I've heard quite a few people say you need to be "flying the fin" to go fast. I think I know what it means and I think I've done it a couple of times but I'm keen to hear from those that really know.

How do you do it and what does it feel like? What techniques and tuning add to your chances of success?

yep i know what your talking about paddymac, i think what flying on the fin is, is perfect board trim.

so really important things here are mast base position and boom height
the idea is that the board should be trimmed with minimal wetted area and as low as possible angle of attack relative to the surface of the water

mast base forward = nose down ( this is one of the things you should do if you are sheeted in but still tail walking or the nose is flying extremely high)

mast base back = nose up ( this is what you should do if the board feels like its stuck to the water)

well at least this is the theory i've been going on
would sure like to hear what some of the pro's thoughts are

Flying the fin in almost no wind conditions:

Best way to increase board lift so you can surf higher over the chop is use a smaller,lighter sail.

Use a bigger sail and you will notice the fin/board will fly less.

Medium to lots of downhaul with very little outhaul [sail touching otherside of boom in lighter winds]

Rail board up,meaning lift windward rail up, lets wind lift board--this is flying the fin.

For me flying the fin is when I'm driving the board hard off the the fin and the board is virtualy free of the water.

Assuming the sail trim is good. I usually start edging the mast base base back and upping the boom height to free the board. I back off the settings when the front foot gets too light or too much back foot pressure.

Its a great feeleing when it all comes together and you usuall see a good increase in speed.

It's a great feeling because it suddenly seems like the water is completely flat. The board is not in the water at all so it's not influenced by the water surface.
It's partly in the board design. Some boards will do it and others won't. Slowy says flying off the fin is the ultimate experience, so he designs all his boards to do it. My Futura does it but my Sonic doesn't.
You need to unweight the board by getting your feet right on the rail with your weight acting sideways, and by letting the sail carry your weight.
Slowy is the expert so hopefully he'll reply with his pearls of wisdom.

Just on planing @ low speeds, a wider board planes sooner than a longer board, a flat hull with minimal vee or concave reduces the water displacement and a thicker tail is better. As for fins Ive made some 'flat plate' fins with no foil as they displace less water and have less water 'stick' to them than NACA foiled fins. I'll rummage around for some pics of the fins...

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ULTIMATS said...

Just on planing @ low speeds, a wider board planes sooner than a longer board, a flat hull with minimal vee or concave reduces the water displacement and a thicker tail is better. As for fins Ive made some 'flat plate' fins with no foil as they displace less water and have less water 'stick' to them than NACA foiled fins. I'll rummage around for some pics of the fins...

I thought the water moving over the shape of the foil provided lift?

Hi

It is a good question. Everybody has their own valid experience with it.

For me "flying on the fin" means that you have lift enough from the fin to rail the board slightly up and get the windward rail free of the water.

You don't want the nose of the board to lift up and fly. This is different and will send you out of control.

You need a good trim and a great slippery fin to be able to keep the flying motion through chop, lulls, gusts etc. When you have this balance and can sail it over the distance in control - then you know you are "flying". In the end it should be feeling like the fin do all the work and the rig / board / body position stay steady.

Back foot should control the trim of the board and you need lift enough so you go through lulls, still with pressure on the fin, without "falling down" and pushing the windward rail in the water.

The formula video might be a bit "extreme" - but yes it indicate what I'm talking about,, (0:50-1:00min)


Trim, trim, trim - tune tune tune - and get a descend fin,, :)

its about finding a balance point where you minimise the weight through your legs onto the board. Use the rig to support you, not the board. The less weight you need on the board to keep it stable, the faster it will be, the more it will fly, and the less effort you need to put in to keep it flying.

Basically you are trying to minimise the amount of lift you need from the water- which puts you at the mercy of the chop. The harder you push the board onto the water, the harder it pushes back in chop (uncomfortable and less stable) and the slower it will be...

Ultimately you want to be using the board just to keep the fin wet. Then you are really flying on a cushion of air over the water. Thats the holy grail

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slowboat said...

.... Then you are really flying on a cushion of air over the water. Thats the holy grail

Yes indeed !! Well said.
.

Thanks all for the responses, some really good stuff

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slowboat said...

its about finding a balance point where you minimise the weight through your legs onto the board. Use the rig to support you, not the board. The less weight you need on the board to keep it stable, the faster it will be, the more it will fly, and the less effort you need to put in to keep it flying.

