what about FINS

[2stand]

  I'm thinking of changing out my fins. Im currently riding a quad. Maybe smaller fins on the outside. Sometimes it good just to change things up! I'm intersted in what other people are riding. Thanks

[OUTSIDEWAVE]

try it  I play around with fins all the time in fact I am having a custom board shaped see shapeshack and I going to have full size boxes on the outside so  I can  try different fin sizes and set ups. I used to grind down  fin bases and try  them in my long boards I  sometimes ran  twin turbo tunnels on a 10 foot ben aipa with a 3 inch center fin. I loved it.

[CMC]

Regularly riding MRTFX Twins in the front and H2 Large side fins in the rear on Quad SUP.

Goes unreal, likes to get on rail and hold, no nursing or cutting off turns.

 

[mike2jay1]

Has anyone tried the Future Elavon's on a sup?  My buddy had one on his Lost Shark and i rode it and gave me a lot of lift. I was interested in how it would do on a sup?

[surfcowboy]

There's a question, how big do you need to go to help a "short" quad not drift so much when catching waves?

I'm about to switch to a board that I'd like to "straighten" out a bit.

[Old School 213]

Would you guys running quads and/or thruster set ups comment on the height and area of your fins?

I'm also curious about the base dimensions as well as rake.

[bean]

There's a question, how big do you need to go to help a "short" quad not drift so much when catching waves?

I'm about to switch to a board that I'd like to "straighten" out a bit.

In general, I think the biggest factor is rider weight.

I was running M-5, FCS quads and at 205lbs or so I was getting alot of slip.  Simply swithching to a slightly larger and stiffer PC7, GX set up, completely changed how the board rides.

If you have Futures boxes you can take advantage of their "fin tree" demo program.

[surfinJ]

It is worth the little effort to mix it up.   The juice of the waves is also a reason to switch
around.  As the waves get smaller I go to really smaller setups to keep the board loose.
Have some fun.

[AJR]

Try only 2 fins or run with a small trailer; talk about loosening it up...

[CMC]

I see a lot of SUP surfers using very small fins for the size of the board.

What seems to happen is this results in boards that will not set a rail properly and people nursing turns or just turning flat.

IMHO if you want to draw similar lines to a shortboard and turn from the bottom of the wave to hit the top or drive down the line rather than paddling across the wave like a lot of people do you need fins big enough for the board.

Luke Egan explained to us that if you design a board as a giant shortboard you would add giant fins in the same proportion to the width of the tail and the thickness of the rail.  Fins are a control surface that need to be increased in area with the sideways force away from the direction of any turn in order to control the turn properly.

Take for example the below:

My shortboard has a 14" tail at 1' from the tail.  On this board I use fins that are around 4.75" depth.

My 8'11 Shortboard styled SUP has a 18" tail at 1', in order for this board to hold the same lines and surf in the most similar to the shortboard I could find I use fins which are 5.5" depth.

By using a calculator (after I played with fins enough to feel what actually felt the best to me, as an ex employee for a major fin co. I had just a couple of fins to try!)  I calculate that my SUP tail width is approx 1.3 times the width.

My fin size is approximately 1.2 times the size.  In effect I think I could go bigger as a thruster set but with the Large rears in the Quad the total area equates to about the same surface area in relation to tail width as my shortboard.


It all sounds a little mathematical but the people that I have convinced to actually try bigger fins than they are using here are blown away at how you can ride your short SUP with a bit more area.

Most people read the fin size recommendation from Futures or FCS and it tells you fins this size for your weight, what people fail to read is that one of the rules of fin size is that you increase the fin size with tail width even on shortboards.

Another thing here, the Aussie Surftech rep told me a long time ago that with EPS boards (most SUPS) the way to give back the drive and alleviate the corky feel through turns was to go up a fin size.


Try it out, nothing makes a board looser than going fast and having the security to drive from the steeper parts of the face to gain speed without having to use the paddle.

