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Stainless fasteners below waterline.

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Stainless fasteners below waterline.

Postby elhewman » Thu Feb 12, 2015 7:15 pm

Well it seems every time I get exited about a boat, I learn something else to watch for and need to walk away from, pretty depressing. I also hope other new boat shoppers like me can take from this as well. But half of the wood boats I have looked at mentioned replacing the bottom with stainless fasteners. I was talking to a very qualified surveyor on a boat and he told me not to waste my time because stainless fasteners under water become active instead of passive. My internet research has confirmed that they indeed can corrode very fast and lose their hold. I would love to hear others thoughts on this. But it seems like a liability to me, no?

When I finally get my troller..... if it ever happens. I want to summarize all I have learned so newcomers like myself can shop smarter(there will always be compromises though). I would hope it could be a sticky in the getting started section so others could add. I owe Curmudgeon everything because he has helped to many times to think twice about purchases I "knew" were the right deal.

Would love to hear you thoughts.
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Re: Stainless fasteners below waterline.

Postby spike christopher » Fri Feb 13, 2015 4:13 am

My boat had sheeting of iron bark all fastened with large s.s. screws. When I removed them as I took off the iron bark to replace ribs and planks the screws where in perfect condition. They had been in for twelve years. My shipwright said not to use s.s. below the water line. I did not argue and all new fastenings are galvanized screws. Some times I wonder about how these things come about. When I did ask him about this he said they where good because of the zincs I had on the boat. Lack of zinc will allow the s.s. to be eaten.
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Re: Stainless fasteners below waterline.

Postby gumpucky » Fri Feb 13, 2015 5:41 am

One would have.to consider the compromised nature of SS these days.
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Re: Stainless fasteners below waterline.

Postby curmudgeon » Fri Feb 13, 2015 8:56 am

Gumpucky is right about the poor metallurgy in some stainless. The issue with nail-sickness is a bit different and the book-section here explains it better than I can...

https://books.google.com/books?id=-Pntz ... ts&f=false

The above book might be another good reference to get your hands on!

Old surveyors will tell you that serious weakness in fasteners usually happens soonest in the lowest/wettest sections near the garboard and aft sections. The sketch in the link above explains why.

Crevice-corrosion/pitting in stainless is a bit of a different animal and happens where there's no oxygen to keep the thin oxide layer that protects stainless intact. Any break in the oxide layer becomes the anode and the rest of the intact film becomes the cathode, and once started this cell of galvanic corrosion can quickly accelerate in severity. Even stainless in prop-shafts can see crevice-corrosion in the areas of the packings and bearings!
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Re: Stainless fasteners below waterline.

Postby BoldVenture » Fri Feb 13, 2015 9:30 am

Zinc up and go fishing. Opinions are like "CENSORED", everybody has one. Especially in this industry. I highly suspect that you would be just fine with stainless fastenings if everything else regarding the vessel is up to par (zinc maintenance, electrical wiring, general hull condition). It's a tool, it won't last forever, regardless of what fastenings are used. If the vessels remaining service life meets the requirements of your business plan's time line then what the "CENSORED". Surveyors, pshhhh :roll:
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Re: Stainless fasteners below waterline.

Postby doryman » Fri Feb 13, 2015 10:19 am

What boldventure said. Dont worry about it. Pulled several ss fasteners out in my boat that were put in c. 1986. Looked brand new. I refastened two years ago with stainless on advice from a very well known shipwright. He said no worries, that is all he uses. The dipped galvanized crap from china these days WILL NOT LAST. Shipwright told me about two instances where they corroded and failed in 3 years. Silicon bronze is probably the best way to go but the price is prohibitive-but you would never have any "bleeders" again. I think with proper maint., zincs, etc. nothing to worry about. I know of many boats that have stainless below waterline with no problems. I think some of these stories of failure are ISOLATED instances that get blown way out of proportion in the survey industry-there is usually more to the story i.e. electrolysis. Bought my boat knowing of stainless below waterline-never looked back. Go fishing-I promise you there will be lots of other stuff to "worry" about.
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Re: Stainless fasteners below waterline.

