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TomG
7th October 2006, 01:07 AM
I still experience too often "spin-outs" (the fin doesn't "work" anymore and the board moves sideways). I believe that I put too much pressure via the rear foot and strap onto the boards. I have tried to straighten my front leg a bit more and almost pull the back foot towards me, which has given some improvement. However, I find it difficult and feel not all the time that my body has good poition / "posture".

Are there any tips that you could give to prevent this phenomena?

Thomas

o2bnme
7th October 2006, 04:34 AM
What size board (& type), sail, fin are you using? What are the wind conditions? How much do you weigh?

Last weekend, I went sailing with a 9.8 and a 56 cm fin. I thought I was using a 66cm fin. ooops. My mistake, but the point is, if you don't have the right combination you might have these sorts of problems.

Technique is important too, of course, but if we can rule out equipment matching as an issue first that would be good.

Roger
7th October 2006, 12:09 PM
Hi Thomas,
Spin out is pretty common, it happens to all windsurfers, from time to time.
Sometimes it's caused by a bad fin.
Sometimes, even with a good fin, it happens, and techniques that reduce the loading on the fin can help.
Sometimes just tuning your rig a little better can make all the difference.
I agree with o2bnme that what board you are sailing, what fin you are using, and what rigs, windspeeds and surface conditions can all be factors here, it's rarely purely a technique issue, unless you tend to "jump on" your fins way to early.
The foils on windsurfing fins REQUIRE a certain minimum flow of water over the foil before you can really "push" on the fin.
Push at too low a speed, and the fin stalls and spins out.
This is why most of us head a little off the wind and try to get fully planing before we put much pressure on our fins.
So, give us a little more information here, and I'm sure we can give you some suggestions to solve your "spin out" issues.
When you put "pressure" on your fin, what is the rail to rail attitude (the roll angle) of your board? Are you sailing with the upwind rail lower than the downwind rail?
Are you trying to sail "on the fin" with the lee rail slightly (very slightly) lower than the upwind rail?
Are you trying to push the tail of the board down, toward the water, or trying to push the tail away from your body?
Either of the above techniques works, but one works best on very small boards with usually a single rear footstrap, where the other works much better on a wide board with a large fin.
At no time will you be able to "pull up" with your back foot (unless you are chop hopping or jumping) and thus reduce the pressure on your fin.
Shifting your weight to the front foot can also cause problems.
Give us a little more info to work with please.
Hope this helps,

TomG
7th October 2006, 03:16 PM
Thanks to both of you Roger and o2bnme,

I have actually 3 boards, all JP's :@ from 85 to 130 l Crossover type (Freestyle Wave) the smallest and Freeide the other two. I have for each board 2 fins, i.e. from Curtis and Selectm which I selected for the specific board and sail sizes. So, the size and quality of the fins should not be a problem. If still helpful I can provide the details later. Sails types vary. 9.0 and 7.0 Freeride, 5.8 Crossover and 4.7 and 4.0 Wave. Water conditions vary but it happens on flat water / choppy conditions (lake) as well as wavy conditions on the ocean (North Sea or similar).

The spinouts typically occur when I am at higher speeds and have some load in the sail and I guess more frequently when I go slightly upwinds.

I don't know the answers to the other questions (below) - I don't do any of consciously, so will pay attention to this when I get onto the waer next time.
When you put "pressure" on your fin, what is the rail to rail attitude (the roll angle) of your board? Are you sailing with the upwind rail lower than the downwind rail?
Are you trying to sail "on the fin" with the lee rail slightly (very slightly) lower than the upwind rail?
Are you trying to push the tail of the board down, toward the water, or trying to push the tail away from your body?

Thanks again and I will get back when I can answer the outstanding questions, which may take a bit of time.

