Jump to content

Antifouling: where, what, how good, etc...


Recommended Posts

On there info it says if it’s still there it will still work so more paint should mean more time before it wears out. Which seems to be true it was put on in 3 colours and you could tell when the layers wore off. Still needed occasional cleaning though.

Link to post
Share on other sites

Yes that is correct. If it is still there, it should still work (to a point), is how soft ablative AF's work. The main cleaning factor is that surface directly in contact with water becomes very soft and water flow rips away growth because the surface is not able to hold on anymore.
Copper and Biocides really only slow and stunt growth of "Flora and Fauna". When the Vessel moves and the surface has become clean, the Copper and Biocide slow the growth of new critters growing. No modern Ablative Fouling will stop growth fully, apart from the first few months when the biocide is very rich in the fresh AF.
Slime is a combination of particles in the water and Algae. Because it is a matt rather than individual things, it can protect the surface of the AF and it takes a bit of speed to wash the surface clean.

Self polishing AF's are the only AF's that will stop this growth. They work by the Surface Chemically reacting and it self releases the surface and thus anything growing in it. But in very dirty water, the slime can attach faster than the surface self erodes.
 

Link to post
Share on other sites

Yep...put it on !!

A rough rule of thumb with most soft ablatives is one coat will give you a safe 10 months. .. But if you have 5 knots running through twice a day on your mooring ...........

The paint thickness has to be even though.....work in set small areas and get up a rhythm.. 

You should put even more on the leading and trailing edges...around the prop and along the water line.

Dont dry sand. 

You need to remove any excess salt and the immediate surface of the old paint (if it is all in good condition)

Removing lots of existing antifoul with hard sanding is just removing useful product...

A local tie coat should be applied to any areas that have been scrapped or damaged and also if the surface is back to the original primer. A full cover of a tie coat has merit if you have a dogs breakfast of situations with different antifouls and conditions. Eventually you will need to take the whole lot GENTLY back to primer in this situation..

You can look up the various brands and the quantities of their active ingredients. It is a good starting point.

So my rules (and I have lost count of how many boats I have taken poison paint off and put poison paint on.....) is for 2 years between hauls.

2 ...and best 3 coats ..on all surfaces. plus 4 on the high wear areas (as above). 

Stuff coming out through below water through hulls can effect the longevity and the repaint of the immediate surface and above if it is oily.

Dont  in water scrub unless you really really have to.... (them racing people) ..Just go sailing. You can prematurely wreck your protection by scrubbing through. Ablative antifoul in water is very soft. Even a sponge can take months of protection off....that (chose your colour) swirl in the water is $ and effort floating away.

 

If you want to get serious ...have a look at the commercial / professional data. Systems will run up to 60 months and are quite cheap in comparison to some ... I have no brand loyalty but its worth going onto the Jotun industrial web site and doing some research.

The most common brand here is International. The most talked about in a positive sense in Altex. The cheapest and cheerful is Hempel. I use what ever my customer prefers but I prefer either Jotun or Altex.

 

All of the above is about soft ablative..NOT hard leaching..

Link to post
Share on other sites

I tried the M 66 which didn't fare well in our mooring area, then the following year tried M 77 which I can confirm is definitely not 11 better than the 66. Basically the same result. We use the boat a lot and wipe it regularly but both had an effectiveness of 3-4 months then it got harder and harder to keep it clean.

This year Im giving Ultra a try, results soon.

Link to post
Share on other sites

I had my bottom wrapped with Silikon this winter by NZMPS. Not cheap, but like trying new technologies. It's a foul release system, as opposed to antifouling. I don't go fast enough to self-clean, but it is easy to swim and wipe down before races. Takes about 25 minutes for 9m yacht using low pressure regulator and pump, and bare hands to wipe. Hoping I'll get several years out of it. I was previously using Ultra but the barnacles in BOI have been real aggressive over the summer season and seem to stick to about anything. Also biocides were spent after six months, so still had to clean regularly and was more work. I'm happy with the system so far, but recognize its not for everyone due to high initial cost and regular cleaning regimen.  

 

Also NZ phased out several biocides last year, so the paint you buy this season could be different from last year's brew - see https://www.yachtingnz.org.nz/news/new-rules-antifouling-paints

Link to post
Share on other sites

We use Altex No 5. two coats. If we use the boat it is great with just light slime after a year. If we leave it two to four years (both of which we have done recently) without using boat we got a bit of weed after the 2 year stint and sh*t loads after 4 years. This does tie in with altex specs of one coat will last a year. We were surprised the No4 did so well for the 2 year stint as ablativws are not best for a static boat.

We are based at Lyttelton and have plenty of weed and mussels available.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...