Everyone's entitled to their opinions.
Speed sailors in flat water might favor singles.
Bump sailors in waves, often underpowered, might favor tris.

philn said..
Who's this bloke that claims thrusters are crap?

m.facebook.com/story.php?story_fbid=3541705579198329&id=139691419399779

That's not what he says.

He says the tri fin is not his preferred set up except when using his board somewhere where there are currents - in which case early planing and drive are maybe best served by a tri fin.
The rest of the time, he prefers a twin fin set up - for looseness when sailing in onshore conditions.
And then he appreciates the drive of a quad when driving along proper wave faces in cross-off conditions.

I'm just pleased that the twin fin is back, as that works well at my local beach. We typically have onshore conditions.
(My 83 Pyro arrives next week)

Basher said..

That's not what he says.

You're no fun. I'm a seppo, from the land of fake news, straw man arguments and other forms of logical fallacies. We like to put words in other people's mouths.

For guys running quads as twins in mushy conditions:
How do you select a fin size/template and where do you position it compared to sailing as a quad?
I'm tempted to try my Quatro as a twin. The stock front fins are already on the smaller size but its rear boxes have very limited adjustment. It seems to prefer rears with a more upright template as a quad.

Grantmac said..
For guys running quads as twins in mushy conditions:
How do you select a fin size/template and where do you position it compared to sailing as a quad?
I'm tempted to try my Quatro as a twin. The stock front fins are already on the smaller size but its rear boxes have very limited adjustment. It seems to prefer rears with a more upright template as a quad.

I have a Quatro Cube 95 L and a Goya Custom Quad 116 L that I run as twin fins. For the 95 L I have 16.5 cm Black Project fins, and for the 116 L I have MFC 18 cm fins. I weigh 85 kg and my switch over point between the boards is for 5.5 and down I use the 95 L. Initially took me a while to get used to the skatey off the top, but now I find quad set up too stiff in anything less than cross off.

I generally run 9f/15 or 16 rear. I have some 17 Scorchers but they are quite swept, lots of area at the base though.
Usually if its quite strong I'm stepped down to a board which runs well as a thruster.

I have a custom tri-fin and two quad SSD boards. My experience is mostly with quads and twin fins. Including fin positioning, fin sizes, fin style, fin profiles, fin foils (e.g. asymmetrical), fin angles in relation to center line. However, nowhere near the number of fins and amount tweaking some of you do .

Found a number of factors that can be more (or less) important such as:
1. Board size
2. Board shape, especially tail outline, V and kick
3. Conditions such as wind strength, sea state, wave size/type, wind direction and tide/current
4. Weight of rider (I'm a welterweight)
5. Fin tuning and sizing

I love my old tri-fin board. It's probably hard to compare your or manufactures setups as it uses 120mm surf fin side biters that have approx 80/20 foil shape. Surfers reviewing these say that they turn significantly quicker and smoother than flat inside foil ones. I would say this trait holds true overall for this board compared to other boards that I have tried or owned. The feel is closer to my surfboard especially taking off down the wave.

The side fin boxes have 1.2 degrees of toe-in. My relative spacing is closer in relation to the centre fin (52mm) than most I see. Back leading edge roughly aligned with strap back screws. The centre fin is a 155mm (labelled 16 cm) K4 Flex-fin. Which apparently is Graham Ezzy's favourite. This board is faster than my quads and easier to sail in a straight line than my previous twin. Although blasting around is not my priority.

Initially ran my SSD tri-fin with a 7" (17.8 cm) middle G10 fin. Found that too much area or stiff as turns were smooth and tight but not as snappy. A friend really liked it to loosen up his large 105 litre tri-fin board. From memory the side fins he had were quite large and this made it more responsive.

I use the quad boards when conditions dictate as they are bigger and what they where are designed for or came with. When overpowered, in rough conditions and in bigger waves the quad with a few more litres volume is more settled and controllable than my tri-fin. The "mid sized" quad configured as as twin is great in onshore mushy conditions (as long as upwind performance is secondary).