Thomas

Roger
8th October 2006, 09:16 PM
Hi Thomas,
OK, smaller freeride-freestyle type boards with small curvy loose fins.
On these smaller boards, you normally use very small (20-30 cm) fins that have a very curvy outline profile and and very twisty "tip".
They turn really easily, and are made to be very "loose" so you can do the tricks (on the freestyle boards) or slash and off the lip on wave type boards.
So, they seem to "spin out" very easily with these tiny fins.
If you get a more slalom oriented (more vertical and straighter planform) fin for your board, you won't get s much spin out, and your board will be more directional and easier to sail in the "back and forth" mode.
You also will get much better upwind performance and better speed as well.
Hope this helps,

TomG
31st October 2006, 04:44 AM
Hi Roger,

I had the opportunity to sail last weekend, not great conditions though. However, I used a 9m2 sail with JP Freeride 129 (width 69cm) and 48cm fin (Curtis CR12). Foot straps in the outer position and in second but last screw position. I don't know the wind speed. And I had spinouts 3 or 4 times.

Here are your questions and my answers:
When you put "pressure" on your fin, what is the rail to rail attitude (the roll angle) of your board? Are you sailing with the upwind rail lower than the downwind rail?
The upwind rails was actually higher than the lee (downwind) rail. I did it not by purpose but struggled to get the board horizontal at higher windspeeds.

Are you trying to sail "on the fin" with the lee rail slightly (very slightly) lower than the upwind rail?
Ref. rail position, see above response - lee lower than upwind by a fair bit it felt. I still try to understand how to ride "on the fin". I have the feeling that the wetted area is relatively large (and long) but don't know for sure - difficult to judge when on the board I find.

Are you trying to push the tail of the board down, toward the water, or trying to push the tail away from your body?
I wouldn't say that I try to push the tail in a direction but as a matter of fact I push it away from my body while I try to reduce the pressure by bending the back leg and straighten the fron leg. Occasionally I even try to "pull" rather than push with my back leg but I guess whenever I don't concentrate on my back leg I push away.
There were times that I remember when I tried to almost lift the front foot to lift the entire board a bit out of the water.

Water conditions rather flat (lake) but in gust some small waves/chops. Once the upwind rail got lifter from one of those small waves and I lost immediately grip (means spinned out).

The sail needed actually more downhaul I realised later. It was (just) ok for the lowest wind speed and got me to plane early but in the gusts I struggled to hold it. To same extent lack of practise (TOW) I presume.

Overall I felt reasonbly good, got to plane earlier than a guy with a 9.8m2 Nitro and was quite fast compared to others (although most had smaller sails)

Hope this helps you to get a better understanding what I do wrong and waht I could do to avoid the spinouts.

Thomas

Roger
31st October 2006, 09:10 PM
Hi Thomas,
Your description of "pushing" over the top of the fin does not sound quite like what I'm suggesting, and "pulling" toward upwind with your back foot is only something I would suggest to "recover" a fin that's already "spun out".
So, try this on your next sesh.
Get your board going as fast as you can on a beam reach (straight across the wind at 90 deg.).
Then begin to lift (not pull) a little with your front foot in the front footstrap to get the upwind rail up slightly higher than the lee rail.
Now begin to "push" across the top of the fin with your rear foot.
Imagine that you are trying to push the board away from you straight across the top of the water.
You can determine which rail is lowered, and how much waterline length you have in the water by looking down at your board momentarily.
If the "splash" of spray and white water is coming out from under your board on the upwind side, and you see pretty much "green water" (no splash) off the downwind rail, you have it right.
Notice the place (along the rail of the board) where the "splash" comes out from under the upwind rail. If you can get the splash to come out from under your board at or behind the front footstrap you have it right.
If the splash comes out forward of the front footstrap, your board is riding too low at the nose. Maybe move your mast foot back a little and see if you can get the exit point of the spray to move back under the front footstrap.
Also, try giving your sail a little more downhaul, to make it slightly less powerful, or get an adjustable outhaul "kit" so you can have your sail be really powerful to get planing and less powerful and more "slippery" once you are on plane and the apparent wind has accelerated due to your forward speed.
Also remember, (esp. on your smaller boards and fins) that if you are feeling alot of pull with your back hand, that force needs to go somewhere, and it travels from that back hand, through the arm to your back shoulder, down through the torso, and down your leg to the foot in the rear footstrap.
So you may want to change your mast foot postion, harness line length, boom height, and trim and tuning of your sail to get that pressure off the back hand and hence off the fin.
Hope this helps,

tonyP
19th November 2006, 09:23 AM
>>>>Also remember, (esp. on your smaller boards and fins) that if you are feeling alot of pull with your back hand, that force needs to go somewhere, and usually it travel from that back hand, down the arm to your shoulder, through the torso, and down your leg to the foot in the footstrap.
So you may want to change your mast foot postion, harness line length, boom height, and trim and tuning of your sail to get that pressure off the back hand and hence off the fin.<<<<<