I find getting this feeling easier on the bigger gear for some reason - maybe cause it's usually sailed in flatter water conditions. Sometimes it almost feels like I'm weighting the harness enough to lift the board through the top of the straps and everything seems to smooth out. It sounds like I need to keep trying to replicate that.

interesting all the different thoughts on the subject
i think that everyone had part of the story some a bigger part than others
but the comment that did it for me was jespers

"trim, trim,trim - tune tune tune - and get a decent fin"

i recon that this sums up just about all of it except for the technique and feeling
which seems to be well covered in slowies comment
fantastic that we have such talented knowledgable guys on the forums answering questions

I am certainly no expert on this, so this is more of a question than answer....

I use freeride gear (free race sail and FSW board), and I find that if I have my sail rigged badly, or the mast base to far forward, or the boom or harness lines, the board tends to stick to water. It feels slow, not very lively, and makes the board difficult to jump on small chop. So back to the beach and more tuning. Normally more down haul (and/or outhaul), and adjust mast base and boom height to get my weight onto the rig, and nicely balanced to front/rear feet. When I get it right, the board livens right up. It feels light and free from the water. Much faster (sometimed a little too lively in choppy conditions), and now doing a jump off small chop takes next to no effort... just unweight your feet and by taking your weight on the rig as you go over a chop and you get air easily.

Could this change in the way my board rides be like the "flying the fin" people describe. Could it be concluded that to go above a certain speed, you must be doing this to some extent? As in, if I have gotten my FSW to 33 knots in medium chop bay conditions would that have required this technique?

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slowboat said...

its about finding a balance point where you minimise the weight through your legs onto the board. Use the rig to support you, not the board. The less weight you need on the board to keep it stable, the faster it will be, the more it will fly, and the less effort you need to put in to keep it flying.

Basically you are trying to minimise the amount of lift you need from the water- which puts you at the mercy of the chop. The harder you push the board onto the water, the harder it pushes back in chop (uncomfortable and less stable) and the slower it will be...

Ultimately you want to be using the board just to keep the fin wet. Then you are really flying on a cushion of air over the water. Thats the holy grail

.... well I think I have managed that once Chris, probably a few weeks ago I seemed to have my kit trimmed so I was sailing above the chop ! I know I need to learn a lot about trimming my kit .........

I read an article by Guy Cribb or Peter Hart and its said to move your mast track back and/or boom up until for are flying off the fin, too far and you start to lose control, is it as simple as that ?

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Haggar said...
I read an article by Guy Cribb or Peter Hart and its said to move your mast track back and/or boom up until for are flying off the fin, too far and you start to lose control, is it as simple as that ?

yep thats a pretty good starting point. Moving the track back reduces the effect of rig pressure on the board, which means the board trim is more at the mercy of nose aero lift, foot pressure, and chop impacts. Moving the boom up takes your weight off the board and reduces rig pressure through the mast foot.

For downwind sailing, where you are hanging more off the back of the board, I run the mast track further back until I cant sheet in without the board tail walking, adjusting the boom down to keep things under control.

For back and forth sailing where you are hanging more off the side of the board and your apparent wind is stronger, I sometimes move the track forward to help keep the board stable using rig pressure through the mast foot, and raise the boom to keep my weight off the board.

In light wind I tend to move the track back and the boom up. This compensates for the lighter wind generating less nose lift in the board, and suits the more upright stance from being underpowered most of the time. Shortening the harness lines also helps in this case.

Rowan mentioned to me once that in w/surfing you need to be analytical in choosing gear.

Your reasoning for gear trim takes this to another level.

Careful you don't end up like the golfer Faldo who 'lost it' suffering from paralysis by analysis.

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petermac33 said...
[br>>>>>

Careful you don't end up like the golfer Faldo who 'lost it' suffering from paralysis by analysis.

Don't think there's any concern about that happening with slowy, I'm sure that's how he got where he is in the first place.

Now in my case you may have a point.

So does mast track position effect pointing ability?

how about his for an example.....

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redsurfbus said...

how about his for an example.....

I don't think this photo depicts steady state sailing. It looks like he's in the process of settling down after a bit of a tail walk. The picture however does a great job of showing the channel that must be dug in the water in the background where he enters the turn, in a more controlled steady state.

