Hi there, just had a thought about water flowing across the bottom of the board at a 45’ angle to the stringer most of the time throughout the ride (aproximately), what would happen if the toe-in was the other way? fins splaying out instead of in and directing water flow to the center fin? then you could have a crazy turbine center fin or somethin wierd??? lol. but seriously, has anyone tried this?
The fins already have a “venturi” effect, even with the toe-in… …thus it
creates a slight high-pressure spot in the middle of the cluster.
I’ve seen some Gold Coast surfers who were pointing their side fins outwards.
They had an articulated fin system that allowed for full movement.
That was over 10 years ago, I’d figure if it was a great success, that it would
have spread to the rest of us.
It could be worth a try, if your curiosity so-inclines.
Sounds like a job for 4wfs (four way fin system). My guess is that the board would get sucked into the wave and it just wouldn’t work.
My first board, 15 years ago or so,
in a rush to get the fins glassed on,
and with all of my superior knowledge
had the fins toe’d out.
Would NOT turn toe’d out, went straight great,
if you aimed your take off.
Would not turn, boogie board style, both hands
on rail, cranked.
after one surf, sawed them off, reset them
toe’d in about about 1-1/2" off the nose. much better.
Maybe neutral alignment with something like 4wfs or surf trux?
your results may vary,though.
Pete
I have the best of both worlds.H
Quote:
I have the best of both worlds.H
well, i’d like to SEE that , fer sure! you teaser you , herb. So, is your signature related to that (the botched sex change operation?)
peta
Peta !
You know that’s a secret !
You stay wam and moist girl !
Love H
…and with a deep butt crack , you can get your toe in right …
Here’s a basic lesson on fin cant and toe in.
The common shortboard (i.e. 6’4") tri fin you see today has side fins toed in 1/4" more toward center on the leading edge than the trailing edge. Often times slightly less toe in is used for longer boards (guns, funshapes or longboard sidebiters). I used to use my rocker stick and line the fins so the trajectory was slightly off from the center stringer. Some people triangulate so the line of the inside flat of the fins meet right on the tip of the nose. This method of meeting right on the tip can create considerable variance depending if we are talking about a 5’6" or a 9’9".
If flat inside foiled fins are parallel to the stringer they track and are stiff. An exception to this rule are some fins I made around '84 or’85 with a parallelogram type of foil specifically to test when placed parallel to the stringers. Each fin had flats positioned diagonally across from each other and leading edge and trailing edge foils also diagonally opposite of each other. The fins did not track. In another thread I make mention of some multi fin boards that Bob Krause and I built during one week long swell at Rincon…basically surfing and making everything from one thru ten finned boards. In the case of the 6, 7, 8 and 10 finners, we did have varying foils on sets of fins placed in a curve that had rear-most sets toed outward to coincide with the flow created. This theory was sparked by the Greek principle of a vent. These boards did not track…they glided and had similar characteristics to a keel fin.
If the toe in is greater toward center so that the projected lines intersect before reaching the nose, the board is looser (more manueverable) but may lose speed in the process. I have one rider that swears by this setup on high performance longboards…I will also note that he stands much farther forward than average.
Fin cant basics: common cant (tilt) is 3 to 4 degrees…if you cant them more they are more maneuverable. Concave boards that are flat rail to rail work well with more cant than usual…8 degrees produces a board that turns easily and cutbacks well. More upright fins are drivier.
These are in general terms as you have to take into account fin area, planshape, flex, vee, and/or many other aspects that may or may not coincide with the fins but for the most part this is pretty reliable info.
Bottom line for flat inside foils if you make them parallel to the center stringer, you will hate them.
Hey DS,
Can you explain this so I can get my head around it?
“Each fin had flats positioned diagonally across from each other and leading edge and trailing edge foils also diagonally opposite of each other.”
A drawing would be awesome, I’m having trouble picturing this for some reason…
Thanks!
JSS
I rode a board… a retro fish with big single foiled keels that were glassed on… a few years ago that had the fins toed out, but no cant. Very unpredictable. Felt like you just were trying to hang on the whole time. Didn’t seem to slow the board down at all.
After thinking about it, I came up with a theory… As you started a turn, or as the direction of water flowing across the bottom of the board changed for whatever reason, the inside fin created lift while the outside fin didn’t, pulling the board toward the wave. Going flat across the water, all things were equal, and everything balanced out. But as soon as you got one fin to work differently than the other… whoop!.. crazy stuff started to happen lift because the fin was going straight, with lift on one side of the fin and no drag on the other.
Quote:
My first board, 15 years ago or so,in a rush to get the fins glassed on,
and with all of my superior knowledge
had the fins toe’d out.
Would NOT turn toe’d out, went straight great,
if you aimed your take off.
Would not turn, boogie board style, both hands
on rail, cranked.
after one surf, sawed them off, reset them
toe’d in about about 1-1/2" off the nose. much better.
Maybe neutral alignment with something like 4wfs or surf trux?
your results may vary,though.
Surftrux are not really neutral alignment…most of the time the rail fins rotate to minimize their resistance to the water…when you are on rail the inside rail fin is identical to a thruster inside rail fin - not moving, same angles. The outside rail fin is toed in or out (usually out) to minimize its resistance to water flow, works great that way.
MM…you guys are giving me a headache with all this banter.
