Propeller Antifouling Failure

C

captmikecoin

Well-Known Member
Joined
7 Nov 2010
Messages
103
Location
Cambridgeshire, Spain, yacht Greece
Visit site
Last season I painted my propeller with several coats of Velox antifoul, having first thoroughly rubbed the bronze with wet/dry paper, applied a couple of coats of Hammerite Special Metals Primer followed by the antifouling. As you can see from the picture (if I manage to upload it properly) there has been a failure of adhesion all over the prop but just in small spots. When the boat came out of the water there were no barnacles nor any weed or slime. Can anyone suggest what I might do to prevent loss of adhesion next year? I suspect that I'm going to have to completely remove the old paint layers anyway.

Mike

)IMG_2250.jpg
 
I have also tried Velox since last March, but I did use the proper Velox primer. I am due out in March so will report on here how this has worked. The fact you have no barnacles I would say is a good result though.
 
I did the prop with Trilux over Special Metals Primer, the Trilux all fell off. The following year I did the same again but abraiding the primer, same result .
 
I use the Velox primer, in the absence of accessible Hammerite (of any type). I follow the instructions pretty meticulously. I might be a bit more aggressive with the prop preparation. I grind off all the old coating, completely. I use a 'paint stripper' on angle grinder. I think its rated at about 60# and is a bit like a resin impregnated brillo pad. When the prop is ready its rough and catches the skin, feels really nasty. I do not touch the metal with my hands/fingers and I wash down with water, to remove any metallic dust. I then give it 2 or 3 coats of primer and 2 coats of Velox. The Velox bonds to the primer. All wet on wet. It all stays on. Once I used Interprotect and it all fell off - but I think my 'pre-abrasion' was insufficient.

If you have used a silicone coating previously unless you are really aggressive nothing will stick - and one answer is to acid wash - I think both Prop Speed and Prop Gold offer their own acid wash (for removal). So grind, acid wash, fresh water wash - do not touch the prop with your fingers! and then primer.

I find Velox marginally better than Prop Speed and Prop Gold, much more user friendly but I'm realistically only getting 12 months, whereas I can get 2 years from the AF. My next test is to try CopperCoat, November 2018 (or thereabouts), I'll eke out the Velox in the interim.

Jonathan
 
Last edited:
Although not entirely related to your question but regarding Velox I can't speak for the antifoul but I used Velox primer last year and it all fell off. I think some very well respected forumites have questioned this product. The instructions quote quite a limited range of conditions for the application and are quite a bit more specific than other primers which suggests there is a history of the formulation not working unless you follow their guidelines exactly ; I have tin which I will not be using again.
 
Last edited:
captmikecoin said:
Last season I painted my propeller with several coats of Velox antifoul, having first thoroughly rubbed the bronze with wet/dry paper, applied a couple of coats of Hammerite Special Metals Primer followed by the antifouling. As you can see from the picture (if I manage to upload it properly) there has been a failure of adhesion all over the prop but just in small spots.
Click to expand...

If it's any consolation for 2 seasons in a row I have done exactly the same thing (Hammerite primer/Velox) and at the end of each season my prop looks exactly like yours (spots where the Velox has disappeared from the primer). I don't have an answer though...
 
I used Trilux 33 on Special Metals Primer this year, the primer lasted well but the Trilux disappeared... My thought for this year (as SMP seems to adhere) is to put a coat of Primocon on before the Trilux
 
Thank you all for your replies. It appears the bond between the prop and the primer has failed on all the small dark patches seen in the photo. I'll try abrading more vigorously and making sure the prop stays grease free. The reason I tried Hammerite special Metals Primer was that it was recommended for the job by someone on the forum (I think it may have been Vyv Cox). Unless I hear to the contrary then it's Velox primer next time although, as you can see, even with the Hammerite most of the paint has stayed on over a 5 month cruising season.

Mike
 
Mike,
I personally would be happy if my prop looked liked that at the end of a season. I usually get my boat (inc prop) antifouled in late April/early May; in the past (before using Hammerite) by June I was having to go underneath to scrape the prop - fortunately I live in Italy, so the water is quite warm!!
This year I used Hammerite with some anti-foul which the boat yard swear by (I don't remember the make) and at the end of September my prop looked very much like yours, but I had'nt needed to go underneath to scrape the critters off all summer!! In the past I have used various types of anti-foul on the prop (Velox, Silicon based, etc etc) and they didn't last more than a few weeks. So last year (2017) I used Hammerite (beacause someone on this forum recommended it particualarly for use with an Autoprop) and the result last time I looked was very much like yours .......... this is the best result that I have ever had!!!

So, this year I shall be sticking with Hammerite and with maybe Velox on top; my opinion is that the a/f is not so important as the primer and if at the end of mext season my prop looks like yours I will be well pleased.

If I was you I would stick with Hammerite - it is the best primer that I have found in 17 years of anti-fouling every year.

Alan.
 
If you do a quick fag-packet calculation to find the tip-speed of your prop at crusing revs I think you'd be astonished that any paint manages to stay on it at all!
 
Hi
I use the Hammerite & Velox formula that you are using after first trying the Velox undercoat with poor results. Invariably by the end of the season there are small patches where the Velox has come off (not as many as you have) but the Hammerite primer is intact underneath, I cannot quite see from your photo's if you have retained the primer or not. My winter process is just a light wet sanding and a new coat of Velox - this is still a better performance from prop antifoul than I have had previously with a much simpler winter ritual.
 
You must log in or register to reply here.

Share this page

Top