often people say too much back foot preessure cause spin out,because you overload fin..

So you obviulsy must shift pressure to front foot

1.Why do you think that back foot push more on fin than front foot?
ONLY BEACAUSE IT IS CLOSER TO THE FIN??

2.were then pressure form front foot goes,if not to the fin?to the board rail,how much board rail can produce lateral pressure??

So question is why exactly too much back foot pressure cause spinout?..
When you do spinout on purpose, do you move sail more back?(maybe here is reason why board spinout=rotate upwind.)

If all of someones weight was on the fin then it wouldn't grip, the board needs some grip for it to track and go in a straight line.
If the fin is too big it causes too much lift and then the board will be uncontrollable.

You cannot put both feet over the fin as you as a person will loose stability and also wont be able to apply mast foot pressure which puts the power of the sail into the board ( unless its a board reach ).

Theres a fine line between where you are placed on the board, where the rig is placed and where the fin is placed and how big they all are.

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Madge said..
If all of someones weight was on the fin then it wouldn't grip, the board needs some grip for it to track and go in a straight line.
If the fin is too big it causes too much lift and then the board will be uncontrollable.

You cannot put both feet over the fin as you as a person will loose stability and also wont be able to apply mast foot pressure which puts the power of the sail into the board ( unless its a board reach ).

Theres a fine line between where you are placed on the board, where the rig is placed and where the fin is placed and how big they all are.

ok so key is that board produce significiant amount of lateral force?

The fin creates more lift as you go faster.
When going slow, the fin creates very little lift.
So, when full speed, more of your weight can be placed on your rear foot. But, some amount of weight is needed on your front foot to create directional stability.

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LeeD said..
The fin creates more lift as you go faster.
When going slow, the fin creates very little lift.
So, when full speed, more of your weight can be placed on your rear foot. But, some amount of weight is needed on your front foot to create directional stability.

So at full speed you cant do spinout at purpose,even pressure on back foot is 100%?

Weight distribution is onle one part of the spinout equation.
You can introduce air to the water at the fin area of your board.
You can suddenly push the fin sideways at speed.
Most likely, spinouts from too small fin at low speed.
Or, too large fin at high speed.
Or, too crappy a fin you chose to use.

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fpw9082 said..
often people say too much back foot preessure cause spin out,because you overload fin..

So you obviulsy must shift pressure to front foot

1.Why do you think that back foot push more on fin than front foot?
ONLY BEACAUSE IT IS CLOSER TO THE FIN??

2.were then pressure form front foot goes,if not to the fin?to the board rail,how much board rail can produce lateral pressure??

So question is why exactly too much back foot pressure cause spinout?..
When you do spinout on purpose, do you move sail more back?(maybe here is reason why board spinout=rotate upwind.)

Interesting question:

Firstly, we know that the sail exerts a sideways load on the board and for the board to head forwards we must then have an opposite or counteracting load to negate the sideways force. In simplistic terms, yachts have keels and we have the fin. But it is a mistake to assume that all sideways resistance comes from the fin.
The windsurf hull also produces friction or resistance against sideslip by virtue of it being in the water, and so at slogging speeds the rails also take the sideways load form the sail as we sheet in. Once the hull starts planing the rails shoot out spray to one side and that also adds sideways resistance - in addition to the lift we get from the fin. We might describe the 'shooting spray' at the rails as 'hydrodynamic lift'.

To understand this further you need to know that the rig loads are felt in the hands and the load on the front hand tends to transfer to the board via the front foot, whereas the sail load on the back hand tends to load the back foot. The rig load through the mast foot also acts more on the front of the board.

So, to answer your question, loading the front foot takes rig load off the back foot and applies is less on the fin and more over the rails and planing spray of the board.
The faster the board goes, the more lift the fin produces and so you can load the back foot more as the board starts to fly.

For newbies reading this: The simplest way to sail off the front foot more - so as to keep the board more level and to spinout less - is to move your front footstraps forwards, and to shift the mast foot backwards (which brings the rig more upright).
If you are still overloading your back foot too much then shift your harness lines back on the boom.

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Basher said..

fpw9082 said..
often people say too much back foot preessure cause spin out,because you overload fin..

So you obviulsy must shift pressure to front foot

1.Why do you think that back foot push more on fin than front foot?
ONLY BEACAUSE IT IS CLOSER TO THE FIN??

2.were then pressure form front foot goes,if not to the fin?to the board rail,how much board rail can produce lateral pressure??

