I recognized that i am frequently spinning out in the lagoon where water is shallow and flat, but once i go out to deep choppy water almost no spinouts happen.
In lagoon, it starts with upwind side front fin spinout (or is it called cavitation?), board gets a little drift angle towards wind but still can stay upwind, a little slower, olso because I can't apply full power, or rear fin spins out too. No way to correct it unless i get out of straps, unhook and fully depower, where as in deep water i can easily correct by snap pushing the board really downwind.

Is there a different hydrodynamic situation going on when its shallow?
Or maybe i am railing the board without recognizing?

By the way i am using dyno 95, 12,5f/20r, outside footstraps, bottom is mostly sandy and some short fresh weed, almost no current in lagoon, water about 30-40cm deep.

Probably grass or weed at shallow sites..require big weed fins.

Using the inboard straps would be better on thruster set up. Only use the outside / outboard straps with a large single fin.

Not sure about the water depth issue, probably is some sort of bizzare explanation for it.

Your riding a wave or freewave board yes??? It's about your change of stance I guess. On flat water your leaning out more loading up the fins, In choppy water you go more over the board as a response to the bouncing going on. The fins in production boards are on the large size anyways so should be fine which means it's technique. To get up wind ride the rail don't load up the fins, For free ride it's ok but don't put all the pressure through the back foot. Learn to put pressure through the front foot and really pull up on the toes...Front and back. Slipping you back foot out a bit so you're toes just catch the back strap also improves upwind sailing. Also hang hard in the harness and lean way forward.
my 2 cents J.

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Madge said..
Using the inboard straps would be better on thruster set up. Only use the outside / outboard straps with a large single fin.

Not sure about the water depth issue, probably is some sort of bizzare explanation for it.

I use outside straps because my ankles stretch too much and muscles that pull the foot upwards gets sore very quick if i use inside straps, its more comfortable with outside straps and i feel i can apply more power.

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jh2703 said..
Your riding a wave or freewave board yes??? It's about your change of stance I guess. On flat water your leaning out more loading up the fins, In choppy water you go more over the board as a response to the bouncing going on. The fins in production boards are on the large size anyways so should be fine which means it's technique. To get up wind ride the rail don't load up the fins, For free ride it's ok but don't put all the pressure through the back foot. Learn to put pressure through the front foot and really pull up on the toes...Front and back. Slipping you back foot out a bit so you're toes just catch the back strap also improves upwind sailing. Also hang hard in the harness and lean way forward.
my 2 cents J.

Spinouts happen going downwind as well, usually at high speeds, sometimes just before jibing which gets scary.
I try not to put pressure on back foot, and i am a lightweight. Used a friend freestyle board with 18,5cm fin last week and had no problems. So i start to think its not back foot pressure. So railing while going fast doesn't cause spinout?

That's odd, Maybe you are just picking up weed. Down wind is always solid for me, I run wave boards at 30-40+ knots in shallow water at lake Illawarra (30-50cm max depth) and have never had an issue going off the wind. Maybe the board just isn't built for the outboard straps to be it's optimum. Try the single strap and see if that settles it down as you can't load it up as much. Otherwise go up in fin size by 2cm.

could be the fin foil profile, too fat at the front can cause ventilation/cavitation at speed. I had a fin once that span out as soon as I hit 32kts.
Was OK in chop because I never achieved those speeds in chop. I shifted the thickest point back a bit, so the front wasn't as fat, that fixed it.

I had the same thing with a wave fin, would spin out with no load, but high speed, like dropping down the face of a biggish wave. Could feel the board go sort of loose, if I tried a bottom turn would just go sideways. I had to cut back instead, the fin would then "reattach" and I could pull a good bottom turn. This was again the leading edge too fat

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decrepit said..
could be the fin foil profile, too fat at the front can cause ventilation/cavitation at speed. I had a fin once that span out as soon as I hit 32kts.
Was OK in chop because I never achieved those speeds in chop. I shifted the thickest point back a bit, so the front wasn't as fat, that fixed it.

