Zink installation

[gazelle]

I was wondering if there is anything I should know about installing zinc on my aluminum boat? It is a 33 year old boat and I just took it down to bare aluminum and am almost done painting. I did notice some pitting/corrosion on the bottom of the boat.

I would like to replace the zinc and I was wondering are there any rules of thumb?
1) How do you determine how big a piece?
2) do you just bolt it to the boat?
3) what type of bolt metal should I use?


Basically I want to do as much as possible to stop anymore corrosion to the boat. So if you have other suggestions please let me know

Boat details
21 ft starcraft chieftain (Al)
Will be docked in a freshwater marina for 6 months


thanks

 

[iwombat]

Re: Zink installation

Where is it now? There's usually a zinc on the anti-cavitation plate of your outdrive or outboard.

 

[gazelle]

Re: Zink installation

I currently have 4 pieces of Zinc on the boat. There are three pieces on the outboard and one on the transom. I removed the one on the transom to paint and plan on replacing it. The bolts that were holding it on had to be cut off since they were caulked to stop leakage. When replacing it I wanted to make sure that I use the proper size and mounting material.

The one that was on the transom was looking oxidized so that is why I am replacing it. The three on the motor look brand new so I did not plan on replacing them.

 

[iwombat]

Re: Zink installation

In simple terms you need a big enough zinc to not corrode prematurely so as to become inneffective. Sounds like you've got plenty of coverage with the annodes on your outdrive if they're not looking all that gnarly.

 

[gazelle]

Re: Zink installation

thanks iwombat

What about the bolts to hold it in place? Can I use any type or do I have to worry about a type that will promote corrosion?

 

[iwombat]

Re: Zink installation

You'll want to use stainless. If nothing else, so that you can take the annodes off and replace them later. Anything else will probably rust in place.