Stupid question / varnish

[oksalahti]

Hi,

I'm going to ask a really silly question, even at the risk of becoming labeled as a complete moron for eternity.

Consider a wooden boat, made of mahogany for example, with shining sides having 32 layers of the finest varnish one can find. The varnish looks great and protects the wood from water, sun and other elements. Below the waterline, however, you would find a coat of primer and an anti-fouling paint.

What would happen if you were to use varnish all over, also below the waterline? Would the bottom be swarming with barnacle? Or would the varnish prevent the bottom from breathing, thus resulting in rotten/mildewy wood over time?

The varnish would be applied only to one side of the hull (outside). Has anyone tried it and if so, what was the result?

Cheers,
Mikko

[Matt J.]

Why? Varnish does nothing to prevent bottom growth - you would have a shag carpet farm.

[Ian McColgin]

The bottom would foul. There is a reason for anti-fouling paint. Boats that are dry sailed don't need bottom paint and one sometimes sees such boats finished bright on the bottom. It looks better if the topsides and bottom are set off by a nice contrasting boot stripe, but no harm will come to the boat from varnish all over.

[wizbang 13]

It would work perfectly, for a week.

[Michael D. Storey]

What would happen if you were to use varnish all over, also below the waterline? Would the bottom be swarming with barnacle? Or would the varnish prevent the bottom from breathing, thus resulting in rotten/mildewy wood over time?

Remember that article by the Funny Guy who had an opening column in The Magazine maybe 10 years ago where he talked about this tree with lungs? Since then, I could not keep from laughing at any interior painter who would not paint the top or bottom or a door, so that it could 'breathe.'

[Phil Y]

M o r o n

[Seneca]

I want to know what the finest varnish one can buy is. Half of this forum is devoted to that Holy Grail!

[rvanvoris]

If you dry sail or in my case row the boat varnish does look good. That is the way my single scull is done. However always bottom paint a boat that stays in the water for any length of time. I keep a Rhodes 18 dailsailer in Sippican harbor off Buzzards Bay, unless I renew the bottom paint every year it is a Marine Biology science project.

[pcford]

Any kind of topside finish, varnish or paint, will blister and fall off if left in the water more than a few days. And, yes, you have the marine growth problem as well.

(By the way...not a stupid question.)

[kc8pql]

Any kind of topside finish, varnish or paint, will blister and fall off if left in the water more than a few days.

^^^ That's the real reason.