate the actual working strength of various chains and rode sizes and quality. Now I am not going to get technical here as I am not an engineer but I did need to understand the working load limit (WLL) of various chains and rode. The Industrial Rope Access Trade Association defines WLL as “the maximum load which should ever be applied to the product, even when the product is new and when the load is uniformly applied - straight line pull only”. But Nigel Calder has simplified the definition of the WLL as “a percentage of the breaking strength”. The first is somewhat hard to comprehend but the second is simple. If the load limit is X the ABCY gives various components of the anchoring system a percent of X as the WLL. Now if I know the percent and the breaking strength it is easy to calculate the WLL. Better yet a quick check of the latest edition of the West Marine catalog has the safe working load which is the equilviant of WLL listed for various chains.
Anchoring chains come in various quality but the most common are proof, BBB, and High Test that comes in either Grade 40 or Grade 70. Proof chain is made of low carbon steel and due the link size is questionable for most windlasses. For the 5/16” windlass on SoulMates it has a WLL of 1,900 pounds which is well below the 2,500 to 3,000 pounds we are looking for. BBB chain is also made with low carbon steel and works well in windlasses. However, it also has a WLL of 1,900 pounds. Grade 40 high test is made with high carbon steel with link size that fits windlasses and has a WLL of 3,900 pounds which exceeds our requirement. Grade 70 is similar to Grade 40 only slightly stronger with a WLL of 4,700 pounds. It becomes apparent that for our application we needed either Grade 40 or Grade 70 chain. The difference in weight between the two for the 300 feet is 30 pounds heavier for the Grade 40. The cost difference however is quite substantial. Grade 70 would cost an additional $500. Given all these factors our decision was to use the Grade 40 given the WLL that was greater than required and with a cost advantage.
Rode size is not as clear cut. When a boat is at anchor in high winds and seas there is not a steady pull but a bucking motion that will stretch the nylon rode and absorb a lot of shock. Back to the Nigel Calder article and his use of a 25% of breaking strength for the WLL based on his experience and research. In fact, he references studies done by the Oil Companies International Marine Forum on nylon rodes used for mooring oil tankers. In the study “rodes are progressively stressed to 50% of breaking strength for 1,000 cycles, then 60% for 1,000 cycles, then 70% of breaking strength, and so on until failure occurs. Most fail at 60% of load limit.” This data would suggest that the 25% he uses if very conservative. The rode we removed was 5/8” three strand. It has a breaking strength of 12,200 pounds and at a conservative 25% would have a WLL of 3,050 pounds, meeting our requirements. Our decision was to go with the 5/8” three strand with 200’ on the primary and 125’ for the backup. That gave us 350’ on the primary anchor and 275’ on the backup anchor.
Finally there is the interface between the various components. It is common knowledge that wherever there is an interface a point of weakness is introduced. For the chain/rode interface we chose a rope to chain splice for two reasons. First it would fit through our windlass with ease and we were not sure anything else would. Second, it had a breaking strength that is 90% of the original rode according to West Marine.
For the anchor/chain interface we chose the biggest galvanized shackle that would fit through the chain link; 3/8”. This is the weakest part of the entire system with a WLL of 2,000 pounds per the West Marine catalog and Nigel Calder rates it at 2,500 ponds. We would prefer something that is stronger but the chain link would not take a larger shackle and we were concerned that an anchor connector that uses set screws could work lose without our knowledge and we could lose our anchor. With the shackle we use stainless steel wire to secure the pin.
The system we designed for our boat and our cruising life style met our needs and represented a solid systematic approach using available data. It also is very close to other full time cruisers we have met that have ventured beyond our current cruising grounds.

[Dockhead]

Originally Posted by rnjpinz

I am sure this subject has been discussed many times but I need a refresher. I have a Caliber 40 and have just purchased a 45 lb Manson Supreme. I am also getting ready to order my Lighthouse windlass. My question is this: What is the best size chain and how many feet should I have. My wife and I are preparing to cruise the Carrbean next year.


Bob

Check this out:

Main Page (Rocna Knowledge Base)

In my opinion it's all very good data, and has pretty much everything you would want to know.

I would have chosen a somewhat bigger anchor than the 40 lb. Manson if I had been you, but the Manson is a great anchor and that size technically should be within the limits so probably you will be ok.

I would probably use 200 feet of 3/8" G40 chain if I were you. We have 100 meters of chain on board (more than 300 feet), but we are a deeper draft boat than you and we sail in areas with a big tidal range. For you 200 feet will probably be enough. To figure out for yourself whether it will be enough ask yourself what is the deepest water you could conceivably be anchoring in and the biggest scope you could ever want (although need for scope diminishes with depth). At a 7:1 scope, 200 feet will be enough for 28 feet minus the distance from your bow roller to the water -- so what, 24 feet? Is that enough? Only you can say.

Whether you go with all-chain or chain/rope rode is a matter of choice. I think it has been proven that the weight of your anchor rode doesn't play much role in your anchor's ultimate holding power. So having twenty or thirty feet of chain for abrasion resistance and then a bunch of rope is a good idea from the point of view of cost and weight. Like many cruisers, however, I prefer all-chain because you don't have to worry about chafe, and probably even more because I am too lazy to futz around with a mixed rode.

