Are fin-shaped annodes needed?

Rokomo

Cadet
Joined
Sep 26, 2017
Messages
8
Hi everyone. I'm new to this forum and have questions about trim tab annodes...
I realize that many people use fin shaped annodes to fine tune their steering issues, but if their primary purpose is to prevent galvanic corrosion, then who cares what shape they are and why do we try to use them for steering ??
is there any reason a flat disc shaped or a half spherical shaped or a simple block shaped annode wouldn't prevent corrosion as well as a fin shaped one ?
 

garbageguy

Lieutenant Commander
Joined
May 8, 2012
Messages
1,531
Hello. Can you post some pictures of what you're asking about, and identify what type of drive system? I think that will help to get you the answers your looking for.
 

Rokomo

Cadet
Joined
Sep 26, 2017
Messages
8
Props and Annodes

Hello all- here's a question: why are anti corrosion annodes located where they are, so close to the turning prop ? Is there some way that the spinning prop creates a lot of corrosion in that specific area ??? Or could you put your annode somewhere else on the motor or out drive and it would prevent corrosion just as well ?
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Many drives have flat flush faced anodes here (if it's where I think you mean) usually fin shaped Ines are found on outboards that occasionally require fine tuning to counter listing or steering issues caused by tourque or prop steer caused due to a lack of steering resistance found on a cable type set up.
Most Mercruiser drives won't have a fin. Just a counter sunk flush fitting flat one.
 

ahicks

Captain
Joined
Sep 16, 2013
Messages
3,957
Hello all- here's a question: why are anti corrosion annodes located where they are, so close to the turning prop ? Is there some way that the spinning prop creates a lot of corrosion in that specific area ??? Or could you put your annode somewhere else on the motor or out drive and it would prevent corrosion just as well ?

I think it's just a convenient place for it. It's protecting the prop while at rest where it's at. Another location might be fine - as long as you could be assured it would provide the same level of corrosion protection. Myself, thinking it would be tough to beat all the experience Mercury has accumulated, when selecting the place it is now.
 
Last edited:

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
OMC outboard trim tabs are painted so their primary purpose is steering & cooling with no corrosion protection.
Mercury use them for steering & corrosion protection with no cooling built in.
 
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