Hi Roger,
Good point re: recovering from spinout by pulling the tail of the board with the rear foot. Also, I like the description of the spray above as a means to tell when the board is correctly angled to ride the fin. I&#39;ll be printing that part and putting it in my &#39;windsurfing binder&#39;. I did the same with your recent detailed description of how to pump onto a plane.

Re: the quote above, might I ask you to comment on how to eliminate the "pull on the back hand" by changing the variables that you mentioned there. The reason I ask is that when faced with that situation (back hand pressure) I just assumed that my harness lines weren&#39;t set right, and moved the lines back a little on the boom.

I&#39;m looking forward to your comments, thanks for your time and insights.

Tony

Roger
20th November 2006, 09:29 AM
Hi Tony,
Let me think about this one for a few days.
I started to "write a book" today on the overall dynamics and physics
of how you can re-balance your rig, reposition your mast foot, change your harness line positions and spacing, and change the length of your lines and boom height to get everything more balanced so you don&#39;t exert too much pressure on the fin.
But I need to go sailing a bit and try out some of my "ideas" here before I write them up.
Please be patient and I&#39;ll have a good answer for you.

o2bnme
21st November 2006, 05:08 AM
Roger, that sounds like a more professional way of writing a &#39;20 knot clause.&#39; I saw the forecast too. ;-) I guess while it is raining, you&#39;ll have time to write it up again.

Tuesday: Rain likely, then occasional rain and possibly a thunderstorm after 1pm. Some of the storms could produce heavy rainfall. High near 60. Very windy, with a northeast wind 30 to 33 mph increasing to between 46 and 49 mph. Winds could gust as high as 65 mph. Chance of precipitation is 100%. New rainfall amounts between one and two inches possible.

Wednesday: Occasional rain and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 61. Very windy, with a northeast wind 34 to 37 mph increasing to between 43 and 46 mph. Chance of precipitation is 100%. New rainfall amounts between two and three inches possible.

On a more serious note, with waterskiing, people tune their waterskis with calipers. They keep a notebook log of the changes and how it affected their performance. There aren&#39;t as many things to move on a ski, but I like how they explain what you can do to tune your set up. Maybe this would apply here? I only say this because I haven&#39;t seen a good explanation of this stuff anywhere on the web yet. If it is written up, please share the link! :D

Could you produce a list of the things you can tune and what the change affects? Bigger/smaller fin, mast track forward/back, footstraps, boom height, harness lines, etc. Has this been formalized before?

Roger
21st November 2006, 06:48 AM
Hi Bill,
If you look through the archives on the forums here, on each specific tuning option, I&#39;m sure you would discover a wealth of information, but I think you are correct.
No one has "compiled" all the suggestions, and then gone out on the water and changed them one at a time (maybe with a training partner
to get some realtime change vs no change data) to determine what each change does, and how it affects the overall physics and balance.
It&#39;s something I&#39;ve wanted to do, but to do it right I need alot better graphics skills as I think animations may be the best way to illustrate
the physics. I&#39;m working in that direction with an online book and some other ideas.
As far as the 20 knot clause, I&#39;m heading to the west coast of Florida tomorrow morning, so I&#39;ll be driving into the gale up the island and hoping to have it push all 7.5 tons over to and down I-95 to FL.

TomG
16th December 2006, 05:21 PM
Hi Roger,

I still don&#39;t have as many opportunities as I would like to get on the water. However, I think I start getting the "message". Although a number of other things (such as rig tuning to avoid unnecessary drag) may have an impact it seems to boil down to board control. Where I had the opportunity to sail more recently it was extremely gusty, wind speed ranging from ~10 kn well into the (mid) 20&#39;s and I battled with my 7 sqm sail, getting a bit better every time (better rig tuning has helped at least here - I have new sails, so another variable to get used to). This meant that I didn&#39;t have a lot of opportunities to watch the board (trying hard to stay on the aboard and some lack of confidence). Used my 129 l and 104 l boards.

