Anodes on trim tabs?

[Cresco750]

Hi
My boat is fiberglass with a Mercruiser outdrive and stainless steel trim tabs. Along with the anodes on the outdrive, I was wondering whether I should install zinc anodes on the trim tabs as well? I've seen this on some other boats, yet most don't. Interestingly, the hinge pin of the tabs has started to show some rust stains so i suspect they are made of some sort of ferrous metal? I might look at replacing the pins with a stainless steel rod if I can source the correct size.
The boat is used exclusively in the salt but stored on a dry stack.

 

[25thmustang]

Re: Anodes on trim tabs?

I have them on my tabs.

 

[IllesheimVet]

Re: Anodes on trim tabs?

^ X2 Installed them when I started getting pitting around the edges of the tabs.

 

[sasto]

Re: Anodes on trim tabs?

Normally not a problem when on the hard. Inspect the thru bolts used on the installation of the tabs from the inside. Is there a green (bonding) wire attached to a machine screw? If so... not much worry.


If you fell the need, your trim tab company makes one, or just buy an R-2 Zinc, drill out a 5/16th hole, and install.

Good Luck!

 

[Cresco750]

Re: Anodes on trim tabs?

Ok, thanks guys. As well as the possibility of getting pitting of the tabs themselves I'm wondering whether corrosion of he outdrive would be reduced with the addition of zinc on the trim tabs (dissimilar metals, etc?)?

 

[Bondo]

Re: Anodes on trim tabs?

I have them on my tabs.

Ayuh,... Ditto,.... I used ssteel carriage bolts to hold on a Mercruiser acorn anode to each tab...

 

[Tabman]

Re: Anodes on trim tabs?

Usually if the boat is not stored in salt water zinc anodes are not absolutely necessary. If the boat is kept in salt water then they must be installed unless the Trim Tab is connected to the boat's bonding system (that's the green wire satso mentioned), but that is usually only found on much larger boats.

I think it is a good idea to add zinc anodes to a boat used in salt water, even if it is dry stored. It's easy to do and provides inexpensive insurance in case you encounter stray current from a dock or another source.

We recommend installing one half of an R-3 zinc on the top of the Trim Tab using a 1/4" machine screw with the head of the screw on the bottom. One R-3 will do two Trim Tabs.

Make sure that there is no paint under the zinc so that it makes good electrical contact to the Trim Tab.

 

[Chris1956]

Re: Anodes on trim tabs?

Cresco, First of all there are different grades of stainless steel. Some show minor rusting. I had real small rust spots on the SS bow railing of my SeaRay.

Secondly Trim tabs do need zinc anodes. If you need to drill a hole in them, drill very slow and keep the bit cool. Otherwise the SS will harden itself and will be virtually undrillable. Machine shops often punch holes in Stainless Steel for that reason.