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Go Back   SailNet Community > On Board > Gear & Maintenance > Chain anchor rode length
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Thread: Chain anchor rode length Reply to Thread
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Topic Review (Newest First)
10-25-2009 12:06 AM
Craig Smith Yes it becomes less important on larger boats, obviously the length required cannot scale down with a smaller LOA, which is why using high tensile grades to attain the require strength for less weight is a good idea.

Don Dodd is 100% correct with regard to an anchor rode in normal circumstances. Heavy chain is entirely pointless with regard to "helping the anchor", and a shock absorber is important. However, on a world cruise, depending on the destinations, "...the elasticity of nylon is more important than the abrasion resistance of chain, using only enough chain to deal with coral, rocks..." will give you lengths similar to those discussed above. Deep water anchorages with high coral heads in the Pacific or steep rocky cliff-side drop-offs in Antarctica require a lot of length to avoid rope ending up on something sharp. On the other hand if you are day sailing in Maine, Don's advice is exactly pertinent.

If you have those "all destinations" chain lengths, then you end up using a 100% chain rode (chain never leaves the gypsy) by default in the majority of anchorages. That then mandates the use of a snubber, nylon or otherwise, as a shock absorber; always on smaller boats, and sometimes on larger ones. A more minor factor is also the convenience of the chain not leaving the gypsy, again more of an issue on a larger boat, and the extra layer of security that brings (should the nylon chafe or otherwise fail).
10-24-2009 08:37 PM
mightyhorton On the other hand, contrary to my own views, Don Dodds' book "Modern Seamanship, a Comprehensive, Ready Reference Guide" makes a good argument, starting at page 171, for using mostly nylon rode, with only half the boat's length or so of chain. Dodd argues that the elasticity of nylon is more important than the abrasion resistance of chain, using only enough chain to deal with coral, rocks and to give some weight around the anchor.

He argues, correctly, that in enough wind or big enough waves the chain may lose its catenary and get straightened out. Since it has no give, tremendous momentary and damaging shock loads may result.

He deals with nylon abrasion at the bow by suggesting putting plastic hose around the line where it goes through chocks or at cleats, and, though he doesn't say so, going back up to the bow several or more times a day and night to replace the chafing gear. Hopefully, without hurting yourself.

Maybe there isn't a best answer, maybe it is a personal choice about which advantages and drawbacks each person choses.

Can somebody comment on whether, as your boat length and weight increases, the weight of the chain you are carrying becomes less important? My guess is that 300 feet of chain in a 30 boat is more of a problem than the same amount in a 45 boat, even with thicker chain for the bigger boat.

As an aside, I found the Dodds book online at Google books and read his section on anchoring there. Very cool.

Ian
10-22-2009 03:24 AM
mightyhorton If 60 feet is as deep as you might be expected to anchor, a scope of 3 to 1 is 180 feet of chain out. 3 to 1 is really no good if there is any kind of serious weather or big seas are hitting your anchorage. 60 feet deep at 6 to 1 is 360 feet of chain. If you are anchored in a bad storm there is a real danger of chafe on rope. You will feel a lot better with chain at the chafe points, or at what will be the chafe points if your anchor bridle lets go. If you are going cruising plan for riding out some major storms on your anchor, and accept the burden of the extra weight of an abundance of chain. I don't think you need much chain for your stern anchor.
10-21-2009 09:23 PM
Greenflash35
Ericson 35

This thread caught our eye not because of the anchoring theme, but because we have a 1976 Ericson 35. We carry a 45 pound CQR with about 70 feet of chain and intend to increase that amount plus a 22 pound delta lunch hook with the same amount of chain. That's done well in Gulf waters (Keys, Mississippi Sound, intracoastal waterways, Georgia, Carolina). Off topic: we'd be interested to follow your adventures once they start. We just hauled out for 6 months worth of projects and hope to begin some similar adventures soon enough. We've only had our Ericson 2 years, but will be happy to share any tidbits you might find helpful, either through the forum or private messages. Best of luck!!
10-21-2009 08:29 PM
tdw
Quote:
Originally Posted by Craig Smith View Post
TDW no that is a secondary bow rode, the third rode which would be used for a stern anchor is 30 m chain + 100 m 8-plait rode shackled. Fourth rode is 15 m chain, plus a selection of 100 m rodes, and other bits and pieces. It's all the same size matched to both windlasses' gypsies.

