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Old 30th May 2011, 05:04 PM   #21
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Just wondering what your harness line position is and how long are your lines? if you have them too far forward you will have massive pull in you back hand causing you to press hard on your rear leg causing you to head up. Also short lines will tilt the sail windward causing you to also head up wind.
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Old 1st June 2011, 10:57 PM   #22
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At risk of contradicting a few on here ....
Too large a fin (when planing) can definitely cause you to head up to wind.

As speed increases so does lift of fin (not lift against gravity but lift against leeward action;ie upwind)

If for a given speed that lift is greater than force down wind generated by drag on sail the board will head up and become difficult to bear away.This is usually precursor to fin generating so much lift it tries to flip board.!!! Point it happens at will be lower for lighter sailor..
!!
There is a correct size fin for given weight of sailor/size of sail and likely speed and conditions.
Too large afin (which it is !) will make things harder. As for getting upowind on smaller fin !!! It just needs to be travelling faster to generate sufficient lift !! (ie head upwind when fully planing;which is always good technique anyhow)
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Old 2nd June 2011, 06:26 AM   #23
Ken
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Just to keep it fun.......

Big fins don't cause a board to go upwind, the sailor steering the board causes the board to go upwind. However, a big fin will go upwind easier/better than a small fin. The excessive lift from a large or small fin given enough speed can cause the board to become unstable and ultimately "turtle" or flip the board because the fin is trying to reach the surface.

Most sailors when overpowered with or without too much fin intentionally head upwind to reduce their speed trying to regain control, but it's not the fin causing the board to go upwind.

I tend to sail with larger than normal fins and the board always goes where I steer it, regardless of the fin. As I said before, I use a 42cm fin in my iS 111 in 20-25 knots of wind with a 6.6 sail and the board always goes where I point it regardless of the lift from the fin. I have done some tail-walking, but always in the direction I choose.
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Old 2nd June 2011, 07:19 AM   #24
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I agree. I would also point out that sailing down wind is a skill that is learned. I depower in high winds by turning deep down wind as well as up wind.
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Old 2nd June 2011, 11:34 AM   #25
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While I agree that the weight of the sailor, the size of the sail, speed and conditions play a part in fin size, I think board width-specifically tail width-plays a huge part in the equation along with the type of fin. Without knowing which 130 liter board he has I can’t justify telling him a 42 cm fin is too large for his board.

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Old 2nd June 2011, 02:37 PM   #26
nicolo.piccolomini
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the board i have problems with is the 130 lt Thommen FreeX. compared with many other boards its quite thin (67 cm max width). the fin is a meanline 42cm fin that came with the board, and this is why i am confused that people say i should change the fin.
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Old 2nd June 2011, 04:31 PM   #27
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Keeping it more fun
Ken

What device takes a board upwind ??? The Fin is responsible for perhaps 90% (more ?) of the drive upwind?(rail helps aswell?) Without the fin the board would simply never go upwind.

First indication I get that I`m approaching overpowered (irrespectivce of rig) is boards desire to head upwind and both mine and boards reluctance to bear away. Solution? Change to smaller fin. Result ? I can bear away easier and boards looses desire to head upwind ... Yes I know all theory about CoE and CoR but results speak for themselves..One of symptoms of too large a fin is
a) Difficulty bearing away
b) Board heading into wind (without sailor input)
and later
c) board wanting to rail (ie flip)

Changing to a smaller fin can alleviate sall above.

Having said that I would /could use a 42cm fin in a 67cm wide board with down to perhaps a 6.5. Especially if I weanted to stay upwind well and wasnt too bothered about Vmax. But I weigh 105 kg.

As for sailor steering upwind ??? Best progress upwind is made angling windward rail up slightly.Driving off fin and leeward rail; in "theory" board should steer down wind ! But it doesnt; it flies upwind if you get it rightr and balanced. (Railing)

Board luffs up when overpowered for 2 reasons.
a) Sail CoE moves rearwards. (can be offset by moving lines back)
b) Fin produces more lift than required.
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Old 2nd June 2011, 10:41 PM   #28
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Bottom line..............boards don't go upwind without input from the sailor and or rig. No rig, no sailor, big fin = the board WILL NOT go upwind even if it is being blown along with a few knots of speed.

