Golf ball dimples on the hull bottom for better MPGs?

[ScarabChris]

Yeah that sounds crazy. But its a known fact that golf balls are dimpled for longer flight. Something about the dimples allows the air to slip over the ball easier.

I just watched Myth Busters. The myth was would a dirty car get better milage than a clean car because of the golf ball effect. Well the dirty car got worse milage.

But when they put dimples in the car resembling a golf ball the car went from 26 MPG to 29 MPG at 65 MPH.

How about dimples on the hull bottom to achieve the same effect? I have heard that some boat racers sand the shine off the bottom to help break the boat from the water.

Any thoughts?

[baypro21]

I think a few thousand small airholes in the bottom attached to a engine driven air pump might do something

[Boatdood]

There is a point at which a less than smooth point of contact with the water reduces drag therefore increasing speed. Coincidentally I've had the golf ball dimple conversation with folks from Yamaha years ago. It's not surprising to me that the size and shape of the irregularity of the surface affects the drag. Think about it like this....a slight chop on the water usually results in a slightly higher top end speed, but there is a point where surface irregularity will surely slow you down. Reggie Fountain is one who told me face to face that he sands the bottom to increase the speed. I believe him, but I wonder what grit paper he used for the best results.

[BiloxiGuy]

They put dimples on high end road bicycle tires to improve speed.

[marlin7]

Some of the go fast SF's use the teflon bottom paint on the bottom below the waterline not exposed to the sun, regular antifouling on those parts sun exposed. Some of the crews will lightly wet sand the boat bottoms from time to time. I have heard the mfg's say to keep the boat bottoms as smooth as possible for max performance. I'm sure you know that any bubbles, blistering, poor faring, etc will decrease performance.

[Mr. Demeanor]

Originally Posted by baypro21

I think a few thousand small airholes in the bottom attached to a engine driven air pump might do something

This gets to golf balls and boat hulls about half way down.
http://www.mothboat.com/CMBA/Building/notwax.htm

[ken2]

A boat builder friend of mine said they tried it and didn't get any results.
Not to say it didn't have an effect, it may have just been hard to measure.

Steps on a hull effectively do the same thing. Just a little more exagerated.

Most racing propellers are satin finish instead of polished as well for the same reason.

[itwonder]

You can give it a try, see http://www.dimpletape.com/

[Pierless]

A golf ball goes further if you reduce wake turbulence. Golf ball dimples reduce the turbulence behind the ball because there is less surface area contacting the air flow at the same time. Newer airplanes have the wing turning up at the tip to reduce turbulence. It is fluid dynamics so it will apply to boats.

Any thing that reduces wake turbulence will increase speed. Dimple and air bubbles might really work. But I have no ideas what the current angles and edges on a hull due to increase or reduce drag. Do you go flat hull to reduce drag and then get pounded by the chop?

[Bly]

Originally Posted by baypro21

I think a few thousand small airholes in the bottom attached to a engine driven air pump might do something

We can recycle old air hockey tables? Put all the boat companies out of business? Opps they are already headed there.

[Following C]

Many years ago when we raced the little wood hydros, we would varnish the bottom to protect it while the boat sat. Just before the race, we would sand the gloss from the varnish with 300 grit as I recall. When the bottom was dry, once again we'd revarnish until the next outing.

[patrickg]

There is a shear force between the hull and the water. If you knock the shine off a boat by wetsanding it, it creates pores for water to attach to the hull. Water moving across water does not create a shear, so wet sanding the hull does slightly decrease that form of friction. A dimpled surface probably wouldn't catch water as well as small pores, but it might have some other positive effects.

[wingless]

When I tried a similar principal, using barnacles, I found it did not have the desired effect.

[The Business]

I remember watching a discovery type show when I was a kid that used a paint to mimic sharkskin on a racing sailboat to increase speed. It worked if I rememeber correctly.

The Russians made the bubbe thing work http://www.globalsecurity.org/milita...sia/shkval.htm

[Mr. Demeanor]

Just read the article I posted authored by an aeronuatical engineer.

Bill from Starbright claims their wax has been banned from one of the sailboat racing sanctioning bodies and I keep asking him for a link to that rule.