We very very rarely use a second anchor, including the stern anchor. We simply don't find it necessary. This Rocna, which replaced the old stern pick, has been here since leaving New Zealand several years ago, and despite all that time spent in Chile, Patagonia, and Antarctica, it's still unused
Craig,

I'm beginning to fear you might have an anchor fetish..... or is it just that you into a bit of BDSM ? All this talk of chains and shackles.....

Cheers

TD
10-20-2009 11:29 PM
Craig Smith TDW no that is a secondary bow rode, the third rode which would be used for a stern anchor is 30 m chain + 100 m 8-plait rode shackled. Fourth rode is 15 m chain, plus a selection of 100 m rodes, and other bits and pieces. It's all the same size matched to both windlasses' gypsies.

We very very rarely use a second anchor, including the stern anchor. We simply don't find it necessary. This Rocna, which replaced the old stern pick, has been here since leaving New Zealand several years ago, and despite all that time spent in Chile, Patagonia, and Antarctica, it's still unused

10-19-2009 11:08 PM
tdw
Quote:
Originally Posted by Craig Smith View Post

On Kiwi Roa, the two main anchor rodes are 100 and 50 meters chain respectively, plus 50 and 100 meters respectively of 8-plait polyester. "From those that have been", this is more than adequate.
Craig,
Are you saying that when you laid a stern anchor you had up to 50 metres of chain on it ? I honestly didn't think that one needed more than a short length of chain (of course plus line) out the back. Interesting.
Regards
10-19-2009 11:01 PM
Bene505 Looks like you are getting great advice. You might want to re-read some of it.

Regards,
Brad
10-19-2009 10:27 PM
braidmike I had not considered that in 'extra deep' anchorages coral (and therefor chafe) may not be the issue it is in more normal situations. The comments on stainless steels are appreciated. I'm leaning toward the danforth for the stern & Rocna on primary. If I put 'only' 270' chain on the main with a 250' 8braid It sounds like this will be sufficient. I still question the stern, only because I have chain already and have a place low midship to store it. An extra 200# ballast won't hurt, although it is not instantly available for use. I've sailed the boat for 5 years now with the weight in the bow, and it behaves well, maybe due to the long overhangs inherant in a 40+ year old design. Many thanks for the insightful comments from all.
10-19-2009 12:35 PM
sailingdog First, I wouldn't go with that much chain. Chain adds too much weight forward and will increase the boat's tendency to hobby-horse and to bury the bow. At most you will probably want 100' or 150' of chain. More than that really isn't all that useful for several reason IMHO.

A) It adds a lot of weight forward.

B) The primary advantage of chain over nylon is chafe resistance, and in deeper anchorages, coral, one of the primary causes of chafe, won't exist.

C) A combination rode generally offers better anchoring performance than all chain.

Second, I wouldn't go with either a danforth or plow anchor as a primary. While a Danforth or Fortress makes a great stern anchor, they're not ideal for a primary anchor, since they don't deal well with reversing winds/current situations, and in a circumnavigation, you'll probably find yourself in a lot of anchorages that suffer from one or the other.

A next generation anchor, like the Rocna or Manson Supreme will have more surface area than an older plow design and set better and reset better than a Danforth or fluke-type anchor. They are also far less likely to jam, which a Danforth can do and that can prevent it from resetting.

Third, I also wouldn't recommend a stainless steel anchor as a primary for several reasons:

1) Stainless steel is much weaker than steel is for the weight unless you're dealing with very expensive, special purpose alloys of stainless steel

2) Stainless steel suffers from crevice corrosion and after enough can fail with little or no warning—whereas galvanized anchors will generally give you a lot of warning and a long time to remedy the situation

3) Stainless steel anchors are far more expensive than galvanized steel anchors and you can often buy several excellent galvanized steel anchors for the price of a single mediocre stainless steel anchor.
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