yes and Mark Paul (australia) had trifins with bombora boards in the early 80's. the first shortboard i sailed was a bombora with 3 fins.
to be honest i think people were just copying surfboards.

santi4 said..

I think most brands benefit from people who still don't know how to adjust their board...they sell new boards every year without explaining that all riders rides custom boards in their quiver...it's normal for them to use standard boards in some tests ... but they don't hold up or work like the custom ones ..

That s the bottom line !!!

GESALT " you can see that as the front fins get bigger or have increased toe angles that get slower."

causation ?

...... Maybe yr observation is correct ..... OR .... devils advocate ..... maybe the bigger fronts need offsetting bigger rear to counter their leverage (nose down , pulling more front rocker / rocker flat into the mix ) ... so maybe that 11cm front needed a 19cm rear to counter - to get a true equivalent picture .... adjusting for gusts / wind variables etc etc

Either way - sacrificing 0.7 of a knot between fastest singlefin , and thruster with 10cm 2 deg Ezzy ..... that's not alot !!! I would have expected more singlefin vs set of thrusters .... diff between symm straight fronts and TOED fronts probably nothing !!

intersting post anyhow ....

I would counter also - maybe flat out top speeds a slight difference between straight boxes / symm vs toed/assy ..... but I know from personal experience - once you trust yr fins and rail - you will fire into a bottom turn at warp speed vs the odd mid face grubby symmetry straight box set up - so there bottom turns become WAAAAAY faster , more intuitive .... and assertive .... (and even more with CANT imo) .... that's the difference right there ... ! .... and in wavesailing - that's what matters if that's what your after - if yr looking for speed - you might as well go Bump and jump FSW performance

I think we are creating an interesting guide for everyone... I hope more experienced people could provide more information

Gestalt said..

I wonder if manufacturers are designing boards to suit many different people in many different conditions from Hawaii through to lighter wind crumble in less than ideal surf.

if you take the boards in maui ridden by pros, most people just wouldn't want those for their home spot which is probably more bump and jump then ideal surf. i'll guess that is more to do with heavy continuous rockers then toe angle.

Manufacturers design different types of boards for different types of conditions and/or riders. There is choice enough for everyone.

Gestalt said..

maybe that's more the case then people not understanding how to tune boards. it's more boards are designed to suit less than ideal conditions and for that they excel. To be honest i haven't met a windsurfer yet that didn't constantly tweak every bit of their gear and especially fins. whether surf or flat water blasting. Over the years board manufacturers have been criticized heavily for making boards that had too much rocker.

I don?t know about other brands but I don?t know anyone who fiddles with the fins. They may change fin(s) once but that is maybe around 20% of my customers and then they stick with that. Most keep their fins in there for 5 years or more. End users should not have to fiddle with their fins, thats the shapers job IMO

Gestalt said..

here is the K4 testing on toe in on a speed run. you can see that as the front fins get bigger or have increased toe angles that get slower.
www.k4fins.com/2017/08/28/fin-testing/

Well that makes the 31 knots by GPS in float n ride conditions, so just powered by the wave, at One Eye with much bigger 13.5 pre twisted sides and 15.5 centre fin (all with a thick profile) in a 95L board, pretty fast.
One customer did a 33 knots GPS run on a 86L flex tail with 12.5 pretwisted sides and a 14cm centre fin and a 4.5 wave sail at Sotavento some years ago. And Sotavento is loads choppier than West Kirby.

And these fins can pull a lot more Gs.

Bouke-Witchcraft said..

Gestalt said..

I wonder if manufacturers are designing boards to suit many different people in many different conditions from Hawaii through to lighter wind crumble in less than ideal surf.

if you take the boards in maui ridden by pros, most people just wouldn't want those for their home spot which is probably more bump and jump then ideal surf. i'll guess that is more to do with heavy continuous rockers then toe angle.

Manufacturers design different types of boards for different types of conditions and/or riders. There is choice enough for everyone.

Gestalt said..

maybe that's more the case then people not understanding how to tune boards. it's more boards are designed to suit less than ideal conditions and for that they excel. To be honest i haven't met a windsurfer yet that didn't constantly tweak every bit of their gear and especially fins. whether surf or flat water blasting. Over the years board manufacturers have been criticized heavily for making boards that had too much rocker.

I don?t know about other brands but I don?t know anyone who fiddles with the fins. They may change fin(s) once but that is maybe around 20% of my customers and then they stick with that. Most keep their fins in there for 5 years or more. End users should not have to fiddle with their fins, thats the shapers job IMO
L

Gestalt said..

here is the K4 testing on toe in on a speed run. you can see that as the front fins get bigger or have increased toe angles that get slower.
www.k4fins.com/2017/08/28/fin-testing/

Well that makes the 31 knots by GPS in float n ride conditions, so just powered by the wave, at One Eye with much bigger 13.5 pre twisted sides and 15.5 centre fin (all with a thick profile) in a 95L board, pretty fast.
One customer did a 33 knots GPS run on a 86L flex tail with 12.5 pretwisted sides and a 14cm centre fin and a 4.5 wave sail at Sotavento some years ago. And Sotavento is loads choppier than West Kirby.

