Has anyone ever tried aluminum chain?

[Montanan]

Aluminum / Aluminium has a comparative density of 2.7 relative to seawater of 1.03 and of steel with about 7.8.

The beneficial catenary effect of the rode would be much less if aluminum of equal strength properties as steel was used. The displaced water makes for an offset of the weight of the rode that is suspended.

Aluminum would not last long due to its inability of the links to sustain against the chafe as it's surface is not capable of being hardened to an equivalent level.

And it would be very expensive.

Not even worthy of consideration.

[noelex 77]

Originally Posted by wholybee

Not many people anchor in > 50 feet very often, and then it isn't usually rocks or coral.

If you cruise worldwide, the ability to anchor in 50+ feet is valuable, or even essential in some locations.

Unfortunately, even in anchorages with predominantly sand or mud there are occasional outcrops of rocks or debris (more often than not man made rubbish).

This is why the default standard for long distance cruising boats is something around 100m (330 feet) of chain. You can make do with less, but it does mean that you will have to avoid some anchorages.

Below is an example of a situation where rope rode would not last long:

[Lodesman]

Originally Posted by rslifkin

Having all of the rode lifted isn't necessarily a problem though. Yes, more angle gives less holding power. But if you have enough at the higher angle (provided it's not excessive), you're all good. Bigger anchors give more surplus holding power, meaning you can use shorter scope and still have enough (allowing you to fit in tighter areas).

You mean "any angle gives less holding power." Less than what? You can't really define your 100% hold - not with absolute reliability. To then trust that your anchor will hold at some undefined fraction of its undefined potential max hold in that given bit of seabed on that given day, just because it's gotten a bit breezy (17 kts isn't an uncommon expectation) seems a little foolish to me. While a big enough anchor has "surplus" hold, it's still pretty dicey assuming the anchor can reset in the opposite direction while being pulled upwards from the horizontal. My 2 cents.

[noelex 77]

Originally Posted by rslifkin

Having all of the rode lifted isn't necessarily a problem though. Yes, more angle gives less holding power. But if you have enough at the higher angle (provided it's not excessive), you're all good. Bigger anchors give more surplus holding power, meaning you can use shorter scope and still have enough (allowing you to fit in tighter areas).

Personally, I tend to go for between 3:1 and 5:1 unless I'm expecting really awful weather. And no matter how shallow I never have less than about 75 feet out.

What Rslifkin said. .

[rslifkin]

Originally Posted by Lodesman

You mean "any angle gives less holding power." Less than what? You can't really define your 100% hold - not with absolute reliability. To then trust that your anchor will hold at some undefined fraction of its undefined potential max hold in that given bit of seabed on that given day, just because it's gotten a bit breezy (17 kts isn't an uncommon expectation) seems a little foolish to me. While a big enough anchor has "surplus" hold, it's still pretty dicey assuming the anchor can reset in the opposite direction while being pulled upwards from the horizontal. My 2 cents.

I always power set at my desired scope to confirm it'll set and hold my test power at the scope I'm using in the current button. I agree that blindly trusting it to work is a bad idea.

100 percent hold would be what the anchor can give with a perfect horizontal pull in the current bottom. Some upward angle will reduce this, but every anchor can tolerate some angle before it will just pull out or fail to reset.

Keeping chain on the bottom gets significantly easier in deeper water. That factor and general anchoring comfort (plus less crowding) is why I tend to anchor deeper when a good deep spot is available. Last weekend we spent 2 days anchored in 17 feet. That's probably the shallowest water I've anchored in during the last 2 seasons.

[Kettlewell]

I currently gave 100 feet of chain backed up by 200 feet of nylon. Here on the East Coast that means I am almost always on all-chain rode. Yes, in a few gales I have let out all the chain and some nylon, but that is rare. My average anchoring depth is 15 feet or under. I would skip the aluminum chain and go for 5/16 steel on a 36 footer.

[Franziska]

Here is the video I reffered to in post#26:

https://www.youtube.com/watch?v=Kg5PxfYnWGM

Pretty clever for a small boat.

[sailingharry]

Originally Posted by Franziska

How about a short piece of high tensile chain, an oversized Dyneema rope combined with a riding weight and a relativ elastic snubber.

First, I sail on the chesapeake. I draw seven feet. I have much bigger issues getting into a decent Anchorage than I do having enough chain. And the swing circle in most places that I would consider a good Anchorage would put me in the trees with 150 ft out. But if you find you need it, that's your situation, not mine.

