Protecting my logs from salt water - to paint or not?

[rbiederwolf]

I boat/leave boat in salt water and knew I needed to bottom paint. I didn't want to use traditional bottom paint as I remember my fathers boat, and bottom painting it was a nightmare and it didn't last for too long, then you had to touch it up every year, and redo.

Thus I used a silicon epoxy made for air boats. Meant to reduce friction and because of the silicon it is very difficult for anything to attach to the paint. The company had yet to test it for saltwater applications.

I took the gamble. It is only been about 4 months, but it has made a worls of difference. The amount of growth is considerably less (especially barnacles), and the ones that do stick come off super easy. The company believes I should get 2 plus years before any touch up would be necessary.

We'll see...

[Ron Burgundy]

I boat/leave boat in salt water and knew I needed to bottom paint. I didn't want to use traditional bottom paint as I remember my fathers boat, and bottom painting it was a nightmare and it didn't last for too long, then you had to touch it up every year, and redo.

Thus I used a silicon epoxy made for air boats. Meant to reduce friction and because of the silicon it is very difficult for anything to attach to the paint. The company had yet to test it for saltwater applications.

I took the gamble. It is only been about 4 months, but it has made a worls of difference. The amount of growth is considerably less (especially barnacles), and the ones that do stick come off super easy. The company believes I should get 2 plus years before any touch up would be necessary.

We'll see...

Can you post the brand info? I have bottom paint and it dosen't seem to be helping much.

[RonKMiller]

This may be it? Looks interesting. The more I think about it I'm really inclined to paint those bad boys!

http://airboatcoatings.com/

They specifically recommend this for pontoon boats:

http://www.wearloncorp.com/index.php/pr ... Super_F-1M

Very interesting:

"Reduction in drag resistance of a craft through water has brought out the advantage of using Wearlon as a marine coating. In particular, the addition of controlled superficial microtexture while maintaining critical surface tension between 20 and 30 mN/m provides a drag reduction advantage that can usher in a new generation of energy-saving marine coatings.

Results suggest the following for best reduction in drag resistance:

Low to very low surface energies such as Wearlon at a 20 to 30 mN/m surface tension.
Surface - layer turbulence suppression by coating compliance
Micro-roughness, at a scale that supports nucleation, entrapment, and release of microbubbles into the boundary layer and free stream flow."

It appears that a dimpled surface applied with a 3/8 in napped roller is BETTER than a smooth surface. That does NOT surprise me. Boundary layer stuff is way, way out there.

[Liquid Asset]

That's interesting about the texture of the paint. I guess it's a good thing that I never bothered to wetsand my logs. I painted with a roller just due to the fact it was the cleanest way I knew how since the boat was already built. I didn't want to think about getting a sprayer near the boat or trailer. It took long enough to mask off what I did ! I did alot of research on painting with a roller first. I found tons of info where guys painted cars and boats to show finish, it just takes time. The secret is to thin that paint a bit for extra flow. I also then added enamel hardner to speed up the dry time and have a harder/glossier end product. If you get right up on my logs like 3' you can see the texture other wise it's smooth. Now I can tell people I have texture for a reason ! They are really smooth to toutch so who know if it's doing anything.

As the drag question you asked. I went and looked for the post I had in my rebuild at another site and can't find where I have the mph , but I see that I posted 400 rpms were gained after it was done. This was running the same prop and load as before the paint. I'm pretty sure it was a couple of mph. I'll keep looking for the numbers !

[Gonefishing]

Just make sure the primer and paint is for alum. Or it we eat through the toons.

[badmoonrising]

Just make sure the primer and paint is for alum. Or it we eat through the toons.

Yep. Paint containing copper = makes aluminum into swiss cheese

[RonKMiller]

Thanks for the heads up on the copper - that would have been a disaster...

[RonKMiller]

That's interesting about the texture of the paint. I guess it's a good thing that I never bothered to wetsand my logs. I painted with a roller just due to the fact it was the cleanest way I knew how since the boat was already built. I didn't want to think about getting a sprayer near the boat or trailer. It took long enough to mask off what I did ! I did alot of research on painting with a roller first. I found tons of info where guys painted cars and boats to show finish, it just takes time. The secret is to thin that paint a bit for extra flow. I also then added enamel hardner to speed up the dry time and have a harder/glossier end product. If you get right up on my logs like 3' you can see the texture other wise it's smooth. Now I can tell people I have texture for a reason ! They are really smooth to toutch so who know if it's doing anything.

As the drag question you asked. I went and looked for the post I had in my rebuild at another site and can't find where I have the mph , but I see that I posted 400 rpms were gained after it was done. This was running the same prop and load as before the paint. I'm pretty sure it was a couple of mph. I'll keep looking for the numbers !

I think you did it perfectly - 400 rpm is not easily gained... and I'll bet your fuel economy went up as well - although probably impossible to quantify.

Just tell them micro bubbles produced by the texture increase flotation and reduce drag. Like millions of air filled ball bearings attached to the surface.

[badmoonrising]

Thanks for the heads up on the copper - that would have been a disaster...

A guy signed up here last year who bought a 'toon that had copper paint on it, brought it home and it was full of holes from the copper. Haven't heard back from the guy. Ron had issues with his boat too and a 'toon in our marina a few years back. You'll get a season or two and that's it. The you notice everything is turning green white white powder. You are creating a battery by combining aluminum with copper plus water...

[RonKMiller]

...and for more info on microbubbles:

http://www.nmri.go.jp/turbulence/group/ ... ubbles.pdf