Is there really a difference between marine and regular polyurethane?

[Bigjim]

Many “marine” polyurethanes are pretty expensive. Is there really a difference between marine polyurethanes paints and regular brands? Is the difference worth the premium price?

[TheOffice]

Practical Sailor did a review of varnishes recently. A minwax product did as well as many marine finishes. Be sure it is for outdoor use, as indoor varnishes don't have the UV protection needed.

[1affiah]

I walked into the storefront of a paint manufacturer in Watervliet, NY (Passano)
asking about "boat paint". I was told my boat wouldn't know the difference!

I wound up buying Imron Industrial from them, at about 1/2 the cost of similar 2-part LP's. It rolled & tipped on my Mainship just fine.

[belizesailor]

Originally Posted by Bigjim

Many “marine” polyurethanes are pretty expensive. Is there really a difference between marine polyurethanes paints and regular brands? Is the difference worth the premium price?

Yeah, the word "marine" and about a 100% mark up.

[JPA Cate]

A BigJim,

When it was time to paint our boat, we asked the yard boss of the place where the work was done, and he told us that he could sell us Marine or Automotive LPU for our topsides. We went with the Automotive, huge choice of whites (some 600 different shades), have to survive dust storms and sun, wind, and rain. We've been quite pleased with it.

I would say, if you have a fiberglass boat with gelcoat, do everything possible to renew the gelcoat [check out TSRW or PolyGlo] before you consider painting. Painting needs to be re-done every 20 yrs. or so to stay looking tippy top. Good boat painters are not cheap. Pain is also fragile, prone to chipping, scratching, and if you do dark over light, all those little gouges will show through like stars in the desert night sky.



Ann

[Valmika]

Originally Posted by belizesailor

Yeah, the word "marine" and about a 100% mark up.

Then if you add Aviation to it take it up another 200% over that.

[FionaJC]

I thought the price order was Normal < Leisure < Marine < Medical < Aviation < Military

[jmschmidt]

I use ordinary "Rust-Oleum," not their marine version, for interior areas like previously gel-coated headliner, cabin soles and sidewalls. Floes own easier and drys faster. Roll and tipping it holds up well (for years so far). I've even used it for small touch-up areas externally and it holds up as well as "professionally" (if there is such a thing) sprayed Awlgrip.

[model 10]

There is quite a bit of difference between cheaper paint and more expensive paint. You will notice the better paints use less catalyst. The more solids you have in a paint the smother and durable the finish. Many industrial poly paints are 2:1, a good paint might be 4:1. Then there is the apples and orange thing. Very few cars use polyurethane paint. They almost all use acrylic urethane. It is not nearly as good as polyurethane, but it does shine for a while.
If you went to an airliner paint facility you would see them using all kinds of paint brands. What they all have in common it the high solids content. The only way for the regular person to tell is by how little catalyst is needed.

[Bellissima]

I used PPG polyurethane auto paint on our interior. On pilot house coamings I sprayed undercoat, 1hr later sprayed poly top coat and looks really good. On interior bulkheads etc I used a epoxy high build (international 256) appyed with a goop loop roller, as used for Kiwi Grip deck paint, which gave a textured surface and then applied poly over that. Easy Pessy, not so much sanding and covers most small blemishes. In the heads I used same high build u/c but rolled on international Reaction Lacquer with a nook and cranny roller, looks like it's been sprayed. This is a very tough finish, and after 7yrs of living aboard, sill looks like new. G.

[jacktheflyer]

Originally Posted by Valmika

Then if you add Aviation to it take it up another 200% over that.

I thought aviation was expensive then I bought a boat.

[SteveSadler]

Dupont was the first to develop linear polyurethane paints (Imron) and dominated the aviation market with it. Awlgrip, produced by a small company, went after the yacht market. In Hawaii, I've painted hundreds of gallons of Linear Polyurethane on the big charter boats. Mostly Imron, but some requested awlgrip. Both look and last a very long time, but awlgrip has had issues of dissolving the primers and fillers used to prep. Imron can and is best painted without primer, over the old gelcoat, epoxy, laquer putty, etc. It bonds extremely well to almost anything. If I'm stripping a planked boat to fair the topsides, I'll use 3 thick coats of epoxy resin as the primer, sand and paint. On existing paints, I use it as it's own primer as it dries harder than primer, sands well within a day, and the gloss shows the imperfections you want to fix. Not to mention wider distribution, more color selection, cheaper, etc.
It used to have a brushable activator available but not recently. Obviously Imron is my favorite, but automotive urethanes are also impressive, but at least as expensive. The clearcoats on autos hold up to 15 years in the sun! Thats worth putting on your teak. Again, right over your varnish! Although for table tops expecting hard wear, I apply 2-3 coats of epoxy resin on the wood first, sand and paint with LP. Mirror finish, hard as glass.

[GordMay]

Greetings and welcome aboard the CF, Bellissima.

[Bigjim]

The cockpit of my 27 foot Cal was extremely oxidized. I tried buffing it out but it was still dull afterward. I decided to sand and paint and the results are amazing so far.

Here's what the boat looked like before painting the cockpit



Here's was she looks like now:

[Bigjim]

I used Interlux Brightside Semi-gloss white. Interdeck deck nonskid and Interlux beige.

I had to lay down some new fiberglass on the cockpit sole and bridge deck. Everything looks like new now.