My previous dedicated custom twin was amazing for that, using 15.5 cm Maui Ultra Fins X-twins. These should also work well on quad boards if the size is appropriate. Their fin profile is quite narrow and upright which might be contributing to the tight turns possible. Appears to be a few other riders apart from top sponsored riders that like them. (They unfortunately don't fit on my quad boards without modification and are too big for my weight/them).

Running my smaller quad board with only two rear fins get's me close to the same experience. However, the general board characteristic are another major factor. Removing the side biters is an alternative way of reducing the fin area without sizing down the rears. Recently had a Fanatic Quad with relatively small 8 cm asymmetric sides with 1 degree inbuild toe-in which made it turn better and tighter than the original symmetricals. It had 14.5 cm swept back rears.

Generally I would say twin fin boards require more sailor input and the tail can be pushed loose easily. Have also tried the twin fin with a trailer fin. Even a 8 cm centre fin stiffened it up considerably, but obviously doesn't give it the same feel as a thruster.

At the other end of the spectrum my light wind board is a quad and good for schlogging up wind and early planing. It could be reconfigured as a tri-fin but I have not seen any need to try yet. The middle box has a resined blank so a slight obstacle to route out. Mark Stone recommended to use it as a quad. The tomo-tail shape is very wide and short. Which may suit a quad better than a tri-fin?

I've seen other tri-fin boards that have proportionally bigger sides. More like thruster surfboards. That would be interesting to try. Does anybody here have experience with that setup?

sprayblaze said..
So whats the bottom line ? Twins=loose. Quads =control. Both could be fast. So tri sound more like the ALL season auto tyre thing-not too good for winter and not too good for summer... Look at the PWA top five-no one rides a tri fin on a regular basis, in the top ten only Traversa, Mussolini and Stone whoose total body weight is less then 200 kilos... This says a lot imho.

The body weights of the lads on thrusters actually says very little. Musso and Thomas use big floaty boards for their weight (thomas for example is about 60kg and uses a 72 I think as his all rounder) and mid sized thrusters. They also sail with very upright styles and super high old school booms. Their turns tend to be light and skates.

Jaeger on the other hand has an extremely low, powerful style with lots of leg movement and a reasonably low, modern style boom height. He also sails pretty small boards from what I've seen/heard/read, between 65 and 72l and I think he weighs around 65kg. I'm pretty sure that's the case but he is on this forum so he can correct me if I'm wrong haha.

His turns are crazy powerful, using the sail and his legs a lot to generate speed and power. Traversa and Musso use the wave a lot more and tend to flow around a lot more. There are times where Traversa looks a lot more like Jaeger in his style but generally from what I've seen they're very different in their styles.

The point I'm making is board shape, sailing style, kit, kit setup and body shape etc all have massive effects on the way people sail. Victor Fernandez for example used thrusters in all his stubbies (and now his new mamba/stubby hybrid customs) and has a massively different style to musso, traversa and Jaeger. The big diametrical differences are less to do with fin setups. There are definite differences between fin setups but it's more how those setups interact with all the other factors that results in such vastly different styles.

the definite differences have been explained well up above and elsewhere but for the sake of being boring I'll jot down my opinions too:

twins: great fun for crappy conditions where you just want to mess around and get the tail out on a mushy wave. However, there are exceptions: the famous Hooper-designed Nuevo which is a super surfy twin that holds really nicely in good waves and in my experience of it only ever released the fins when you wanted them to.

quads: a similar feel to twins but more versatile. They tend to make boards more sticky and grippy and in my experience work best in everything because they provide a good amount of drive and grip without too much surface area to get stuck when you want to throw them out back. Especially useful for sailors who like to use the rail of the board to turn and/or who want to be able to throw the tail out almost as much as with a twin, without sacrificing as much grip and high end control.


Thrusters - usually fast to plane, piles of drive especially on the bottom turn. I find them to be very on and off - the rear thruster fin is quite long and can get often get stuck in the lip or the whitewater if you don't time your turns perfectly meaning you tend to either get a very good turn or a very ehh turn.

