Has anyone ever tried aluminum chain?

[marcjsmith]

Rohan

My boat when I bought it had all chain about 250'. since i'm not going outside of the Chesapeake any time soon, I kept 60' of chain, and added about 200' of line. it has served me well over the last several years.. I have a manual windlass but i dont use it... i would think long and hard at reducing the amount of chain...

[GordMay]

I've never seen aluminum anchor chain.
Has anyone ever found a listing for it?
Link?

[deltaten]

Gord...link to a chain supplier?
Now, that right there is funny, intended or not
Thank for the giggles

[boatman61]

Originally Posted by GordMay

I've never seen aluminum anchor chain.
Has anyone ever found a listing for it?
Link?

Happy to help Gord..
https://www.mcmaster.com/products/aluminum-chain/

[NorthCoastJoe]

I looked at the aluminum chain link that Boatman posted.

The first thing I noticed was " Not for Lifting " There is your answer if it's usable for anchors.

A big fat NO.

[SailingHarmonie]

Originally Posted by GordMay

I've never seen aluminum anchor chain.
Has anyone ever found a listing for it?
Link?

You have never seen it because it does not exist--and never will.

Chain is ALL about tensile strength. While Al is stronger than steel on a weight basis, on a cross sectional area, it is very much weaker, very roughly, 1/4 that of steel. So to get an aluminum chain with the same strength as a 10mm steel chain, it would have to be similar in size to a 20mm chain. Completely impractical. Think about installing the anchor windlass that would be needed to handle 7/8" chain on a 40 foot boat...

[Lodesman]

I was going to ask the same question of the OP - do you have a source for aluminum anchor chain?

There's plenty of aluminum chain out there, that is mostly decorative. Aluminum doesn't have a high tensile strength, so not typically useful for anchoring - afaik.

I do know that aluminum-bronze anchor chain exists; it's used in minesweepers as it's not magnetic. It actually has a tensile strength similar to steel, however it is quite a bit heavier, so wouldn't suit the OP's purpose. I've always thought it would be ideal for cruising yachts, due to its corrosion-resistance, but am unaware of any supplier in suitable gauges.

[Shrew]

Originally Posted by Rohan

Well honestly, in my marina I'm probably the one who anchors out the most often. With 5' of draft, I try to anchor in about 10', because there is about 1 foot daily change in the tide level, and sometimes there is unexpected stuff under the water.

But that 10' is really 14' because of the height of the boat above the water, and if you put out 7:1 rode (although realistically most people put out about 4 or 5:1), that's 98' right there. And there are plenty of times I anchor in as much as 20' in some spots if I don't want to get too close to wreckage or shore, which would be 168' of rode.

With precautions, I don't need an all chain rode, but the security of it would be nice. I was just wondering if aluminum chain was a feasible compromise.

I honestly think of scope needs as:

10:1 Line = 7:1 chain
7:1 Line = 5:1 chain
5:1 Line = 3:1 chain.

It is incredibly rare to need more than 5:1 with an all chain rode. In a storm, I might lay out to 6:1. Then again, my scope is based on:

1) True depth, not transducer depth.
2) Depth at high tide
3) height of bow pulpit.

So in 10 feet at high tide, with a 5 ft bow pulpit, 5:1 = 75 feet.

[Lodesman]

Originally Posted by Shrew

It is incredibly rare to need more than 5:1 with an all chain rode. In a storm, I might lay out to 6:1. Then again, my scope is based on:

1) True depth, not transducer depth.
2) Depth at high tide
3) height of bow pulpit.

So in 10 feet at high tide, with a 5 ft bow pulpit, 5:1 = 75 feet.

Have you ever used a rode calculator to figure out what sort of performance you're getting out of your rode at those lengths?

Using those numbers for my boat/chain set-up, it calculates that all the chain is lifted off the seabed in any wind over 17 kts. The 165 ft of chain I would be inclined to deploy, would be pulling the anchor horizontally until the wind exceeded 35 kts. ymmv

[rslifkin]

Originally Posted by Lodesman

Have you ever used a rode calculator to figure out what sort of performance you're getting out of your rode at those lengths?

Using those numbers for my boat/chain set-up, it calculates that all the chain is lifted off the seabed in any wind over 17 kts. The 165 ft of chain I would be inclined to deploy, would be pulling the anchor horizontally until the wind exceeded 35 kts. ymmv

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.

[Franziska]

I'm just thinking out loud here.

Dyneema as well as Aramid are highly abrasion resistant.
How about a short piece of high tensile chain, an oversized Dyneema rope combined with a riding weight and a relativ elastic snubber.
Could be hauled by a capstan and is possibly lighter.

I also like this for a small boat that comes from "the sailing frenchman."

I can't find the video right now, I'm sailing and have only limited network access, but he combines two or more chainweights.

The bit closer to the anchor is heavy and fits the gypsy. This is followed then by a longer piece of thinner chain. His logic is that the heavy part is usually the last bits when weighing anchor, necessitateing the windlass. The lighter chain part can be hauled by hand.

