gap FCS fin and board

[radical ronald]

There's a small splitt between the base of one of my new thruster fins and the bottom of my board. Probably very important, because I expect the lift to be maximal at the base of the fin. Also this will create lots of turbulence, possibly even spinouts.

Do other surfers recognize the problem? How to counter the problem best? I am thinking of using sander to take material away at the very top end of the fin, the two chunks that fall into the board's FCS fin boxes.

Looking forward to your views and experience...

[jaffa1949]

Are the fins genuine FCS fins or the plugs non genuine have other fins fitted before.
There are a lot of look alike that are not dimensionally suitable. Try a set of genuine FCS place the tabs against your fins and see if they fit in the plugs. That should give you an answer. Fin boxes( they are the ones that can support center fins with slide forward and back) are sometimes sanded to meet rocker curves. This cause many fin fit problems.

Now short answer, screw the grub screws out a little more, try to fit fins, no fit , a little sanding won't hurt.

Post a picture of the fin gap that is worrying you!

[oldmansurfer]

I haven't ever had that problem but my question is do you notice anything? I surfed a board with a 2 plus 1 fin configuration and noticed that it was becoming looser or I was suddenly becoming much better at turning the board. I found that the box fin had lost the screw and it was flopping all over. It didn't seem to adversely affect the way the board rode. I imagine it created a lot of turbulence but as far as I could tell it worked awesomely. By the way I got a screw and screwed it back in and it only minimally affected performance in a negative manner so less drag didn't amount to much.

[kookextraordinaire]

As stated above, "after-market" fins by different companies (Shapers, Captain Fin, etc) tend not to fit as well. I believe that the base of genuine fcs fins between and in front of/behind the plugs are machined at an angle to fit the cant of fcs plugs, which on thrusters are usually set at/around 9 degrees.

The best way to fix the problem is described in this video: https://www.trueames.com/pages/fin-installation-tips

But, honestly, apart from aesthetically, it won't make a difference in the way the board surfs. I don't really see how your board would spin out unless you are trying to make the fins release. Your leash causes far, far more drag than a tiny fin gap. I think there have been thousands of posts about this written on swaylocks.

Hope this helps.

[Tudeo]

I don't really see how your board would spin out unless you are trying to make the fins release.

I don't know for wavesurfing but in windsurfing spinouts happen, when you go straight, because of the tiniest bit of turbulence around the fin. The main difference is in windsurfing you put a LOT of pressure on the fin when the board is in horizontal position.

In wavesurfing the dynamics are different. Still, the less turbulence around the fin the better, I would think.

[Big H]

I've had it happen with non FCS two tab fins. I checked the fins in another board and it was the same story so I filed the tab down to fit. Had a plug in another board that made all fins I tried sit up a bit so I changed the plug out and it was all good.

[kookextraordinaire]

It's funny how FCS sells a system that doesn't fit properly, and that the surfer has to tinker with it to a fit a built-in problem.

I think that this subject may have been broached before, but fin systems were invented so that more surfboards could be shipped at a time and take up less space in a surf shop, maximizing retail space. The surf consumer is told that different fin models make one surf better. We are sold fins for different conditions, but the best way to surf varied conditions is, simply put, to surf better.

There is of course the argument that pros surf fin systems such as FCS and Futures. But keep in mind they get payed a hell of a lot to do it; it's simply marketing. Sure, Kelly Slater has FCS fins so we all think they must be great fins. But think of the millions of his signature K 2.1 fins that FCS sold as a result of his endorsement. He's never payed for them, but we the consumer do. I'm of the opinion that the whole thing is a scam. Another salient example of this is Jordy Smith. He has his own signature fin which you can buy for a fifth of the price of a surfboard, but he mostly surfs glass-ons of a different template. Probably not the only example.

I went the glass on route with my surfboards and I prefer it infinitely. I never had to think about problems like the one which started this thread, or which fins suit which waves. I suppose if you travel frequently it can be a pain to pack them, but done carefully I've never had a problem.

Bit of a rant. Thoughts on this, anybody? Agree, disagree?

[Tudeo]

I'm of the opinion that the whole thing is a scam.

I noticed a big difference in how some of my boards felt when I changed from L to XS thrusters, I also clearly felt the difference with a quad-setup vs thruster. But as an intermediate surfer I'm sceptical I could identify the smaller changes in fins the way the marketing promises. Because every wave is different you must be a very experienced surfer to feel the true difference the fin makes. Maybe wave pools offer a more laboratorium like setting, where all elements exept the one you want to test are controlled.

I think a lot of reports from intermediate surfers on the feel of fins are based on fantasy. But maybe I must adjust my opinion on this in time if I do more testing with different fins.

[dtc]

I agree that changing the size of the fins is really noticeable, which is why I prefer a fin system over glass on - because for a glass on you just have to hope the fin is the right size (I have a glass on and its probably the right size, but I have swapped fins around on my other boards in order to get what I want even though the shaper provided an initial recommendation).

Anyway, size makes a big difference. Rake is probably what I notice next and then base size; but the vast majority of thurster/quad fins are pretty close in terms of rake and base so its not really a differentiator between a $150 set and a $40 set. Similarly for flex, once you are past the really flexible rubber type fins, the differences are pretty small. Construction material I dont think makes much difference at all. I guess if you go to extremes you will notice, but most fins are just minor variations on a pretty standard average

Single fins is a whole different story however, as there is a lot more variation