you can buy an adaptor that converts the long box to FCS/Futures.

milko said...

you can buy an adaptor that converts the long box to FCS/Futures.

Really? I've seen the FCS converter but not a Futures one. I rang Futures a few months back and they didn't have one then.

Have you got/seen a Futures one Milko?

Check out probox fin systems: www.proboxhawaii.com

There what I've been using on my home made boards - dead simple to install all you need is a trim router and some contact glue (3M Super 77), good selection of cool fins (and normal ones), guys that work there are super helpfull.

The only bummer is that angles change a bit depending on concaves so if you want an exact angle theres a bit of fiddling around but you can get different cant angles so you can get it pretty close to were you want to be.

log man said...

OK, so another stupid question, what would happen if I put an ordinary centre fin type fin on the rails . So what I mean is a fin that is foiled on both sides and not flat on the inside of the fin?.

It wouldnt turn I wouldnt think, havnt tried it tho. CMC will know........

I have bought a second-hand custom prototype with US boxes for rear quad positions. I use FCS adapters with FCS fins in them (the red ones).

The FCS adapters are not well designed mechanically: their screws push on the tabs at an awkward angle (they actually puh the fin out of the box), and they push on the tabs so they can induce breakage (I already broke one fin at the tabs in them). So maybe you want to glue them in the adapter or add pins/screws through them.

However, being able to change the positions of the fins is great to experiment (this was the goal of this prototype, to experiment fin positions for a future production board with just FCS plugs)

You can also try to find vintage twin fins (1980) in US box formats, but the foil will be often crude. Or windsurfing/kite fins, but they may be too stiff.

CMC said...

micksmith said...

Its all about hydrodynamics, I tried similar thing on a short board some 25yrs back didn't work then and I doubt if it will work now. something about high and low pressure flow over the fin, just as like an aircraft wing is not symetrical or a sail. it needs that flow to get the drive so as not to stall or something like that. read up on hydrodynamics and angle of attack before you decide.
good luck.
be good to see pics whatever you decide

This is exactly why. Think of side fins like aeroplane wings. The difference is the lift is not vertical but outwards from the rail. This is the idea with cambered foils rather than flat inside edges as they create more lift for the size and also are more efficient.

If you put centre fins in there is much less lift or drive. They would not create much drag but no lift equals no drive and would not help you to turn much.

This is the same argument for quad rears. Center fins are more neutral, 80/20 are a bet each way and sides in the rear mean more drive from the rear.

My quad has gone so much better after I put in a set GQX rear fins with the 80/20 foil. Smaller fins with better drive.