I thought about Franziska's thought a couple of years ago. We carry 260 ft of chain and 40 ft of nylon. The anchor locker is pretty full, if we put out more than 125 feet I have to knock over the castle, and that is an easy. But we were heading to the St Lawrence and Newfoundland where deaths are deep (our deepest anchorage was 75 ft) and I feared our 300 ft wasn't enough. Adding another hundred or 200 ft of nylon was in an option because of space. Since this would be an extremely infrequent event, ease of use was not a high priority. I seriously considered adding in 200 ft of six or eight mm dyneema. It would take up very little room, add essentially no weight, be plenty strong, and with 260 ft of chain out I had plenty of the alleged catenary benefit (I'm not a big believer in that). With all the other preparations, that one didn't get addressed, and anchoring wasn't quite as bad as I feared.

All that is to say that if you intend to sail primarily on the Chesapeake, but wish to have an ace in the hole, you could consider 100 (or 150) ft of chain and another 150 ft of dyneema.

Dyneema has zero stretch. But that's no different than chain.

[Lodesman]

Originally Posted by sailingharry

Dyneema has zero stretch. But that's no different than chain.

Dyneema has zero catenary too. But then you don't believe in that

[Franziska]

Originally Posted by Lodesman

Dyneema has zero catenary too. But then you don't believe in that

Of course it doesn't. Read what I wrote. If one wanted to take a gamble on going light:

Anchor
Reasonably short chain
Dyneema (fairly abrasion resistant)
Riding weight (possibly)
Elastic snubber/Bridle

[sailingharry]

Originally Posted by Lodesman

Dyneema has zero catenary too. But then you don't believe in that

Assuming that somehow the catenary is important, he would have a hundred feet of chain out. He would have more chain and more of that effect with 100 ft of chain and 100 ft of dyneema then he would when anchored in 10 ft of water and only 75 ft of chain out.

A big part of why I don't really subscribe to the catenary shock absorbing effect is anyone who uses chain has to put in 20 to 30 ft (or more) of nylon snubber to reduce the impact and jerk associated with an all chain rode. If the catenary really reduced the impact load, you wouldn't need the nylon. The jerk comes when the catenary is essentially gone.

Now, in lighter air and really deep water, it can be quite helpful. The 75 ft of water that I anchored in referenced in my above post, we only put out 150 ft of chain (2:1) and while it was an unnerving night, we did not drag. It was a fairly calm night or I wouldn't have tried it. My biggest fear was not dragging, but running aground -- the mud flats were very close. I suspect that with water that deep and the wind that light, the angle of approach to the anchor was fairly decent.

[rslifkin]

In deep water catenary is definitely a factor. In shallower water you can pull an awful lot of chain fairly straight in any decent breeze.

[wholybee]

Originally Posted by noelex 77

If you cruise worldwide, the ability to anchor in 50+ feet is valuable, or even essential in some locations.

Unfortunately, even in anchorages with predominantly sand or mud there are occasional outcrops of rocks or debris (more often than not man made rubbish).

This is why the default standard for long distance cruising boats is something around 100m (330 feet) of chain. You can make do with less, but it does mean that you will have to avoid some anchorages.

Below is an example of a situation where rope rode would not last long:

I know that is the default standard, I am saying I disagree with it. It's old thinking, just like old thinking with old styles of anchors, that a kellet increases holding, or thinking a slow full keel is "better" than a fin keel (with or without a skeg). It assumes that your anchor won't hold without 7:1 scope, where you then need more chain to keep the rode off the bottom. Modern anchors hold at 3:1, and 5:1 if a gale. And of course in a gale it's easy to keep the rope off the bottom, even with reduced chain length, so let out all the scope you need.

In my example, that shown in your picture won't happen, because the chain is on the ground, and the rope is not. So, you could imagine the chain transitioning to rope just outside the picture frame, and would be fine.

FWIW, I have 35,000 miles of cruising, mostly at anchor. The conditions you need 300 feet of chain are very rare. The deepest anchorage I was in was 80ft. I was there for over a week, and with 130' of chain I don't think my rope ever touched having just enough wind to keep it lifted off the bottom.

[rslifkin]

If in anchorages with a questionable bottom, you don't want rope getting within a few feet of the bottom. So I'd say 1x depth (not including freeboard) is the most rope you can safely deploy after the chain in those places.

In many places a mixed rode is perfectly fine. But if you can carry the weight, chain is always more abrasion resistant and therefore safe in a wider range of situations.

Personally, I'm looking to swap my current rode out for one with more chain. Currently it's 90 feet of 5/16" G43 and 300 feet of 5/8" 8 plait nylon (so about 375 feet usable). Plan is to buy a half drum of the same chain (275 feet) and then add 100 feet of something like Samson Tenex (12 strand polyester, stronger than the current nylon and a good match for the chain in terms of working load). That will give about 360 feet usable, which is plenty. And the rope portion should rarely leave the locker. It's common for me to have 200 feet out, but more than 250 happens fairly rarely.

[Jim Cate]

FWIW, I have 35,000 miles of cruising, mostly at anchor.

Now THAT is some serious dragging, logging all those miles whilst at anchor!

Jim