preventing more corrosion on an aluminium anchor

[vyv_cox]

I don't think I have ever previously seen the series 'upside down' as in your post. I have recently drawn up my own for a book I have written but did it the conventional way up. No difference in the data of course, just a convention in the layout.

 

[Neeves]

Worry levels appear to be being raised unnecessarily.

100,000s of thousands of Fortress owners and a few alloy Spade and alloy Excel owners have been using alloy anchors for years (and in the case of Fortress - decades). I have never seen a complaint of corrosion at the shackle hole and as far as I know everyone uses either stainless or galvanised shackles (unless other people invest in titanium or even more way out - soft shackles) - and I would think most of the zinc on the galvanised shackles has worn off.

We have now using our 8kg alloy Spade, Excel and Fortress (on a 38' cat) as primary anchors regularly now for 6-8 years (alloy, gal shackles) and corrosion is simply a non-event. We did grease the bolts on the Fortress. Both the Spade and Excel have lead ballast and there is not a single sign of corrosion, but the lead is isolated from the alloy.

Corrosion does occur - but its at the first link (or few links) in the anchor chain and when we had our 8mm G30 chain we simply chopped them off every couple of years. We are now using our 6mm G80 chain, without any problems) but it is not quite 12 months yet - so another year or so to wait to see if it enjoys the same corrosion.

Now why the chain corrodes preferentially over the aluminium alloy - there is something to discuss

Jonathan

 

[Neeves]

With those stainless steel bolts in direct contact with aluminium a compound like Duralac or Tef-gel should be used to prevent the influence of dissimilar metal corrosion. Unfortunately it needs to be used when the anchor is first assembled it will not fix an existing problem (although it will probably prevent it getting worse). Strangely, and wrongly in my view, this does not seem to be mentioned in the assembly instructions of Fortress/Guardian anchors.

I assume the anchor is a Fortress Fx-16 or Guardian G-16. If it is the former the parts with corrosion can be replaced at minimal cost under warranty. If it is the Guardian model there is no warranty to cover this problem.

It merits note that the Guardian has a 12 month warranty. This would not cover this situation - but I'm not sure that neglect should be a manufacturer's responsibility anyway.

Jonathan

 

[Fortress Anchors]

It merits note that the Guardian has a 12 month warranty. This would not cover this situation - but I'm not sure that neglect should be a manufacturer's responsibility anyway.

Jonathan

Jonathan, actually our warranty would cover this situation. We will typically not ask how damage to a customer's anchor occurred when they request parts replacement under our warranty. Once again, galvanic corrosion is extremely rare during normal anchor use and so we are not "breaking the bank," so to speak, with this level of generosity.

Safe anchoring,
Brian

 

[Poey50]

really good and useful knowledge re preventing corrosion coming out for general use.

Thanks - off to order some Duralac.

I decided to dig out an old tube of Duralac and re-assemble my as-yet-unused Fortress. If there is any stuff in the world more messy I don't want to hear about it. Wish I'd applied with a very small brush. I'll never wear those trousers again.

 

[thinwater]

Now why the chain corrodes preferentially over the aluminum alloy - there is something to discuss

Jonathan

I've always wondered if the loss of zinc is electrochemical or because the first few links see different movement.