Fin toe-in on directional boards

[Don Lester]

Has anyone ever rode two nearly identical directional boards, one with standard fin toe-in ( about 4 degrees ) and the other with none.........?

I'd like to get more speed by reducing the hugh amount of drag that toed-in fins present and I'm curious what you would be giving up.........

Seems to me that single sided foils are also a source of extra drag.........

I know a lot of guys say you need all of that stuff for turning, but really......... these boards turn so well and hold a edge so well in the turn that I'd like to think these concepting are just carry-overs from surfboards and arn't really needed. Any thoughts ?

[BWD]

Never really rode one with ZERO toe in.
But, toe-in is still good on kitesurfboards, I think.
Surfboards are ridden on a rail.
Kitesurfboards, too, only more so.
Boards never ride straight, the nose always points a few degrees to windward of the true direction of travel.
Water does not travel under the board in a straight line from nose to tail, so there is no need to align the fins to this line.
An outside fin always gets flow from under the center of the board, moving out towards the rail as it moves back towards the tail. So it is often more efficient to have this fin be assymetrically foiled.
There are exceptions.
When the board shape has parallel rails, and/or it is ridden flat, like a raceboard, less toe in is used. Sometimes none.
There are lots of aspects to this fin stuff, but these are some basics as I understand them, applied to surfboard-style directionals.

[Dan Glyaire]

i still ride old directionals, from back in the day..twin fin, and tri-frin.. fins are parallel, way less drag than any surfboard ive ever used, very noticeable in lighter wind, and ya, they turn just fine.
maybe not as good as a surfboard in real surf, but for bumpy onshore stuff i havent tried anything i like any better.

[BWD]

Cool, what models? Curious to see....
Was out on a naish sky pirate recently for a bit, fun and smooth ride.
Skinny and heavy, it shot through the chop very comfortably.
Turned like a boat though in my opinion.

[Dan Glyaire]

BWD, youll laugh, but my favourite all round board is my first ever kiteboard, a custom..as i think they all were at the time, by Donnie Bowers.. from 1999. didnt work too well on the two-line kites of the era, two much board to edge against in the gusts, and so sat in the relic room for years, was between boards a few years ago so i dusted it off and gave it a try. works great for the conditions i have.. a bit flatter rocker than a surfboard, harder rails, and parallel fins, and narrow, great for choppy conditions.
ive found it planes earlier, and is faster than a surfboard, and is smoother than a modern wide lightwind board.. <and are they faster, or do they just feel fast because youre bouncing around...i dunno.
and it turns ok, just need to get over the fins a bit.
but, it is getting a bit worn now.. if it goes, id get a copy made.
i suppose in real wind and waves, where early planing and speed arent an issue, a surfboard would be better though.
and, ive got quite a collection of other old kiteboards as well, mostly old airush from 00-03..all with parallel fin setups, and id say all plane out quicker than any toed in fin board that ive used.. although some of those do turn like a boat, especially the old 7'2''.

[Don Lester]

What BWD says about toe-in having no effect when riding in a straight line makes sense, because boards don't ride parallel to their center line, but empirically I have doubts............
So I took an old windsurfing fin, cut it down and rebased it to fit in my Slingshot Celeritas. The new fin is quite high aspect @ 7" tall and around 3" at the base. I installed it in the rear and removed the two thrusters and headed off to my local sailing spot, which is river swell, no white water waves..........Within seconds you could feel the difference, much smoother and faster, but with some loss of directional stability that will need to be addressed. So I'm assuming the smoothness is from the lack of fin cavition caused by either the lack of toe-in and or the lack of single sided fins. More experimenting needs to be done to gain back the lost directional stability.................

Bigger single rear fin or thrusters with no toe-in ?

Removing toe-in on this board will be difficult without replacing the fin boxes. I'll try shimming the fins themselves and regrinding the base to fit, but I'm not sure I can get all the toe-in out. The other thought is reshaping ( grinding ) the thrusters and turn them into double sided foils............

[BWD]

Yep, fast and squirrely with one unswept high aspect fin in place of 3 low aspect swept fins (regardless of foil and toe-in).
That windsurf fin will probably let you ride the board flat too, so adding side bites with no toe may give you the balance you want.
Or you could throw on a longboard (or windsurf wave) fin in the back and call it a day, the sweep in the fin may give enough directional stability.
Personally Iike the thruster set up though, I never felt good on a kitesurfboard with one fin.
Fins are fun to play with though....

[Don Lester]

Here's what seems to be the best overall compromise. I rebased these fins to take out almost all toe-in. The board has good up-wind angle, rides smooth and fast and turns very well. The wide tail with no center back fin is also great for freestyle tricks............

So why do manufactures use toe-in ?

So why do people use low aspect "wave fins" ?

[Peter_Frank]

Hmmm, I think you are not "full" into waveriding ?

In my eyes, toe in increases the agility and good feel on the waveface by a huge margin

Of course it is on cost of speed and upwind ability - but hey, that is the last thing we are concerned about when riding waves, right ?

It just has to be "adequate" for going upwind, and thats it

You dont necessarily need the same amount of toe in as on surfboards (and YES, I definitely believe kitesurf waveboards should be different from surfboards), but having high AR fins and deep fins is definitely a no no in my world - even fins that are just a few mm too wide at the tip, feels AAAARGH in waves

Too big or too deep fins are the WORST that exists IMO, I just hate it bigtime - feels just WRONG

On raceboards it is just the opposite of course

Peter

[Bille]

...
Boards never ride straight, the nose always points a few degrees to windward of the true direction of travel.

Water does not travel under the board in a straight line from nose to tail, so there is no need to align the fins to this line.

An outside fin always gets flow from under the center of the board, moving out towards the rail as it moves back towards the tail. So it is often more efficient to have this fin be assymetrically foiled.

There are exceptions.

--BWD--
Sounds interesting !!!

Do Ya think you could build a One-Off board made of
three layers of 1/8th" Lexan ...
Tape several 3" strips of yarn or bright colored string on the bottom
to act like flow indicators ???
THEN
Strap a GoPro to your harness, pointed down ??

Be COOL to see your theory at work !!

UAH ---
More than COOL, this was taken from another thread but
directed towards ME.
And i'm all of a sudden REALLY interested in this subject !!!!!!
I Really wanna go 25 in 10k of wind, but i weigh 210lb.

...
The challenge is the board.
It will take a good raceboard and big fins, plus/minus whatever you have to do to adapt it to your needs.

Bille