Anchor Chain

[Ancora Latina]

“I am planning to up grade my ground tackle from a 20# Danforth with 1/2" three strand nylon rode to a 35# Manson Supreme and 5/6" high test chain.”

Hi Duke,

For a 32’ boat, on our Web page, we recommend a 3/8” chain and a 5/8” Nylon rope.
- 5/16” proof coil chain is a little bit too weak, high test should be OK. If you take a stronger chain, the only disadvantage is that you will have more weight on the bow, some boats can accommodate it, and some others can’t.

Concerning the rope, you need rope mainly for “ELASTICITY” and bigger the rope, less is the elasticity. Use the right size rope,- using a bigger one will not ad anything to your security.

Delmarrey Most cruisers carry at least two or three different anchors.

Look at my answer to Talbot on: http://www.cruisersforum.com/forums/f55/anchor-chain-21616.html#post230449

I cannot believe I am going to disagree with a Yachtmaster Offshore Instructor, »

Like Noelex 77, I have also to disagree with a « Yachtmaster Offshore Instructor » One good (bow) anchor will be OK in 98% to 100% of the cases (you may need to use a stern anchor in some specifics cases)


[quote] Delmarrey Not sure, but he may have been suggesting two anchors in series,[/quote]

But it has NEVER be proved that two anchors « Tandem set » have more holding than only one GOOD anchor (the opposite has been proved)

[GordMay]

A storm anchor assembly, for a typical 32' sailboat, should be rated at about 1,800 Lbs.

Accordingly, a 1/4" High Test Chain (rated 2,600# WLL) should match nicely to a 7/8" 3-Strand (rated 2,160#) or a 3/4" Double Braid (rated 1,813#) Nylon rode.
Alternatively, a 5/16" Proof Coil Chain is rated at 1,900 Lbs WLL.


A 3/8" PC Chain is rated 2,650#, and a 5/8" 3-Strand Nylon Rope rated 1,114# (1,275# for Double Braid) - an obvious mismatch.

See also:

Design Loads for Deck Hardware
http://www.cruisersforum.com/gallery...r&imageuser=79

WLL for Anchor Rodes
http://www.cruisersforum.com/gallery...r&imageuser=79

NACM Chain Spec's
http://www.cruisersforum.com/gallery...r&imageuser=79

[exranger]

Hmmm, I thought I had this worked out for my boat -- an O'Day 32 CC, but maybe i am wrong, seeing this thread. I was set on using 1/2 inch 3 strand for rode with 5/16th chain.

Comments??

[GordMay]

Originally Posted by exranger

Hmmm, I thought I had this worked out for my boat -- an O'Day 32 CC, but maybe i am wrong, seeing this thread. I was set on using 1/2 inch 3 strand for rode with 5/16th chain.

How did you set upon using 5/16 chain /w ½" Nylon?

A 32' sailboat might desire a 900# to 1800# anchoring system. Certainly a cruiser should opt for the higher capacity.

5/16" Chain (rated 1,900#) matches up with 7/8" 3-Strand (rated 2,160#) or a 3/4" Double Braid (rated 1,813#) Nylon rode.

1/2" Three-Strand Nylon is only rated at 709 Lbs WLL - about 1/3 the chain's rating.

[Jim Cate]

.


A 3/8" PC Chain is rated 2,650#, and a 5/8" 3-Strand Nylon Rope rated 1,114# (1,275# for Double Braid) - an obvious mismatch.

Interesting figures, Gord, but I wonder if this sort of analysis covers all the factors? Matching SWL of rode and chain sounds like a no-brainer, but doesn't take into account the advantage of the extra weight of the 3/8 inch chain. Heavy chain both increases the friction with the bottom, and more importantly increases the catenary between the bow roller and where the chain lifts off the bottom. The latter both acts as a "shock absorber" in reducing heaving loads on the anchor, and helps insure a horizontal pull on the anchor itself.

Of course, this applies to all-chain rodes, not to the use of a short bit of chain and a long bit of nylon, but the latter surely does not belong on any serious cruisers' primary anchor system.

And finally, in all my years of cruising, only once have I heard of a boat being put ashore due to a chain breaking... and that was a chain that had been purchased second hand from a Mexican fishing boat, who thought it was too worn to use! Failure of nylon rodes (usually due to chafe) is pretty common.

We do try to keep weight outof the ends of the boat, but ground tackle isn't one of the better things to skimp on!

Jim and Ann s/v Insatiable II lying Gladstone Qld Oz

[exranger]

I found it here:

Anchor weight guide

Which was apparently taken from SAIL 1997 Sailboat Buyers Guide

Almost as important to me as finding out I was wrong, is finding out what sources of info should be used as a guide! Is it that off? That's not good.

I am glad I posted this question, as I was getting ready to buy some line!!

THANK YOU once again!!!

[exranger]

Hey, Gord, this brings me to another question from a post you wrote years ago, which i was re-reading. You seemed to be saying that anchor rollers are NOT actually a great idea, mostly because it's nearly impossible to get a fair lead?

[forsailbyowner]

[quote=Jim Cate;231234].


A 3/8" PC Chain is rated 2,650#, and a 5/8" 3-Strand Nylon Rope rated 1,114# (1,275# for Double Braid) - an obvious mismatch.

