Stainless steel and galvanized iron (?)

[Sea Hunt]

I recently had a local boating store (not WM) make a 150' anchor line (1/2" New England Premium 3 strand nylon). My anchor is a 14 lb Danforth with Acco 1/4" proof coil and WWent anchor shackles (galvanized). I purchased the anchor, chain and shackles from Defender. I am assuming the chain and shackle are galvanized iron.

The boat store installed a stainless steel thimble instead of a galvanized thimble. I have not yet purchased this line as the rigger has been out sick and I have not had a chance to talk with him to try to learn why he installed a stainless steel thimble.

So, at present, if I accept it, the stainless steel thimble will be in direct contact with the galvanized shackle. At present I plan to use this anchor for hurricane protection only. However, I am seriously considering the possibility of "upsizing" to a Cape Dory 25D. Yes, I know, many of you told me this would happen. Anyways, I will keep this ground tackle if and when I sell S/V Tadpole and use it as a day-to-day anchor for the CD 25D, including overnight anchoring.

I know very little about metallurgy but according to the Galvanic scale, stainless steel and galvanized are not close on the scale.

Question 1: Should I be concerned about these dissimilar metals being in contact with each other, especially at what seems like an important connection (the chain to line shackle)

Question 2: Can the issue be mitigated by wrapping duct tape around the thimble to lessen contact with the galvanized shackle

Thanks for all of your continuing support, suggestions, etc. They are much appreciated and much needed.

[rtbates]

I wouldn't think that it would be a problem unless you anchored for a very very long time. And even then the danforth will most likely pull put and skip along the bottom till you hit someting solid with the first wind shift. Let me make a statement so you know where I'm coming from. I HATE DANFORTH ANCHORS. THREE times, yes three times, while anchored to a danforth, a REAL danforth, not a knock off, I encountered storms while anchored at night. The storms brought 180 degree wind shifts. The danforth broke out and we drug till we hit shore. Danforth anchors hold good IN A STRAIGHT line. They were, after all, designed to drag military landing craft back to sea after landing on a beach. And as long as the pull remains in the same direction, the work great. With a 180 degree wind shift they are terrible. I would never go to sleep anchored to a danforth. I gave all my danforths away and bought Bruce anchors. Seraph., our 25D, carries two Bruce anchors. A 22lber on the bow and a 16.5 lb, as back up, extra. They have never broken out with 180 wind shifts. I've even used the motor to try and break them out by driving around them and going off 180 degrees. They simply pivot in the bottom and keep on holding. When I first got a Bruce, I used scuba to observe it's action while my wife drove the boat 180 degrees around it and headed off. Much to my pleasure the Bruce pivoted in the bottom and actually dug itself deeper. I knew I now had an anchor that would allow a good nights sleep without fear of waking up to bumping the bottom.

[Boyd]

I have had the same experiences he describes. Its particularly bad when you have the boat doing the CD dance around the anchor line with a conflicting current and wind situation.

I do still have a fortress aluminum in the cockpit compartment in case I need a kedge.

I have removed all stainless components from my anchoring rode. My anchor chain quit rusting out. Before I had major rust in a couple of years when I had stainless shackles, etc. in the system.

Boyd
s/v Tern
CD 30 MkII
Fort Lauderdale, Fla.

[SPIBob]

In Brion Toss' Rigger's Apprentice, he warns against using a thimble to attach the anchor line to the anchor chain. He says that "the thimble is inclined to chafe the rope, or to pop out, or both. You can seize the thimble to the rope, but seizings can chafe away too." Seems like this would be especially relevant for storm ground tackle. Also, when hoisting the anchor, you can have problems when the thimble hits the bow roller, windlass or hawse pipe.

Toss recommends using a rope to chain splice and he includes a couple of these splices in his book. This way there's no thimble or shackle to deal with. Another option is to keep the shackle and use an anchor hitch secured by two half hitches with the bitter end seized to the standing part. How-To's for these splices and the anchor hitch can be found on the internet, I believe. Bob

[Joe CD MS 300]

I'll vote for using the thimble. I'm not sure that you can buy a prespliced anchor line from any of the major suppliers with out it unless it was specifically requested. Take a look at Westmarine, Defenders, Hamiton Marine websites. All of the anchor lines and mooring pennants that I could find come with the thimble. If you are doing the splice yourself, chafe or it popping out might be an issue. But with a professionally spliced line I think that the chafe risk of a bare line would be much greater. I've done my own splicing on docklines and chain snubbers but when it cones to an anchor, even a secondary I'll go with a pro.

[Tod M]

My boat is 17', 1,600# and the primary anchor is an 11# Bruce + (shackled to) 17' of 5/16" stainless chain + (spliced to) 200' of 3/8" three-strand nylon.

I've had good luck with it with only one drag in 8 yrs of use (although I am usually anchored with good protection). That drag happened when the anchor was not only holding my boat but SEVEN others similarly sized when a thunderstorm blew through shortly after this pic was taken. The bottom was very soft mud (Edwards Creek off the Piankatank River, Chesapeake Bay) and the anchor just slowly plowed a furrow in the bottom, giving us plenty of time to break up the raftup.

<img width=540 img src=http://www.htmills.com/images/ChesRaftupPicByFrankD.jpg>

Here is the splice. So far no signs of wear (although the stainless is nice and smooth). There isn't much movement between the nylon and chain (the last link tends to move with the nylon). I prefer this splice over the kind where the rode is woven into several links of the chain, but I suspect they are pretty similarly reliable.

Somewhere on the web are the results of a test of the splices and the splices were strong enough to deform shackles. [found it] http://www.ussailing.org/safety/Studies ... splice.htm

<img width=540 img src=http://www.htmills.com/images/LF-rode.jpg>

If money were no object I suppose I'd go with a Rocna/Manson type anchor, but the Bruce has served me well.

I keep the anchor & rode in a milk crate

<img width=540 img src=http://www.htmills.com/images/LF-milkcrate.jpg>

and launch from the cockpit, walking the rode forward. If it is calm and hot, after I've anchored normally, sometimes I'll take the rode between the anchor and the bow cleat and walk it back and flip it over a stern cleat. It really helps get air through the cabin. If the wind picks up, all I need to is flip the rode off the stern cleat and the boat turns around head to wind.

When retrieving, I normally hoist the main while at anchor, sheeted in tight and with the helm free. Then I'll go forward and weigh anchor while the boat slowly self-tacks, nearly staying in place. That amount of chain and anchor is about as much as I'd want to hold in one hand while I walk back to the cockpit (on the temporary weather side of the boat). Then I put the anchor back in its crate, followed by the chain and nylon rode. I don't coil the line; it seems to tangle much less if I just feed it into the crate hand-over-hand.

<img width=540 img src=http://www.htmills.com/images/LF-WeighingAnchor.jpg>

Tod

[Joe CD MS 300]

Tod,

Nice looking splice. Did you do it? I'm not that good at it.

Joe

[Tod M]

Yes, I did it. A little practice goes a long way. Should I see wear or a cut in the rode, it would be an easy matter to cut off the bad section and make a new splice.

[Steve Darwin]

The wire used to seize mooring shackles (keep the pin from turning and unscrewing itself) is stainless steel, and it was my understanding that stainless and other ferrous metals (like galvanized iron or steel) are compatible in seawater. Not so?

[Tod Mills]

Stainless is more noble than the galvanizing (zinc), so it causes the zinc to disappear, leaving whatever it is coating vulnerable.

I guess I need to get out on the boat more, because I haven't had that problem.