Remember the "waxed hull = slower boat" debate?

I found this article on the subject:

http://www.geocities.jp/schocklm/wax_or_not_wax.htm

thats alot of reading. whats faster?

waxed hull = slower. end of.
I used to work with a friend building small sail craft hulls and the better sailers used to ask for their hull to be wet sanded with 800 grit paper as this is faster through the water than a polished hull.

Yes, that's right. A waxed hull is surely slower than a wet sanded hull. I am a dinghy sailor (practicing racing at a high level) and I can confirm you this. Nobody when racing wishes to have a waxed hull. The fact is that the wax makes the drops of water adhere to the hull instead of sliding away. If you could have the hull upside down (as it is possible on dinghies) and you poured water over the hull, you would see that on a waxed hull the drops of water remain on the hull instead of sliding away. This slows down the boat.

For the sake of ski boats, I don't think it really matters. Most people wax their boats to keep them looking nice longer, not to make them go faster. These boats have more than enough power to make up for the increased surface adhesion of the water. The wax or not wax is really only an issue on human or wind powered racing shells such as sail boats or rowing shells where power is your limiting factor to speed.

werd aj

It appears that none of you neither read the article or have any formal engineering training in fluid dynamics. I have done both, and it is best to keep your mouth shut when you don't know what you are talking about.

AJ is correct, it won't matter for us "speed" boaters.

That was supposed to settle the argument, not fuel the fire!

Ahhh yes, most wakeboarders I know have both an engineering degree and are well versed in fluid dynamics. I'll have to get them to add a post to this thread so you don't tell them to shut their mouth.

I wax because I hate unsightly lake scum, not to go any faster or slower. What a stupid argument for wakeboard boats. This is still Wakeworld...isnt it?

I don't know how stupid it was. I thought it was a pretty interesting debate. But I am a geek.

we better get tom cruise to settle this, cause you don't know!

"It appears that none of you neither read the article or have any formal engineering training in fluid dynamics. I have done both, and it is best to keep your mouth shut when you don't know what you are talking about."

Cookie?

Robert, that's a pretty condescending tone for someone who doesn’t say what he means. Due to your use of a double negative, you effectively wrote... "It appears that all of your either read the article or have formal engineering training..." However, since you're an engineer, I have assumed that you must be grammatically challenged (my brother is an engineer - I know these things ) and actually meant to just rag on everybody. Please chill out. As the article states, "an in depth study of this is about as fun as a root canal and so dry one must be hooked up to an IV just to read..." I gave up reading the article shortly thereafter when my IV ran out. The rest of us need the experts such as yourself to give us the answer, not to tell us to shut up. So are you saying the belt sander I bought last night was a waste of money?

I'm a naval architect, so I've heard alot of discussion on this. The sanding really only makes a somewhat noteable difference on displacment boats where the entire boat is always in the water. For a small planing boat such as ski/wakeboard the difference is so slight it's not worth noting, so wax your boats and keep the re-sale value up.
~Justin

I am a H2O Diplacement Engineer, and I say that it doesnt matter either way on a Wakeboard Boat.

That was never an issue. The debate was an academic one for those of us who enjoy arguing over completely inconsequential matters.

who cares? what makes the wake bigger? 1200#s of wax

Cookie?

What kind?

I am partial to m&M cookies if you are offering.

BTW, I am almost done sanding the boat, do I now need to wax it?

I am confused which will make me go faster while pulling a wakeboarder?

lmao @ all of this crap.....first off....what in hell is a diplacement engineer? Displacement? Secondly.......If someone wanted to go faster with a wakeboard boat, it would be much much more effective to change the pitch on their prop. These boats could actually be quite fast. The reason they wax their hulls is only for proper maintenance. Hell...if what you say is correct....then great...it could actually add more drag to possibly add more downward pressure for an even greater wake.

(Message edited by wakepirate on July 07, 2005)

Lift depends on the density of the fluid, the square of the velocity, the fluid's viscosity and compressibility, the surface area over which the fluid flows, the shape of the body, and the body's inclination to the flow. In general, the dependence on body shape, inclination, fluid viscosity, and compressibility is very complex.

One way to deal with complex dependencies is to characterize the dependence by a single variable. For lift, this variable is called the lift coefficient, designated "Cl." This allows us to collect all the effects, simple and complex, into a single equation. The lift equation states that lift L is equal to the lift coefficient Cl times the density r times half of the velocity V squared times the wing/hull area A.

L = Cl * A * .5 * r * V^2

For given fluid conditions, shape, and inclination of the object, we have to determine a value for Cl to determine the lift. For some simple flow conditions and geometries and low inclinations, wakeboarders can determine the value of Cl mathematically. But, in general, this parameter is determined experimentally.

In the equation given above, the density is designated by the letter "r." We do not use "d" for density, since "d" is often used to specify distance. In many textbooks on fluid dynamics, the density is given by the Greek symbol "rho" (Greek for "r"). The combination of terms "density times the square of the velocity divided by two" is called the dynamic pressure and appears in Bernoulli's pressure equation.

Drag depends on the density of the fluid, the square of the velocity, the fluid's viscosity and compressibility, the size and shape of the body, and the body's inclination to the flow. In general, the dependence on body shape, inclination, fluid viscosity, and compressibility is very complex.

