All chain vs 100'

[Bulawayo]

Originally Posted by noelex 77

I use all chain. I have 100m (330 feet).

I think for a long distance cruising boat, all chain is far more preferable. There is too much risk of abrasion from rock, coral and man made debris. See my post #24. It is also important in crowded anchorages to swing like your neighbours and these are likely be on all chain rode.

However, I don't believe the chain contributes much to my anchor's holding ability. This can be shown mathematically or shown practically by observing the rode in strong wind conditions. The effect of catenary is largely lost in strong wind unless the anchorage is deep.

That is not stay the chain weight is totally useless in assisting the anchor's holding ability. It does help in the initial setting phase of the anchor, it also makes a practical contribution in deep anchorages and especially if you are forced to use a short scope when the upwards pull of rope ride would be significant. Finally, if the substrate is very poor and there is a risk of dragging in light or moderate conditions once again chain is of practical help. However, even with these exceptions, the heavy weight of chain gives a very poor rate of return in terms of the extra holding power for the additional weight.

The 200 + kg of my chain is earning its keep in terms of abrasion resistance, but not in terms of holding ability.

Because chain is far preferable for abrasion resistance this can perhaps be viewed as largely academic argument, but it does have practical implications. The best practice is for boats to use chain as thin as possible providing it meets the required strength, adding some of the weight savings to the anchor. This is still resisted by those who feel chain weight is essential for good holding.

Hi Noelex,
You keep missing important matters. Under adverse conditions it is rare that that you get a steady state wind/sea condition (never!). The boat is constantly sawing or snatching at its anchor arrangement. The weight of the catenary helps absorb this without placing total reliance on the elasticity of warp. Anything that helps to avoid a sudden upward snatch movement to the anchor shall obviously assist with keeping the anchor set.
Like most cats we use a bridle. Our arrangment is slightly unusual as we were advised many years ago, by a respected multi-hull sailor, to ensure that each bridle leg was 1-1.5x our waterline. As a result our bridle is pretty long but it also absorbs any shock loadings.

[Muckle Flugga]

Originally Posted by Jim Cate

Re all those responses from folks who say something like "I've anchored on rope for X years and it has always worked fine"...

We have seen a number of boats beached/wrecked when their rope rodes parted due to chafe, coral or rocks, or other debris on the seabed, or even on their own keels. Prior to those sad events, each and every one of their skippers would have made a similar comment to the above.

IMO (based on a lot of years of anchor-out cruising) if you plan to cruise to unfamiliar waters and anchor, an all chain rode is the only intelligent solution. The amount of chain required for general usage is, again IMO, a minimum of around 200 feet, and that with some additional rope rode for the occasional very deep anchorage. In such places (say 75 feet plus) if one gets most of that 200 feet on the bottom the rope portion will not be exposed to chafe (except on the bow of the boat), and thus be reasonably safe.

If you stick to familiar waters where you have local knowledge of bottom conditions, a shorter bit of chain may safely get you through... maybe!

Jim

Exactly. If rope rode comes in contact with a coral head, it will part in minutes. I too have seen at least a dozen boats wrecked that way over the years. Inductive logic of the kind of "so far so good" is not good enough in this case. Gunkholing and anchoring in sandy or muddy bottoms or with even surfaces then rope with chain is fine. But this severely limits your options if unrestricted cruising. To be truly secure in all circumstances (paraphrasing Cromwell): "All chain hath no fellow." You can always carry a combination of the two. One rode all chain and two line and chain as kedges/stern anchor arrangements. The latter is my choice. But it's good to have a choice.

[noelex 77]

Originally Posted by Bulawayo

Hi Noelex,
You keep missing important matters.

In strong wind and moderate anchor depths the catenary is largely lost. It also means the shock absorption effect is also largely lost.

This is why you have been advised by the respected multi-hull sailor to use a long bridle.

A long bridle will continue to dampen the high shock loads even in strong wind when chain weight will no longer perform this function.

(Note the bridle has functions other than shock absorption. It also takes the load off the windlass and reduces sheering, but the long length is only required to restore the shock absorption when the effect of chain catenary is lost).

[Muckle Flugga]

Originally Posted by Ann T. Cate

And, an excellent reason to service the windlass, more heat being accrued when then is more friction. What Jim has always done, has worked so well for us, I would not be eager to add rope rode. The chain, so far, has always been retrievable, the windlass maintained, and it all just works.

Ann

Absolutely spot on. I strip my windlass down completely once or twice a year. I check the terminals and other aspects every week. A correctly rated windlass will handle even an extraordinary amount of chain.

