I am in the process of upgrading a few stainless fittings on my aluminum mast. I contacted the manufacturer, Goodall Design (formerly AHPC), to see how they attach the fittings. They use stainless rivets with a Duraloc Jointing compound.
I Googled Duralac Jointing Compound. It provides protection from galvanic corrosion due to the dissimilar metals. It looks like really good stuff to use for this application, but I can't find a supplier in the US.
Has anyone used this stuff? Do you know where to get it? Is there a functional equivalent sold under a different name here in the US?
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Jon -- Dallas, TX
Taipan 4.9
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Attaching mast fittings with SS rivets and Duralac Jointing Compound
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Posted: Sep 24, 2014 - 01:36 PM
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Posted: Sep 24, 2014 - 02:19 PM
http://www.apsltd.com/c-4…rotectionlubricants.aspx
Scroll to the bottom
I use LanoCote
Edited by nacra55 on Sep 24, 2014 - 02:20 PM.
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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Posted: Sep 24, 2014 - 03:07 PM
Many of the guys in Florida use the product at the very bottom of the page, Tef Gel.
It is useful to understand why/how galvanic corrosion occurs, & what can prevent it. In most of our Cat situations it is aluminum as the less noble metal, mating with SS. Al becomes the anode,(sacrifices)so never have a small AL part surrounded by a large, more noble part,(SS). This could occur by using Al rivets to hold a comparatively large SS part.
More expensive is not always better. Anything that promotes itself as "marine" will cost more. Ditto for a TSO'd product(aviation).
You can get very good protection, for little cost by using product designed for commercial transport, think buses & trucking.
ECK comes to mind.
Edited by Edchris177 on Sep 24, 2014 - 04:32 PM.
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Posted: Sep 26, 2014 - 09:14 AM
west marine also has a spray can of stuff that does the same thing... it's probably $20, but will last forever as you only need squirts... it dries to a tan rubbery substance... some folks use electrical tape... eventually the stickyness goes away, but the rubber stays put as a barrier between metals.. besides if you wash the boat a few times a year and pay attention to fittings, it probably won't be an issue for many many years.. -
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Posted: Sep 26, 2014 - 02:30 PM
All,
Thanks for the info. I have another related question. I am adding a halyard block designed for the Viper F16 to the top of my mast. My Taipan mast has the same cross section but the length of mast above the halyard lock is a little shorter than the Viper mast, so the upper holes of the mounting plate are above the top of the mast. I designed an aluminum plate which overlaps the halyard fitting and extends onto the mast to transfer the load to the mast.
In short, I have a sandwich of AL (mast)/ 16ga 316 stainless (viper block) / 16ga Aluminum (not anodized) (my cover plate) which will be riveted together. What should I do for corrosion protection? Should I paint anything? Is one of the above corrosion protectant sufficient? I would prefer using AL rivets, as my tool cannot pull stainless. Do I really need stainless rivets?
Thanks
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Jon -- Dallas, TX
Taipan 4.9
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Posted: Sep 26, 2014 - 03:05 PM
Another question... Given that this is at the top of the mast I want to be sure the rivet holes are water tight. What is the best process?
My plan is the following; coat the rivet in silicone, insert, pop, fill the center with silicone.
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Jon -- Dallas, TX
Taipan 4.9
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Posted: Sep 26, 2014 - 03:26 PM
$20 at harbor Fraight http://www.harborfreight.…ection-bottle-66422.html
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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Posted: Sep 26, 2014 - 03:27 PM
Also use http://www.murrays.com/19-5020.html
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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Posted: Sep 26, 2014 - 06:28 PM
If you make the sandwich you describe...YES
Please read my post above re a large cathode combined with a small anode, (Al river in SS).
You are operating in a warm, humid, salt environment. What you are doing in regards to the setup you propose is to build a battery, which results in a current. (Large SS plate sandwiched in AL, with salt moisture as an electrolyte) Nothing comes for free, in this case the Al rivet will disappear.
Isolate the two dissimilar metals with Tef Gel, ECK, etc.
Buy Monel or SS rivets & buy, or borrow a tool to pull them. The other option is to replace the Al rivets, frequently.
That is adequate, at least for as long as the rivet exists.
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Posted: Sep 26, 2014 - 08:09 PM
I got the message. Heading to Harbor freight to get the heavy duty rivet gun.
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Jon -- Dallas, TX
Taipan 4.9
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Posted: Sep 27, 2014 - 08:20 AM
For a bedding compound, I have had good results with 3M 5200. If you buy that Harbor Freight rivet gun, I suggest you buy two. Harbor Freight tools tend to break quickly.
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Posted: Oct 19, 2014 - 08:05 PM
Quick update. I completed my project adding a halyard to my Taipan. See attached image. You advice was appreciated
As I mentioned earlier, my mast is a little shorter that the new Goodall Viper mast, so I had to be a little creative. I built the white plates to transfer the load from the upper rivet to the mast. I used stainless rivets and sealed the whole thing with 3M 5200.
I also purchased the Harbor Freight heavy duty rivet puller. It worked flawlessly for 10 rivets. I bet I will get at least 100 rivet pulls out of it. Which for me is a lifetime worth of use.
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Jon -- Dallas, TX
Taipan 4.9
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