Now I come more to the point. I recognised few times that the board was sort of dancing a bit, potentially allowing too much air to get under it. I also changed the straps to the outer positions while I used to use the inner ones (I focussed more on manoeuvre). The outer positions seem to have made it more difficult to control the board. I am not fully comfortable with this position when I get into what I consider as (well) overpowered conditions and struggle occasionally to quickly slip into the rear one (can&#39;t find it first time and then I struggle to stay control and have to stabilise first again). I had some good runs though where the board/fin started to howl/sing when I was on a slightly downwind course and the board control felt ok. Is this normal by the way (I think I have good qauality fins)?

Does the above (board control most important, outer strap positions can make it more difficult) make some sense or not?

Thomas

Roger
16th December 2006, 09:06 PM
Hi Thomas,
Yes, footstrap position (inboard or outboard) can affect your control, but not perhaps in the way you are thinking.
Moving the footstraps outboard does basically 2 things.
It gives your foot and ankle more "leverage" to control the attitude (side to side or "roll" angle) of your board and fin.
It places your weight more outboard off the centerline of the board and if you aren&#39;t getting your weight totally committed to the harness lines and rig, having the footstraps outboard can lead to some control issues. If you are getting all your weight off your feet and onto the rig, then it becomes pretty easy control the roll attitude of the board as you can do that with better leverage, and virtually no weight on the tail of the board, so your ankles have the ability to hold the board at the attitude that gives the best control, and when you get enough TOW (Time On the Water) you soon find the board&#39;s attitude can be controlled very precisely even over the chop.
Having the footstraps inboard kinda does the opposite, and for your smaller boards (esp. for chop hops and jumping maneuvers) having the footstraps in the center position can be used to minimize the "leverage" giving better control on the narrower board with the smaller fin. Landing a chop hop or other "jump" in the outboard footstraps, on a really small board with a very small fin can be more difficult because you don&#39;t need the extra leverage, and you also don&#39;t really want your weight applied very mch off the centerline.
So, you need to adjust the positions of your rear footstrap (s) to suit the conditions, the board, and what sort of sailing you intend to be doing.
The flatter the water and the more "back and forth" (B&F) slalom sailing you are doing, the more you need the footstraps outboard.
The rougher the water, the more you are jumping and landing, and the more B&J (Bump and Jump) type sailing you are doing, the more desireable it is to have a singe footstrap over the centerline.
It sounds like most of your "spinout" issues occur when you start to head upwind.
Be sure that when you change course to more upwind, you do so gradually and when you roll the board and apply more pressure that you do it smoothly and with a steadily increasing pressure until you get the course you want.
Also, more time on the water is going to "teach you" how to "feel the fin" and become much more sensitive to when it&#39;s beginning to let loose and "spin out". In essence, you learn when you have the max. pressure and angle the fin can withstand (at a given speed) vs when you&#39;ve applied a bit too much and the fin begins to "let loose".
Then you can begin to "ease off" when you get near the max. load and angle and keep your fin solid, but right on the verge of spinning out.
Try different fins.
Some let go with a bang, all at once. Normally this would be with larger more vertical fins.
Some fins never really seem to "hook up" solidly, and are a bit "loose" all the time. These normally are smaller very curvy planform wave and bump and jump fins. The "looseness" has been designed into these fins on purpose, so the board will be very loose and slashy, but they don&#39;t work very well for B&F straightline slalom sailing or fast speed sailing.
Actually, when I read your reply and you said your board was "dancing" a bit, I found that very encouraging.
When the board "dances" a bit, that usually means it&#39;s sailing fast, and on the minimum sustainable waterline length.
Now we just need to send Thomas to "dance class" so he can learn to dance to the same tune. ;)
That&#39;s probably the big "secret" to solving your spin out issues. More time on the water so you become more sensitive to when your fins are going to let loose, and how to moderate the pressure and angle (with your feet and ankles) to keep the fin "right on the edge".
Hope this helps,

TomG
17th December 2006, 12:29 AM
Roger,

Thanks again for your elaborate response. With winter in the UK and some heavy work over the next few months it will be unlikely that I get much TOW (if any at all) - apart from a 1.5 week break at the beginning of next year on Bonaire where I also intend to hopp few times on a board. Unfortunately I will miss you by few day.

