Bottom is mud of the "galvanising stripping" variety

[Zoid]

Just pulled into the port of Algropoli, Italy. There appears to be a perfectly open area to anchor here, but in Rod Heikell's Imray guide to the area he says: "The bottom is mud and is said to be of the 'galvanizing stripping' variety." I've never heard of this and couldn't find anything after some searching on the web. Can bottom (mud in this case) degalvanize the steel in my ground tackle? If there any danger of this if I anchor here for a few days?

Any input or explanation on what Rod means would be helpful.

Thanks,
Zoid

[atoll]

if there is a lot of acid or alkali soil run off from the surrounding land into the bay this might account for degalvanising properties of the mud.

i would think it takes weeks rather than days to do much damage

[Zoid]

Thanks for the reply. We figured it would take some significant time rather than a couple of days, but wanted to get other perspectives.

Thanks again

[Jim Cate]

FWIW, the bottom off of the Suva YC in Fiji is just such a chemical mess! In that case, there is a big rubbish tip on shore, and I suspect that it is leaching some acids into the seabed. At any rate, two years running I ruined new galvo on chain there. Pretty stupid, eh? But I hadn't twigged to what was going on, and in the first year we were only anchored there for a couple of days IIRC. Oh... it was pretty soupy mud, too, and every time there was a frontal passage most of the boats dragged. Not our favorite place in that lovely country!

Jim

PS: I should add that this was in the early 90s. Things may well have changed there, but the possibility of stripping the galvo off of chain is a real-life worry.

[simonpickard]

I was there two days ago and read the same thing! Others were anchored but we just moored up as it's now low season.

[barnakiel]

Yes mud in e.g. le Marin, Mangareva, or in Guadalquivir strips. That in Mangareva will strip your skin too.



b.

[a64pilot]

Hydrogen sulfide?


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[Alan Mighty]

I'm currently anchored in Bass Harbour, off the town of Kuah on Pulau Langkawi in Kedah state, Malaysia.

The bottom Bass Harbour is also famous for stripping the zinc galvanising coat from chain, leaving it black.

A week or so ago, I anchored s/v Led Myne in the Dindings River (Sungai Dindings) upstream of Lumut, in Perak state, Malaysia. The old hands also warned me there that the bottom and/or water is famous for stripping the zinc from anchors and chain.

The old hands (cruisers who have lived aboard in Malaysia for a decade or more, it seems) gave me two suggestions about why the zinc gets stripped:

1. reclaiming peat swamp for agricultural land (on which oil palm is then planted) several years back led to acid sulfate released from the soil when the soil dried out and was oxidised; and

2. much of Perak is heavily mineralised. It was once the major source for the world of tin, used for plating steel sheet to can foods. Perak means 'silver' and was a misnomer for tin. The capital city of Perak state, Ipoh, is called 'the city that tin (exports, from the port of Lumut in the Dindings river) built'.

The old hands pushing idea #1 reckon the stripping of zinc, leaving a black chain, is a seasonal thing and doesn't happen so much the past 5 or 6 years, because much of the acid sulfate effect has been either leached out of the former acid sulfate soils or the plantations have learned how to manage the soils better.

The old hands pushing idea #2 reckon that if you anchor for a few weeks, the chain will also have a concretion of coral-lime deposits on it. Suggesting either some chemical effect or fast biological activity.

I've only been anchored in Bass Harbour overnight and not yet weighed anchor to see if any zinc is left!

Al

[Chasamba]

We anchored off Port Klang, in the Malacca Straits in 2010 for ONE NIGHT, on the way to Singapore. When we pulled the anchor chain in it was completely black, and went rusty soon after. That's an expensive free anchorage!

[Coxswain]

Good old Malacca Straits... should be called the Malacca Strip! we too had our anchor chain destroyed over the 10 days motoring the Malacca's. Kuah was just the icing on the cake, two weeks anchored there and it finished it off!! haha.