[Lee Jerry]

Originally Posted by SailingHarmonie

You have never seen it because it does not exist--and never will.

Chain is ALL about tensile strength. While Al is stronger than steel on a weight basis, on a cross sectional area, it is very much weaker, very roughly, 1/4 that of steel. So to get an aluminum chain with the same strength as a 10mm steel chain, it would have to be similar in size to a 20mm chain. Completely impractical. Think about installing the anchor windlass that would be needed to handle 7/8" chain on a 40 foot boat...

Originally Posted by Lodesman

I was going to ask the same question of the OP - do you have a source for aluminum anchor chain?

There's plenty of aluminum chain out there, that is mostly decorative. Aluminum doesn't have a high tensile strength, so not typically useful for anchoring - afaik.

I do know that aluminum-bronze anchor chain exists; it's used in minesweepers as it's not magnetic. It actually has a tensile strength similar to steel, however it is quite a bit heavier, so wouldn't suit the OP's purpose. I've always thought it would be ideal for cruising yachts, due to its corrosion-resistance, but am unaware of any supplier in suitable gauges.

Aluminum comes in many alloys and tempers, and they have a wide range of strength. Those alloys (and tempers) typical of marine applications, such as 6xxx series and 5xxx series, have yield strength similar to or even higher than mild steel. (Steel also comes in a range of strengths.) 7xxx series can be significantly higher (but used for aero not marine applications, as far as I know; not good with corrosion IIRC).

However, aluminum is weakened a lot in the heat affected zone of arc welding. Down to around half as strong as steel (not 1/4). So, if a chain were made with an arc weld closing the link, it would need about twice the area as the steel link. Thus the weight savings might be around a third of the weight of the steel. But if the aluminum link could be closed with some type of friction stir weld, there is no HAZ, and it could be the same size as steel and also a third of the weight.

(But I don't see why you'd want this. Cost would be significantly higher and the weight of the anchor chain improves holding. Among other things good/bad.)

[Montanan]

Originally Posted by Rohan

In another thread, I talked about problems I had with my anchor rode, and a lot of comments here recommended all chain. But holy cow - steel chain is heavy. It's roughly 1 pound per foot (or about 1.4kg per meter length). So if I wanted 400' of chain, that would be 400 lbs! Shipping would be expensive. I wouldn't even be able to lift that into my car, much less my boat.

I could usually do fine with 200', but even that would be difficult.

So has anyone tried aluminum chain? It's not as common, but it does exist. It's significantly more expensive, but it weighs 1/3rd as much. But I'm wondering if that would be feasible?

200 feet = 200 pounds, heck that is just a little bit heavier than one keg of beer, and just like our anchors, we carry at least one spare keg onboard. We don't have a water maker so bring our own hydration. Much easier than stocking 99 bottles.

Recall during my college years when my brother and I together carrying a single keg between the two of us far out a floating dock [100 meter] to load one of the four large houseboats we rented for a water ski vacation gathering and to turn around and see my brother's friend easily carrying two full kegs, one of each of his shoulders, made us feel like weaklings. He looked like
Thor, huge and handsome and very strong. So if you need help with moving the chain, recommend just finding a Thor.

[dlj]

Anchor chain requirements would not lend themselves well to aluminum. None of the alloys do well articulating against each other. You have a lot of that kind of movement in an anchor chain.

I would never use an aluminum alloy in an anchor chain.

dj

[wholybee]

Originally Posted by Rohan

In another thread, I talked about problems I had with my anchor rode, and a lot of comments here recommended all chain. But holy cow - steel chain is heavy. It's roughly 1 pound per foot (or about 1.4kg per meter length). So if I wanted 400' of chain, that would be 400 lbs! Shipping would be expensive. I wouldn't even be able to lift that into my car, much less my boat.

I could usually do fine with 200', but even that would be difficult.

So has anyone tried aluminum chain? It's not as common, but it does exist. It's significantly more expensive, but it weighs 1/3rd as much. But I'm wondering if that would be feasible?

Aluminum I think is a bad idea.

But, while I am in the minority, I think I am right in my opinion that all chain isn't necessary, almost anywhere.

There are 3 issues brought up. Strength, Holding power, and chafe.

Rope is plenty strong. That is a non-issue.

After about a boat length or two of chain, for holding power it is better to add weight to the anchor than adding weight to the rode. In a blow, when you need the holding power, the chain is tight and any weight in the chain is useless for holding. So spend your money and add weight with a bigger anchor.

So, that leaves chafe, which is really the only valid reason for having a lot of chain, then only in areas with rocks and coral and such. And you only need chain for the part on the bottom. So, in 30 feet, with a 5:1 scope, you would need 120 feet of chain, and 30 feet of rope. In 50 feet, you would need 200 feet of chain, and 50 feet of rope. In reality, even then you could probably use a lot less than 200 feet because the rope will only touch the bottom while drifting with the rode completely slack.

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

I circumnavigated with 130' of chain. It seemed about perfect. Very often I just put all the chain out (usually more than needed for the depth), and skipped using a snubber because I had enough rope out.