Tuesday, December 2, 2008

Review : Maui Ultra Fins

I'm a huge proponent of fins. I see so many people who are struggling with a board, or a their sailing in general and they're all focused on the rig or something else when the problem stems from their fin.

People spend thousands on a sail quiver and almost nothing on fins, which are equally important in terms of board control and handling.

I recently got to test out some fins from Maui Ultra Fins and while I'm still puzzled about their claim of "Advanced airfoil design" since we're using them in water and not in air, I'm pleased with their performance. (Hey guys, drop the "air" from the tagline)

One thing about these guys, they "get it" in terms of what matters. The number one most important part of the fin is its foil. If you get this wrong, it wont matter what the outline shape is, the fin is gonna suck. The foils these guys use are really good - almost supercritical in design terms for how the foil keeps the flow attached even at crazy angles of attack (the angle of attack is the angle of the fin against the direction of travel - too high of an angle and you get a stall and stalls are bad). When I'm buying fins, I'm always looking at their foil first, square area second, length third and lastly outline. Anyway, back to the foil...

The feature about the foil that you'll appreciate is this : No spinout.

Its true, really it is. No gimmicks, no hype. The foils keep the flow attached and also shed separated flow caused by a bad board/fin/air interface in wicked chop.

I tested their all around bump and jump fin at Kanaha, overpowered on a 5.3 on the Starboard Kode and I really put it through its paces with balls to the walls downwind runs, hard upwind drives, and broad reach sloppy sailing that would make any fin spinout.

While I could get the fin into a flow separation position, it immediately reconnected and continued sailing as if nothing happened. Mind you, this happens in less than a second and I really had to work hard to actually get it to happen in the first place.

Once I had a good idea as to how the fins reacted to spinout conditions, I took them through a few tests that I knew would also be interesting - stall testing. To do this, I would sail as high into the wind as I could, forcing the board's angle of attack higher and higher to get the fin to stall and stop "flying" as it were. Could I get the fin to stall? Yes. All fins will stall above the critical angle of attack, but what was really nice is how the fin handles under a stall and how easily it reconnects and resumes "flying" with good water flow. This testing shows how good a fin's outline works in terms of dealing with tip stall (stall that begins at the tip of the fin) and stalls caused by the interaction between the board/water and fin. The net result, the fins handles great even when you beat on it.

There are a lot of fins out there, and most people buy them based on outline (or planform) and length. What they need to know is foil and square area, then worry about length and outline for performance optimization.

Remember, a good fin can make a bad board good and a bad fin can make a good board suck. So, before you give a board low marks, play with the fin. Feel free to ask me about problems with your board, etc. I'd bet I can make you love your board again!

If I had to make a proper analogy, its like having traction control and anti-lock brakes for your board. They keep you out of trouble and make you a better driver.

Can't wait to test out Ultra's twins on my RRD WaveTwin. ;-)


Catapulting Aaron said...

What about turning ability? The strange thing about MUF's from what I've seen is their wave line doesn't look wavy (aka swept, like most wave fins). If wave fins don't need to be swept, why is everyone else doing it?

David said...

Their turning ability is fine. The sweep in wave wins gives them "looseness" - turning ability comes from the board, not the fin. Sure the fin can hold a board back, but the Ultra's don't. Most highly swept fins don't do much with the swept part in terms of usefulness.

Outdrsmn said...

Aaron, In the FAQ's on the website they address that very question.

I was looking for more information on their weed fins.

Scott said...

Hey, what other fins have you used? I've been using the 22cm MFC Freestyle Pro on my JP Freestyle 100. I've got a 25cm MFC Freewave for my JP Freestyle Wave 84, and a 23cm MFC 2K for my JP Real World Wave 83.

I like all these fins, especially the Freestyle Pro, which has a pretty pronounced foil. But in a recent session, the 25cm Freewave had a disagreement with a rock; and I got it for a 93 liter board, and it's a bit too big for the 84 liter board I use it with in windy conditions. I've been thinking about trying a 23cm MFC K-One, but I'm also thinking a 22 or 24cm MUFin Wave or C-Wave might be a good choice, too.

Have you used any of these MFC fins? How about the Wave or C-Wave? If both the Wave and C-Wave, what differences have you noticed?


PeconicPuffin said...

You've convinced me...I'm going to have to start using fins.