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Offside ski "porpoise"


rodecon
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So I have never touched or adjusted my fin from the stock settings (2011 radar vice) but I have noticed recently that on my pullout to drop at the end of the course (offside pull) that the ski tends to porpoise on the way out which is a little unnerving. If I ride the back of the ski it will stop.

 

Should I try a fin adjustment or a skier adjustment?

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@rodecon‌ if you have the ski since 2011 and you have never touch the fin chances are that the screws are stacked. Do your fin adjustments at a place where you have the Means to fix a broken bolt, not at the lake prior to skiing cause it might ruin your day.

 

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Thanks for the feedback guys, I will check my fin tonight, but I know my boots are at the stock setting.

 

One thought I had though is that I have monster feet (size 15) and I wonder if that naturally puts my weight farther forward than normal since the measurement is from the heel of the front boot? I think I might move the boots back 1 hole (radar vector bindings, prob 1/4" per hole) and see how that feels.

 

I am skiing in the morning and will report back what happens.!

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@rodecon How tall, weight, etc. What size ski? Post a video if possible? I've always thought weight along wasn't the only indicator for ski size because the taller your are the more leverage you have on your ski. Its strange how you haven't noticed this before, that why I was thinking something moved. But really most of time I've seen porpoising it was due to the skier being bent at the waist and weight back.
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So I checked my fin and stock should be D 2.505/ L 6.843/ DFT .755 and binding 29-7/8" my binding is right on spec but the fin was at 2.555/ 6.752/ .892 so the DFT was way forward. I moved it to .775 and went out for a ski this morning (free ski, no balls) and it made a big difference, much more stable on the offside pull to the wakes.

Up until this morning I have been to "scared" to try adjusting my fin...thank you for giving me the info I needed to try it!

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Normally, the first thing I look at if someone has the ski hopping around into their offside turn is the fin length. Adding length is usually the fix.

 

Your fin is way deep and short. As Deano suggests above, go to stock and see if that doesn't provide some answers.

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@gregy I am 6'-4" 190lbs on a 2011 68" radar vice. You raise a really good point about position on the ski/ bent at the waist. I have really been working on my offside stack but still struggle with breaking at the waist and I am sure that is part of the problem. Lot's of stuff to work on.....I love this sport!!!
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@rodecon‌ That was a SERIOUSLY compromised setup. It must have been a real handful. You are going to LOVE the factory setup. Good on ya for posting with this issue! Every time I hear one of these stories, I wonder how many thousands of recreational skiers are out there wrestling with perfectly good skis because of random fin placements.

 

If you're curious to know why this all lead to porpoising, here's what you had. Tiny changes to DFT (~.003") make a noticeable difference to the way the back of the ski finishes a turn. Yours was .137" forward of stock which would make the tail of the ski REALLY loose. And even though the fin is .050" too deep (also a huge deviation from the norm), the fin length was so short that the resulting fin area was significantly reduced from stock, making the tail even looser. And as if this small-fin-way-forward setup didn't want to spin out enough, the long DFT shoved the fin's leading edge .046" forward of stock despite the short FL, (which is also a LOT), so the tip would bite hard very easily. The porpoising you felt was a high frequency series of tip-bites, followed immediately by tail-swings, caught by the deep fin which flattened the ski in roll, momentarily disengaging the tip pressure, only for the cycle to repeat in rapid succession. That must have felt SO unstable! You should get a badge for bravery!

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Just wanted to report back, I did adjust my fin to stock settings and was able to ski this morning to try it out, HUGE improvement!!! Offside is very stable through the wakes and the whole offside turn is much more smooth and consistent then before, much easier to carve a smooth turn and finish with good angle, prior to the adjustment the ski would tend to "slam dunk" the offside turn.

 

I am really feeling foolish to have been so hesitant to try adjusting my fin, I should have checked/ adjusted this 3 years ago!!! If there are any ballers out there that like me, didn't own a set of calipers, and really didn't know anything about fin adjustment, learn from my mistake! Borrow or buy some calipers and check your fin, you could be skiing at a serious dis

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