Cover your bottoms

[brak]

I think this may be important enough, so I am making this a separate thread. The following picture illustrates a difference in condition of underwater gelcoat between an area that was painted with 4-5 layers of ablative bottom paint, and an area that spent its life unpainted and unsealed (behind the ground plate).



The previously covered area on the left, the uncovered area on the right.

High resolution pictures here:
Good - http://images47.fotki.com/v1473/file...9/P1010513.jpg
Bad - http://images46.fotki.com/v1483/file...9/P1010509.jpg

Same boat, same area (on port and stbd. side respectively).

Based on this I suspect that any barrier coat is better than none (and that we do not give enough credit to protective properties of regular bottom paint).

I know I made my conclusions about whether barrier coats are useful.

[sailingdog]

Those photos are pretty telling.

[brak]

Originally Posted by sailingdog

Those photos are pretty telling.

Yup.

To be honest, I was not surprised by condition of "good" gelcoat. I had previously sanded down a few areas to do repairs, install thruhulls etc - and always found clean gelcoat in good condition. In fact, with light sanding using 100 grit paper it begins to show a not-unpleasant shine and phrase "as good as new" comes to mind.

I was pretty stunned to find what I found behind the ground plate, but it is this comparison side by side that finally "drove it home" for me. I think people overestimate polyester resin water resistance and under-estimate the same for bottom paint.

Or may be there is a different explanation here, but what it is I do not know

[kaluvic]

Very interesting...certainly not what I would have expected.