Fortress anchor: what material for shackle?

[Martin S]

Connecting a Fortress Anchor to a galvanised chain, is a SS or steel shackle best to minimise galvanic corrosion? Any other tips applicable to using a Fortress anchor? Thanks all.

[UNCIVILIZED]

Just use a quality galvanized shackle of the appropriate load rating, & properly mouse it. Any more than that & you're kind of overthinking things.
That, & in general, unless you can't avoid it, stay away from stainless in items which will be pretty much continually immersed.

[estarzinger]

It would be interesting if Fortress would modify their anchor just a little to allow the use of dyneema (soft shackle or lashing) - they would just need to round the edges a bit.

This would allow a very strong zero corrosion and zero wear on the aluminum connection. It's how we connected most stuff to our aluminum toe rail.

I probably would not want to use dyneema for 'all purpose' anchoring because of the long term chafe and cut potential (on random stuff on the bottom) (Note: you could make a quite cut resistant connection, but obviously just not as metal).. But that is mostly not how fortresses are used. They are rather mostly used a short term kedges (using the term very broadly), often with a line rode (and quite short chain), which is a higher chafe/cut potential already than a dyneema connection.

You could DIY this with a dremel, but it would break the anodizing and you would either have to live with that (probably not terrible) or get it re-anodized yourself.

[Fortress]

Originally Posted by Martin S

Connecting a Fortress Anchor to a galvanised chain, is a SS or steel shackle best to minimise galvanic corrosion? Any other tips applicable to using a Fortress anchor? Thanks all.

Martin S,

Thanks for your question. Galvanic corrosion is extremely rare with our aluminum-alloy anchors, as it requires them to be in contact with a dissimilar metal and a saltwater environment for an extended period of time, which does not occur during normal anchor use.

Exceptions would be if the anchor was being used as a permanent mooring, or if it was stored below deck in a leaky bilge area while in contact with a steel chain and shackle.

To answer your question, if you are deploying the anchor for only a matter of several days, or for possibly just a few hours, then it will not matter if you use either a galvanized or stainless steel shackle.

As a side note, we replace any damaged anchor parts under our Lifetime Parts Replacement Warranty for free, the customer only pays for shipping & handling and he or she is not required to return the damaged parts or prove that they are the original purchaser.

Safe anchoring,
Brian

[Martin S]

Thanks for all replies, particularly Fortress for long term storage tip.

[captstu]

I don't think stainless is EVER suitable for use in an anchoring environment. By its nature, an anchoring environment is subject to load stress that is essentially unpredictable.

Stainless snaps, galvanized and aluminum deform and are subject to inspection. In the case of a Fortress, you have the ideal world - my catamaran lived through a boat destroying veer of a hurricane several years ago. My anchoring system consisted of a 50 kg Bruce and an FX-37. The Bruce was closest to the boat with the FX-37 tethered to the trip point of the Bruce with 8' of chain.

The chain stretched, the bridle and storm bridle both snapped, and 2 of the 3 shackles deformed. But, ultimately, the boat held. Most of the Fortress were replaced - free - because it deformed so badly -- but it did hold. There was no boat damage beyond the windless pulling out of its mounts when the bridles failed.

Had there have been stainless in the system, I would have lost the boats.

Walking the shore among the damaged boats that washed up on land were many snapped swivels. Best thing about a swivel, you always know where the anchoring system will break.

Use good galvanized, inspect for corrosion and deformation after a heavy blow, and understand that Fortress is designed to hold after deformation - and it does - and they will replace the deformed parts.

There is significant debate about the best primary anchor - the one closest to the boat/tripper for everyday use.

But, in my experience, there is no debate about the best secondary or storm anchoring system. Tether a good size Fortress to your claw, Bruce, CQR or Manson and sleep well, assured that the only boat movement you will see in a storm is the other boats going by.

BTW, when I went to recover my anchoring system after fixing the windless mount, only the Fortress was visible - the Bruce was buried to the end of the tether holding it to the Fortress.

[estarzinger]

Originally Posted by Fortress

Martin S,

Thanks for your question. Galvanic corrosion is extremely rare with our aluminum-alloy anchors, as it requires them to be in contact with a dissimilar metal and a saltwater environment for an extended period of time, which does not occur during normal anchor use.

I will note that there was most definitely (visible but minor) 'corrosion' on my fortress on the top of the shackle hole. We had similar and a bit more severe where the chain was stowed in the bag touching one of the blade edges - there was a small half moon 'bite' eaten out of the (thin/sharp side) blade edge.

