SS trimtabs...add copper sheet metal to keep the barnacles off?

[A_8]

Maybe its just me but I have tried everything getting the paint to stick to my SS trimtabs but it all just falls off eventually resulting in a huge barnacle build up and then all the work getting them off etc.

The idea to attach a copper sheet metal to the downward surface of the ss tabs have sort of been lingering in my mind for a while but worries about electrolysis/galvanic issues have held me back but now its come to a point when I am almost ready to try.

Any metallurgies or other experience on here who can advice how to make it work? For example should I let the copper electrically float in relation to the tabs and the rest of the ground circuits on the boat, should I connect the copper and ss tabs and let them electrically float in relation to the rest, should I connect everything and keep copper, zink anodes and the ss tabs connected?

I've got a pair of aluminum outdrives in the back as well so its really a bit of a mess from a galvanic point of view.

 

[jrudge]

I suspect this is not a good idea.

http://en.wikipedia.org/wiki/Galvanic_corrosion

 

[A_8]

I suspect this is not a good idea.

http://en.wikipedia.org/wiki/Galvanic_corrosion

Thats what I've been thinking but if you consider it in terms of galvanic series http://en.wikipedia.org/wiki/Galvanic_series and keepng the anodes (maybe adding a bit), the zink is still the most sacrificial followed but the Al in the legs and then the Cu so will I really change the dynamics of this adding the copper sheet metal?

 

[[2068]]

Thats what I've been thinking but if you consider it in terms of galvanic series http://en.wikipedia.org/wiki/Galvanic_series and keepng the anodes (maybe adding a bit), the zink is still the most sacrificial followed but the Al in the legs and then the Cu so will I really change the dynamics of this adding the copper sheet metal?

You'll be making a battery ... could be used to power some very small underwater lights?
Let us know how it dissolves, or goes?

 

[Portofino]

Why not replace the Al tabs .
Go to a kitchen shop get some acetate chopping boards -plate these with copper .
Easy material to work with , drill bolt through etc .

 

[A_8]

You'll be making a battery ... could be used to power some very small underwater lights?
Let us know how it dissolves, or goes?

How is it not a battery already?

 

[sarabande]

"metallurgies " nice work to describe corrosion effects.

 

[[2068]]

How is it not a battery already?

The difference is, you will be putting the dissimilar metals very, very close together.

 

[A_8]

The difference is, you will be putting the dissimilar metals very, very close together.

Agreed but the Zn, SS and Al are pretty close already, I am just adding another and still zink is the most sacrificial or anodic so as long as there is enough Zn it will get sacrificed first or I am missing something?

 

[[2068]]

Agreed but the Zn, SS and Al are pretty close already, I am just adding another and still zink is the most sacrificial or anodic so as long as there is enough Zn it will get sacrificed first or I am missing something?

You're right, it's close, but I still think you will lose a bit more SS than if the copper was not there.

 

[PCUK]

Use Coppercoat. No galvanic problems and does the job.

 

[GrahamHR]

"Thinking out of the box" an inherited phrase from when I was employed gainfully by a US company, why aren't tabs made of GRP/ CRP ; so no possibility of corrosion?