Yamaha F250 and Thruster Zincs

[Fishtales]

I just ordered them for next year. I use boat zincs on the web. Just sharing as the prices are good... Don't forget aluminum for saltwater.

For the Sidepower SP55Si thruster (I change this every year): SM71190A. This is made from aluminum.
For the F250s, 6GS-45251-01 strap and the 61A-45371-00 Trim Tab. I change these every two years. These are made from zinc.

 

[Meanwhile]

Thanks. I order mine over the winter. Gives me something to do as I'm retired.

 

[Fishtales]

So I get the zincs today and they are lighter in color and weigh less than I'm accustomed to. I tried the white vinegar test (turns black on magnesium and stays clear on aluminum).
It stays clear, but I still think the weight is off. Sent a mail to boatzincs to check.

 

[Fishtales]

The plot thickens...

I guess anodes can be made from one of (3) materials - zinc, aluminum and magnesium. In the past magnesium was for freshwater and zinc for saltwater. Aluminum can be used in either salt or fresh. I'm told new Yamaha engines ship with aluminum anodes now; which seems to make sense as the motors can be used in salt or fresh water with no issue. The downside is all sacrificial metal anodes should be the same material for each piece of equipment. I know the sacrificial anode strap "aka handle" zincs at the base of the outboard bracket are zinc on my engines, the spares I have in the cellar are zinc as well as the internal sacrificial anodes inside the engine. So, I'm going to swap the aluminum trim tab sacrificial anodes out for zinc to ensure I keep everything the same on the engines.

The sacrificial metal for the thruster has always been aluminum, so I'll stay with it. I believe it is the only metal offered for that anyway.

One thing I notice is that aluminum does not last as long as zinc in the saltwater. I end up changing the engine zinc sacrificials out every 2 years (could probably get 3) but the aluminum sacrificial on the thruster one needs to get changed every year. Not sure if this is because it is always submerged or is the material itself.

 

[journeyman]

Good Info.

One thing I notice is that aluminum does not last as long as zinc in the saltwater. I end up changing the engine zinc sacrificials out every 2 years (could probably get 3) but the aluminum sacrificial on the thruster one needs to get changed every year. Not sure if this is because it is always submerged or is the material itself.

Same here. Thruster every year. And it NEEDS it! Not convinced it a submerged thing though. The anode on my engine bracket is always submerged and it goes several years... Think you're on track with the difference in metallurgy.

 

[Fishtales]

I'd say your right. I don't think the aluminum one on the thruster would even last 2 years. When prepping in the spring the 33 next to me didn't have the thruster anode. One of the blades on the thruster was missing as well. It was a reminder - change it every year.