reactivating antifouling after 3 months on the hard

[stravaig459]

Hello

Back in March, I applied 3 coats of Seajet Emperor 034, a fairly standard, self-polishing antifouling. (The boat’s hull is aluminium so my choice of antifouling is limited.)

Unfortunately my sailing season was interrupted in mid June and I had the boat hauled, lightly pressure washed as there was minimal fouling, and put on stands to bake in the Greek sun for 3 months.

With the boat about to go back in the water, I am curious to know if there is anything I need to do to ensure the antifouling is active. The surface of the antifouling is slightly shiny and fairly hard, more so than it was when first applied, and none comes off when I rub my finger along it. If I give it a light scrub with a scouring pad, the surface goes matt and rubbing my finger along it results in a very grubby finger.

I have asked Seajet in the UK and the distributor here in the Med who supplied the antifouling. I haven’t had a reply yet from Seajet (and I’m not holding my breath) but the distributor said “you will need to give it a light sanding and reapply a coat of antifoul as the old antifoul will not be active”.

After 3 months on the hard, I can understand that the surface of the antifouling may not be active and may not ablate, and that sanding the surface will resolve both problems, although the specification for the paint states that the maximum time between application and immersion is 6 months.

However, it makes no sense to me that the entire 3 coats of antifouling is compromised and forever inactive.

So, two questions.

1. Can anyone explain why taking the boat out of the water would deactivate the entire antifouling (or is this just waffle / a sales pitch from the distributor).
2. What's my best course of action: do nothing, pressure wash, light sand, serious sand, other?

I look forward to reading your replies.

Thank you

[GordMay]

The copper [biocide], in antifouling paints, oxidises, when exposed to air, rendering it ineffective.
Soft antifoul [self-polishing] erodes slowly, as the vessel moves through water, so that a fresh film of biocide is always present, on the hull’s surface.
SEAJET 034 EMPEROR A’s maximum immersion time, after application, is 6 months; and it can be burnished [lightly sanded] during the season.
➥ https://www.agl-marine.com/wp-conten...14-08-2021.pdf