So question is why exactly too much back foot pressure cause spinout?..
When you do spinout on purpose, do you move sail more back?(maybe here is reason why board spinout=rotate upwind.)

Interesting question:

Firstly, we know that the sail exerts a sideways load on the board and for the board to head forwards we must then have an opposite or counteracting load to negate the sideways force. In simplistic terms, yachts have keels and we have the fin. But it is a mistake to assume that all sideways resistance comes from the fin.
The windsurf hull also produces friction or resistance against sideslip by virtue of it being in the water, and so at slogging speeds the rails also take the sideways load form the sail as we sheet in. Once the hull starts planing the rails shoot out spray to one side and that also adds sideways resistance - in addition to the lift we get from the fin. We might describe the 'shooting spray' at the rails as 'hydrodynamic lift'.

To understand this further you need to know that the rig loads are felt in the hands and the load on the front hand tends to transfer to the board via the front foot, whereas the sail load on the back hand tends to load the back foot. The rig load through the mast foot also acts more on the front of the board.

So, to answer your question, loading the front foot takes rig load off the back foot and applies is less on the fin and more over the rails and planing spray of the board.
The faster the board goes, the more lift the fin produces and so you can load the back foot more as the board starts to fly.

For newbies reading this: The simplest way to sail off the front foot more - so as to keep the board more level and to spinout less - is to move your front footstraps forwards, and to shift the mast foot backwards (which brings the rig more upright).
If you are still overloading your back foot too much then shift your harness lines back on the boom.

So we cant say that spinout, caused by COE behind CLR?

Select to expand quote

Basher said..

fpw9082 said..
often people say too much back foot preessure cause spin out,because you overload fin..

So you obviulsy must shift pressure to front foot

1.Why do you think that back foot push more on fin than front foot?
ONLY BEACAUSE IT IS CLOSER TO THE FIN??

2.were then pressure form front foot goes,if not to the fin?to the board rail,how much board rail can produce lateral pressure??

So question is why exactly too much back foot pressure cause spinout?..
When you do spinout on purpose, do you move sail more back?(maybe here is reason why board spinout=rotate upwind.)

Interesting question:

Firstly, we know that the sail exerts a sideways load on the board and for the board to head forwards we must then have an opposite or counteracting load to negate the sideways force. In simplistic terms, yachts have keels and we have the fin. But it is a mistake to assume that all sideways resistance comes from the fin.
The windsurf hull also produces friction or resistance against sideslip by virtue of it being in the water, and so at slogging speeds the rails also take the sideways load form the sail as we sheet in. Once the hull starts planing the rails shoot out spray to one side and that also adds sideways resistance - in addition to the lift we get from the fin. We might describe the 'shooting spray' at the rails as 'hydrodynamic lift'.

To understand this further you need to know that the rig loads are felt in the hands and the load on the front hand tends to transfer to the board via the front foot, whereas the sail load on the back hand tends to load the back foot. The rig load through the mast foot also acts more on the front of the board.

So, to answer your question, loading the front foot takes rig load off the back foot and applies is less on the fin and more over the rails and planing spray of the board.
The faster the board goes, the more lift the fin produces and so you can load the back foot more as the board starts to fly.

For newbies reading this: The simplest way to sail off the front foot more - so as to keep the board more level and to spinout less - is to move your front footstraps forwards, and to shift the mast foot backwards (which brings the rig more upright).
If you are still overloading your back foot too much then shift your harness lines back on the boom.

So we cant say that spinout is caused by COE behind CLR?

Front foot pressure pushes towards the mast not the fin.

A. At fast planing speeds, especially on a fast freeride or slalom types of boards, there is insignificant lateral resistance contributed by the board 'rails'. i.e., the board sitting down in the water and getting sideways resistance from the 'rail' pushing against the water. There simply cant be, if the sides of the board are clear above the water surface and water is actually 'sheeting off/releasing off' the bottom of the board and the board is not laterally tilted.

B. Moving your harness lines on the boom does not change the centre of effort in the sail and does not change the centre of resistance on a planing board. It simply changes the centre of 'pull' you feel on your body, which you immediately compensate for with by loading your arms differently and moving the relative position of your body. it does not change the relative amount of force transferred to the board through either foot if the CofE and CofR are still balanced. This is simple Physics.

C. Changing the position of your harness lines makes you more, or less, comfortable. That is all! (but that is VERY important! )

D. Agressively tilting the windward rail down a significant amount can significantly increase lateral resistance at slow marginal planing speeds and can sometimes used to help get upwind in marginal planing conditions, especially on a narrow, low volume speed board. And when you do this you will notice that you have to swing your weight (and rig) significantly forwards to compensate for the big forward shift in the centre of resistance.

