Soon I will be dry docking my Hanse 455 for a long weekend to do the antifouling with a friend. I don't have any experience doing this myself, and I hear conflicting things.

It was done extensively in May 2022, and has been in the Med since in the water.

There is mostly only a slimey layer on the hull which comes off pretty easily, and some spots are even unaffected. Of course some barnacles here and there. 

Should I high pressure clean it all off and do it completely over with primer + antifouling

or

clean it (with low pressure water i presume) and touch-up?

Thanks in advance and good health!

Nicholas

All the best

Paul

It is unusual that a antifouling paint available in and conforming to EU regulations would last longer that 12 months unless the boat had been kept out of the water for a extended period of time over that period. So although your current antifouling appears to be working well now it is likely to stop working sooner than later.

There are two general types of antifouling paints (ignoring Coppercoat and the Teflon types) which are "soft" and "hard". Soft includes self polishing and ablative paints which wear away as the boat travels through the water. 

The hard type paints leech their toxin out over a period. You need to know which type you have on now and use the same type again. As your existing paint seems to be working you need to find out what type and brand it is from the previous applicator or your dealer. 

If the boat is pressure washed a soft antifouling will be mostly taken off in the process. A hard antifouling generally will not. All growth needs to be removed before repainting. Any areas where the primer has been worn through or damaged needs to be primed again. The whole area needs to be lightly sanded (80 grit) to give the new paint a better key to adhere to. The general process it to apply one stripe coat of antifouling to the high wash areas - water line, front of keel and rubber. Then apply two coats over the complete surface making sure you keep to the manufacturers recoat periods and prep and applicationinstructions. 

There are probably many Youtube videos on reapplying antifouling and some paint manufacturers are likely to have instructional videos on their websites. The effectiveness of either the soft of hard antifoulings is related to the applied thickness of the paint which is why multiple coats are generally applied for a year of service.

Keep in mind that these antifouling paints are toxic so make sure you wear the appropriate PPE when sanding or applying these paints.

 

It is a soft paint, as it comes off easily even while rubbing it gently with your hand.

I asked the boatyard (in France) that did the previous anti-fouling what they used, still waiting for their reply.

I will see what happens when I pressure wash it.

Good luck

Paul