Where did you get these numbers?Every spec sheet Ive seen for nylon 3 strand half inch states 5700 lb tensile strength. 5/8"at 9000lb breaking strength
Twisted rope

[forsailbyowner]

on two anchors, I use them sometimes when Im in a tight spot with no room to swing. I have a heavy shackle that I put at the end of my chain then run the spare rode out with the dingy the opposite direction. I use a heavy 3/4" line run through the top of the shackle and put on two bow cleats. If I have to pull up in a hurry I put a float on the rode and pull the chain up with the windlass.

[richardhula]

I try & avoid using two bow anchors if possible for all the reasons given above. Occasionally it is necessary though in a reversing current situation with limited anchorage space. Nassau & Normans Cay in the Exuma's spring to mind. The important key here is that everyone uses two anchors. As this is usually well documented in cruising guides it's not normally a problem. However I do recall one occasion in Nassau when a "cruiser" arrived at a relatively empty anchorage & put out one anchor and a huge scope of nylon rode to compensate for his lack of chain. He then spent the whole week dingying over to anyone who tried to anchor within line of sight explaining that when the current changed he would be swinging into them.

[Bash]

hmmmm. at West Marine the Rocna 15kg (33lbs) is only $50 more than the Manson 35. If you switch from high test to BBB, a recommendation I second, you'd come out spending less with the Rocna/BBB combination than the Manson/high test. Seems like a no brainer.

[Jim Cate]

[quote=forsailbyowner;231292]

Originally Posted by Jim Cate

.


A 3/8" PC Chain is rated 2,650#, and a 5/8" 3-Strand Nylon Rope rated 1,114# (1,275# for Double Braid) - an obvious mismatch.

Where did you get these numbers?Every spec sheet Ive seen for nylon 3 strand half inch states 5700 lb tensile strength. 5/8"at 9000lb breaking strength
Twisted rope

Hi, forsale --

I was actually quoting Gordmay's figures from a posting just before mine. None the less, the discrepancy that you note is because you are quoting breaking strength, and Gord and I were quoting either SWL (safe working load) or WLL (not sure precisely what that stands for), but again with a large safety factor thrown in. As you can see, common practice is to severely "downrate" the ultimate strength when sizing for the real world.

Cheers,

Jim and Ann s/v Insatiable II lying Gladstone Qld Oz

[GordMay]

Originally Posted by Jim Cate

... Gord and I were quoting either SWL (safe working load) or WLL (not sure precisely what that stands for)...

Working Load Limit vs Safe Working Load vs Breaking Strength:

The WLL or SWL is derived by taking the Breaking Strength (Tensile Strength) and applying a (derating) Safety factor (5:1, 8:1, 10:1).

The Breaking Strength is an average figure, arrived at by testing samples under laboratory conditions in straight-line pulls with consistently increasing loads, to see at what point they would break.

DO NOT use Breaking Strength (BS) for design or rating purposes; use Work Load Limit (WLL) instead.

The term Safe Working Load, (SWL) was formerly considered to be the breaking load of a component divided by an appropriate factor of safety giving a ‘safe’ load that could be lifted or be carried. The use of the term SWL was discontinued about 20 years ago (due to the legal implications of the word “safe”), at which time Working Load Limit became the standard term.

If the WLL is thought of as an assessment of the maximum load an item could lift under ideal conditions (when used correctly, in a particular configuration or application), the SWL (if the term is going to be used) can now best be thought of as being a further derating of WLL, following an assessment (by a competent person) of the maximum load the item can sustain, under the conditions in which the item is being used.

I got my figures for Rope & Chain WLL from the (linked) ABYC Table II in Section H-40, Anchoring, Mooring, & Lifting.

[GordMay]

Originally Posted by exranger

... Almost as important to me as finding out I was wrong, is finding out what sources of info should be used as a guide! Is it that off? That's not good...

Originally Posted by exranger

Hmmm, I thought I had this worked out for my boat -- an O'Day 32 CC, but maybe i am wrong, seeing this thread. I was set on using 1/2 inch 3 strand for rode with 5/16th chain.
Comments??

The Sail article suggested 5/16" Chain with ½" Nylon Rope for a 32', 10,000 Lb sailboat (31 - 35'). They don’t specify what type of rope.

The ABYC Tables suggest Working Loads of between 1,400# (30') to 1,800# (35'), and specify 5/16" PC Chain at 1,900 Lbs WLL, and 3/4" 3-Strand Nylon at 1,598# WLL.

Since ½" 3-Strand Nylon only has a Working Load Limit of about 709 Lbs, and ½" Double Braid a WLL of 816#, they would be more properly matched to a 3/16" PC Chain (800# WLL). Accordingly, I would not trust the Sail charts.

The ABYC Tables calculate design loads to include the effects of wind, current, and wave action.

[GordMay]

Originally Posted by exranger

Hey, Gord, this brings me to another question from a post you wrote years ago, which i was re-reading. You seemed to be saying that anchor rollers are NOT actually a great idea, mostly because it's nearly impossible to get a fair lead?

Having written a few posts over the years, I don’t recall that particular reference (perhaps you could provide a link to my post).

I like anchor rollers for rode handling (deploying & especially retrieving), but would not normally recommend leaving a secured rode within the roller (when deployed), for 2 main reasons:
1. It will be difficult to avoid chafe at the cheeks on most bow rollers*.
2. Running the rode over the cantilevered roller results in an increase in loading, due to leverage.

* Also watch for skipperaris to elaborate on his chafeless system at:
http://www.cruisersforum.com/forums/...oring-533.html