Aluminum anchor connection to ss shackle

capta · May 14, 2017

Unless your anchor is going to be in the water 24/7/365, I wouldn't give it any thought at all. It's not like this is a tight connection like a screw or bolt, the shackle will move around in the anchor easily.

Ralph Johnstone · May 14, 2017

Dusty Mac said:
I understand aluminum to stainless steel shackle for connecting to
anchor rode will cause galvanic corrosion.

It's doubtful if you will ever see any corrosion on aluminum shank of the anchor. Although the aluminum is anodic, it has such a large surface area relative to the SS shackle, the corrosion is spread out and not noticeable.

jibes138 · May 14, 2017

Why not use a soft shackle made from line and laced to the chain?

thinwater · May 14, 2017

jibes138 said:
Why not use a soft shackle made from line and laced to the chain?

Is this how you attach your anchor? How many days so far?

No, this is definitely not meant as sarcasm. Dyneema has been suggested before. But if you are going to suggest something new like this, walk the talk and do the testing. For example, I'm testing Dyneema leaders, but not the shackle itself, and not because I'm concerned about corrosion--as others have explained, I think that is a non-issue, based on decades of experience. One of my Fortress anchors is 25 years old.

Of course, you could use a galvanized shackle--there is very little difference in potential between Zn and Al. Why on earth use stainless?

capta · May 14, 2017

jibes138 said:
Why not use a soft shackle made from line and laced to the chain?

Is that what you use?

Whatfiero1 · May 15, 2017

Check with anchor manufacturing spec. But I believe you need some chain on that anchor to set properly

Chief RA · May 15, 2017

Whatfiero1 is right on with his assertion that you need chain on that aluminum anchor! I owned one and it was not much of an anchor. I put 25' of chain on it to make it usable as an emergency triple backup anchor and still didn't trust it to dig in. Lack of weight in an anchor presents a serious problem as far as I am concerned. As far as using a SS shackle: use it as it will not matter, but I would use galvanized to match the chain. Chief

dlochner · May 15, 2017

The use of SS shackles has been questioned for good reason. SS while strong can also work harden and then catastrophically fail without warning. Plain old galvanized steel will not do that as readily.

Of course if the shackle should fail it will only do so in the dead of night in the middle of a T-storm.

BigEasy · May 15, 2017

If you decide on a galvanized shackle, do some research on Crosby shackles. They are used for heavy lifting in all industrial applications. Practical Sailor rates them highly. Many of the online chandleries have them available; just select the appropriate size for your anchor/chain. Don't forget to place some lanacote on the threads and lock wire it with SS wire.

Ralph Johnstone · May 16, 2017

Chief RA said:
Lack of weight in an anchor presents a serious problem as far as I am concerned.

You'll notice on the Fortress web page that their underwater demonstrations show the anchor just diving into a soft sandy bottom. Anything harder and it's going to skid from here to the next anchorage. Just a pretty anchor.

And the anchor battle is ON, again

thinwater · May 16, 2017

Actually, chain can be a detriment in soft mud, dragging the shank down and inhibiting setting.

Feeling the anchor in is often the solution. There are, of course, a few bottoms fortress dislikes.

Chief RA · May 16, 2017

thinwater: I do not agree with the idea that soft mud would reduce an anchor set as it would drag the blades down with it. This could help an aluminum "danforth" more than hinder. If a Fortress aluminum anchor is any good just think how much better it would be made of 25 lbs of steel and 25' of chain! Chief

Ron20324 · May 16, 2017

Gentlemen, GENTLEMAN... Okay, flare guns at 40 paces

dlochner · May 16, 2017

Fortress only recommends 6 feet of chain minimum with an additional 6 feet for every 25 ft of water depth.

The more expensive Fortress has adjustable mud palms which improve holding in mud.

Chief RA · May 16, 2017

I would not care what Fortress recommends for chain length for an aluminum anchor! If your hanging off of one I would recommend that you "stand watch 1800 to 0800"! Chief

JamesG161 · May 16, 2017

capta said:
Unless your anchor is going to be in the water 24/7/365, I wouldn't give it any thought at all.

The Aluminum will "re-oxidize" a protective coating when not in conductive salt water.
Jim...

capta · May 16, 2017

Chief RA said:
thinwater: I do not agree with the idea that soft mud would reduce an anchor set as it would drag the blades down with it. This could help an aluminum "danforth" more than hinder. If a Fortress aluminum anchor is any good just think how much better it would be made of 25 lbs of steel and 25' of chain! Chief

I just picked up a large Fortress anchor that still weighs less than the silly 44# Bruce I've been carrying since I bought the boat (it came with the boat). I believe the Fortress to have considerably more holding power than the Bruce (and a better tried and true design) even though it is lighter.
Efficient ground tackle is not all about the weight of the anchor, but more about matching the various pieces of the system for maximum holding power. We know someone who bought a 120# Mantus as her #2 anchor on a 40ish foot boat and 3/8" bbb chain to go with it. If conditions are bad enough to actually deploy that anchor, I doubt that the extra weight of that anchor will make any difference over a 65# anchor.

Aluminum anchor connection to ss shackle

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SBO Weather and Forecasting Forum Jim & John

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