high aspect ratio longboard fin

Roy disagrees with everything in this thread...

 

you're not just pushing on the rail, otherwise you wouldn't load up that super flexy fin you've got in your hull. if rails were the only thing used in turning a surfboard, fins a. never would've been created & b. wouldn't have so many variations. if fins were just about traction on the face of the wave & didn't create any lift, there wouldn't be all this debate over materials, flex, size, etc...they don't work exactly like wings, since there are so many things going on underneath a surfboard when it rides a wave, but they certainly do create lift in the same/similar way sails create lift...

 

Kept thinking shane dorian but new the guy was an aussie, thanks...not sure if it cost him any titles...I remember people use to say that about quads costing people victories. I had a quiet flight quad back in the 80's with 757 fins (at least thats what I called them after the airplane, not sure on the correct name)...people would laugh because it was a quad and it had a very odd shape fin...the top was squared off...actually, when I think about it, it looked very similar to the fin in question with more rake, but certainly didn't stand up as tall or have the winglets. Wish I still had that board...different.

 

I find this stuff interesting in that someone is willing to try something different. If it was cheap i'd try it just for the experience. That said, I don't think it will do anything more than cause less drag than an equivalent sized (I mean total area) fin. I come from the aviation world. In my world hi-aspect ratio wings provide more lift and less drag (as advertised). What he doesn't mention is that they also are slow, unweildy and inherently less manuverable. For an example, take a bird's eye view of 2 wings. One of a glider and one of an F-16 or any other true fighter jet. The glider will look like that fin laying on its side and the fighter will be a triangle. When designed, a fighter should be unstable to the point of being highly manuverable and needs a lot of power to go (you can get a brick to fly if you put a big enough engine on it). The glider is the exact opposite. Is it any wonder that the HP shortboard fins look like 1/2 of a triangle and seem to work pretty well when the waves get bigger and faster...

 

for whatever reason in my mind, I dont see how a surf fin can create lift. I somewhat understand the dynamics, but to create actual lift from a fin, I would think a portion of the fin would need to be perpendicular to get that lift...I guess like a winglett or the weird keel cheyne used.

 

I agree with your question but remember... often times your surfboard is sideways on the surface of the wave. so the fin's orientation is not pointing straight towards the ground.

 

alright...i think i understand lift...it seems it doesnt actually lift the board but actually allows the rails to dig in due to the foil/asymetrical outer fins.

 

Check out some videos of alaia surfing. There isn't any drive or thrust AKA lift, just glide. The rail allows for some directionality but limited to trimming. The lift created by a fin keeps you from sliding down the face of the wave.

Lift, when talking about fins isn't the wing of the airplane, it is the vertical stabilizer/rudder on the back.

 

I decided to try for myself. PUt the wavegrinder on my Tim Nolte 9' HPLB. Rode some smallish waist to chest waves on it, didn't really feel a huge difference in catching waves, but did feel a lot of hold in sharp turns.