Trim tabs + paint ????????

[Bay Runner]

Bryan A,
Do you have a battery charger on you boat and do you keep it plugged in to shore? It sounds like you might be "leaking electricity" from your boat.

[Trayder]

Bay Runner

same with my boat, it sits on a mooring, no other boats around, not pugged in, all power off except the direct wiring to the bilge pump(s) yet I go through two sets a year.


but....the anodes on the outboards stay fine, even the two that stay submerged on the lower half of the engine mount. and there is no deterioration of any of the thu-hulls or other submerged metals.

Do you think it is still stray current or just the fact the reaction of the SS from the tabs with zinc is greater as opposed to the zinc against the aluminum on the outboard?

[hermco]

For corrosion to occur, four elements must be in place. These are:

Two dissimilar metals.

A connection between the two metals.

An electrolyte, such as water.

A potential difference between the two metals.

Therefore you have S.S. tabs with S.S. mounting screws,no dissimilar metals,little or no corrosion, and you are adding a zinc making the difference and the zinc being the most active it is eaten away. Save your money buying zincs and leave the tabs alone. Do not paint them or put zincs on them and they will give you many years of service.

Using the boat occasionally will cut down on the barnacle growth. The boat has to be stationary for some time to allow growth to begin. Frequent use will also contribute to the economy due to incresed fuel usage which will allow the oil companies to make more profits which will equate to stockholder earnings which will allow stockholders to buy more stuff which will allow mfg.s to hire more workers to build the stuff! Trickle down economics! So don't use those zincs!

[Trayder]

Using the boat occasionally will cut down on the barnacle growth. The boat has to be stationary for some time to allow growth to begin. Frequent use will also contribute to the economy due to incresed fuel usage which will allow the oil companies to make more profits which will equate to stockholder earnings which will allow stockholders to buy more stuff which will allow mfg.s to hire more workers to build the stuff! Trickle down economics! So don't use those zincs!

thanks Don I will follow your advise and I think the above section of your post is one of the best reads I have had in a while

tx

[paulfurnari]

Hermco, are you saying we don't need zincs or paint on our trim tabs even if the boat is stays in all season. No corrosion, no growth. Please explain?-PF

[hermco]

I am saying that galvanic corrosion is a well understood reaction between two dissimilar metals immersed in an electrolyte.

http://www.engineersedge.com/corrosi..._corrosion.htm

And that a moving boat does not grow barnacles. (Sorry no documentation to prove this but I believe it to be true)

[hermco]

Barnacle Reproduction

Surprisingly, the sexes of barnacles are separate, males having proportionately probably the largest penis in the animal kingdom. It reaches out of the shell and transfers its sperm to a female neighbour. After fertilisation the female barnacle broods its eggs until they hatch as a minute cypris larva which swims until it is ready to settle head-down on a suitable surface.

[Bryan A.]

Interesting.

[RS]

Therefore you have S.S. tabs with S.S. mounting screws,no dissimilar metals,little or no corrosion, and you are adding a zinc making the difference and the zinc being the most active it is eaten away. Save your money buying zincs and leave the tabs alone. Do not paint them or put zincs on them and they will give you many years of service.

But wouldn't this put the outdrive/ouboard at greater risk since its aluminum becomes the least noble disimilar metal in the equation?

Why not just include the tabs in the boat's bonding system?

[Bay Runner]

Hermco,
Thanks for more scientific reasoning. The dissimilar metal issue had not waived a flag but you are correct.
Thanks again,