Forums > Stand Up Paddle Foiling

Tail shims vs mast placement

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Created by RichJam A week ago, 14 Nov 2020
RichJam
WA, 44 posts
14 Nov 2020 5:48PM
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So I'm slowly getting to the bottom of tuning a foil setup to work.
However my knowledge is letting me down. Regarding the shimming of the tail / stab does this or should this alter mast placement?

Scotty Mac
SA, 1973 posts
14 Nov 2020 10:04PM
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Kind of different as both change different characteristics I think. If the mast is too far back it feels like your having to apply back foot pressure while hanging weight over the front! The tail wing spacers give more lift, more drag/ less left less drag adjustment. Kind of true with the mast position too if it's too far back reduces lift too.

Scotty Mac
SA, 1973 posts
14 Nov 2020 10:05PM
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Get the mast position correct first then play with the tails wing angle

toppleover
QLD, 1768 posts
15 Nov 2020 6:55AM
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My way if looking at it is...
Mast position = course adjustment
Shim = fine adjustment

RichJam
WA, 44 posts
15 Nov 2020 6:49AM
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Thanks all.
Backs up what I'm doing and feeling.

tightlines
WA, 3318 posts
15 Nov 2020 10:08AM
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We are all still learning and experimenting but my take is that if you have the tail shimmed for less lift/drag you can (possibly should, not sure?) move the mast forward because you are not getting as much lift and vice versa.

By doing this, you should have more control over when you want it to lift and also make it a bit looser to turn, more pivotal.

So many variables.

toppleover
QLD, 1768 posts
15 Nov 2020 2:58PM
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I've found when I was first learning, I preferred the mast back & stab shimmed for more lift - now a few years later, I prefer the mast forward & shimmed for less lift.

Same but different - lol

airsail
QLD, 484 posts
15 Nov 2020 4:09PM
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It's a lot more noticeable on a kitefoil due to the speeds you can do but here is what I find. If you have too much front or rear foot pressure throughout the speed range, move the mast.
Stab shimming has changing effects with speed so if you get more or less pressure with speed, shim the stab accordingly. I like to keep even front foot pressure at all speeds.

Stingersup
WA, 50 posts
15 Nov 2020 3:55PM
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There's so many variables here but I'll try a brief summary on my take.

Mast position- At your normal cruising speed, for me around 20-25kph, and standing where you want to on the board, neither leg should fatigue before the other. If your back leg tires first that means you're leaning back to balance the foil, so move the mast forward, and vice versa. When that is sorted move on to shimming.

Tail shims- Now try riding faster. If you need more and more front foot pressure to keep the foil in the water as you accelerate, you need to try shimming the trailing edge of the tail down. You know you've gone too far with shimming this way when front foot pressure gets lighter with speed (not a nice feeling) or you can't catch the foil drop as you pass through a wave trough. I try to have mine set so there is a very gradual to all but nil increase in front foot pressure with speed.

As far as efficiency goes, the foil produces the least amount drag and is fastest when the tail is shimmed correctly.

Once you have the shims sorted then, as tighlines mentioned, you'll probably have to readjust your mast position.

RichJam
WA, 44 posts
15 Nov 2020 6:03PM
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Thanks all.
I have to say that the new batch of wings like the HS1250 and the NL's are totally different beasts.
What was working on a GL is no longer working on the NL. The stability or at times lack thereof requires a different mindset. These wings are fast and manoeuvrable, sometimes too fast.
After 2 months on the NL I'm slowly coming to terms with it and how to set it up. I've moved the mast back an inch and a bit and added a front shim to the tail to create more lift, tail is on bottom of fuse. This doesn't actually cause more drag or not noticeably. I'm still consistently getting speeds over 22kts. Without the shim the wing is difficult.
I am stoked with how the foil is now performing.
Rich.

Scotty Mac
SA, 1973 posts
15 Nov 2020 8:41PM
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I put my mast about 1/2 inch further forward with the NL.

RichJam
WA, 44 posts
15 Nov 2020 8:36PM
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Went that way initially but now moved back with a shim. Works awesome on a 5'2 wing board for me.

hilly
WA, 5698 posts
15 Nov 2020 9:24PM
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Select to expand quote
RichJam said..
Went that way initially but now moved back with a shim. Works awesome on a 5'2 wing board for me.


Can vouch for that. Looked good out there today got that combo dialed

Scotty Mac
SA, 1973 posts
16 Nov 2020 8:11AM
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oh yes dingle. Not so mast position critical, different with a paddle.

Stingersup
WA, 50 posts
16 Nov 2020 10:37AM
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Hey RichJam, just wondering what size nl foil and tail you're using to get to 22kts? Is that on a wave or winging or both?
I've got the nl's on my possible list of next foil to buy. Have tried the nl190 and really enjoyed riding it.

RichJam
WA, 44 posts
16 Nov 2020 5:42PM
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Select to expand quote
Stingersup said..
Hey RichJam, just wondering what size nl foil and tail you're using to get to 22kts? Is that on a wave or winging or both?
I've got the nl's on my possible list of next foil to buy. Have tried the nl190 and really enjoyed riding it.


Hi Mate,

On the 160 at present. Speed on a wave. Max speed wing assisted is closer to 20. Max so far is a shade under 27kts. I expect the NL130 to be a bit faster again. Brilliant wing just took me a while to work it out, making my own tails and changing multiple aspects at once hasn't helped me but it's getting more sorted every session.

jondrums
36 posts
17 Nov 2020 5:19AM
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I look at mast position and tail angle to be completely orthogonal factors (no relation to each other).

Dial in the tail angle based on how well the wing flies if you get your feet in the right spots - sharp turns, sweeping turns, pumping.

Once you have the tail dialed in, move the mast foward and back to match your desired foot position and weight center on take-off.



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"Tail shims vs mast placement" started by RichJam