Prop Zincs lasting only 2 to 3 months

R

River Bank

Well-known member
Joined
Apr 27, 2013
Messages
115
Fluid Motion Model
C-248 C
Vessel Name
RIVER BANK
My 2010 R25 is having its prop zinc chewed up every couple of months.

Is it because of the there is a connection between the prop (shaft) and the rudder (which does not have a zinc)?

Seems to me my Prop zinc has to take care (protect) too much metal.

Would a simple "shaft" zinc help with this problem? I couldn't find the "shaft" diameter in the Ranger manual.

Another possible solution would be to attach a zinc directly onto the rudder, however I need a diver or have the boat hauled out for the attachment.

Any suggestions?
 
Are you in a marina slip? There could very well be a boat nearby that is causing the issue. You could try a zinc with a cable right off the battery or a galvanic isolator.
 
I had the same problem on my R27. The prop zinc is protecting the prop, prop shaft, rudder, and through-hulls. They are bonded together. The thruster gear legs are isolated and protected by their own anodes which are aluminum. The trim tabs are also isolated and should have zincs installed on each one.

I am at a marina connected to shore power most of the time so I installed a galvanic isolator, this keeps my zinc from protecting other boats at the dock. I also use a hanging zinc (from Boatzincs.com) and connect it to the battery negative post when docked.

Even with the galvanic isolator the prop zinc alone was not adequate to last an entire season so supplemental protection is required. Some have installed a transom zinc, others use a hanging zinc. The transom zinc is more work to install but is automatic, you do not need to remember to hang the zinc when you dock.

I was also burning through trim tab zincs pretty fast even though they are not bonded to the rest of the system. This is probably because they were not painted and there is a lot of surface area to protect, the small zinc would not last long. I now have painted the tabs with two coats of Interprotect 2000E followed with bottom paint. The trim tab zincs now last all season and are about half consumed when I have the boat hauled in the fall. If you do this be sure to mask the area where the zinc attaches so it has a good electrical connection to the tab.

If you search this site you will find more info.

Howard
 
Yes, I'm in a very busy marina.

The battery solution that you've suggested sounds good.

Where does one clip an attachment to an over the side zinc and to which battery (house, start or thruster)

Can you add anything to the "shaft" zinc solution?

What is the size (diameter in inches) of the shaft on my boat and it's general effectiveness?

Thank you for your reply.

Bob
 
Howard

Many thanks, I'll be talking to my electrician tomorrow.
I do like the more permanent solution with the "transom zinc."

Bob
 
You mention you have a 2010 R25.....have you had this boat since new? If so is the zinc consumption problem new to the boat? If so what has changed? As pointed out new slip, new marina or a new boat next to you that creates the problem. We added a galvanic isolator to help reduce this problem, but all the suggestions here are good ones.

Let us know what you find out and what path you decide to take and how things are working in three more months so we can all learn from your experience. Good luck,

Jim
 
River Bank":16fnrui8 said:
Yes, I'm in a very busy marina.

The battery solution that you've suggested sounds good.

Where does one clip an attachment to an over the side zinc and to which battery (house, start or thruster)

Can you add anything to the "shaft" zinc solution?

What is the size (diameter in inches) of the shaft on my boat and it's general effectiveness?

Thank you for your reply.

Bob
Click to expand...
You can clip it on any negative terminal of your batteries. The batteries should all be connected via the negative terminals, so any terminal should be good.
 
Thank you for all your inputs, this is what I'm going to do.

Install a over-the-side zinc and connect it to any battery negative terminal. Boatzinc.com $46.00.

Install a Galvanic Isolator, Promariner Prosafe 30W $316.00.

I am tentatively considering a "shaft" zinc if the above is not quite enough, maybe two? Just joking about the second one!

Last May I had the zincs checked and the new Prop anode installed.

Apparently the old one fell off as it simply wasn't there this May.

Had the Prop anode checked last week and it was 95% corroded away and was on the verge of simply breaking off.

Two months! How long had the previous Prop anode been missing? I shudder to think of it.

Next inspection will be early October when I have the boat hauled and inspected for corrosion damage etc. Fingers crossed.

In May I was told that those little Side-Power thruster aluminum anodes (SM3-1180A) were good for another 6 months .... they were changed out two months later (three days ago) only to find them actually 90% corroded away.

Both on the verge of breaking off of the securing bolt.

These little units cost $8.90 apiece from Boatzincs.com, local marinas don't seem to stock them here. I'm going to simply keep a spare pair on board and have them changed out whenever the other zincs are checked.

Whether you add a clam-shell zinc to your rudder or not, then the next time the boat is out of the water consider having an appropriate sized hole drilled through the rudder, so if you decide later to add one you can with a diver rather than a haul-out.

I've learned that zincs are very cheap, boats are very expensive!

Anyway that's the "plan."

Bob
 
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