You will have to choose not only size, but grade of chain to use. If you are using an all-chain rode, it will be lighter if you use one size smaller but a higher strength grade like G70. Many people swear by this, but I don't like it personally -- G70 chain can't be regalvanized and its strength can be compromised in other ways. I prefer G40 which is stronger than G30 or "BBB", but doesn't rely on fancy heat treating, which is destroyed by regalvanizing, for its strength.

[barnakiel]

3/8 g4(0) is a good chain

It is nice to have at least 100' of it in the West Indies. More, if your chain locker allows. There is no reasonable maximum, but mind that the more you carry, the heavier the bow, which is not all that good.

Make sure you take a second anchor too, with some chain for it, and a spare.

b.

[rebel heart]

Here's mine:
Rebel Heart - Sailing, cruising, liveaboard blog and website - Eric's Blog - our new manson supreme*anchor

Rebel Heart - Sailing, cruising, liveaboard blog and website - Eric's Blog - got the new anchor*rode

[rnjpinz]

Lots of good info guys. I greatly appreciate it. If I could have gone bigger with this anchor I would have. The jump was from 45lbs to 60lbs. In a anchor the style of the Manson, that is a monster and I was not sure it would even fit. So my question is this, since I have gone with the smaller Manson, can I maximize its holding power by using heavier chain, say, going to 7/16 or am I fine with 3/8 HT. I am planning on buying 250 feet of chain.

Bob

[rebel heart]

Originally Posted by rnjpinz

Lots of good info guys. I greatly appreciate it. If I could have gone bigger with this anchor I would have. The jump was from 45lbs to 60lbs. In a anchor the style of the Manson, that is a monster and I was not sure it would even fit. So my question is this, since I have gone with the smaller Manson, can I maximize its holding power by using heavier chain, say, going to 7/16 or am I fine with 3/8 HT. I am planning on buying 250 feet of chain.

Bob

Do you already have a windlass that accepts a certain size? If so, you either need to use the chain size that fits your windlass or get a new wildcat.

For proper chain and anchor sizing you can calculate the maximum shock load of your vessel in varying wind and wave conditions (there are graphs and tables floating around on the Internet), and then at minimum you make sure that you're well under the working load limit for all of the different pieces of ground tackle you assemble. So if the 3/8" chain fits that number, you can safely say that it's "enough", although if you want to run heavier chain you're more than welcome to and it certainly won't hurt. There will be additional weight (bigger chain is heavier), but the weight of ground tackle is absolutely offset by its holding advantage when deployed.

[rnjpinz]

Do you already have a windlass that accepts a certain size? If so, you either need to use the chain size that fits your windlass or get a new wildcat

This is the main reason I am inquiring now. I am going to order my windlass next week. I will need to specify gypsy size at that time.
I won't be able to change my mind after the fact so I am doing home work now.
Bob

[Vasco]

The 45# Manson Supreme will be plenty big enough for your boat.

[MarkJ]

I have 100 meters of 10mm chain... thats about 328 feet.
10mm is about 3/8ths

[rebel heart]

Originally Posted by rnjpinz

Do you already have a windlass that accepts a certain size? If so, you either need to use the chain size that fits your windlass or get a new wildcat

This is the main reason I am inquiring now. I am going to order my windlass next week. I will need to specify gypsy size at that time.
I won't be able to change my mind after the fact so I am doing home work now.
Bob

Based on the numbers I'm looking at:

Anchor weight guide

I think 3/8 should be more than ample. You could probably get away with 5/16; 7/16 is monster.

[roverhi]

We had 250' of g40 3/8" chain with a 45# CQR on our 22,000 pound boat. It proved to be ideal as we never dragged, including a 50 knot tropical depression. Some people say the weight of the chain is not a big thing in anchor performance but I'd have felt nervous with a smaller diameter, lighter chain especially in that tropical depression. If it's a choice between a rope chain rode or all chain, I'd most definitely go with slightly smaller chain, however. 250' of chain proved an ideal length as it gave us all chain 4-1 scope in depths up to 60' or 7 to 1 in 30' of water. Using a rope/chain rode except for very deep anchoring is foolish to me.

It's not the strength of the ground tackle that's an issue, it's chafe. I am not aware of a single anchoring snafu that occured because chain broke. I run out of fingers real quick in the boats I know have been lost because their rope rode chafed through. All chain is also a no brainer to retrieve. Just push the button and the winch hauls it right up. With rope/chain, you have to monitor the rope section to be sure it doesn't jam and probably hand feed the rope/chain splice through the windlass.

[btrayfors]

I have a 42' monohull with 27,500lbs displacement. Eleven years in the Virgin Islands, and 9 years coasting from Maine to Bahamas.

I carry 200' of 3/8" G40 chain, and have never wished I had more. It's plenty for this area, and it's more than strong enough for a Caliber 40.

I agree, too, that a 45lb Manson is plenty big enough for your boat.

For a second anchor, my choice would depend on sailing area. For many areas a big Fortress (FX-37) would be more than adequate, with at least 30' of chain and 200' of 5/8" nylon rode.

JMO,

Bill