The term "forgiving" gets thrown about a lot too. The tricky thing with that is, what exactly are you trying to get forgiven? If you're a bit lazy getting on the plane, then a thruster will forgive your errors. If you tend to not work as hard as you should to drive into your bottom turns, thrusters will again forgive your errors. If you cheat on the top turn and push hard on the tail to make it slide out, a thruster will forgive you in bigger waves where you need the grip, and stop you sliding down the face on your back so much. But if you struggle with timing on your top turns, the added surface area of the rear fin will be less forgiving and either give you a good turn or a bad one, with little in between

A twin will tend to give you the opposite results. But be careful not to push hard, or they'll slide out.

for me, a quad is a nice in between. A fair bit of grip and drive when you want, but looseness when you don't. I think that's why it's a popular choice for the PWA guys as it's very versatile. A best of both worlds, a jack of all trades. There will however, be overlaps. Some boards are grippier, drivier, faster or more slidey than others. Different waves, different sails, boards, styles and sailors will have different effects. But those are to the best of my knowledge, the basic rules of the different setups.

k257 quote - " Thrusters - usually fast to plane, piles of drive especially on the bottom turn. I find them to be very on and off - the rear thruster fin is quite long and can get often get stuck in the lip or the whitewater if you don't time your turns perfectly meaning you tend to either get a very good turn or a very ehh turn."

Or - that bigger rear fin can give you 'drive' out of the whitewater sh1tfest ... 1st time I used my 5 box as tri - couldn't believe the amount of extra drive / speed over a whitewater lip when you hitting a section coming towards you , it would chew up say 4m of high line whitewater lip line floater and get to the face the other side way better / quicker / more assertive than a quad .... And sometimes - that extra fin grip behind the backfoot is vital - like landing an aerial in aerated whitewater , or sailing OUT of stuff like wave360's , where smaller quad rears can slip when applying pressure to get out of the move .. and a tri-fin will 'hold' and give you fraction more grip and get you up and out a split second earlier ...

So depends what your priorities are ...

seabreezer said..
k257 quote - " Thrusters - usually fast to plane, piles of drive especially on the bottom turn. I find them to be very on and off - the rear thruster fin is quite long and can get often get stuck in the lip or the whitewater if you don't time your turns perfectly meaning you tend to either get a very good turn or a very ehh turn."

Or - that bigger rear fin can give you 'drive' out of the whitewater sh1tfest ... 1st time I used my 5 box as tri - couldn't believe the amount of extra drive / speed over a whitewater lip when you hitting a section coming towards you , it would chew up say 4m of high line whitewater lip line floater and get to the face the other side way better / quicker / more assertive than a quad .... And sometimes - that extra fin grip behind the backfoot is vital - like landing an aerial in aerated whitewater , or sailing OUT of stuff like wave360's , where smaller quad rears can slip when applying pressure to get out of the move .. and a tri-fin will 'hold' and give you fraction more grip and get you up and out a split second earlier ...

So depends what your priorities are ...

Funny you should say that! I was having that same issue for a while when I was using small super stiff quad fins, now I've moved to .5cm bigger (to make up for the decreased drive you get from flexier fins) fins with a lot more rake and tip flex. These days I can punch through the messiest sections no bother (I'm very partial to floaters haha) and it lets me get away with mistimed aerials too. Like I said, it's all in the little variations

I can see why a guy like Koster likes twin fins as they are easy to break out when doing skaty moves on sloppy waves. Trifins and quads have more grip due to having more fin area on the rail. But most boards have small side fins and thus trifins need to have a big centre fin. Quads have more drag due to having more fins. Trifins or thrusters with three similar sized trifins are at least as loose and grippy. I use for example 3 x 12.5 or 12.5+14cm under an 80L, 13.5+14 under a 90-95L or 14.5+15.5 under an 105L. But when you have bigger side fins, it becomes more important they are set up correctly. The water flow under the board is directed from the centre outward so the further away from the centre, the more toe-in you need. But this effect is the biggest directly under the board and diinishes over the length of the fin. We use 2? toe-in and then the fins have another 2.5? toe-in in the base. The fins then twist back to pretty much zero toe-in at the tip, depending on the size of the fin. This may not seem much but water has a lot of power. We just can?t see it.
You can see the same principle on the wings of wind turbines, propellors or our sails: The angle of attack changes over the length of the foil thus the foil should twist over its length accordingly.