E. the faster you go, the more force ('weight') you will be transferring through your back foot as the certre of resistance moves closer the the rear of the board, but the biggest increase in force is created by the greater force in the sail, and higher lift from the fin with the weight of your body providing the balance in between.

F. Spinout is caused by not having enough 'lift' from your fin (too small or too slow), or by air being drawn down the fin causing 'ventilation', or by the fin 'stalling', meaning too much angle of attack (high force-low speed) which can be trying to transfer too much load on your fin before you have enough speed (lift) to support that load. You can also 'stall' a fin buy bouncing/jumping and landing 'sideways', but in this case, 'ventilation' will almost certainly also play a large part in the loss of lift.

E. Try sailing your board at planing speed with no fin in it sometime and report back how much lateral resistance you manage to get.

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Basher said..

fpw9082 said..

So we cant say that spinout, caused by COE behind CLR?

Yes we (still) can.
Centre of effort (COE) is the sail and centre of lateral resistance (COLR) is whatever makes that lateral resistance - in this case the foil lift plus the hydrodynamic lift from the hull.

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sailquik said..
A. At fast planing speeds, especially on a fast freeride or slalom types of boards, there is insignificant lateral resistance contributed by the board 'rails'. i.e., the board sitting down in the water and getting sideways resistance from the 'rail' pushing against the water. There simply cant be, if the sides of the board are clear above the water surface and water is actually 'sheeting off/releasing off' the bottom of the board and the board is not laterally tilted.

B. Moving your harness lines on the boom does not change the centre of effort in the sail and does not change the centre of resistance on a planing board. It simply changes the centre of 'pull' you feel on your body, which you immediately compensate for with by loading your arms differently and moving the relative position of your body. it does not change the relative amount of force transferred to the board through either foot if the CofE and CofR are still balanced. This is simple Physics.

C. Changing the position of your harness lines makes you more, or less, comfortable. That is all! (but that is VERY important! )

D. Agressively tilting the windward rail down a significant amount can significantly increase lateral resistance at slow marginal planing speeds and can sometimes used to help get upwind in marginal planing conditions, especially on a narrow, low volume speed board. And when you do this you will notice that you have to swing your weight (and rig) significantly forwards to compensate for the big forward shift in the centre of resistance.

E. the faster you go, the more force ('weight') you will be transferring through your back foot as the certre of resistance moves closer the the rear of the board, but the biggest increase in force is created by the greater force in the sail, and higher lift from the fin with the weight of your body providing the balance in between.

F. Spinout is caused by not having enough 'lift' from your fin (too small or too slow), or by air being drawn down the fin causing 'ventilation', or by the fin 'stalling', meaning too much angle of attack (high force-low speed) which can be trying to transfer too much load on your fin before you have enough speed (lift) to support that load. You can also 'stall' a fin buy bouncing/jumping and landing 'sideways', but in this case, 'ventilation' will almost certainly also play a large part in the loss of lift.

E. Try sailing your board at planing speed with no fin in it sometime and report back how much lateral resistance you manage to get.

So in general spinout has nothing to do with clr vs coe missplacement ,it happend when sail side force is greather than force that fin can produce for current flow condition?

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sailquik said..
A. At fast planing speeds, especially on a fast freeride or slalom types of boards, there is insignificant lateral resistance contributed by the board 'rails'. i.e., the board sitting down in the water and getting sideways resistance from the 'rail' pushing against the water. There simply cant be, if the sides of the board are clear above the water surface and water is actually 'sheeting off/releasing off' the bottom of the board and the board is not laterally tilted.

B. Moving your harness lines on the boom does not change the centre of effort in the sail and does not change the centre of resistance on a planing board. It simply changes the centre of 'pull' you feel on your body, which you immediately compensate for with by loading your arms differently and moving the relative position of your body. it does not change the relative amount of force transferred to the board through either foot if the CofE and CofR are still balanced. This is simple Physics.

C. Changing the position of your harness lines makes you more, or less, comfortable. That is all! (but that is VERY important! )

D. Agressively tilting the windward rail down a significant amount can significantly increase lateral resistance at slow marginal planing speeds and can sometimes used to help get upwind in marginal planing conditions, especially on a narrow, low volume speed board. And when you do this you will notice that you have to swing your weight (and rig) significantly forwards to compensate for the big forward shift in the centre of resistance.

