Drilling a hole in the anchor?

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Inselaffe

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I want to mount my anchor on the bow roller.

There are a couple of pins that I could put through the anchor to secure it, I guess I just drill through the anchor shank.

I can't see that the size of the holes will significantly reduce the strength, but what do people do to stop the exposed steel in the holes rusting (mainly to avoid staining of the hull)?
 
Not alot - short of re-galvanising.
Most paint solutions, would be fairly temporary especially if used for securing.

I'd try and find a way of secring it using something (lanyard) attached to the anchor.
 
I am thinking of doing the same thing, just drilling a small hole in the shank and securing the anchor with the same pin that ensures the chain stays on the roller. I guess having a stainless anchor will get rid of the rusting problem, but the downside is it's not easy to drill stainless.
 
My 35lb CQR was drilled by Westerly Yachts when the boat was made/sold. It allows a drop-nose S/S pin to be fed through it, and the stemhead fitting, and is a perfect solution in our opinion.

Oddly, there has never been the slightest sign of rust/corrosion where the hole is, but I've no idea why this is!!

Turning and pulling out the pin is a lot faster than undoing a lashing, and a lot safer, IMHO, in a heavy sea.
 
The galvanizing on the rest of the anchor will protect the exposed steel, no need to paint/treat it, it will not rust appreciably. This is how Zn anodes protect a steel hull afterall.
 
A question really, would galvfroid paint be any good and going on from that, my anchor is beginning to look a bit stained, can you paint them rather than having re-galvanized or is it a waste of time
 
Thanks,

The galvanizing stopping the rust makes sense to me,

Anyway I drilled it this pm, now the problem is how to stop the anchor moving around. At the moment I have a lashing on it, but will try to think of summat a bit more solid...
 
[ QUOTE ]
I want to mount my anchor on the bow roller.

There are a couple of pins that I could put through the anchor to secure it, I guess I just drill through the anchor shank.

I can't see that the size of the holes will significantly reduce the strength, but what do people do to stop the exposed steel in the holes rusting (mainly to avoid staining of the hull)?

[/ QUOTE ]You can drill a hole but for our part we don't recommend it. Firstly, you reduce the strength of the shank by the % the hole's diameter is of the entire shank's height at that point. I.e., a 10mm hole where the shank is 100mm high will decrease its strength by 10%, it's that simple.

Also, you will have broken the galvanizing coating, and should ideally use cold zinc to coat the raw steel in the hole (and maintain always). Overall zinc loss will be accelerated. However, the galvanizing on the rest of the anchor is self sacrificing and will protect this exposed steel to some extent.

Moreover, we do not like pins through the shank – they tend to bend too easily. The Rocna has a large fluke, and if solid water hits this at sea, it can bend the pin and so jam it. We have seen too many have to be hack-sawed! Better to lash the anchor with rope or use a special over-the-top restraining bar or pin that cannot keep the anchor 100% captive if it is bent.
 
Bife, I am inclined to agree with Rocna, bit late tho. FWIW there is a galvanizing outfit on the N. side of Lisbon. Three letter name, E something. I got the stuff up early and they had it ready by 2pm. Very friendly and cost little.
Andrew
 
I am scared to suggest something that the man from Rocna anchors said isnt a good idea, but so what if the anchor strength is reduced by a modest percentage when you drill a hole for a retaining pin? The drilled anchor shaft will still be many times stronger than the chain will it not? Not to mention the rope I have afgter the length of chain. I drilled mine and put a bit or araldite on the exposed edges and have no rust after 3 years. But the earlier posts suggest you dont get rust anyway.

A bent pin in very severe weather is a different matter, and more serious I would think. I confess I didnt think of that one, perhaps because if my pin bent I would by that time be thinking of taking to the liferaft rather than anchoring!
 
[ QUOTE ]
I am scared to suggest something that the man from Rocna anchors said isnt a good idea, but so what if the anchor strength is reduced by a modest percentage when you drill a hole for a retaining pin? The drilled anchor shaft will still be many times stronger than the chain will it not? Not to mention the rope I have afgter the length of chain. I drilled mine and put a bit or araldite on the exposed edges and have no rust after 3 years. But the earlier posts suggest you dont get rust anyway.

[/ QUOTE ]If the rope is matched properly to the chain, it is typically as strong if not stronger than the chain.
In any case, will the anchor shank still be many times stronger - heavens no, bent anchor shanks are very common! Foul the anchor in the right way then play tug of war trying to free it, and it's often the anchor's shank which will fail first. It is the sideways bending force mind you, never a direct inline force (in which case the shackle is usually the weak point). They tend to fold at the "neck" too, which is generally where you will want to put the hole. Anyway the strength issue isn't necessarily a deal breaker, but it is significant - in the order of 10 or 15% reduction. It's up to you if you want to do that.

[ QUOTE ]
A bent pin in very severe weather is a different matter, and more serious I would think. I confess I didnt think of that one, perhaps because if my pin bent I would by that time be thinking of taking to the liferaft rather than anchoring!

[/ QUOTE ]It's not at all unusual, we have seen it a number of times. Usually on larger anchors of course, with smaller ones it is less of an issue and our 4Kg actually has a hole in the right place and shape to suit the pin on a common prefab roller unit. But put something like a Rocna 20 or larger into green water at sea, and the force will bend many pins. Then you're coming into an anchorage after that kind of passage, you're tired and it's nearly dark, and you go up onto a wet foredeck to get the anchor ready... did you remember to stow a hacksaw? /forums/images/graemlins/tongue.gif

Naturally these two issues are incompatible with each other; i.e. solve the one with a larger stronger pin, and you need a larger hole... smaller hole, weaker pin.
 
The reason there is no rust, is that Galvalising, unlike chrome plating, is a sacrificial coating. The oxygen goes for the surrounding zinc, and not for the iron, so no problem drilling a hole.

Doing the same with a noble plating will cause all the corrosion to focus on the defect in the coat.
 
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