Propeller residue...normal/not normal?

[Walsh0575]

Hi, I'm a first time sailboat owner as of spring 2022 - so this fall was the first time I hauled the boat for winter storage. Here is a picture of my propeller. Is this white residue normal? Should I / can I remove it? Should I do anything to prevent this from happening next season?

- Looking at pictures from spring launch '22 it looks the same - but that doesn't mean the past owner was caring for it properly
- You'll note in the picture my zinc is nearly depleted, will replace that before launch in spring
- I'm in saltwater

Thanks.

 

[dmax]

It looks to me that the PO sprayed the prop and shaft with cold-galvanizing spray paint (zinc): Rust-Oleum Professional 20 oz. Flat Gray Cold Galvanizing Compound Spray 7585838 - The Home Depot
I use it on my prop and shaft and have no barnicle problems. If that's the case, you can lightly sand it and spray it again in the spring. Additionally, you should have two zinc anodes on your prop shat - you can see that the one is pretty eaten. Make sure the anodes have good electrical contact with the shaft (sand down to the metal).

 

[JamesG161]

Is this white residue normal?

It depends on the material of construction for the propeller.
Do you have that information?

Jim...

PS: It is not the white residue that is important, but the trailing edges of the propeller for corrosion.

 

[Don S/V ILLusion]

PS: It is not the white residue that is important, but the trailing edges of the propeller for corrosion.

upon review, I think JAmes made a good observation - the prop tips don’t look good and should be examined closely. Maybe a result of that single zinc long past it’s useful life.

 

[Rich Stidger]

I have used the Rust-Oleum-Professional-20-oz-Flat-Gray-Cold-Galvanizing-Compound-Spray-7585838/100142963 for years and have observed the same whiteness at haul-out. I believe that it is exactly the same product as the Pettit barnacle spray product except it is $8 instead of $30 and the can is 25% larger. To me the trailing edges of the blades look to have pits in the spray paint vs a corrosion problem, but it is hard to tell from a photo. Once you sand it should be obvious.
And yes, given the condition of the zinc, I would place two of them on the shaft. If next year the zincs are in the same condition, I would investigate electrolysis leakage.

 

[Walsh0575]

@dmax thanks...interesting...I never thought it was intentionally sprayed as a protectant. Good to know...I'll re-coat it this spring after a light sanding. I'll grease it after that. Also, never thought of putting two zincs on the shaft. The PO was in a brackish marina and when I received the boat in the spring '22 the past year's zinc was in not too bad shape, but I replaced it anyway. I keep mine on a mooring in a harbor and was surprised by how much the new zinc corroded this season! I'll put two on this spring.

@JamesG161 The prop is a Max Prop 2 Classic which I believe is bronze?

 

[Don S/V ILLusion]

was surprised by how much the new zinc corroded this season! I'll put two on this spring.

adding multiple zincs serve only to magnify the “battery effect” of more anode and isn’t a solution to a corrosion problem. It merely prolongs it. You are better served finding out if the prop is as badly corroded as it appears in the picture and,if so, finding out the source(s) of electrolysis causing it.

 

[JamesG161]

adding multiple zincs serve only to magnify the “battery effect” of more anode

Or protect the Stainless shaft, and the Zincs do help protect a Bronze Props too.

Jim...

 

[JamesG161]

The prop is a Max Prop 2 Classic which I believe is bronze?

There is more than paint needed on your propeller, much more.
I am uploading the instructions for you

 

[JamesG161]

You are better served finding out if the prop is as badly corroded as it appears in the picture

There is more to the Galvanic protection on his Max Prop 2 Classic

see the instructions from PYI, I linked him.

Jim...

 

[fstbttms]

adding multiple zincs serve only to magnify the “battery effect”...

Not true. Using two shaft anodes is very common and in fact provides twice the protection of a single anode. And considering the state of the anode in the pic, installing two next season would be a wise move.

 

[Don S/V ILLusion]

Not true. Using two shaft anodes is very common and in fact provides twice the protection of a single anode. And considering the state of the anode in the pic, installing two next season would be a wise move.

Here we go again. Simple explanation:
when you have any anode, it provides an enhanced electrical path in the presence of any voltage potential. Adding more anode ”spreads out the anode circuit surface but changes nothing to affect the catholic side and can exacerbate the current flow. Whether doing anything common is irrelevant -lots of people simply don’t understand the theory. Don’t add to the myth.

 

[fstbttms]

Here we go again. Simple explanation:
when you have any anode, it provides an enhanced electrical path in the presence of any voltage potential. Adding more anode ”spreads out the anode circuit surface but changes nothing to affect the catholic side and can exacerbate the current flow. Whether doing anything common is irrelevant -lots of people simply don’t understand the theory. Don’t add to the myth.

"The amount of protection a zinc anode provides depends on its surface area. The zinc surface area needed varies with the kind of metal being protected and with the chemical makeup of the water, but you can use 1% of the surface area of the protected metal as a starting point. Check the protected metal frequently. If it shows signs of corrosion despite the zinc, you need more surface area."

You seem to make the assumption that a single collar anode will provide enough protection, regardless of how much metal it's being asked to protect. That is simply not true.

 

[Don S/V ILLusion]

,

You seem to make the assumption that a single collar anode will provide enough protection, regardless of how much metal it's being asked to protect.

no cherry picking internet excerpts needed. We’re talking about the OP’s 2 blade prop.

 

[JamesG161]

Per the science...

Mass Transfer Rate depends on ...

1) The Force [Galvanic Potential]
2) The Flux [Electrons flow/ Surface Area exposed]

The Analogy for Water flow
1) The Force [Pressure]
2) The Flux [gal/minute / pipe cross sectional Area]

Both @Don S/V ILLusion and @fstbttms are correct.

But a different view the elephant, so to speak.

Jim...

 

[NYSail]

Like was said, looks like paint…… my prop looks the same at haulout. If you have concerns about the prop, pull it off and send it to the manufacturer for an over haul. I hey will let you know what is what.

In regards to the zinc, do you know when it was last changed? Some boats that dont come out of the water don’t change them regularly….. it may be 2+ years old and in that case the wear looks fine. Though on my boats I always have used 2 (1 shaft collar and one prop) as I am in a marina and am always plugged in during week when we are home.
Greg

 

[JamesG161]

If all would read the PDF file for his Max Prop 2 Classic
My Post #9
There is a Zinc built into that propeller. That MUST be changed in addition to the Shaft Zinc !!!

Jim...

PS: 2 Degreed Chemical Engineer with SBO moderator powers too. Keep the discussion to help @Walsh0575 please.

 

[fstbttms]

If all would read the PDF file for his Max Prop 2 Classic
My Post #9
There is a Zinc built into that propeller. That MUST be changed in addition to the Shaft Zinc !!!

Older model Max Prop 2-blade Classics do not have an anode. This is the prop the OP has.

 

[JamesG161]

Per @Walsh0575

@JamesG161 The prop is a Max Prop 2 Classic which I believe is bronze?

Now from the manual..


Also he needs to grease his propeller too.

Jim...

 

[fstbttms]

Now from the manual..
View attachment 211184

That diagram is for a Max Prop mounted on a saildrive. The OP does not have a saildrive.