E. the faster you go, the more force ('weight') you will be transferring through your back foot as the certre of resistance moves closer the the rear of the board, but the biggest increase in force is created by the greater force in the sail, and higher lift from the fin with the weight of your body providing the balance in between.

F. Spinout is caused by not having enough 'lift' from your fin (too small or too slow), or by air being drawn down the fin causing 'ventilation', or by the fin 'stalling', meaning too much angle of attack (high force-low speed) which can be trying to transfer too much load on your fin before you have enough speed (lift) to support that load. You can also 'stall' a fin buy bouncing/jumping and landing 'sideways', but in this case, 'ventilation' will almost certainly also play a large part in the loss of lift.

E. Try sailing your board at planing speed with no fin in it sometime and report back how much lateral resistance you manage to get.

Hmmm. I'd describe some of this stuff differently.

A. The board is often tilted one way or another so we're either digging in the windward rail or else (on longer boards) the leeward one. This continues to be the case with wave boards even at top speed (where we go upwind best on the windward rail). But slalom boards tend to fly faster just on the tail, with fin lift becoming the key factor in sideways resistance. At slogging speeds we use the rail on all boards. In light winds we get upwind best by sinking the windward rail. Kiters on wakeboards also go upwind on the rail. Course-racing kiters still use long fins for more efficient upwind work.

B and C. B. is a bit wrong because line position affects the load on each foot. The harness lines should line up with the centre of pull, and if positioned behind this neutral point will load your back hand more and in turn that will load the back foot. I actually set my lines a bit behind the centre of pull on my wave and freestyle gear - to give myself more pull on my front hand - so as to load the front foot more. Kauli Seadi does this on his wave kit, and Steven Van Broeckhoven does this on his freestyle kit. It's certainly not just about comfort. Most beginners and intermediates set their lines too far forwards, and then they get heavy backfoot load - which is why they spinout. They also set the mast foot too far forwards which then adds to the problem.

D. Not sure I'd describe it like you have. But, yes, I do bury the rail and lean forwards when heading upwind in lighter or marginal conditions.

E. For greater speed we do indeed try to drive off the tail more. This is a simple adjustment of weight towards the rear of the board as it starts to fly.

F. Spinnout is caused by you loading the fin more with your weight than the fin - any fin - is providing in lift. For sure, choppy water conditions can mean the fin attracts more air at the tail to aerate, which means full lift is lost.

E. You can go upwind on a freestyle board remarkable efficiently with a very small fin, with good front foot biassed sailing stance. The board goes upwind on the rails not on fin lift. But you do need some sort of fin to keep the board taking in a straight line, so 'no fin' is not really possible.

I certainly wil agree that wave boards boards are a bit different from faster boards. Clearly, there is a lot of the time where the water is not sheeting off the rails and they are semi displacement. You also will ride them with more tilt - slalom and speed boards are almost alwasy best ridden quite flat.

B,C,D? It may well be a bit different on wave boards as well when in semi displacement planing. But it defies physics that moving the harness lines forward or back nessasarlily, puts more or less load in the fin if you have all your weight possible driving the sail and going as fast as possible. If you stand up and release/spill some power, then that can change. Otherwise, the forces will have to be balanced out. I strongly contend that this reasoning about harness line placement and load on the back v's front foot is a MYTH.
Of course, if one is less experienced and skilled, and have the harness lines too far forward, then try to sheet in hard before you have got enough speed to get enough lift off the fin to counter this, you may well spin out. Positioning the harness lines neutrally, is a good teaching tip because will it almost certainly allow you to commit your weight to the sail easier, more fully and accellerate faster, reducing the tendency to prematurely overload the fin. There is the Physics of balance, and there is poor technique. It might sometimes be a useful teaching point with beginner/intermediates just learning to plane, but the reasons why it might work in that situation are completely different.

D. We agree.

E Pure Physics. Everything in balance

F. I prefer the word 'force' as 'weight' can infer downwards direction.

G. Yes, and I can go upwind on a 40cm speed board very effectively with a 16cm fin too. But both would be fully planing - not in displacement. Freestyle board can probably do it a bit slower because it has a wide, flat,effecient planing area and high lift fin shape. Speed board probably a bit faster (21-22 knots according to my speed talk GPS). Semi displacement is different. If you have enough speed and fin lift to plane fully, the lateral resistance of the rails in nil as they are clear of the water. If they are not clear of the water, you are in semi displacement mode. This is why we rail up our long race boards so much upwind in moderate winds. We DO use the resistance of the side of the board for lateral lift, but we are in semi-displacement mode.