Saltwater/Zinc's

[Morpheus]

That's what they are called right?

Ok I don't keep my boat in the water (trailer) but I do boat in saltwater.

Question how often do/should the zinc's be replaced.

It's been 1 year I took it into MM for it's 1 hr main (only about 50 hours on the boat) and well I pointed at the Prop hub zinc and asked if it should look that bad. It looked pretty bad compared to all the others.

It was suggested to go ahead and replace it (apx $12) so that will be happening.

I just wanted to see if that's normal. The tech said it goes quicker then the others cause the prop which seemed to make sense.

 

[Hampton]

Sounds normal to me. If they look bad, replace them. If not, let 'em go. Just don't let them wear out and fall off.

 

[Morpheus]

:thumbsup: Makes sense especially only costing about $12 for the prop one. Not sure how that one goes on and off but the others looked like they just had some screws and would be something I could do myself.

 

[tphinney]

My zincs have 3 years on them, but the boat is kept on a lift and it gets hosed off as soon as it comes out of the water. they still look fairly new even after 150 hours and serval over nights out at caladesi.

rememver they wont compare to a new boat thats ever been in the water, but they also should look like their complete corroded.

 

[Morpheus]

My zincs have 3 years on them, but the boat is kept on a lift and it gets hosed off as soon as it comes out of the water. they still look fairly new even after 150 hours and serval over nights out at caladesi.

rememver they wont compare to a new boat thats ever been in the water, but they also should look like their complete corroded.

The others looked fine. The ones on the shafts that raise/lower the outdrive were a little corroded but the others look new. The prop one though looked like it's been through a war.

I to hose off/flush within a couple of hours of being out of the water (depends how far I have to trailer home before it happens) but it's never just sat with saltwater on it.

 

[Dave S]

I had over 300 hours on my 2002 240SD when I sold it. The boat was dry stored but it was never necessary to change the anodes (zincs). Even if yours look a bit corroded, in all likelihood they do not require changing. Now if they look like this then change them out.:wow::wow:

These are from my 260DA after having the boat in the water for 13 months.

 

[Morpheus]

I should of taken a picture with my phone camera.

They all looked fairly smooth.

The prop one though looked worse then that picture looked like someone took a ice pick to it and put holes and chiped pieces off.

I pointed it out to the Tech who will be the one working on the boat and he recommended changing it. He said in the Florida waters most boats need them changed every year but was a little surpised at the ware on mine and suspected it was cause of the prop. If I got a stainless steal prop would that change things? I'm sure that's not cheap and the annode was only $12.

 

[Dave S]

The prop annode is the one that will likely corrode first because of it's proximity to the stainless B3 props. As long as the outdrive itself shows no signs of corroding, then the annodes are doing their job.:smt038

 

[Henry Boyd]

Morpheous,

The rate of corrosion is directly proportonal to the distance between the disimiar metals,i.e. zincs closest to the props (in the case of a BIII) will go at a faster rate.

Visual inspection of the zincs should not be used as a criteria for replacing them because as the chemical process progresses (zinc becoming zinc oxide) the zinc becomes coated with zinc oxide. In doing so the zinc becomes electrically insulated and becomes less effective.

As an illustration, anodizing aluminum is the intentional creation of aluminum oxide on the surface of pure aluminum. Aluminum oxide is both porous (absorbes dye great) and harder than pure aluminum. Anodizing is done by submerging the alu in a bath of acid and using sacricial electrodes, a current is run through the acid bath. The point is that the process is controlled by measuring the current through the circuit. The current will drop as the oxide layer increases (the oxide is acting as an insulator). Anodizers have developed curves to tell them how thick the oxide layer is by the level of current drop.

So yes, physical condition of the zinc tells you when it is exhuasted, but the performance of the zinc as protection decreases as the zinc (or magnesium) oxide increases. Moral is, newer zincs work better than old zincs.

So it is better to do a replacement at least annually, or when exhausted - whichever comes first. I do a mid season replacement on the Bravo trim piston zincs long about end of July, and the rest annually.

Henry