Probably in use the steel shackle rubbed off the anodizing, leading to bare aluminum, leading to the normal bare aluminum 'white powder'. (I believe) that is not 'galvanic' corrosion, so you are correct about that, but it is 'corrosion'. The chain on blade effect might well be actual 'galvanic' corrosion.

A dyneema connection would avoid the shackle side of this (which is why that suggestion came to mind). Probably this is more of a 'cosmetic' benefit that an actual 'safety' benefit, because your anchors are built with a lot of beef, and a little corrosion would take a long while to become meaningful.

[S/V Alchemy]

Originally Posted by UNCIVILIZED

Just use a quality galvanized shackle of the appropriate load rating, & properly mouse it. Any more than that & you're kind of overthinking things.
That, & in general, unless you can't avoid it, stay away from stainless in items which will be pretty much continually immersed.

You could, if you really wanted to, make a bushing or insert for the Fortress's shank to isolate (until it wore away) the galvanised shackle, but I agree that it may be too thorough.

[S/V Alchemy]

Originally Posted by captstu

I don't think stainless is EVER suitable for use in an anchoring environment. By its nature, an anchoring environment is subject to load stress that is essentially unpredictable.

Stainless snaps, galvanized and aluminum deform and are subject to inspection. In the case of a Fortress, you have the ideal world - my catamaran lived through a boat destroying veer of a hurricane several years ago. My anchoring system consisted of a 50 kg Bruce and an FX-37. The Bruce was closest to the boat with the FX-37 tethered to the trip point of the Bruce with 8' of chain.

The chain stretched, the bridle and storm bridle both snapped, and 2 of the 3 shackles deformed. But, ultimately, the boat held. Most of the Fortress were replaced - free - because it deformed so badly -- but it did hold. There was no boat damage beyond the windless pulling out of its mounts when the bridles failed.

Had there have been stainless in the system, I would have lost the boats.

Walking the shore among the damaged boats that washed up on land were many snapped swivels. Best thing about a swivel, you always know where the anchoring system will break.

Use good galvanized, inspect for corrosion and deformation after a heavy blow, and understand that Fortress is designed to hold after deformation - and it does - and they will replace the deformed parts.

There is significant debate about the best primary anchor - the one closest to the boat/tripper for everyday use.

But, in my experience, there is no debate about the best secondary or storm anchoring system. Tether a good size Fortress to your claw, Bruce, CQR or Manson and sleep well, assured that the only boat movement you will see in a storm is the other boats going by.

BTW, when I went to recover my anchoring system after fixing the windless mount, only the Fortress was visible - the Bruce was buried to the end of the tether holding it to the Fortress.

I find this a very telling anecdote, particularly as I own a FX-37 on a steel sailboat with considerable windage. Thanks for relating it.

[S/V Alchemy]

Originally Posted by estarzinger

A dyneema connection would avoid the shackle side of this (which is why that suggestion came to mind). Probably this is more of a 'cosmetic' benefit that an actual 'safety' benefit, because your anchors are built with a lot of beef, and a little corrosion would take a long while to become meaningful.

It is telling concerning the conservative nature of sailors that I believe very few would opt for a soft shackle between chain and anchor, even with these advantages and empirical proof that a properly made-up Dyneema soft shackle is stronger than the properly sized steel shackle to which it is fixed.

Yet the same people would consider (and as I have seen) a really thin run of Dyneema to a float as a tripline from the crown of an anchor, because it's known you can't bust it even with (most) mechanical advantage!

[TheThunderbird]

It looks like the 50kgBruce made a good work.

I was ever cautioned NOT to shackle one anchor before the main one,.... possibly using a salmon (weight) along the line and after the main anchor...


But with videogames the 'more' wins..

Shackles fail because you can't fix a bigger one into a normal - size chain....

[Cruisingscotts]

Practical sailer had a issue addressing anchor connections recently, I begrudgingly had to admit my set up failed in their tests. A suncor swivel, I think the bottom line was a safety wired galvanized bow shackel of the proper size in the anchor and chain, with the bow in the anchor eye is the best solution. Probably the biggest issue is sourcing good quality galvanized shackes. Lots of garbage out there. Love the aluminum fortress for a non swinging 2nd hook.

[UNCIVILIZED]

Originally Posted by TheThunderbird

Shackles fail because you can't fix a bigger one into a normal - size chain....

Upon what data are you basing this statement?

[TheThunderbird]

Receptacles in the anchor and in the chain define the largest shackle you can fit in.

No doubt the shackle fails first, unless chain integrity is compromised.

It is enough to consider how is the geometry of any chain

[Cheechako]

I always used a big Shackle on the anchor and smaller one on the end of the chain. The big one will not see any appreciable corrosion but the Fortress may a bit.