In the mean time I will attend a dance school :D.

Thomas

Roger
17th December 2006, 02:36 AM
Hi Thomas,
After you sail the boards with the "cut off to 33 cm" fins in Bonaire, NA
(if you sail in Lac Bay at "The Windsurf Place" or Jibe City) you may find that the fins on your boards at home in the UK are "rock solid" in the spring.
When will you be in Bonaire?
Sorry I&#39;m going to miss you as I&#39;d like to see what your stance is and how you are sailing to get a better idea if your "fin issues" are totally related to the fins, or if there are some technique issues mixed in there as well.
Enjoy Bonaire! B)
R

TomG
17th December 2006, 06:50 PM
Hi Roger,

I will be in Bonaire 3rd to 13th January, so will miss you. Windsurfing is not the main objective but still want to do some. I will be in Lac Bay - may be the short fins are the best training opportunity.

I am sure that the spin outs are a technique issue rather than a fin (equipment) issue. What helps I guess is largely TOW, means practicing.

Coming back to the unrelated observation from my last sailing, that the board/fin started to howl/whistle/sing (fits to the dancing:D) few times when I felt that I was goinf fast and reasonably controlled. Is it normal? As I mentioned earlier, I use only one of the stock fin, all other are added and as I believe of good quality (Select, GSport/Curtis). It happened this time with the 42cm JP stock fin on the 129 l board and a Select Eagle 35 on the 104 l board.

Appreciate your comments.

Thomas

Roger
17th December 2006, 09:09 PM
Hi Thomas,
The "howling/whistling" noise could very well be coming from the fin, and as you suggest it&#39;s almost an "audible knot meter" as it only occurs when you are really going very fast.
The most common reason this happens is that the trailing edge of your fin is "thinned out" a little too much, or sometimes there is a little "concave" area just ahead of the trailing edge that&#39;s too thin.
You can check for the "concaves" with a small hardened and ground dowel pin or a precision straight edge. Roll the pin or drag the straightedge down the foil of your fins perpendicular to the vertical axis.
If you see light coming between the pin/straightedge (now resting on the back half of the foil from the thicker part of the chord to the trailing edge) then you have some concaves and the best way to fix them is to get a flat sanding block and work down the fin to remove any "concavity" between the max. foil point and the trailing edge of the fin. This will "sharpen" the trailing edge, so when you have all the concaves worked out of your fin, you need to "blunt" the trailing edge slightly.
If you have no concaves, and the trailing edge is simply too thin and setting up a hydrodynamic "vibration" (the source of the noises) then you simply need to "blunt" the trailing edge.
To do this, take a sanding block and lay it perpendicular to the fore and aft axis through your fin&#39;s foil. With "smooth" (320 grit) abrasive cloth on your sanding block, run the block down the trailing edge of the fin 3 or 4 times. This will create a very tiny "flat" on the trailing edge that will be thick enough to eliminate the noise.
There will be very sharp edges at the sides of this tiny flat, so take your sanding block and put it at 45 deg. to the fore and aft axis of the fin and run it down the sharp edge once on each side to "chamfer" the very sharp edges slightly.
Try your fin on the water.
I&#39;ll bet the "howling/whisling/singing" will be eliminated. If it still sings, but at a lower pitch (your fin now "growls rather than howls" :o) try the sanding block down the trailing edge a few more strokes and then the 45 deg. chamfers on the sides of the flat.
This should quiet your fin down so that you only have to learn to "dance" with your board and fin.
Don&#39;t think you could dance to the "howling fin serenade" anyway as the pitch is way to high. You&#39;d shake yourself apart very quickly! :o
Hope this helps,