! And these fins can pull a lot more Gs.

yes I know manufacturers design different boards.. I was trying to be less blunt by phrasing the statement as a question.

yes that does. I'd be keen to try some. Do you make them with fcs or futures bases?

Wow Groundhog day, didn't we do this topic like over 10 years ago on another forum And it goes like this a couple of people preaching to everyone that all multi fin boards should have tow in, others saying it's not needed. Then various manufacturers talking themselves and their products up and bagging other products concepts and ideas. Lots of sweeping generalizations. The last time around nothing was proven or agreed. A few egos strutted around and a lot of false beliefs were presented as facts that would confuse most average sailors. One character is missing the Lake sailor who thought he new all about tow in for wave boards

Gestalt said..

sheddweller said..
Just check the spray release direction on the back of this board. This is why you always run a bit of toe on your side fins. (Chose this video as it shows the spray direction well. It is not different on a wave board)
L

There also seems to be plenty of evidence that doesn't support this idea which makes it hard for me to agree. Possibly its to simplistic an idea and what is happening is way more complex in reality and so something else is going on.


.

What evidence?

Bourke

You posted some drag data a few posts back. Can you also post the data of the zero toe and zero aoa as well for that same foil.

Also had a question. Where the test says for eg 2 deg toe and zero aoa does that mean the flow is also at 2deg to the centrline of the board? I dont understand how a fin with toe can have an aoa of zero

SteveThorp said..
Send me some @Bouke, I'm happy to give them a fair and honest review. Really I am.SB 10 or 11cm fronts would be easiest.

Youre welcome to buy some but I dont have them that small for SB. The idea is that with less drag and without the straight lining effect, you can use bigger side fins and a smaller centre fin. I do a 10.5 Witchcraft side fin but that is for boards of 70L and less. 14.5 is the biggest, that is for wave boards of 100 to 130L.
I also recommend to use all fins with the same profile and twist so they work together. Youd not put some off road tires combined with slicks under a sports car. Or like using carbon-kevlar or carbon innegra where the carbon is 10 to 15 times stiffer and thus takes 10 to 15 times times the load over the kevlar or Innegra but only 50% is carbon. No one, who has a bit of technical insight, would use elastic to reinforce a steel cable would they? I just made some Slot/Star box and Minituttle fins for boards without toe-in to see the feed back of other people but they are nearly sold out already. I do not see it as my priority to help other brands boards work better: It is more like a teaser to make people wonder what else is possible. Even if with selling fins there is probably good money to be made, especially with molded plastic fins, less so with CNC milled G10 fins.....
Also it depends on the board, the placement and the toe in on the boxes how good the result will be. They have been optimised for Witchcraft boards, where I still tweak from 0.1 to 0.3 degree angle in the boxes depending on the shape. If with other boards and their box placement, they would work as well, I cant say. Following the guide lines, probably somewhat better than other fins.

Wow ! Mr. Bouke, respect !!!Your are really a breed of your own.

Bouke

So here are my Questions.

Surely any foil with a 0 degree aoa should have zero lift which means zero lift drag. Whilst I am not across your software it appears to me you are testing form drag only. If you were to use zero toe and zero aoa for each foil I would think the drag numbers would be the same.also if your fins are twisted doesn't that make it assymetric?'
if the aoa of a fin toed at 2 . , deg isn't zero then those charts arent really telling me anything. Fair enough there maybe something I'm missing and if I am please forgive me but I wonder why post this data.

I'd love to see a telltale on the board in front of the fins to see how the water flows. The video I posted above suggests this was tested and the water scatters. it's a great test though.

Did you video the fins with no toe as well for comparison.

also, great to se plenty of fantastic tests reviews of your boards.
do you have futures bases so I can try some

I'd also like to see some gps testing

Gestalt said..
Bouke

So here are my Questions.

Surely any foil with a 0 degree aoa should have zero lift which means zero lift drag.

When the side fin has zero aoa, it has about 2 degree toe. With zero aoa, the drag is lowest but not zero.

Gestalt said..
Whilst I am not across your software it appears to me you are testing form drag only. If you were to use zero toe and zero aoa for each foil I would think the drag numbers would be the same.

I am testing both for zero lift everywhere (like when you are going DTL without lateral sail pressure) as this is the ideal situation for any initiation of a turn. And simultatneously for the lowest drag, which is lowest when lift is zero. Ideally on any part of all fins.

If you have zero toe, you do not have zero aoa nor zero lift. The only thing is that when you have all fins in the water, you do not feel this lift as they counteract eachother. For example with a 12.5 symmetrical fin without toe and an average speed of 6m/s, you have about 30 Newton lift outward from each fin. See image below. You only feel the excess drag. Untill you make a hard turn and the outer fin (that was helping the turn in a positive way) leaves the water and the inside fin that is working against the turn, is still in the water, causing the board to straight line. The bigger the fin, the worse this effect.