[Cardiff Sweeper]

I prefer smaller fins on my 7'4" Starboard POD than what came with the board...Quad setup. On the 8'5" Pocket Rocket, the FCS 3DS fins are in front, and the rears are the same height (but this oddly works quite well).   Helps gives the board the "bite" I need to crank it up the wave face.  

[Beasho]

I appreciated CMC’s comments because they were based upon experience and data, which I like.  

That said I have often had a hard time understanding fin language. Kind of like wine drinking adjectives.  “Drive” has never made sense to me.  I get ‘loose’ and ‘stiff’ and have even experienced ‘slide’ when fins were too small which I assume is the opposite of ‘bite’.

 On a prone surfboard I gravitated to quads because I thought they went fast and turned well.  My first SUP, a 10’ X 28” relatively gunny Jeff Clark custom, felt stiff with a Tri-fin but much better as a quad.  My 12’ gun was terrible with a set of expensive Gerry Lopez quads, it felt like a super tanker that would not sway.  When I put on a smaller set of (crappy) plastic quads it turned better.   Lately I have been experimenting with a large single fin on the 12’ gun in bigger waves (e.g. 2X++).  The theory being that the single fin (with no toe-in) will present the least amount of drag, and go fast (see the Naish Hokua Gun).  Foot placement, a la on the tail, also helps enormously.

Since I do have a background in aerospace engineering I recall that lift (and drag) are proportional to the square of speed, surface area and density of the fluid.  A 747 has a massive tail because it requires stability at low speeds and heavy loads (e.g. at takeoff full of fuel).  Once up to speed that tail is just holding back the rocket ship.

Shouldn’t we therefore be talking about intended board speed in a fin discussion?  Big waves are much faster than small waves certainly up to 2X faster.  Once up to speed the fins are therefore generating 4X++ as much lift and drag.  If the takeoff isn’t a problem, from too much adverse board yaw, then shouldn’t we be looking to smaller and more efficient potentially higher aspect ratio (long and thin) fins in bigger faster conditions?  

[Dwight (DW)]

Shouldn’t we therefore be talking about intended board speed in a fin discussion?  

I'm with you on this one.

My feel from the board takes me to the smallest fin that produces enough lift to drive me, without stepping over that edge when it slows me down. So I test until I find that edge. The only time an over sized (compared to prone board) fin worked out better for me, was when I owned a SUP with  chunky monkey rails that didn't work very well. I sold that lemon long ago. I'm not SUPing with a slow board. My 7'8 screams.

[Cardiff Sweeper]

DW has it. 
My current dilemma, when the waves get overhead here (rarely) the 7'4" has plenty of speed at the expense of control.  The loose-slideness that is fun in smaller surf isn't fun when flying down the line trying to do a nice controlled power turn. 

 Bigger rears might help on bigger days(?). Going to try the Nubster.

[CMC]

Here's a quote I remember from an article many moons ago.  It said that the front to back foot weight ratio for each surfer is as unique as his fingerprint.

Meaning, everybody is different, people like to surf a different way to each other.  I personally like layed over late bottom turns, carving styled powerful drawn out turns and being able to hold in the steepest parts of the wave.  It's the same as I like to surf my shortboard.  To get this feeling from my SUP and be able to approach the waves in the same way I needed bigger fins.  Nothing says this is right or wrong for everyone.  It's why fin systems are the only choice.  I tried most fins and to feel right this is where I ended up.  On my 10' PU I had much smaller fins, I found the lower floatation allowed the rail to bury more readily without the added fin area.

Beasho makes some very good points about speed and lift, you would also note that on the Gun it has a much narrower tail.  This brings the fins closer together so that they are now working together.  As per my previous post in using larger fins for greater tail area the opposite is also true.  I would use M3's in my 7'0 prone gun, in my 6'2, Al Merricks or M7's.  You would use smaller fins, I would also assume that the 7'4's mentioned in this post are narrower tails than my current board, the riders are probably much lighter also.

Point is, you need to try fins to feel the best for you.  My post was basically to say to not be afraid of bigger fins especially if you like a board with more drive to be be surfed in a more arc styled way.  You can also change this setup per the conditions.