Shaft Zincs

romiaway06

romiaway06

New Member
Nov 16, 2008
13
Long Island, NY
Boat Info
48 Sundancer 2006
Engines
Cummins 540
MarineMax does not put Zincs on shafts. My next door slip mate a 52 Sedan Bridge ended up with a $9000 bill to replace his props after his first season because of no zincs on shafts, Comments Please!
 
sea ray do NOT put zincs on shafts on new boats.
loose zincs may cause expensive damage.
bonding system on your boat should protect shaft and prop (assuming that bonding system is in good condition - no rust, lose wires etc)
If you have extensive corrosion - check your electrical system, but your neighbours boats with electrical problems may speed-up corrosion on yours under water gear.
 
I've never heard of "expensive damage" caused by a loose shaft zinc. Documentation?

In the "Boatowner's Illustrated Handbook of Wiring" there is an excerpt from the ABYC Standard E-2.4, Cathodic Protection of Boats:

2.4(l)(1):

"Propeller shafts do not provide reliable electrical continuity to the boat's bonding system without brushes and/or slip rings and brushes"

So, if SR says "no" to shaft zincs- they'd better be providing shaft brushes. Did his boat have them?

For that kind of money, I'd hire an expert to determine if the cause of corrosion was an improperly or un-bonded shaft. If SR did not install shaft brushes, and they refuse to install zincs, I'd be handing them the bill...
 
The bonding system should be checked to make sure that all underwater metalic parts are bonded. The erorsion of the props in one year says that there is a significant source of stray current in the water. That source better be identified or else there will be further damage to other underwater metalic parts. Given the noble nature of nibral versus zincs, zincs on the shafts would have been gone very quickly. I know on my boat that every thing is bonded except the trim tabs which have zincs on them. It would also seem to me that a boat that size would have a zinc saver system on it, so there would seem to be much more to this story.
 
Install a set of shaft brushes and forget about the shaft zincs forever.
 
tobnpr said:
I've never heard of "expensive damage" caused by a loose shaft zinc. Documentation?......
Click to expand...


This is what happens when they let the teenage part-time yard monkey install a shaft zinc......

P5130005.jpg


Luckily I caught this 'before' it got expensive......

This was caught just as the soft zinc was wearing against the strut 'and' just befoe the harder stainless steel nut/bolt had a chance to start working on the strut itself.

The zinc didn't quite make it to the bushing, so I was spared the expensive repair.

That zinc was only placed on the shaft for a few hours....installed March....that pic was early May.
 
The other issue is throwing the zinc off. You have roughly a 50% change of slinging a good sized hunk of scrap metal at your hull when one of the bolts snaps.

But, I use them. I never let the yard guys put them on during a bottom job and do it myself just before splashing. If you put them on correctly and seat the annode as you tighten the bolts they are fine. Shafts and props are expensive; zincs are cheap by comparison, and there is some room to debate whether those parts are adequately bonded since you are relying on transmission bearings and splined shafting as a contact points for bonding. Sea Ray omits them after about 1997-98 as a cost savings measure, not because they aren't a good thing.
 
osd9 said:
This is what happens when they let the teenage part-time yard monkey install a shaft zinc......

P5130005.jpg


Luckily I caught this 'before' it got expensive......

This was caught just as the soft zinc was wearing against the strut 'and' just befoe the harder stainless steel nut/bolt had a chance to start working on the strut itself.

The zinc didn't quite make it to the bushing, so I was spared the expensive repair.

That zinc was only placed on the shaft for a few hours....installed March....that pic was early May.
Click to expand...
The issue with this displaced shaft zinc is that the water flow to the cutlass bearing is obstructed.

In a proper setup, the front of the strut has a larger opening created because the bearing stops a coupla inches short, that scoups water through the bearing ribs.

Running the boat w/ the zinc out-of-place would cause excess wear on the bearing.
 
wingless said:
The issue with this displaced shaft zinc is that the water flow to the cutlass bearing is obstructed.

In a proper setup, the front of the strut has a larger opening created because the bearing stops a coupla inches short, that scoups water through the bearing ribs.

Running the boat w/ the zinc out-of-place would cause excess wear on the bearing.
Click to expand...

Very good point......also a good reason to install the zinc closer to the hull than closer to the strut.
 
I was hesitant to install shaft zinc's due to some recomendations. But to my suprise when I pulled her this spring I found MM had installed shaft zinc's and they were deteriorated. So I will put them back every season. Cheap fix.
 
I saw a guy use a zip tie to stop a wayward shaft zinc. He said it works. HE installed a zip tie between the strutt and the zinc. He claims the same zip tie has been in place for 4 years and has never moved. Just something to think about.

Rob
 
When we first bought our boat 2 years ago, there were no shaft zincs on it.
So....... me being me, put them on..........
We did a lot of cruising last year and on our last trip in October, we heard a very, very loud thump / bump.
I of course brought it down and thought I had hit a hidden crab pot. We saw and found nothing around. So I proceeded along.

When we pulled the boat in last November, I noticed a ding / dent in the starboard prop. A rather small one but also 1 of the shaft zincs was gone.
I had the props done and tuned by Miller Island Props and put them back on.
When prepping the bottom before launch this spring, I then noticed a small ding.. and a scuff, scuff on the hull behind the prop going in the direction of the prop rotation.

Wa... la..

I now know what the noise was and I will not put shaft zincs back on.
 
Last edited:
Nope......
Boat is 10 years old, no evidence of any previous proplems.
 
Jacob installed shaft brushes and talked about them here. I am going to seriously look at this option for next season....it's too late this year.
 
Thanks osd9.
I did sea that about the brushes and I am thinkin about it.

Right now, I'm actually done with this years projects and I am anxious to just start using the boat.

It's running perfect again!

Maybe next year?
 
wingless said:
Will you be bonding the shafts or just replacing the props and shafts frequently?
Click to expand...

So where are all these Sea Rays from the past ten years piling up their props and shafts?

Should be a pile somewhere if its frequent right?
 
efizjb said:
So where are all these Sea Rays from the past ten years piling up their props and shafts?

Should be a pile somewhere if its frequent right?
Click to expand...

I don't think anyone said it's frequent. It's possible to achieve bonding through the transmission, but it's unreliable. Not to mention the boat's environment. I'm on a private canal surrounded mostly by small boats, most of which are lift-kept. Not a boat within a hundred yards of me on shorepower, so stray current- a main cause of electrolysis- is not a factor for me. I replace my zincs every year, even though sometimes they don't even need it then. In a crowded marina, with a gazillion boats leaking stray current into the water, it's a different story. I would always have either shaft zincs or bond them with brushes.
 
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