I just receive a set of K4 Thruster fins to put on the 109 SB Kode and I have no idea how to best set it up. For example, would it change anything to the board's behavior by installing the side fins close or far away from the center fin? Any advice is welcome. Thanks.

Black project fins used to have a page explaining this but its gone. The closer the fins are in a fore-aft dimension the turnier your set up is, the further apart less turny, more of what they called “drive.” Single fin of the right size has the most drive.

I just put mine where Starboard recommends or farther apart. I wont feel any difference anyway.

Thank you both for the answers. I will try both ways and see the difference.
I went back on the water on Monday and tried the single fin all the way back and it almost completely eliminated the spin-outs I had last Saturday.

Maybe just don’t push too much ?!

the more you spread the fins out the more directional the ride will be... for the most pivoty feel, center fin all the way forward and side fins all the way back. some of this also depends on the location of your rear footstrap. for most freewave boards with a power box, the leading edge of your center fin will be roughly even w/ the rear edge of your back footstrap (power box limitation). In this case, the center fin is providing plenty of drive relative to your rear foot... best to bring the side fins back if you want a more turny ride.

If your center fin is US Box or slot box, then box location via footstrap location is up in the air. On wave boards, usually the back footstrap will be on top of the center fin to various degrees. Really depends on where you mount your rear footstrap and where the board maker put the fin box.

Personally with US Box or Slot box center box for a thruster setup I like to have the leading edge of the main fin in the middle of my rear footstrap and the the trailing edge of the side fins about 4-5cm forward of the leading edge of the main fin. YMMV

David Mark wrote:
Hey David,

Been sailing with your brother the last two days... well actually only sailed w/ him today cuz i have a bum elbow and took yesterday off. But Candlestick has been windy... 4.0 type conditions yesterday. Today I sailed 3.8. John borrowed a 3.7 from my friend Heidi today when he got blown off his 4.5! When this shit is all over you gotta come out and sail with us! It's been fantastic out here and my body is worn out already. Had an epic day at Fort Point/South Tower on Tuesday... best day of the year... double overhead + set waves on a big ebb with 25mph wind... i think that's why my elbow hurts now... it was totally worth it!

There is one important thing that I should have started with actually-I mix and match my tri fin sets! Most brands /including Starboard/ sell the freewave boards that way, usually a combination of composite and g10 fins and I got convinced myself that this is the right way when I bought a set of 3 composite MFC TF fins and started having spinouts. It didn’t take much after that to realize that a stiffer g10 center fin and softer composite sides work perfect with my bigger sails for lighter wind and a composite center with g10 sides are fine for stronger wind and smaller sails. A set of only g10 fins on the other side feels kinda overly stiff and directional-like on tracks. So don’t hesitate to experiment with your own combinations and try to ignore the less appealing aesthetic side .
Now that I got myself acquainted with my boards and fins and know how they react in different situations I have a lot less of guessing and know that if I have too many spinouts its my fault and either I’m pushing too much when I shouldn’t or my sail has not enough downhaul /or both/.

Great advice from all. Exactly what I was looking for: A few pointers to start experimenting and knowing a bit more what to expect.
If anything worth noting, I'll come back here and add a line or tow to share my experiments.
Thanks a lot.