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Discussion Starter · #1 ·
Before my first season with my "new" boat, due to a number of circumstances (which had never occurred before and haven't since), I paid someone to prep and paint the bottom, including the prop and shaft. He used Propspeed on the prop and shaft, telling me that it was the best. It didn't work so great for me as you can see from the first picture. I think I had even removed some of the barnacles before this photo was taken.

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Given the lack of effectiveness, the price, and the application complications inherent in the product, I decided not to use it again. I did some internet sleuthing and found that a number of people highly recommended zinc cold galvanizing spray paint. I picked one at random on Amazon (about $20), and applied three coats to the prop and shaft. The second photo shows the results. I'd call that a smashing success.
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Well, that sounds painful.

Which is the jam nut, and how should it be positioned?
As per ABYC, CE, ABS, American Machinists Hand Book and US MilSpecs (along with a dozen other references) all require that the jam nut (the thin prop nut) be against the propeller hub.
 

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The blades and hub in the first photo don't look all that much more fouled than the second photo. It's the shaft that looks nasty. Are you sure that the shaft was coated with propspeed in the first photo?

In the second photo, the anodes look exactly like the the rest, which make me wonder if they were painted. If they were painted, they were not able to do their job, as they were insulated from being anodes, by the paint.
 

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Discussion Starter · #9 ·
The blades and hub in the first photo don't look all that much more fouled than the second photo. It's the shaft that looks nasty. Are you sure that the shaft was coated with propspeed in the first photo?

In the second photo, the anodes look exactly like the the rest, which make me wonder if they were painted. If they were painted, they were not able to do their job, as they were insulated from being anodes, by the paint.
The prop was painted with propspeed before the first photo. And I think I took some of the barnacles off the prop before I took the picture. But the prop fared much better than the shaft regardless with the propspeed. And no, the anodes were brand new and put on after painting before splashing that first season. I also masked the anodes before spraying with the zinc paint before the second season. So I don't think the anodes were a factor.
 

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Discussion Starter · #10 ·
I tried the zinc primer 1 year. Got no pictures, but the barnacles LOVED it.
I have to admit that I was surprised at how well it worked. I'm going to try it again next year. Let's see if the results are the same. Fun fact: Petit makes a spray paint for props and shafts that is basically the same stuff: 90+% zinc. But like most "marine" products, it's significantly more expensive.
 

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The prop was painted with propspeed before the first photo. And I think I took some of the barnacles off the prop before I took the picture. But the prop fared much better than the shaft regardless with the propspeed. And no, the anodes were brand new and put on after painting before splashing that first season. I also masked the anodes before spraying with the zinc paint before the second season. So I don't think the anodes were a factor.
If the anodes were installed on top of the paint on the shaft their effectiveness would be greatly
reduced if not totally defeated. There must be very good continuity between anodes and shaft.
Suggest you check resistance between anodes and shaft. There should be 0.0ohms
 
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Hi MSTERN
I am convinced and will give it a go
I have used Propspeed in the past which was professionally applied and have never been satisfied.

A few questions about your application.
1, How did you prepare the prop and shaft before application.
(I am imagining, remove gunk, wire brush and rough up with 320 grit or the like, then degrease with acetone)

2. How much gal did you apply?
( I am imaging a light undercoat spray and then a complete coverage spray. That would leave a lot of paint left in the can)
Or did you just lay it on thick and empty the whole can on the job?

Thanks in advance

gary
 

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So I don't think the anodes were a factor.
I didn't mean to imply they were a factor in whether either antifoul application would work.

I was off on a tangent, recognizing the typical decay and fresh exposed zinc in the first photo. However, the second photo looks like non-decayed anodes, with the same growth as the shaft. Anodes don't typically have much growth, as they are continuously sloughing off their outer surface. Made me think something was preventing the anodes from working in the second photo.
 

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Discussion Starter · #14 ·
If the anodes were installed on top of the paint on the shaft their effectiveness would be greatly
reduced if not totally defeated. There must be very good continuity between anodes and shaft.
Suggest you check resistance between anodes and shaft. There should be 0.0ohms
I attached the anodes in the second picture after I cleaned the shaft, but before I painted. Getting the masking tape off the anodes after the painting was probably the most time consuming part of the process.

A few questions about your application.
1, How did you prepare the prop and shaft before application.
(I am imagining, remove gunk, wire brush and rough up with 320 grit or the like, then degrease with acetone)

2. How much gal did you apply?
( I am imaging a light undercoat spray and then a complete coverage spray. That would leave a lot of paint left in the can)
Or did you just lay it on thick and empty the whole can on the job?
To clean the prop and shaft, I used a wire brush on my drill/driver, then used acetone. I used the spray paint version of the cold galvanizing paint, so no brush or can. I followed the directions on the can for applying, waiting the appropriate time between coats (I think 30 minutes), and applied three coats. The most time consuming part of the process was taping newspaper around the strut and hull, and masking (and unmasking) the anodes and strut.
 

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My experience with Propspeed and PropGlide for shaft and prop and Ablative paint for the bottom in a high growth area is that the bottom still needs to be cleaned monthly. I suppose this experience adds credence to the argument for hard paint as opposed to ablative. I do think however that the two prop paints do help with the removal of slime when cleaned regularly but if you let any hard growth accumulate both products become basically worthless.
 
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