One way to deal with complex dependencies is to characterize the dependence by a single variable. For drag, this variable is called the drag coefficient, designated "Cd." This allows us to collect all the effects, simple and complex, into a single equation. The drag equation states that drag D is equal to the drag coefficient Cd times the density r times half of the velocity V squared times the reference area A.

D = Cd * A * .5 * r * V^2

For given fluid conditions, shape, and inclination of the object, we must determine a value for Cd to determine drag. Determining the value of the drag coefficient is more difficult than determining the lift coefficient because of the multiple sources of drag. The drag coefficient given above includes form drag, skin friction drag, wave drag, and induced drag components.

Notice that the area (A) given in the drag equation is given as a reference area. The drag depends directly on the size of the body. Since we are dealing with fluidynamic forces, the dependence can be characterized by some area. But which area do we choose? If we think of drag as being caused by friction between the fluid and the body, a logical choice would be the total surface area of the body. If we think of drag as being a resistance to the flow, a more logical choice would be the frontal area of the body that is perpendicular to the flow direction. And finally, if we want to compare with the lift coefficient, we should use the same wing/hull area used to derive the lift coefficient. Since the drag coefficient is usually determined experimentally by measuring drag and the area and then performing the division to produce the coefficient, we are free to use any area that can be easily measured. If we choose the wing/hull area, rather than the cross-sectional area, the computed coefficient will have a different value. But the drag is the same, and the coefficients are related by the ratio of the areas. In practice, drag coefficients are reported based on a wide variety of object areas. In the report, the fluiddynamicist must specify the area used; when using the data, the reader may have to convert the drag coefficient using the ratio of the areas.

In the equation given above, the density is designated by the letter "r." We do not use "d" for density since "d" is often used to specify distance. In many textbooks on aerodynamics, density is given by the Greek symbol "rho" (Greek for "r"). The combination of terms "density times the square of the velocity divided by two" is called the dynamic pressure and appears in Bernoulli's pressure equation.


So, as you can see, there is your answer!


Captain Joaquin
FL250

It is obvious that either waxing or sanding does not make any difference for a wakeboard boat, the discussion was and is purely academic.
It sounds strange to read words of people who offend other people saying that if someone does not know what is talking about should shut his mouth.
I do not know if those words were directed to me, but for your records I am an engineer and I am pretty conscious that we are talking in any case of such small speed diferences that would not be even detectable in a wakeboard boat. However, if any of you had experience of America's cup boats would know that nobody waxes the hull of the boats. May be the engineers that study hydrodinamics of those boats are all stupid? In that field even a really apparently negligible difference can make the difference. For our field, I will always continue to wax the hull to keep it shining. Who cares of a probable 0.0001 % increase in speed ?

I totally agree that for speed boats it dont matter and those wishing to keep their gel in good condition that wax is the way to go.

BUT the title of the post was "waxed hull = slower boat" and yes a waxed hull is slower. End of.

If you wish to debate on whether a waxed hull is a good idea for wakeboardboats then start a thread "waxed hull on wakeboats, any good?"

As Mr. Miyagi so deftly put it "Wax on, Wax off" Who cares?

Wakepirate!!! It was a joke. What is a Diplacement engineer. Hell, I dont know either, but it sounded good when I made it up.

Dont take everything you read so seriously!!!! This whole thread is laughable. To wax or not wax. Who the hell cares!!!!!

Naughtyboy,

That makes perfect sense. Thanks for clearing everything up!!!!

Laughable? It's a very important issue that must be resolved for the betterment of mankind.

I feel dumb for having read, participated, in this post

Everyone, please stop posting so it will just GO AWAY!

Shut up, you...hull waxer.

I tend to steer away from wax, as it usually contains solvents which act as a catalyst for the oxidation process, thus defeating the purpose of protecting the hull in the first place. In addition, most waxes have silicone, which will migrate towards vinyl plasticizers and destroy them (vinyl cracking).

For me, using a polymer protectant which has no solvents or silicone is the only way to go. It provides for the maximum U.V. protection and does a great job of increasing surface tension thereby causes a hydrophobic envirinment. This popular "beeding" effect that people asscociate with a good wax application is actually a by-product of the increase in surface tension. In my research, I have developed a a mathmatical formula which I have termed "WBV Equation":

Purchase Price * Lifecycle wax/protectant applications * Lattitude * Longitude = WBV Sum

As you can see, it is advantageos to have an inflated sum when it comes time to resale your boat.

I didn't read the article. Is it ok to use Mr. Zoggs Sex Wax? Maybe we should notify the Donzi boat forum of this scientific break-thru. And all this time I have been cheating myself by holding my speed back with perfect pass - bummer.

I feel like the odd man out here because I rarely take my wakeboard boat over 25-30 mph......not because I don't like speed but because flippin wakeboard boats arent all that smooth at high speed anyway.......wax sure looks purdy though

Lets ask a plumber....they have "Hydraulic Displacement Engineer" training.....dont they? Hey Scott, give us your professional input!

In order of increasing speed:

waxed < sanded < riblets

For more about riblets, see:
NASA Riblets For Stars & Stripes

For even more speed, without all the high tech, buy a bigger motor!