To add to which: if deep, you will still have to haul the chain all standing, and may well need to switch between rope tender and gypsy to accomodate the transition on the windlass. Much smoother all chain.

[sanibel sailor]

There seems to be great advice here. One thing that has not really been addressed in this discussion is boat size. Bigger boats are more easily able to accomodate the increased weight of all chain where for smaller boats (and perhaps some of the lighter multis) it represents a significant proportion of my overall displacement. My 35 footer is 15000 lb and a 300' all chain rode and oversized anchor is about 2.5% of my displacement. Unfortunately, the anchorage does not get much shallower nor the coral less abrasive for smaller boats. For very small boats of 25-30 feet the situation is even worse.

[Muckle Flugga]

Originally Posted by sanibel sailor

Thanks for all the input. I liked having all that chain aboard before (except for the weight) but had thought much of it was wasted. Most of my sailing has been on the US East Coast, esp Chesapeake and FL. I draw less than 4 feet and try to anchor in 6-8 feet. Anchoring is usually pretty easy, although some folks still make it look tough. I would have to sail 100 miles offshore to find 85 feet of water. Even 100 feet of chain is overkill here.

So anchoring in 85 feet is a little mind boggling. I will admit to some S Pacific aspirations. I get a bit anxious in less than 6:1 scope (taking freeboard into account). Even with 300 feet of chain, that is only 3.5:1 scope. Cannot you get into shallower water or is it too steep to, or filled with moorings etc? Deck level chafe is a major consideration, although chafe on bottom obstruction is invisible. How far above the seafloor do the coral heads grow?

Fatu Hiva is a nice example. The anchorage at Baie des Vierges is narrow and VERY steep to. Flanked by steep cliffs on both sides, a rapidly shelving rocky beach landward, and kilometers deep water to seaward, if there are eight or a dozen boats there (it is often the landfall of choice for the Marquesas from the Galapagos or mainland Americas), you may be forced to anchor in 35 meters or move on North to Hiva Oa or elsewhere. There is space only for perhaps two boats in the depths you are used to. This kind of thing is common in the SoPac and Indo/Pacific waters. But you will find it frequently sailing almost anywhere in recently volcanic waters. As to coral heads, yes, they rise often many meters high from otherwise flat sandy anchorages and are NOT accurately charted almost anywhere. Consider that in atolls the whole of the original igneous island structure is simply eroded to nothing near the surface. ONLY coral remains above or towards the surface as it is continually growing. Some bommies can be many meters tall, and indeed you can regard the motus of atolls as massive conglomerated bommies which may be stacked hundreds of meters above the igneous rock of the ancient vanished island on which they stand.

[Muckle Flugga]

Originally Posted by sanibel sailor

There seems to be great advice here. One thing that has not really been addressed in this discussion is boat size. Bigger boats are more easily able to accomodate the increased weight of all chain where for smaller boats (and perhaps some of the lighter multis) it represents a significant proportion of my overall displacement. My 35 footer is 15000 lb and a 300' all chain rode and oversized anchor is about 2.5% of my displacement. Unfortunately, the anchorage does not get much shallower nor the coral less abrasive for smaller boats. For very small boats of 25-30 feet the situation is even worse.

You are absolutely right. A good friend of mine and a sailor I admire like no other, Alan Martienssen who sails Zebedee, a 34 foot junk rig sailing dory with no engine and only a sculling oar for manual propulsion (with Dougal, his self built rowing dinghy, also no engine), has twice circumnavigated (or is it now his second, I can't remember) but has lived aboard the ocean wave for around 14 years on her and has been a good approximation of EVERYWHERE aboard her. I have had the immense pleasure of anchoring by him and sharing his slightly suspect but very welcome homebrew wine on a good number of occasions in varying anchorages. His dory is more or less flat bottomed and shallow draft so he has the luxury of tucking in where few of us can. She is also very light. And he has only a couple of batteries aboard (or is it one?) so cannot have an electric windlass… but opts not to have one at all (as I recall). His ground tackle is all manual and consists in a startlingly skimpy chain rode with all line backer. And would I sail with him anywhere? Damn straight!

He also uses only sextant and has only a handheld radio for comms, and is one of the nicest and coolest human beings you are likely to meet in all your long travels, be they ne'er so long or longer…

So yes. It does depend on the boat. And the sailor! But then, Alan is exceptional. I once watched him sail into Neiafu against a foul wind and tide. With a motor would have taken around 5 mins. I had a few beers while watching him do it over the course of more than two hours. This is a careful and meticulous sailor extraordinaire who minds not at all taking ALL the time necessary to be safe and seamanlike with the tackle he has. Not so if you want to just drop the hook in half an hour or less and be ashore to the bar…