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Unregistered
31st July 2009, 06:13 PM
Hi,
it seems I am pushing the fin sideways with my back foot too hard,the tail slides forward under my feet sometimes, causing loss of contol. At the same time there is no pressure coming through my front foot. My stance needs changing, what can I do to reduce sideways back foot pressure and increase mast foot pressure. I sail on a freeride/slalom board.
thanks!

Roger
31st July 2009, 06:21 PM
How wide is your board?
How long is your fin?
What size sails?
How much wind?
With this info we maight be able to give you a good answer.
Without this info it will all be a guess.

Unregistered
31st July 2009, 07:12 PM
Which board is it?

Ken
31st July 2009, 10:11 PM
Roger's questions are essential for finding the answer. Also, point of sail determines how much pressure you put on your back foot. The following has been my experience, but much depends on the board, fin, wind, sail, body weight, speed etc. The below estimates assume that you are fully powered up with good speed (planing) and are an intermediate or advanced sailor

Upwind - Majority of pressure on the back foot (90+%)

Beam Reach (across the wind) - more than half on the back foot, less than half on the front foot.

Full Reach (down wind) - Weight balanced evenly on both feet or possibly a little more weight on the front foot.

michelb
1st August 2009, 12:37 AM
I love the spin out.......

Give Us more info.

Michel

Unregistered
1st August 2009, 03:57 AM
just back from sailing and had the same problem
the board is f2 ride (freeride/slalom)
the fin is select s-rde 34 cm
the sails are north sails natural 7.5/6.2 no cambers
my weight is 63 kg
use seat harness, long lines

the wind was 12-15 knots today, comfortably powered up on 6,2, choppy
my level is intermediate, the course is beam reach or higher.

my guess is that I dont generate enough mast foot pressure, so too much of it goes through the back foot and the tail "steps out"

Unregistered
1st August 2009, 04:01 AM
the board is 278 cm long, 63 cm wide (I think) 102 litres
thanks for the input
cheers

leysenkr
1st August 2009, 09:26 AM
I have a Futura 101L and this board needs a lot off back foot pressure to prevent spin out.
I always had problems going through chop till I found out I tried to catch up the chop by pulling up the back foot and had a lot off spin outs. From the moment I started to keep pressure on my back foot, it stopped.

Floyd
1st August 2009, 10:01 PM
Try moving your harness lines further back.Spin out is closely linked with the sail; centre of effort ; and board ; centre of resistance.
Moving lines back prompts you to use rig slightly further forward. (ie entre of effort infront CoR)
Not bound to be problem but give it a try. (Then start playing with fins/technique)

We all spin out now and again. Pushing rig forwards can prevent it developing if you can catch it quick enough !!!
Good luck !!!

Unregistered
2nd August 2009, 02:31 PM
no I am not exactly spinnng out, it,s just that I am pushing too hard on the fin so that is looses grip, same thing happens to Laird Hamilton in the following video when he lets go of the boom http://www.stableroad.com/videos/lairdhamilton.htm

I guess I need to transfer more weight on the harness and lift the weight from the board, I just dont know how yet.

leysenkr
2nd August 2009, 04:14 PM
That is a spin out.

For a moment, his sail is depowered (opened) and then he spins out.

Floyd
2nd August 2009, 06:46 PM
I never saw any sign of spin out in video ??? But ???
He`s sailing (in most of video) well off wind. (120 degrees +) Look at wind direction on water/waves.He`s on a speed board and well well powered up. If I looked anything like that I`d be chuffed ??? He suffers a slight control problem (big for us) when playing; think he got a bit of aeration on jump ???

Good luck.

PS have things really moved on since that video was shot ???

leysenkr
2nd August 2009, 07:15 PM
I never saw any sign of spin out in video ??? But ???
He`s sailing (in most of video) well off wind. (120 degrees +) Look at wind direction on water/waves.He`s on a speed board and well well powered up. If I looked anything like that I`d be chuffed ??? He suffers a slight control problem (big for us) when playing; think he got a bit of aeration on jump ???

Good luck.

PS have things really moved on since that video was shot ???

@ Floyd:
Please define Spin out.
For me it is the moment that the fin starts to slide more sidewards through the water. Not perfectly straight in to the sailing direction.