Going down a wave without lateral pressure of the sail, in this situation you do not want any of the fins to give lift to reduce drag and to help initiate the turn:

Image generated by CFD software of a bottom turn:


Image of a bottom turn in reality:


How the camera was mounted:


Also asymmetrical fins need more toe-in as the asymmetry starts to give lift and drag by itself if the angle is not adapted (like the wings on a plane give lift). About 1? for every percentage of asymmetry (also called camber). See images below which give the lift and drag of a 2% asymmetrical foil with zero angle of attack and -2.07? AoA at which point there is zero lift again and the least drag. The induced drag is 1/3rd with 2? extra toe-in (on average you need 2? toe-in for a symmetrical fin.)



We have also adapted our fins to boards with the side fin boxes set up paralel and they visibly became a lot turnier, faster with more grip and drive in the turn.





Does this sound complicated? Yes, there is a LOT more to it then just a centre fin. But this is what it is, it simply is what happens because of physical laws. The same physical laws that allow us to windsurf in the first place and if you want to do it right, there is no way around it. The first planes also flew but we still learned a lot more after that.

I always wonder when I read the discussions about toe in why a guy like Keith doesn't use it on his Quatro and Goya shapes.
Seems to be a reason and I'm sure it's not that he's willing to use only the second best solution for his boards.

stonny said..
Can anyone explain to me why quad fin setups are considered slow, draggy and planted on a windsurfer yet super fast and lively on a surfboard ? I have a shed full of waveboards but these days all I ride is my 86 ltr Quatro Cube. It seems to do everything and is the best around waveboard I have ever sailed. And it is super fast, loose, early planing and lively......and it's a quad.
When it comes to surfing however, I prefer thrusters because they feel more predictable but I will admit that my level of wavesailing exceeds my surfing.
Personally I think that what a board can do,and how it behaves, is less to do with the fin setup and more to do with the design of the board it's self. Excepting the probability that certain shapes may be suited to certain fin setups. Certainly true with surfboards. So is there really any point in 5 fin boxes ?
I would be interested to hear what people think.
I hope everyone is having a great Christmas and here's to a windy ( covid free ) new year.

The best is to ignore these discussions about "speed and number of fins". Yes, quads are slower in the straight line, because each additional fin creates an additional drag, but this effect is neglectable for mere mortals and especialy in the waves. The only way to test the difference really would be to go to Luderiz and have a multi fin speed board. But why would anyone do that?
For anything else than waves a single fin setup is still the best, simply because you let a board fly with a single fin, because of the lever it has. And a board that flies is so much nicer in the chop than have a board with multi fins, which planes much lower and catches much more chop. But with this statement there will be surely some people who oppose it and they believe in the opposite. But if you ask experts, i.e. slalom riders they all will tell you the same thing. Nothing beats single fin in bump and jump conditions. But there are so many amateurs out there who believe different. I do not want to stop them.

So why different fin setups in waves? Because in waves it is all about personal style. And all these setups feel different to a certain degree.

BTW I can not talk for surf boards this a different topic.

AlexF said..
I always wonder when I read the discussions about toe in why a guy like Keith doesn't use it on his Quatro and Goya shapes.
Seems to be a reason and I'm sure it's not that he's willing to use only the second best solution for his boards.

I think KTs own boards, as well as the other team tiders boards, have toe in. At least all the quatro custom boards I have seen have some toe in, a little more than 1 degree. Boxes on production boards straight. I dont know why the difference, maybe they dont thrust cobra?

I never thought that fin selection is as complicated as brain surgery- who needs that and even if true-so what ? I have tried twins, trusters quads. Not to make things complicated I have picked quads(THE ultimate multifin sensation) imho. Watching Brawzinho and Levi destroying Pozo and Hookipa on production boards -Marcilio on quad and Levi quad/tri is enough said for me, a mere mortal, regarding the evergoing production vs. custom dilemma. Merry X mas to everyone and let this Covid nightmare remain in 2020!