When overpowered, boards want to go upwind, but not because of the fin. When the pull on the back hand (CoE move rearwards), the sailor typically sheets out, taking weight off the mast base and puts more weight on the rear foot. This sends the board upwind, plus the sailor usually wants to lose some speed so he/she typically adds weight to the windward rail, also turning the board upwind.

When I experience a big pull on the back hand on my smaller sails & boards, if I choose, I can keep the power on, stay sheeted in, muscle the back hand through the gust, hang in the harness to keep pressure on the mast foot, use the back foot and toes to keep the board flat, and accelerated to until panic sets in. I have adjustable harness lines on my sails from 6.6 up to 11.0, so the back hand is rarely overpowered on the bigger stuff.

In overpowering conditions, it is difficult to turn the board off the wind because of the above mentioned sailor initiated dynamics, but it can be done if you are skilled (lots of TOW) and are willing to accelerate through a beam reach so that you can head off the wind. The difficulty is not so much technical, but it is very much mental.

I have raced formula in over 30 knots with a 70cm fin. Upwind is the only point of sail that offers any sanity, but only if power is continually applied and you hang in the harness lines to keep maximum pressure on the mast foot (critical for control). if you sheet out or relax, the board will do a back flip or similar nose high crash. Smaller fins help this situation, but it's the input from the sailor and rig that determines where the board is pointed or what happens.

Bottom line for Nicolo - The fin is not too large unless you are planing at 20+ knots of board speed. Even at 20+ knots, the fin may not be too big as your skills improve and if foot strap placements are eventually moved to the outward most locations. However, a smaller fin may make it easier to learn the basics of planing, jibing, foot strap and harness line use. Tell us where you are skill wise, plus the wind speeds you sail in and what sails you are using.

As Coachg said, the tail width of the board is usually the primary factor in determining fin length. If the 42cm fin is the factory provide fin, then there should be no problem.
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Old 2nd June 2011, 11:49 PM   #29
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thank god it is also my skill that determines the direction (no need to buy new fin!). i have done 2 years and i really feel as though i have a lot to improve. also, this all happened the first time i used this board, so i can assume that i need to get used to it. i have heard other advices such as moving the mast base forwards and moving the harness lines back, so i will use these advices. one question that i have not understood: do i move the footstraps in or out to go downwind more?
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Old 3rd June 2011, 12:01 AM   #30
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Hi Nicolo
I looked up the FreeX 130 (nice board) and see it comes with a 39cm fin. I am guessing that the OFO is around 40cm to 46cm based on the supplied 39cm fin. Most here seem to be pointing the finger at your fin, saying it is to big and sending you upwind. I disagree with them (sorry everybody). My reason for this is: Without seeing your fin, it would be impossible to say for sure if you need a smaller fin. If you take 5 fin brands of the same size, they will "all" feel very different. Example: you would need a C3 Venon 45cm to get the same power/lift as a Select SL7 39cm, 6cm difference. Size alone is not a good guide line as there are to many elements for fins.

I do not think that buying another fin will solve your problem. As Ken say's, a bigger fin will drive you upwind more efficiently c/w a smaller fin, but a big fin will not automatically go upwind (unless you are seriously over-powered).

Without actually seeing your gear set up, we are all just speculating, but I am pretty sure that the problem is with your sail set-up. The HTS is only a guide line, it is marked at the average beam reaching position. Moved back 3cm to 5cm will allow easier downwind runs. On my Norths I have my lines about 5 to 6cm behind the HTS, I always found the recommended setting was very wrong for me.

Also, if you down haul to the max VTS, the sail will breath easier and will allow excessive power to exhaust, this will stop extra pull on your back hand and in turn will stop you pushing against the fin with your back leg, sending you upwind.

Your outhaul ideally should be slightly negative to help downwind, but if your worried about getting back upwind, set it at neutral. Do not set it with positive outhaul as this also send you upwind.

Short harness lines will also send you upwind. If you have a pair of longer lines, try them out, or maybe you can butcher your existing lines to make the longer. Longer lines really help for downwind.

Deck plate and footstrap position will make a big difference as well. Deck plate forward, easier upwind, pull it back and easier downwind, same for the footstraps.

All in all, if your settings are upwind biased, yes your board will try to creep upwind and make it uncomfortable downwind.

Is there an experienced sailor/guru at your local beach that look at your kit for you?

This is just my thoughts and feeling on what might be wrong, and hope you find out soon what the problem is. Good winds
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