Floyd
3rd August 2009, 03:18 AM
You are right. I watched video again. He does spin out , (but recovers with help of rig !!!) a few yards after sailing with no hands !!! (When rig had come back !!!) (see below cause C or B ; perhaps a combo?)
Missed it first time; he had a slight "moment" after a chop hop early in video; was assuming that was that was "the spin out".

Ps Fin is never travelling straight through water ; it always has at least 3 degrees AoA. (look at GPS trak logs its amazing just how much side slip there is !!)

Spinout is when;
a) Force going into fin is greater than lift generated; fin stalls and spins out sideways. With modern fins travelling fast unlikely to happen. (Look at amount of drive AA puts into board without spinout)Generally happens when board is loaded too early.(ie at too slow speed)

b) Lift created by fin degenerates. (Aeration) so board spins out.(Likely cause in choppy water)

c) Centre of effort (of sail) moves behind centre of resistance of board; board should luff but sailor footsteers down wind. Board will spin out. (Its effectively overloading fin)

IMO its nearly alwayd B or C that causes spinout. Overloading a good fin takes some doing.(If everything else is ok)

Hence try moving your lines back ;to almost too far !!?? (ie you are over loading front hand)
Just try it . (But be carefull rig doesnt spill as easy)

PS
All the books talk about cavitation. Personally dont think we ever get true cavitation but thats another argument !!!
Good sailing

Apologies again.

Unregistered
3rd August 2009, 04:08 PM
Spinout is when;
a) Force going into fin is greater than lift generated; fin stalls and spins out sideways. With modern fins travelling fast unlikely to happen. (Look at amount of drive AA puts into board without spinout)Generally happens when board is loaded too early.(ie at too slow speed)


I think this is the case with me, need to find a way to generate mast foot pressure more consistently

Ken
3rd August 2009, 10:35 PM
The fin itself can be a big problem. Some fins "push out or spin out" more easily than others of identical size. Some that spin out are VERY difficult to pull back in unless you drop your speed below 10 knots, while others come back with little or no effort at any speed. The Drake fins that come with the iSonic boards are good examples of fins that spin out easily, while just about any good aftermarket custom fin works much better (in my opinion).

I think Starboard / Drake fin design was based on downwind slalom and speed,so they created fins with very little foil shape for less drag. However, for beam reaching or upwind in choppy water, spin out can be a big issue.

Sailor skill plays a big role in all of this. Knowing how much pressure you can put on your back foot, plus keeping the board flat on the water in choppy conditions (no air under the board), both come with experience.

Unregistered
4th August 2009, 03:20 AM
I use a select s-ride 34cm fin (freeride fin, upright shape with a bit of curve)
would a smaller size help on an oldschool narrow tail board? I never have problems when reaching slightly downwind, only beam reaching or upwind, i can almost push the tail sideways at will, even when it feels that I,m comfortably powered up.
thanks!

Floyd
4th August 2009, 05:22 AM
Think you need to be more specific.
Rig ? board ? Weight? Water conditions ? Both tacks ?? and even speed its happening at ???

Dont think going smaller will help at all ; too big a fin causes other control problems. (Unless fin is damaged)

Ken
4th August 2009, 11:07 PM
The tail width of your board is important for fin length, but at 63cm at it's widest point, a 34 cm fin seems fine. Going smaller is not needed, going larger may help, but control issues may surface if you really get going fast.

You may need to borrow some fins to see if something else works better, to help you decide if your fin is bad. I don't know anything about Select s-ride fins so I can't offer an opinon.

Your technique may be an issue. When getting started, bare off until you get good speed. 20+knots of board speed, then begin heading up with more pressure on the fin. If you achieve 25 knots of board speed, the fin should not spin out unless you are in choppy water and air gets under the board while you are putting pressure on the fin.

What's your sail size and wind conditions when you spin out? That will help us understand the situation better.

Two sailors on the same board, fin and in the same wind (20 knots), one on a 5.5 sail and one on a 7.5, both "comfortably powered", one is traveling at 20 knots and the other at 30 knots. This is where skill and experience play a role.

Unregistered
6th August 2009, 12:48 AM
I guess it is more of a skill than fin issue with me, I will try different things and post if I solve the problem

Ken
6th August 2009, 02:03 AM
It could be skill or the fin or both. Unless you try some other fins, you may not know which. Some fins are more forgiving and you don't have to be as skilled. Others take a lot of skill to keep them from spinning out.

Intermediate sailors progressing to smaller boards usually experience spin out frequently. The better you get and the more you learn about fins, the more the spin out decrease.