Antifouling experiment - wet sanding VC17m (or equivalent)

[sy_Anniina]

Background:

My boat was painted with VC17m by previous owned and since then I have annually painted with SVB Seatec GTI30 as it is about the only reasonably priced alternative that sticks to previous coat. We are living on area with mandatory winter haul-out on the hard due to cold winters.

Challenge:

As this type of paint relies on smooth slick (PTFE?) surface and added copper powder, I have been wondering if I could exted the effeciveness of the paint beyond one season. Northern Baltic brackish water does have only limited fouling compared to warmer oceanic environment.

Experiment:

I wet sanded a section of bottom down to 400-grit giving really smooth surface and revealing some fresh copper surface - the rest of the bottom was given another layer of GTI30. I did not want to experiment with the whole bottom, as failure would lead to massive cleaning of the fouling in the autumn. (The first year the broker just re-launched the boat without additional antifouling layer - and the cleaning was quite massive job)

Results: to be seen by end of October 2022 - maybe some interval snorkling if weather allows. I will report in any case - also for learning if failed for others to avoid the trouble.

BR,

Tommi
s/y Anniina

[sy_Anniina]

Based on first look after lift-out the wet-sanded SVB Seatec GTI works just as well as  fresh paint. No barnacle growth and about similar amount of thin slime on both freshly painted and sanded surface. The vertical artefacts on surface are due to crane lift slings - not related to this paint/sanding experiment.


Need to see if pressure washing reveals any differences - but so far it looks like I will not paint for next season, but will re-activate the paint by sanding.

Disclaimer - testing performed on Northern Baltic brackish water

[sy_Anniina]

A bit of talking to myself - but documenting this experiment if anyone else needs this info.

Pressure washing did not reveal any fouling differences between freshly painted or sanded area - the thin slime was equally easy to wash away from surface.

For refence I attach a new photo from washed surface - the sanded part is obviously smoother and feels more "slicky" than painted (felt roller) slight orange peel surface

[sy_Anniina]

Continuing talking to myself - but documenting the chain of experiments for anyone interested.

Based on positive experience previous year, I wet sanded the whole bottom. This time it was random orbital sander with 320grit (readily available) and not to "glass-smooth" level as previously but still removed most of the previous orange peel texture.

Boat now in water and expecting results of this experiment in October-22

s/y Anniina

[Yngmar]

Thanks for sharing. Keep it coming!

[sy_Anniina]

Documentation of this experiment continues:

After one more season - now the whole bottom sanded in the spring and the results are equally satisfactory - slight slime easily washed away - only a dozen or so small barnacles (the Baltic type) easily pressure washed away. Even though for the last month the boat was pretty much stationary in the marina - had not a chance to sail her.

Will continue sanding as long as it works - spreading less toxic solvents to environment and less build-up of hard paint layer.

Note - Experiment performed in Northern Baltic - I might not dare to do this in more aggressive Med or even Atlantic / North Sea waters.

Tommi
s/y Anniina