Nobility question

[Donald Tyson]

If I attached a stainless bow roller to an aluminum deck plate would I need to isolate them somehow against corrosion? Some charts online say yes and some no. It seems to me that there would be issues.

[thataway]

There us no way to insulate in this case. Use TefGel on the SS Screw threads into the Aluminum plate. I would not hurt to use a gasket material between the two also. SS fittings onto boat aluminum boat masts all of the time. There can be minor corrosion and galling, but watch out for it, and nip in the bud when you see it occurring.

[rogerbum]

I wouldn't say that there's no way to isolate it. Use a gasket between the two pieces, cut some delrin inserts to custom length to isolate the body of the bolts and use nylon washers to isolate the heads of the bolts or the nuts (depending on which side would normally come in contact with the aluminum piece). This is what I did to isolate the stainless steel handrail on the Tomcat from the aluminum bracket.

[Donald Tyson]

I'm sorry to carry some of the most basic conversations so far but the truth is I'm learning at such a speedy rate. And I finally have a real boat to apply the knowledge to.

My Bow roller is so short that it won't allow the use of my favorite anchor (a very pointy Fortress). A new but longer bow roller will cost a monthly boat pmt. I reason that I can find a 1.5x4" piece of channel from Stainless or Aluminum and use it as an attachment to push that roller out further. By doing so it will also accept the longer fluke style anchors and also a (hopefully) future delta style or plow type anchor.

I believe the correct washers and protection could go a long way to avoid issues. Of course I may find a piece of stainless where there would be no issues. But is properly isolated I could even use alluminum.

[srbaum]

Another method to isolate is to coat all cells contact surfaces with Lanocote. It’s inexpensive and has been used in the maritime industry for metal isolation for years. I have a 4 oz tub of Lanocote and a 4 oz tub of TefGel. I coat every metal fastener with Tefgel and all larger metal surfaces with Lanocote. This even includes trailer work.

[Peter & Judy]

I have used Butyl 2 sided tape when attaching things like my swim ladder to the deck. It should provide isolation between the layers and is waterproof as well.

[Donald Tyson]

That's cheat'n! Aren't ya supposed to let the corrosion get a good foothold first?
I will have my tub of lanacote soon.

[Donald Tyson]

interesting as I was considering that.

[tsturm]

[Donald Tyson]

Use 5086 Alu. and you won't have an issue. [/quote]

I initially brought this question up while trying to avoid the great expense of buying a new and longer brand name bow roller. I had figured on visiting a local scrap yard or two and get a used 1 1/2' x 4" piece of channel to bolt on the front. If I do that it won't be likely I could know what the actual variant that the Aluminum channel is. So I'll stick to stainless steel. Thanks for introducing us to this special alloy 5086 for marine use. I did find that it will corrode when mated with Stinless...just not badly. I'd still have had to Isolate it with something.

[clayhubler]

There are different grades of stainless also and the lesser grades will rust too. Even high grades that are contaminated with carbon steel will get rust spots on them. Contamination can happen simply by using the same saw or file that has been used on carbon steel.

My roof rack and fillet table bars have rusted even though I used 316L grade tubing. I have wondered if there is anything I can do to prevent this. Is there a conditioner oil or wax I could apply that would make a difference? I notice the bow rail never looks rusted but it also kind of looks like it’s been electro polished.

[Donald Tyson]

This topic always scares me as well as I feel helpless to determine how to avoid it. It's often called Crevis corrosion when referring to stainless. I've found nice knives in streams while fishing, thinking I found treasure. When I look closer all the blades are almost rusted off. There are treatments and there are tapes and things but I have no experience with this subject but to know not to join to wildly different metals.
I found this from a British steel site and it may lead you to other conclusions as well:
https://www.heskins.us/products/corrosion-protection-tape?

[thataway]

I have used Collinite 885 Fleetwax on SS, after cleaing with the Collinite SS cleaner. I also use Collinite wax on my fiberglass. They have specialized products which work well.

I try and avoid any SS fittings made in China--even some labeled 316 have had more corrosion than I find expectable.

[Donald Tyson]

I like the sound of Collinite. It has Carnauba in it, same a Boeshield T9.