I had the same thing with a wave fin, would spin out with no load, but high speed, like dropping down the face of a biggish wave. Could feel the board go sort of loose, if I tried a bottom turn would just go sideways. I had to cut back instead, the fin would then "reattach" and I could pull a good bottom turn. This was again the leading edge too fat

This might be the case, they look almost round at front profile, olso thicker than center fin. Thanks, i will sand them a little and try again.

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Sea Lotus said..

jh2703 said..
Your riding a wave or freewave board yes??? It's about your change of stance I guess. On flat water your leaning out more loading up the fins, In choppy water you go more over the board as a response to the bouncing going on. The fins in production boards are on the large size anyways so should be fine which means it's technique. To get up wind ride the rail don't load up the fins, For free ride it's ok but don't put all the pressure through the back foot. Learn to put pressure through the front foot and really pull up on the toes...Front and back. Slipping you back foot out a bit so you're toes just catch the back strap also improves upwind sailing. Also hang hard in the harness and lean way forward.
my 2 cents J.

Spinouts happen going downwind as well, usually at high speeds, sometimes just before jibing which gets scary.
I try not to put pressure on back foot, and i am a lightweight. Used a friend freestyle board with 18,5cm fin last week and had no problems. So i start to think its not back foot pressure. So railing while going fast doesn't cause spinout?

Were you riding your own rig when you tried the FS board? I also think it is technique/setup...

No it was all his kit. One of the difference i felt was i was closer to mastbase, and stance was more upright. Problem is i can not move the straps more further in dyno (front foot comes out) and i keep the mastbase pretty back.
Board was Fanatic Skate TE, it was very "free" and light, enjoyed it very much. Sail Duotone fs. I did dig the rail to go upwind and it was still fast, doesn't work with dyno, it stalls or spinsout.

Did you get around to sanding the top of the base of that fin Sea Lotus? (From a previous thread)



If the fin isn't flush with the bottom of the board, sailing flat water will exaggerate the spin out/ventilation its causing. Just another thought to add to what has already been said.

I have since got an original center fin so i didn't bother sanding that one yet. Original one is good, even though its smaller.
In this case (or i just realized) problem is side fin spinning out first in lagoon, rear holds on till a point, and sides are flush fit.

In theory a fin will produce more lift (at equal speeds) in shallow water. basically the ground will sort of act like an endplate on a wing.
However because the flow is under more stress, it is more likely to get flow seperation and therefore spin out. A fin with a thicker profile but same chord length might help you out.

I'm pretty sure you cannot get cavitation on everyday freeride/slalom gear. Maybe on speedboards at Luderitz...but even then..
A spinout is just flow seperation. basically a stalled airfoil.
....on a sidenote: There is a starboard video where tiesda You says that their new cutouts reduce likelyhood of caviation....well that is the biggest bs i've ever heard. Please dont fall for cavitation arguments....its not happening on your freeride gear...

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Silberpfeil said..
In theory a fin will produce more lift (at equal speeds) in shallow water. basically the ground will sort of act like an endplate on a wing.
However because the flow is under more stress, it is more likely to get flow seperation and therefore spin out. A fin with a thicker profile but same chord length might help you out.

I'm pretty sure you cannot get cavitation on everyday freeride/slalom gear. Maybe on speedboards at Luderitz...but even then..
A spinout is just flow seperation. basically a stalled airfoil.
....on a sidenote: There is a starboard video where tiesda You says that their new cutouts reduce likelyhood of caviation....well that is the biggest bs i've ever heard. Please dont fall for cavitation arguments....its not happening on your freeride gear...

Yes, people quite often mistakenly refer to ventilation as cavitation, even Tiesda.

Most people i find do actually understand whats going on, they just call it the wrong name. Check out Lessacher fins if you want to see a fin cavitate