I don’t know how to draw something for Sways so I’ll try to explain it. Picture the typical leading edge of a side fin. Excep this time the back half of the foil doesn’t angle to meet the flat inside foil. Instead it goes parallel to the stringer.
Now, on the leading edge again, on the inside part, that line is also straight with the stringer until at the back half it has a foil like the curved leading edge, but instead it is in the back. So the straight (or flat) parts of the fin on each side as diagonal from each other, but both are also parallel to the stringer. Then you have the curved foil in front and the juxtaposed foil in the rear. If someone can draw it and put it on here, I’ll confirm it…or just give me the instructions for drawing it or how to scan a drawing onto Sways…
Here’s what I could come up with on short notice…lemme know if it is right…
If this is right, it is akin to a foil type known as a foil with ‘reflex’. In other words, it is a self-stabilizing foil. True reflex foils have an ‘upsweep’ in the back on the top side as well (not just flat), and are usually used on flying wings, since flying wings do not have tails to stabilize them, they need pitch stability built into the wing.
There are drag penalties associated with reflex, but I can’t quantify them…
Also, the geometries are subtle, here’s an example:
JSS
I also noticed this:
“In the case of the 6, 7, 8 and 10 finners, we did have varying foils on sets of fins placed in a curve that had rear-most sets toed outward to coincide with the flow created. This theory was sparked by the Greek principle of a vent. These boards did not track…they glided and had similar characteristics to a keel fin.”
Sounds like you guys independently discovered high-lift, multi-element foils…like this:
Or this:
JSS
Quote:
Here’s what I could come up with on short notice…lemme know if it is right…
It’s the one on the right except the foil is sharper in the front and the back is the same. No soft rounded front. The water is told where it can go and isn’t allowed to hug…thanks…DS
If this is right, it is akin to a foil type known as a foil with ‘reflex’. In other words, it is a self-stabilizing foil. True reflex foils have an ‘upsweep’ in the back on the top side as well (not just flat), and are usually used on flying wings, since flying wings do not have tails to stabilize them, they need pitch stability built into the wing.
There are drag penalties associated with reflex, but I can’t quantify them…
Also, the geometries are subtle, here’s an example:
JSS
MM…yeah, the colored foils look just like some of the sets of fins we foiled. Actually the bottom one too…Hey, they were a real chore to build and sand on the boards as they were all glassed on.The front set were concave and then we had 60/40’s, 70/30’s, 80/20’s for lack of a better term…the fins were set overlapping each to reduce drift, in an arc, but the ‘fence of fins’ still had so much lift they drifted like a seagull riding apparent wind in front of a wave face.
People saw them and thought “look at all that drag”…we thought “look at all that lift”…the boards had so much lift we inverted vees creating a scoop at the last part of the tails to suck some water up toward the deckline…they worked pretty bitchen. Very smooth and ‘swoopy’.
The first time I did a dark colored resin splash bottom, the tint covered my pencil marks(mistake #1) and I thought I would eyeball it(mistake #2). If I recall correctly, the board was 7’2" x 21-ish, MP-inspired pod tail, tri-fin. After I glassed the fins on, I discovered the side fins were toed out about 1/4" apiece - I don’t eyeball ‘em anymore. The result: paddled like a dog, first off. Even with very low entry rocker, I felt like someone was pulling on my leash the whole time. On waves I could catch (slopey entry with a slight jack before standing up-Ricebowls rights for you Town guys), I was fighting the board the whole way down and leaning super hard (200lbs+) to make my bottom turn. Felt like I was gonna bust the fins out. That board is now a 5’ 9" kneeboard, for what that’s worth.
Mike
by straightening or toeing-out your fins more “parallel” you will increase your down the line speed and drive, but will reduce your ability to turn the board easily.
The key to this all is micro-movements, not huge ones. ie: if you surf a beach break with your current set-up and then suddenly the next day surf a point break like J-Bay or Snapper then toe-ing the side fins outwards by1mm can have a benefit especially the inside bottom-turning fin, giving more drive and hold off the bottom turn at high speeds.
As was earlier stated this is all dependent on a number of factors incl shape of bottom, concave, vee, rails plan-shape outline etc etc… but essentially the principles are all the same for every surfboard made…each surfboard is different and will surf differently as well as for different surfers…
Another important aspect is when you toe-out to increase water flow between the fins for more speed, sometimes that toe-out with a corresponding change in outward splay can assist the “negative” effects of toe-out (specifically turning ability) and by increasing the splay whilst toeing-out, it becomes complimentary.
Having adjustability options in your surfboards allows you to play with these options, IF u WANT or NEED to…
To all out there, there is a wealth of info on our website if u need, or don’t hesitate to email me directly if u need more help…
hope this helps,
cheers
Dean
Funny how different people so often are independently pondering the same scenarios. This thread is a perfect example.
Dead Shaper’s thread on multi-multi-finned boards and blakestah’s development of surftrux got me planning a board that I’m itchin to make as soon as I can start building again:
I’m thinkin a fish with six fins, three per side. Forward-most fins single-foiled, towed in. Follow that with a larger fin, of yet-to-be-determined foilage, more parrallel with the stringer. Follow that with a smaller fin totally parrallel or even towed oh-so-slighty out.
If done with surftrux, the fins should engage and disengage when needed, providing the glide effect DS is describing, without the concern of all those extra fins on the outside rail fighting against you.
Anywho, it’s just an idea that kinda seemed relevant. Think it would work?