There's only so much vertical lift you can get from a raked sail, only so much you can get from a bendy non-vertical fin, the rest has to come from the board which has to dig a hole in the water at a rate which creates downward water momentum equal to what's left of the system's weight. (first rule of rocket science 101) . I'd estimate that to be at least 2/3 of the weight of the rider and rig.

I can't see a raked sail and a bent fin holding any more than about 1/3 of the system weight. Even that's optimistic.

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slowboat said...


Ultimately you want to be using the board just to keep the fin wet. Then you are really flying on a cushion of air over the water. Thats the holy grail

The Holy Grail is a myth!

Unless you're the man of steel, or you live within a special force field impervious to the Law Of Physics, you cannot use the board just to keep the fin wet.

To stop the sinking, you need vertical lift. If you want to get that lift from a sail, you need a very large, and very vertically orientated rig.

Something like this.



Now I'd explain further but I'm busy glueing tennis ball fur to the underside of my Sputnik..

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brad1 said...

So does mast track position effect pointing ability?

That's a top question.

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brad1 said...

So does mast track position effect pointing ability?

(On slalom boards...) If your mast track is in the right place it should work perfectly on any point of sail.

If it is too far forward, upwind performance will be harmed. You know it's too far forward if you keep hitting the deck with the foot of the sail when you try to point upwind. This is because the centre of effort (in the sail) is forward of the centre of lateral resistance (the fin), and so the board will keep trying to turn away from the wind.

OK, no bites on my coherent disproof that any substantial percentage of total lift can be generated from a Windsurfing sail. Yesterday was a rainy day, so, undeterred I devised an experiment to visualise the point I made. Here it is, simply set up a windsurfer on the beach and record how much lift is generated by the sail.




Also, it does not matter that the experiment is stationary, as all the sail can see is airflow.


The next diagram shows that although it may be possible to reduce the wetted area, this does not mean the lift generated by the board has been reduced, it only means the board is riding at an increased angle of attack..

I just thought of another experiment, if we all agree that a windsurfing sail can support our body weight, then let's make a flying machine with two sails aligned in a semi realistic sailing position. This should give us TWICE THE LIFT. I think we should make the angle of the sail, 45, just to be on the safe side..

I know only one guy brave enough to try this.

Vrooooommmmm!

He he he he,,

Good fun to read Barn,,,,

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Jesper said...

He he he he,,

Good fun to read Barn,,,,

Indeed, very much like the child telling Einstein that he knows nothing about energy...

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barn said...
Also, it does not matter that the experiment is stationary, as all the sail can see is airflow.

Forward motion is important! and does affect the lift the sail can generate. Your first expirement would not be valid! The faster you go the more lift the sail can generate.

A good example is a helicopter that is gliding (or more correctly autorotating).
A helicopter can glide quite well, as long as the rotary wing is rotating, if the blades stop it will drop like a stone!

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mathew said...

Jesper said...

He he he he,,

Good fun to read Barn,,,,

Indeed, very much like the child telling Einstein that he knows nothing about energy...

Ahhh Mat, but Einstein didn't really know much about energy, did he?. He refused to accept quantum indeterminism. He wasted much of his life trying to prove that 'God doesn't roll dice'. Meanwhile 'child' physicists superseded him before his time was up (most great minds get at least get a few hundred years before being proved wrong!)..

Because the question at hand is simple mechanics, you can supply the angle of the sail, angle of the rider and width of the board and Newton would have been able to calculate the vertical lift generated by the sail... (hint: not much)

You don't need a GPS on your forehead, 45knot average and a teflon coated asymmetric nanotube fin to know that windsurfers cannot escape the laws of physics..


But I forget, this is The Church Of Speedsailing, and no blasphemous physics allowed.. hahah

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racerX said...

Forward motion is important! and does affect the lift the sail can generate. Your first expirement would not be valid! The faster you go the more lift the sail can generate.

A good BAD example is a helicopter that is gliding (or more correctly autorotating).
A helicopter can glide quite well, as long as the rotary wing is rotating, if the blades stop it will drop like a stone!

Wut, what about a stationary plane in a hurricane? All a wind can see is the airflow over the foil. Groundspeed is irrelephant.

Also, How much apparent wind do you have at the bottom of the speed run at Sandy Point?