Author Topic: Fins: stalling and broaching  (Read 4163 times)

puget sound

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Fins: stalling and broaching
« on: September 01, 2019, 03:36:22 PM »
I'm reading old zoner threads about fins and board behavior. The terms "broach" and "stall" keep coming up, but I can't figure out what they mean in the SUP world. Or maybe I can't imagine how a fin would cause what I'm thinking. A little help?
QB Trifecta 86 (vector net)
Kenalu Mana 82
SIC RS 14 x 23
SIC Bullet V1

burchas

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Re: Fins: stalling and broaching
« Reply #1 on: September 02, 2019, 03:44:14 PM »
I'm reading old zoner threads about fins and board behavior. The terms "broach" and "stall" keep coming up, but I can't figure out what they mean in the SUP world. Or maybe I can't imagine how a fin would cause what I'm thinking. A little help?

Broach in terms of Sup usually means the same as in the boating world:
(of a ship with the wind on the quarter) veer and pitch forward because of bad steering or a sea hitting the stern, causing it to present a side to the wind and sea, lose steerage

Some Board/Fin combinations have a tendency to produce this situation. Most common in Downwind situation where there is a need to steer the board on the face of a bump. Some fins (in certain conditions) might have higher tendency to create oversteering and broach the rail of the sup and in turn flip you over. When that happens, dive in with your hands protecting your head until you are clear of danger of getting hit by the board.

As for stalling. Some Board/Fin combinations do not match due to various reasons such as fin box placement or conditions being used. When that happens you'll feel the board does not behave the way you expect it, like lost of glide, maneuverability and top speed. Look at your fin as the culprit.
- M15 15x27x4.5 https://bit.ly/2WmuEpt
- Ocean Ripple 16x25 @ 251L
- SIC Standamaran (S-16) - https://goo.gl/7myGAo
- Wide Tail 10x31x4 @ 149L
- SIC FX 12.6 2X - https://goo.gl/GOkSHT
- Red 2017 Elite 14x25
- ZRE Lightning 75
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- Kialoa Hulu 87
- QuickBlade Trifecta 86

Area 10

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Re: Fins: stalling and broaching
« Reply #2 on: September 02, 2019, 04:04:17 PM »
Put a totally humongous fin in your Bullet V1 (e.g. a 13” old school surf-type one with a base that is 7” or more wide) then go downwind in 25+ knots of very messy seas. You’ll soon find out what broach and stalling means.  :)

Then put a 10” fcs fat boy fin in the Bullet and repeat the experiment. Notice the difference.

puget sound

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Re: Fins: stalling and broaching
« Reply #3 on: September 03, 2019, 05:22:18 PM »
Thanks, guys. Good explanations.
QB Trifecta 86 (vector net)
Kenalu Mana 82
SIC RS 14 x 23
SIC Bullet V1

 


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