Need to replace the fins on my directional and wondering if surfboard fins are the way to go. These are future fin boxes and there are a million types of fins available. However, I am thinking that surfboards do not need to go upwind whereas a kiteboard does. Does this make a difference when selecting fins?

Well I would choose the fins based on performance in surf...but make sure they have some rake...especially if use a big kite...

Also don't get plastic fins they will break off

Hello,
I've changed and keep changing fins on my kite surfboard, it's my current obsession
There are many global factory specialised in the "science" of fins.
I've never had issues when switching from series to commercial fins.
Why should you have upwind issues ? just be sure you're taking the proper fin size, based on rider weight, board fins configuration and your style.

ciao !

Surfboard fins are fine

In fact maybe the best

You got almost ANY choice with future fin box'es as there are so many surf fins to choose from.

The green glass filled are not costly and works fine.

And if you go for the carbon reinforced ones - they are really awesome ! (but expensive of course).

Size IS important - just the other way around - dont go too big...

Too big fins on a surfboard and it does not work at all IMO

Too small is okay, just a personal thing how "skaty" and slashy or tracking you like your cutbacks

Fins are not used for going upwind really (not that important) - just for the right surf feel.

And it makes a HUGE difference, even a few millimeters change in size on a fin can make the finest board you got a really dog, if you test neck and neck !

Peter

No issues, just trying to figure out if there is a difference. A surfboard goes where it goes and needs fins just to turn. A kite board needs to go upwind and the board has to develop lift. So perhaps the foil shape woudl be different. I thought there might be a difference, but maybe I am overthinking things.



Then what makes the directional go upwind? I always thought it was more the fins than the rail, since the rail is so rounded and you ride it flatter than a TT.

I'd recommend symmetrical fins (both sides foiled)...Like most quad or tow fins. They are faster. Stiff is good.

The reason why directionals go so much better upwind - is not because of the fins (only to a very small extent), but because of its name "directional".

Meaning - it is meant to ride one way, so the rockerline is very flat at the tail and often quite long (even with round edges), and then you got scoop at the nose (and no fins) so it wont catch the water.

Way more efficient with this rockerline (heavy noselift and flat at the tail).

It can be ridden more flat - because it has more volume, and because of the flat rocker at the tail.
Meaning - it gets on a plane earlier - and you dont need so much power (or speed) to get on a plane - thus you will rock upwind really fast as you can glide with the board more flat at a high angle to the wind, and you wont lose your "kitepower" just to keep planing - but convert the power to upwind instead.

Of course - if a waveboard has a lot of tailkick, and very round edges - many flat straight TT's can go upwind just as well, easily (although not as pleasant in chop or waves).

But the very idea of a directional, is that it is NOT symmetrical - so flat rocker at the tail, and lift and no fins at the nose - this is by far the most efficient shape by all means

Because of its bigger size and volume, somewhat bigger fins than on a TT are used, to give the same control.

Then some directionals go to the extreme - having straight sharp edges and really flat at the tail - so even with small fins they ROCK upwind, and gets on a plane ridiculously early
And for going a tad more upwind, really big fins are used - but this is mostly for competition where even the slightest higher angle can decide who wins

So all the good performances of directionals are simply because they ARE "directionals"

Peter

That's good to know. Thanks, Pete.

having big fins I'd say is a large contributor to going upwind. Obviously not the only thing, but definitely a big part of it. The easiest test you can do is to put a set of small fins..you'll go upwind, then put a big set of fins, and you go much better upwind....but
I still mean that if the idea is to ride waves, then choose fins for that.

But also a balance, I guess. I put bigger fins on a small directional, and it just bogged down. I could not get it to go with a kite that I would do well on a TT.