Oxidation - Copper Base Bottom Paint

[nhislander]

I purchased a new Beneteau ST-44 in January. Used the boat for just four months in SW-FL then hauled the boat for the summer (during hurricane season).

I am now back in FL eager to get the boat back in the water... but have heard that copper based bottom paint oxidizes (stops working...) when out of the water for an extend period of time (in my case 6 months)... and that to "reactivate" the paint I need to either sand (or pressure wash) the bottom paint before re-launching? I called the boat yard that did the new/first bottom job and they used:
1 - Barrier Coat = Sea hawk "Tuff Stuff"
2 - Bottom Paint = two coats of Pettit Trinidad 75 – Copper based paint

I am new to the bottom paint world... so any advice would be appreciated. Is it true that simply pressure washing the bottom just before launching will do the trick? Or do I need to sand the bottom?

 

[Comodave]

Here is some info that I found online.

Some of our best performing antifouling paints in our past tests have been hard, modified epoxy paints. One of the drawbacks of these paints is that they can lose their effectiveness after being hauled out and stored ashore for more than 30 days. Even newly painted hulls can lose their effectiveness if the launch is delayed too long. Fortunately, there are ways to reactivate a hard paint on a newly painted boat that has been stored ashore for less than a year.

The following instructions apply for Pettit Marine Paint Trinidad, Trinidad VOC, Unepoxy Plus, Unepoxy Standard, Unepoxy VOC, 1933 Copper Bronze, Trinidad SR, Super Premium Performance, Pettit Pro-Coatings Trinidad 75, Trinidad Pro, and Copper Guard. The advice is similar to that offered by other makers of hard, modified epoxy antifouling paints such as Interlux, Blue Water, and Sea Hawk Paints, although it would be advisable to check with your paints manufacturer to confirm the proper procedures.

Launching of newly painted boats may be delayed up to 60 days after painting without sacrificing antifouling performance.
Boats painted between two and 12 months prior to launch date must be scuff-sanded with 220-grit production paper or abrasive pad before launching.
Boats painted more than 12 months prior to launch date must be lightly sanded with 100-grit production paper and recoated before launching.
Boats in the water for less than 24 hours (e.g. for in-the-water water testing) should be pressure washed lightly to remove dirt, salt or other contaminants and allowed to dry. These boats should still be considered newly painted and may be launched up to 60 days after the date of painting.
Boats in the water for more than 24 hours, but less than 30 days, should be pressure washed when hauled, then lightly sanded with 220-grit production paper immediately before re-launching. If necessary, launching may be delayed up to 60 days after the bottom has been sanded. Note: Boats re-launched within 72 hours of haulout do not need to be sanded before launching.
Boats in water for more than 30 days should be pressure washed when hauled, lightly sanded with 100-grit production paper and recoated with antifouling paint, even when re-launching will take place within 72 hours.

 

[STB]

I had a conversation with my diver about this at one point.

He basically said such boats should be scuff sanded to a uniformly unoxidized surface before relaunch...

...the grit of the sandpaper required to reasonably quickly get to good paint becoming more coarse with time (pressure wash=week or a few weeks, sanding after that)...

...but if the oxidation wasn't removed before relaunch, his scraper would do the job over the next few months of tough cleanings.

...he strongly suggested getting down to good paint with the least amount of abrasion reasonably needed before launch rather than leaving it to his scraper...

...he suggested his uneven scraper would take off way more in 3 months of cleanings until the paint performed well again than the relatively even abrasion of even coarser grit sandpaper.

He basically held up an old drywall blade and a piece of 220 grit and asked....which one would you prefer to clean oxidation?

 

[Comodave]

I would think that your boat would be a good candidate for an ablative paint given the speed it can do. With ablative paint storing on the hard doesn’t matter.

 

[nhislander]

Thanks to all for the quick replies and help...

 

[fstbttms]

Here is some info that I found online.

Link please.

 

[fstbttms]

I went to the "Ask The Expert" page on the Pettit website and described the situation. The reply was that the boat needs to be repainted.



Pettit | Ask The Expert