Postby elhewman » Fri Feb 13, 2015 10:57 am

Thanks everyone, I will at-least look into a little bit it further. After looking at bronze, holly cow its expensive!! Always learning something.
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Re: Stainless fasteners below waterline.

Postby kjwelder » Fri Feb 13, 2015 9:42 pm

There are no perfect boats or permanent projects. Make the best of your options and keep moving forward.
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Re: Stainless fasteners below waterline.

Postby Salty » Sat Feb 14, 2015 7:15 am

I agree with much of the sentiment here. You can never get it all done perfectly and keep it that way. Do the best time and money will allow. Prioriitize safety over cosmetics when budgeting.
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Re: Stainless fasteners below waterline.

Postby Trnaround » Mon Feb 16, 2015 11:24 am

This article may be helpful http://www.estainlesssteel.com/corrosion.shtml
One thing to be aware of, especially if you are using SS chain( which I do) that there is a potential problem with using a SS shackle. The shackle is subject to crevice corrosion (no oxygen getting to the steel in the threads)and over time can weaken. I have heard of a couple of people loosing their stabilizer when the shackle just failed. Might want to open them up and look at them once in awhile if you are using SS shackles below the water line.
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Re: Stainless fasteners below waterline.

Postby joeman79 » Mon Feb 16, 2015 2:20 pm

Trnaround wrote:This article may be helpful http://www.estainlesssteel.com/corrosion.shtml
One thing to be aware of, especially if you are using SS chain( which I do) that there is a potential problem with using a SS shackle. The shackle is subject to crevice corrosion (no oxygen getting to the steel in the threads)and over time can weaken. I have heard of a couple of people loosing their stabilizer when the shackle just failed. Might want to open them up and look at them once in awhile if you are using SS shackles below the water line.

I CAN RELATE!!! Was 12 miles off Cape Addington in 10 ft Seas when a SS Shackle gave way and the Trolling Pole Slammed against the House!! Pin must have fell out. Lost 2 Totes of Gear and New Generator off top of the House!! Was a scary Moment in my life as a deckhand!! But everything turned out fine!!
Last edited by joeman79 on Mon Feb 16, 2015 2:45 pm, edited 1 time in total.
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Re: Stainless fasteners below waterline.

Postby JKD » Mon Feb 16, 2015 2:33 pm

I heartily agree with Trnaround - I lost a plywood stabie on my last boat due to a SS shackle breaking in tough weather. The shackle wasn't in direct contact with the water. Since that happened I have heard that the cheesy 5/8-inch foreign SS stabie line swivels can also come-apart under strain.

Seeing as we are on the topic of SS fasteners, I would recommend that it's a good idea to check on your SS "quicklinks" used in various places in a troller's rigging, too. I have had a couple of the smaller units fail under stress. The first one opened-up when the threaded collar split and disappeared. This was under the surface as part of my stabie retrieval system [on the third spool of my starboard gurdies] so I didn't lose anything. The second one was on the end of a trolling wire where I attach my isolator - between the wire and the cannonball. I noticed that there appeared to be a rust "smudge" on one end of the link so I checked it closely and there were some hair-line fractures on the end which was in contact with the trolling wire. I hadn't really considered the possibility of these links failing, but I replaced every one being used on the boat and I now try to check each one regularly for signs of failure.
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Re: Stainless fasteners below waterline.

Postby Trnaround » Mon Feb 16, 2015 2:43 pm

Worst time for something to fail is when you need it the most. (is that redundant ?) That shackle is an important one. Tip: it is a good policy to use a little grease on the threads whenever you tighten a SS nut or shackle down.
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Re: Stainless fasteners below waterline.

Postby Lulu » Mon Mar 02, 2015 9:21 pm

Agree with the comments. I use galvanize anchor shackles on the floopers. They're built a little sturdier and always use neverseeze on the threads. Another trick is to use a sport boat style zinc on the flopper fin if it is stainless. Mine are and the zinc lasts a season.
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Re: Stainless fasteners below waterline.

Postby akexplorer » Sun Mar 15, 2015 6:18 pm

Why would you put a SS shaft in (or fasteners, rudder, etc) if they are "active" and not "passive". SS fasteners are an upgrade. If your boat eats them up then it has electrical issues, needs to be zinced better, both or bonded.
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