Golf ball boat - install a dimple plate?

[venomousbird]

Originally Posted by Village_Idiot

You need RANDOM PROTRUSIONS on the surface, to break up the eddies before they get too large to disturb laminar flow. See my earlier post. I suspect the protrusions need to be large enough to be rather unsightly.

Barnacles for example. . . ? Just kidding!
Maybe the idea of dimples on a sail could be investigated?

[speedboats]

From what I'm reading you're suggesting dimples (or pimples) on a sail or displacment vessel? What of a planning craft. I've often been asked and given a similar response to what was aforementioned, but the thought of aerating the water under the hull to reduce surface friction is what we try hard to achieve, only it has to be controlled and uniform (symetrically). Has anyone experimented of have thoughts on weather the dimples would trap air at say above 60mph, or turbulate enough to reduce surface tension of the water on the hull? Of would this just increase the nett drag?

[venomousbird]

I was wondering what effect the flow of air under the boat would have myself.

[speedboats]

alot of the so-called 'tunnel' boats are trying to capitalise in the 'wings-in-ground-effect' concept. I have routed exhaust under the hull bottom. Not sure of the benifits (although the boat vibrated and reverberated oddly at non-planning speeds), 'cause if we traveled in anything but a straight line the jet pump would suck air and cavitate, hence we changed to a through-transom exhaust quick smart. Perhaps this'll work in a 'stepped' type arrangement. But 'drizzling' small air bubbles under the hull makes sense on paper, would dimples under the hull help trap these and in effect reduce the friction coefficent

[Pakal]

Good morning everyone - i remembered this discussion last night and i thought i could give you an update about an actual boat that is already on sale in Greece.The manufacturer is AirHull SA and you can find interesting photos and videos on their web site, www.airhull.com .

[cthippo]

Originally Posted by speedboats

...but the thought of aerating the water under the hull to reduce surface friction is what we try hard to achieve, only it has to be controlled and uniform (symetrically). Has anyone experimented of have thoughts on weather the dimples would trap air at say above 60mph, or turbulate enough to reduce surface tension of the water on the hull? Of would this just increase the nett drag?

I wonder if you could use small strakes near the bow to create cavitation in the water and hence bubbles. I'm thinking something like vortex generators on aircraft.

[Mr Efficiency]

I'd be interested to hear the opinions of the folk here about the concept illustrated in Fig. 3 on this site.........

http://docs.hydrofoils.org/SAS03.pdf

[Joakim]

Originally Posted by Mr Efficiency

I'd be interested to hear the opinions of the folk here about the concept illustrated in Fig. 3 on this site.........

I guess that would only work for high displacement and/or low speed hulls. Otherwise air will leak out when you trim up to shorten LWL.

Are there any papers showing the claimed reduction of drag? Did they take different trims into account?

[claydog]

Interesting thread, just to toss out a little food for thought, On the TV show Mythbusters they did a test on whether a dimpled car would get better MPG. they covered a car with about an inch of modeling clay, ran the car on a closed course to get a MPG figure. Then they cut dimples( about 1/2 " deep and 4" in dia.) in the clay all over the car puting the removed clay in the car to keep the weight constant and ran the same course at the same speed and got a significant improvement.

[rxcomposite]

This topic is an extention of Golf Ball Fluid Dynamics TS Inquisitor 11/28/2005

[rwatson]

There is already a product on the markey to dimple your car, but the results arent that straight forward

http://ecomodder.com/forum/showthrea...aims-8321.html

It would be interesting to know what speeds the mythbusters went in their tests. certainly, at consistant high speeds, dimples create more drag from what I can remember. The dimple effect has been examined for over a hundred years, so one would think that what isnt dimpled, shouldnt be ???

[kach22i]

Originally Posted by Pakal

www.airhull.com .

Cool.

[hoytedow]

Originally Posted by rwatson

There is already a product on the markey to dimple your car, but the results arent that straight forward

http://ecomodder.com/forum/showthrea...aims-8321.html

It would be interesting to know what speeds the mythbusters went in their tests. certainly, at consistant high speeds, dimples create more drag from what I can remember. The dimple effect has been examined for over a hundred years, so one would think that what isnt dimpled, shouldnt be ???

So if your car has been in a hailstorm it should go faster?