Rustoleum Neverwet

[idonthaveaname]

Re: Rustoleum Neverwet

Volunteer? hehehehe...I am sure Bruno knows what to do and is paid well to do so. I am a google guy myself so I agree with you. Funny thing about science....while golf balls with dimples make the ball go further, light barnacles (almost like opposite dimples) make the boat go slower. Maybe I should take a ball peen to the hull and dimple it up?

 

['78 Crusader]

Re: Rustoleum Neverwet

The rustoleum repels water away from the surface...doesn't make the surface any slicker. For normal boating applications, this would be a waste to use for the average boater.

This stuff would be good for a high speed craft where hundredths of seconds count.....say during an 800 or 1000 foot drag race.

 

[kungpaoshizi]

Re: Rustoleum Neverwet

Maybe I should take a ball peen to the hull and dimple it up?

YAA!! lol

 

[mrdancer]

Re: Rustoleum Neverwet

Just saw an ad for this stuff, and wondered how it would do on a boat's hull. Would it help the boat's hydrodynamics, creating less drag, thereby better top speed and fuel efficiency? Thoughts?

Poor reviews for NeverWet on Amazon - folks say it works, but doesn't last more than a few weeks.

As for hydrodynamics and smooth vs. rough hull, there was a lot of research done back in the early- to mid-90's (search the science journal 'Nature' for relative articles). The jist of the research was that a smooth surface allowed vortices along the boundary layer to roll along the surface and become larger, much like rolling up a carpet or rug. Once the vortices became large enough, they would break away from the boundary layer and create significant turbulence. By introducing random protrusions on the surface (making it 'rough'), the vortices were broken up before they had a chance to 'roll up into larger vortices', thus reducing shear and turbulence along the boundary layer, and thereby improving efficiency.

The key was that the protrusions had to be random, as uniform protrusions had little to no benefit over a smooth surface. The difficulty lies in manufacturing random protrusions on the surface (plus, not many would be sold due to the huge amount of misinformation rampant in general society). Anyway, the random protrusions resulted in about a 13-17% improvement in efficiency (this was for water flowing through a half-pipe). There are other variables associated with hydrodynamics such that creating such a surface would not result in a 13% improvement in overall efficiency in the end product (say, a boat or an airplane), but probably more on the order of 2-3%. This would make it a worthwhile endeavor for something in the extreme, such as a racing sailboat or yacht, but has been outlawed as an unfair advantage in most such applications.

 

[frantically relaxing]

Re: Rustoleum Neverwet

Many years ago in Popular Mechanics was a story about a boat hull being designed that would resemble an air hockey table with air scoops up front, to force air bubbles between the hull and the water. No recollection of who was doing it or even if there was ever a prototype built, but I can only imagine the headache it would be to build such a hull!

As for slick bottoms slowing you down-- Because of the porosity of gelcoat that smoke' speaks of, when you WAX your hull, you're filling up the pores in the gelcoat with carnuba and silicone. There is a simple way around this problem: POLISH your hull with something that doesn't contain wax or silcone, that will keep the gelcoat smooth and slick without filling up the pores. Me, I've used Dri-wash for years on everything. I haven't waxed a car or boat for nearly 20 years. A friend of mine used to race SS boats, and that's all he ever used, as did most of the race boat owners (so he said). No, I don't sell the stuff, and I'm sure other products will work as long as it's wax and silicone-free...

As for Rustoleum, I can't even seem to buy a can of clear rustoleum that I can use the whole can without the inner tube falling off, or the nozzle covering my hand in paint, or it coming out in globs, or not at all... Not a fan of Rustoleum, and not surprised if reviews are bad...

 

[idonthaveaname]

Re: Rustoleum Neverwet

"random protrusions" HA!!! I have those! :facepalm:

I was watching America's Cup recently; you know...the sailboat races. Let me tell you...I really learned a bunch about hydrodynamics and planing and such. These guys ride this multi-ton sail boat, at 40 to 50 kts while floating it in the air. Why? Obviously cuz the more water contact the slower the boat. They developed these daggerfoils that drop into the water acting like a "ski." The vessel, all 13000+ pounds becomes sort of airborne and these daggerfoils ride just below the surface. Coolest darn thing I have ever seen.

Here's some tech data: Emirates Team New Zealand Uses Pointwise for AC72 Hydrodynamics Design - The Connector - Pointwise

Maybe you can see it in the photo circled in red

 

[ssobol]

Re: Rustoleum Neverwet

The dynamics are similar to airplane wings where laminar flow sticks to the surface of the wing, creating drag, properly managed turbulence decreases drag without affecting lift.

Actually, the best possible flow on an aircraft wing is 100% laminar flow. This would make the airflow parallel to the wing surface across the entire wing. However, it is impractical to build and maintain a 100% laminar flow wing for a number of reasons. For example, a bug splat, or a dent, or a rivet on the leading edge can disrupt the laminar flow. Current aircraft manufacturing and design tries to maintain the laminar flow as far back along the wing as possible. Sailplane wings have the highest percentage of laminar flow of all aircraft designs.

In the water animals like dolphins and toothed whales (any animal that moves fast) has a skin that allows a very high percentage of laminar flow. This is done in part by the animal being able to continually adjust its body shape and skin to maintain the laminar flow. The Navy was/is trying to come up with a comparable system that will work on submarines (more laminar=less turbulence=harder to detect).

 

[Watermann]

Re: Rustoleum Neverwet

This you tube video testing neverwet on a RC boat should end the debate, guy sands the hull bottom and picks up speed then he uses neverwet and it slows it down. If that doesn't do it, go price that stuff out.