Gestalt said..
also if your fins are twisted doesn't that make it assymetric?'
if the aoa of a fin toed at 2 . , deg isn't zero then those charts arent really telling me anything. Fair enough there maybe something I'm missing and if I am please forgive me but I wonder why post this data.

Yes, the fins are asymmetric both in profile as well as the pre-twist. It is not easy to explain this all in words, It?s complex and 3D. I hope it becomes clearer now.

Gestalt said..
I'd love to see a telltale on the board in front of the fins to see how the water flows. The video I posted above suggests this was tested and the water scatters. it's a great test though.

Did you video the fins with no toe as well for comparison.

Yes, that is also a way to see the flow underneath but only what happens directly under the board. Though ideally simultaneously you would have a camera filming from land as well to know what the surfer is doing to give which flow. With my way of filming gave a lot more information. By the water horizon you could tell what the board was doing when plus when there were some airbubbles in the water, you could see the direction of the flow in any depth. Though I am keeping this footage for myself not to give the competition (Sorry Steve:)) too detailed info. I did not test without toe as it was already clear for many years that no toe was no good. From the days without toe, I remember there regularly was a trail behind the up wind fin when cranking up wind and that gave a too big aoa so the up wind fin was stalling.
See below the simulation of going up wind with the current Witchcraft fins. When all fins run neutral when going DTL, once you go up windThe up wind fin gives slightly more lift than the down wind fin because of the asymmetrical profile. We did do a simulation with paralel symmetrical fins where the sum of the side fins was similar but the up wind fin did 164N and the down wind fin 59N (IIRC) and the total drag was only 6% higher. So the difference when going up wind is small but you will reach a stall of the up wind fin much sooner. The biggest difference is when going DTL, then you have some 24% more drag.

Gestalt said..

also, great to se plenty of fantastic tests reviews of your boards.
do you have futures bases so I can try some

I'd also like to see some gps testing

You can test the boards and sails here on Fuerteventura, in Pozo and El Medano and from various teamriders around Europe. Unfortunately not in Australia.

We did some testing with a Shadow box which also records G-forces, higths and position of the board but the device got water in after a few sessions. Also the software did not work well. Since then have not done it again though there are better GPS trackers for this nowadays.But the GPS track records below I got from a customer from Mauritius sailing One Eye, the first track record was in in planing wind (see the higher average speed of 11.1knots over 5.3 knots) with a Witchcraft Wave V3 95 from 2012 with the old symmetrical fins (so just with 2 degrees toe-in) and lateron in float n ride conditions with the pre-twisted fins that we supply since 2015. The wind was also more cross off but still 31.1 knots in float n ride conditions is faster than I would have hoped for.

Gestalt said..

Bouke-Witchcraft said..

Gestalt said..
Bouke

So here are my Questions.

Surely any foil with a 0 degree aoa should have zero lift which means zero lift drag.

When the side fin has zero aoa, it has about 2 degree toe. With zero aoa, the drag is lowest but not zero.

so this is the bit i'm hoping you can help me with.

why 2 degrees. is that a function of your asymmetrical fin or something else?

No, that is what we found in 2005 with the 4wfs and symmetrical fins to be fastest and give the most alround turning behaviour. Over the years this has been confirmed to be between 1.8 and 2.1 degrees, lateron also by CFD only that the 1.8 to 2.1 degrees was just the average, it is 3.7 to 4.1 degrees degrees at the fin base and zero at around 12 to 14 cm of depth. And the toe of 2 degrees was only correct at around 5 to 7cm depth so from the base and tip you still get excess drag with a symmetrical fin. The change in AoA over the depth is not lineair like it is with the blade of a wind turbine.
I have put these fins also on some surf boards over the last 10 years with amazing results. However the surfing fin industry is so powerful with their marketing that I am not even going to try. Plus that it is not suitable for the futures or FCS systems as they do not have enough room to twist the fin on the base. With the slot box it is just on the edge. So first you would need to get shapers to put the FCS or Futures systems with more angle before anyone would be able to try this and then they will not work with other fins, which will make people very hesitant and it will cost a lot of marketing investment to overcome this, sponsor a few Kelly Slaters, etc..

I forgot, you can also test the boards and sails in Sidi Kaouki, Morocco.

Mark _australia said..
I gave up when U said you tweak toe by 0.1 to 0.3deg

Do the fins and boxes even have that tolerance? Under half a millimeter from front to rear of box....


No wonder my wave riding is so poor

Haha, I expected some comment like that. I do that depending on the bottom shape. And yes, the cavities for the fin boxes are CNC milled in the board to the 0.1mm, so to me its just changing a digit in the shape once because after I just copy a shape that is close to what it should be and tweak what I need tweaking. I do not need to measure that and then mill it by hand, that is impossible, the machine does it for me.