Antifouling Propeller

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Ammonite

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In the past I've had no issues priming and anti-fouling both a bronze fixed bladed propeller and a 3 bladed featherstream but I am really struggling to antifoul my autoprop on my current boat. I can get the primer to adhere (either primicon or hammerite special metals primer) but the antifoul won't stay put and just flakes off. I used Trilux in a tin last year and spray prop-o-drev this season and in both cases I abraded the primer with 120 grit and degreased with isopropyl alcohol before applying the antifoul. This has always worked before so what am I doing wrong? In both cases the primer has remained virtually intact. I don't know if there is some form of cavitation unique to the prop design going on or whether it's just my poor painting or choice of antifoul. Either way I need a solution as the fouling on my mooring is terrible. It's a saildrive so cavitation caused by the proximity to the hull isn't the issue.
 
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Ammonite said:
In the past I've had no issues priming and anti-fouling both a bronze fixed bladed propeller and a 3 bladed featherstream but I am really struggling to antifoul my autoprop on my current boat. I can get the primer to adhere (either primicon or hammerite special metals primer) but the antifoul won't stay put and just flakes off. I used Trilux in a tin last year and spray prop-o-drev this season and in both cases I abraded the primer with 120 grit and degreased with isopropyl alcohol before applying the antifoul. This has always worked before so what am I doing wrong? In both cases the primer has remained virtually intact. I don't know if there is some form of cavitation unique to the prop design going on or whether it's just my poor painting or choice of antifoul. Either way I need a solution as the fouling on my mooring is terrible. It's a saildrive so cavitation caused by the proximity to the hull isn't the issue.
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vyv_cox said:
See this Propeller antifouling with Velox Years and years of good experience.
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Thanks Vyv. Your first picture is similar to what I'm seeing with lots of pitting, although mine is considerably worse and sanding the hammerite hasn't helped in my case. It does look like cavitation though and I'm wondering whether this would be better or worse with a 3 bladed autoprop, which is what I have? I'm reluctant to try Velox again as it didn't work very well compared with Trilux on my previous boat in Chichester and the fouling seems equally bad in Portsmouth. I've tried polishing instead of antifoul on both a featherstream in Chichester and the autoprop in Portsmouth and that was a total disaster given our usage pattern and location. Can anyone recommend anything that is likely to adhere more effectively than Trilux or Velox.
 
Is the boat new to you? Perhaps a previous owner used a silicone coating on the prop? I have had a similar experience to you on trim tabs that had previously been coated with silic one. I stripped and sanded them back to bare metal, primed and antifouled, but the antifoul just flaked off as you described.
 
Moonbeam said:
Is the boat new to you? Perhaps a previous owner used a silicone coating on the prop? I have had a similar experience to you on trim tabs that had previously been coated with silic one. I stripped and sanded them back to bare metal, primed and antifouled, but the antifoul just flaked off as you described.
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The primer bonds really well to the prop and is virtually intact at the end of the season, so its not silicone that's the issue. Its the antifoul that won't stay on. I just need to find an antifoul that clings to the prop as well as weed and barnacles!
 
Ammonite said:
The primer bonds really well to the prop and is virtually intact at the end of the season, so its not silicone that's the issue. Its the antifoul that won't stay on. I just need to find an antifoul that clings to the prop as well as weed and barnacles!
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So in fact its the bonding of Primer to the AF ... not the prop.

I note that : " I abraded the primer with 120 grit and degreased with isopropyl alcohol before applying the antifoul"

What happens if you do not do this and just AF on top of the primer ? I just have this thought in mind that the 120 grit may have destroyed the primer surface and the IA may have lifted something where the primer is abraded ?

My Folder on the 38 has been treated with a Silicon based clear treatment designed for props ... no idae of its name as its used by the yard ... they also dab the transducers with it ...
My fixed 3 blader on the 25 has had a double coat of standard eroding to the bare metal - not recc'd I know - but the guy who AF'd the boat after keel repairs just carried on and did it !!

Will see at end of year ...
 
Hammerite SMP dries with a slightly shiny finish that I abrade with 180 wet and dry, used dry. I only wipe any dust off with a rag. Velox adheres well to it after that treatment.

Velox doesn't work well everywhere, it was developed in the Med. I have read several reviews of it not being effective on UK south coast.
 
I also find there is a big difference between a marina berth and a swinging mooring in the same river. Even if you use the same antifouling product.
 
I tried not sanding the primer the first year I antifouled the autoprop (OK - I forgot) and that was even worse, which is why I went back to sanding it. I'm tempted to give propspeed a go but its not exactly cheap and I wouldn't be impressed if that fell off as well.
 
I've been using Velox for several years but when I first used it, it was on the clean metal of a new prop. That was treated exactly as described in the instructions from Velox :- the bare metal was abraded with grade 180 W&D paper used dry I think. Any dust was removed and two coats of Velox own brand primer were applied, followed by two coats of the Velox antifouling paint. At some point, I think that washing with acetone was involved. If the antifouling is not adhering to the primer, that suggests changing the primer.
 
I used to use Trilux on twin outdrives (Botnia Targa) - but found that, whilst effective, the antifoul on the propellors washed off too easily. I still use it on the outdrives - but changed to Seajet Emperor Triple pack. Only on my 2nd season, but very impressed so far - and it's been pretty effective with the weed.
 
Roughcut said:
I used to use Trilux on twin outdrives (Botnia Targa) - but found that, whilst effective, the antifoul on the propellors washed off too easily. I still use it on the outdrives - but changed to Seajet Emperor Triple pack. Only on my 2nd season, but very impressed so far - and it's been pretty effective with the weed.
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Thanks. That looks interesting. I shall take a closer look
 
I have just done my Featherstream following Vyv's regime. obviously don't know yet how well it will work, but my last attempt used Prop O Dev both primer and spray top coat, but not a success. Patchy adhesion and poor antifoul where it did stick. However painting everything did significantly reduce anode wastage. Velox worked fine on the blades of the FlexOfold on my Bavaria. Photos show Ptop oDev after 2 years latest Velox
 

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