rear wings on boats
 

i was glancing thru a speedboat magazine and saw an article about baja trying to reduce drag and make more aerodynamic boats as opposed to stepped hulls. i thout it was interesting that they said a rear wing reduces drag at teh stern of the boat. does anyone have any experience with rear wings or have any input on the subject?

Re: rear wings on boats
 

I would think that any object like a wing would create drag and slow the boat down :rolleyes:

Re: rear wings on boats
 

I would think a wing at speed could create lift, and possibly reduce draggin the rear of the boat.

Re: rear wings on boats
 

I'm not an aeronautical engineer, but doesn't it depend on the shape of the wing whether it produces lift or downforce? For example Indy Cars, Outlaw sprint cars and of course airplanes. I saw the Baja poker run boat last weekend and it has a carbon fiber wing attached to the rear.

Re: rear wings on boats
 

A wing could produce downforce, as it does on a car, or lift, as it does on an airplane. Depends on which side is "up". The force is applied to the flatter, or higher pressure side.

Fabio Buzzi has had wings on a bunch of his boats. They seem to do pretty well. I would think a wing has to be throughly tested tho, to produce the desired effect, and avoid big problems. Too much lift at the rear...can you say STUFF? A lot more complicated than a 20 year old screwing a carbon-esque wing to the back of his civic.

Re: rear wings on boats
 

Fabio always placed his wings at the exact center of gravity. He also incorporated a ton of dyhedral to help correct any chine walking.

Lifting the whole boat seems safer that just lifting the stern.

Look at any new Skater or MTI, notice the sweeping stern, it's done like that to create stern lift.

Re: rear wings on boats
 

Notice the tiny wings on the bow. Those are anti stuff wings. Once underwater, they help to lift the bow.

http://www.biggerhammer.net/offshorepage/photo/lga.jpg

Re: rear wings on boats
 

Dank368's new Skater has wings incorporated on the rear of the deck,overhanging the hull, which supposedly gives the boat lift.Maybe he can share some pics.

Re: rear wings on boats
 

Fabio did his mostly because of chine walking. You'll get dizzy riding his raceboats. I have had the pleasure of riding multiple race boats witrh him, he's a nut.
The back of skater and MTi do create lift as air accelerates and so creates lift.
Some wings do work but have to be in the perfect place and have to be in the perfect position.

Re: rear wings on boats
 

Certainly, any additional structure and/or lifting device placed anywhere on the boat will incurr its own associated parasite drags, however it's usually not without benefit.

Up lift, down force, doesn't matter what you call it, it is still "lift," -- a product of holding any relatively flat object at an angle of attack in a moving fluid medium. In the case of the Indy car cited above, it's an inverted wing held at a negative angle of attack.

Even a flat sheet of plywood will make lift, just not well...Airfoils aim to make lift with as little drag as possible and have infinite variations on chord to thickness ratio, camber, toe, sweep, dihedral, etc. Some are effective at low velocities and others peek in performance in the compressible subsonic, sonic, and supersonic ranges.

In any event, a small "wing" at the stern of a typical V-bottom with a flat transon could be of good benefit. Held at a positive angle of attack, the lift would reduce the apparent weight of the stern and thus hydrodynamic drag, but the most significant improvement could be achieved by forcing the air from above the boat back down to the water, leaving it as undisturbed as possible...In other words, reducing the low-pressure conical region behind the boat which is responsible for a good amount of drag.

Look at your newer skaters and MTI's...There's a slight bulge about a 1/3 of the way from the stern, which makes a good amount of lift at or near the CG, and then the deck slopes way down towards the water...This helps reduce this low-pressure drag cone.

I've been doing a lot of work and research on marine aerodynamic performance, for example take a look at my models of Miklos's 29 Extreme below. Notice the area of yellow and green directly behind the boat. This is low-pressure air being dragged by the boat which is responsible for a great deal of parasite drag. Forcing air down at the stern could help greatly.