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Old 18-09-2023, 05:17   #1
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Grinding away galvanized Rocna

Fitting a small Rocna to a newly installed bow roller on my trailerable sailboat. Due to the way it mounts and the angled shank of the anchor, it doesn’t fit correctly. I want a good fit as the boat will be going 60 MPH on the highway.

My idea is to grind away a bit of the anchor shank. Obviously this will remove the galvanized coating.

Is this a good idea? Will it rust there and spill rust stains down the bow? Paint the ground away area?

I guess I could have the entire anchor re-galvanized, but it’s brand new and I also don’t want to throw that much money at it.

Ideas?

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Old 18-09-2023, 05:29   #2
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Re: Grinding away galvanized Rocna

Sell the Rocna before you destroy its value and compromise its suitability for purpose. Buy an anchor which fits properly.
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Old 18-09-2023, 05:35   #3
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Re: Grinding away galvanized Rocna

It is an unusual mounting situation and if I bought another it would also not fit.

And grinding away such a small amount should not affect its strength very much.

My question is about the galvanization. What will happen? What’s underneath the galvanizing, just mild steel?
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Old 18-09-2023, 06:20   #4
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Grinding away galvanized Rocna

Sacrificing your anchor's performance while anchoring to improve its performance while on the highway is a really silly idea.
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Old 18-09-2023, 06:22   #5
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Re: Grinding away galvanized Rocna

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Originally Posted by chris95040 View Post
Sacrificing your anchor's performance while anchoring to improve its performance on the highway is a really silly idea.
Definitely agree.

Is there anything wrong with putting the anchor in your trunk? Your truck bed? The cabin of your boat?

it’s pretty doubtful you’ll need to deploy the anchor while you are going down the highway lol
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Old 18-09-2023, 06:28   #6
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Re: Grinding away galvanized Rocna

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It is an unusual mounting situation and if I bought another it would also not fit.


So you've identified the problem, then. Fix that?

Your plan leaves you with a questionable shank and a questionable bow roller. Google rocna bent shanks for some additional inspiration to leave your shank alone.

Here's a wild idea: remove the anchor from the bow when trailering?
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Old 18-09-2023, 06:33   #7
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Re: Grinding away galvanized Rocna

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itís pretty doubtful youíll need to deploy the anchor while you are going down the highway lol

One would hope!
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Old 18-09-2023, 06:52   #8
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Re: Grinding away galvanized Rocna

Quote:
Originally Posted by massnspace View Post
Fitting a small Rocna to a newly installed bow roller on my trailerable sailboat. Due to the way it mounts and the angled shank of the anchor, it doesnít fit correctly. I want a good fit as the boat will be going 60 MPH on the highway.

My idea is to grind away a bit of the anchor shank. Obviously this will remove the galvanized coating.

Is this a good idea?

How much shank are we talking about? If you're grinding away half of the width of the shank, it is probably not a good idea. If you're making a 1/4" notch, well, maybe that's OK.


Quote:

Will it rust there and spill rust stains down the bow? Paint the ground away area?

It will probably be fine. I would paint it. The galvanizing on everything else will serve to provide some cathodic protection for the area that isn't galvanized. It will probably last for at least as long as you want to trailer your boat around.
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Old 18-09-2023, 06:54   #9
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Re: Grinding away galvanized Rocna

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Originally Posted by chris95040 View Post
Sacrificing your anchor's performance while anchoring to improve its performance while on the highway is a really silly idea.

There are far worse compromises that must be made to allow a cruising boat to be trailerable. I know, I've done it.
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Old 18-09-2023, 06:56   #10
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Re: Grinding away galvanized Rocna

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Is there anything wrong with putting the anchor in your trunk? Your truck bed? The cabin of your boat?

It adds one more step to launching and landing processes that are already physically exhausting and time consuming.
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Old 18-09-2023, 06:59   #11
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Re: Grinding away galvanized Rocna

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Sell the Rocna before you destroy its value and compromise its suitability for purpose. Buy an anchor which fits properly.

On a boat that size a suitable Rocna is not expensive. One might just as well declare that someone is destroying the value of a foresail by having a window put in it. The boat has to work as a system.
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Old 18-09-2023, 07:02   #12
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Re: Grinding away galvanized Rocna

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Whatís underneath the galvanizing, just mild steel?

Steel, yes. I believe they're forged, and higher performance steel than your average mild steel fencepost.
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Old 18-09-2023, 07:02   #13
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Re: Grinding away galvanized Rocna

Quote:
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My question is about the galvanization. What will happen? What’s underneath the galvanizing, just mild steel?
Underneath the galvanising is high tensile steel. It will certainly rust if you grind away a significant portion of the galvanising, although the adjacent intact galvanising will act an anode, so the rusting will be less than you may otherwise expect.

Make sure you wear appropriate PPE. I believe grinding galvanising is quite hazardous.

It would be nice to know where you plan to modify the shank. Overall, removing shank material is very unlikely to reduce the performance of the anchor. Anchors such as Rocna benefit from the minimum weight possible in the shank, hence the use of fabricated shanks (Spade, Ultra) or specially profiled shanks (Rocna MK2) to reduce the shank weight. Therefore, if anything, the modification is likely to increase the performance rather than reducing it.

However, you will be reducing shank strength. The reasonable number of bent shanks Rocna experienced with only a modest reduction in shank strength (due to the wrong grade of steel) shows that there is little practical leeway. A bent shank is a real possibility of only a slight reduction in shank strength. The most critical factor is horizontal strength. Be particularly careful about small notches that will create some stress concentration.

Obviously, you will invalidate the warranty.
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Old 18-09-2023, 08:02   #14
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Re: Grinding away galvanized Rocna

If your only concern is while trailering, could you use something to brace it better and additionally tie it up more securely? Or take it off and stow it in your vehicle or elsewhere on the boat? Depending on the frequency I can imagine the take-it-off approach might feel like a hassle.
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Old 18-09-2023, 08:13   #15
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Re: Grinding away galvanized Rocna

A roller of a different DIAMETER might help.

---or---

If the bow roller "channel/cheeks" can accommodate one, a second "roller" installed aft and above the original roller might serve to "lock/wedge" the anchor into a more stable position.
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