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Quad vs Thruster same board same day

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Created by damandan Two weeks ago, 1 Sep 2021
damandan
3 posts
1 Sep 2021 9:10AM
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Hi Everyone. Brand new to the forum! I've been SUP surfing for 15 years, live in Cocoa Beach, FL USA and recently got into shaping some of my own boards. I love SUP surfing and everything about it. One this that has really captured my attention recently is quad vs thruster on the same board same day.

I always seem to prefer thruster setup but I keep wanting to find that magic quad setup that fits my surfing style. With the thrusters I can point and shoot down the wave and I love to pump the board. I lose a lot of that with the quads. In the past I've had a huge problem with quads sliding out on my when doing a bottom turn. This setup holds but I still cannot push it hard like a thruster it just doesn't go. The other issue I've had in the past is locking up with lots of speed. If I'm flying down the line it gets really difficult to initiate a turn with the quad setup. Thruster is really free and allows me to turn whenever I want as hard as I want.

Just looking for some fin suggestions as I'm using the standard G5 template fins in the front and 3.5" trailer fins for the quad. And a standard G5 center for the thruster. As well as potentially some fin placement suggestions, did I put them in a bad spot?

Here are the technical specs for anyone interested in where my fin boxes are located. I'm no quad expert I just put the rear fin boxes a little closer to the center and further back, because the boards I have that have the rear quad boxes forward and close to the rail, I do no like at all.

Board Dimensions are 8' x 27 x 4.2 - 92 liters
Fin box placement (measurements off the tail of the board)
Front 15.5"
Rear 7.5"
Center box 3.5"
Run center fin at 7" loose / 6" stiff (it's at 7" in the video inline with the rear quads)
12" off the tail 16" wide

I have an image and a video but I cannot share it since I'm new. Maybe I can reply later with the image/video.

colas
4345 posts
1 Sep 2021 3:22PM
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First, switch to Quobba fins. A lot of your fin troubles will be solved instantly: a Quobba thruster setup is as fast as a normal quad setup.

Second, I would recommend you use the McKee setup for quads: basically it views the quad rears as splitting a central thruster fin, it allows more control than splitting the side fins in two and putting the rears close to the rail and the front fins.

www.mckeesurf.com/?page_id=267

And for quad setup, use 50/50 (symmetrical) fins in the rear, it will give you a smoother rail-to-rail and less tracking, and a bit of the control of a thruster.
I use 80/20 on my small wave board for maximum speed generation (Quobba M Sides), 50/50 otherwise for smoother ail to rail (Quobba M centers).

damandan
3 posts
2 Sep 2021 9:41AM
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Thanks for the reply Colas. I did try to go with more of a Mckee setup this round maybe tweaking the fins will help. What do the Quobba fins do? I've never heard or seen anything like what they've got there. Is it a difference you notice?

colas
4345 posts
2 Sep 2021 12:49PM
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Select to expand quote
damandan said..
What do the Quobba fins do? I've never heard or seen anything like what they've got there. Is it a difference you notice?




A huge difference. Going to normal fins after them is like having weeds stuck in your fins. I use them on all my boards since I discovered them.
Last week I swapped boards with a guy who wanted to test my board, in waist high waves. He had a board I had, so I knew it well... and I could not make anymore the sections I was easily blasting through minutes ago... He had normal (FCS Performer) fins...

Basically, Quobba realized that most of the fin drag happens at the base, at the board/fin junction.
So they designed a fin that created vortices around the fin base that help water low around the fin, avoiding the pressure building up at speed in front of the fin which adds drag and decrease hold.

See their topic: www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/Quobba-Fins-?

Kovert
92 posts
3 Sep 2021 2:26AM
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McKee set up never felt right under foot to me, current placement feels good on Smik spitfire V2 with Shapers ML quad set. Always prefer fins on the larger side as I like to push hard and not nurse turns. I never go smaller than 4.65" for front fins or 4" for rears, works for me!

Yet to try quobba but a board will work well without a very specific fin! Better off dialing placement first then having a real gauge on any performance difference. I have a set of AU fins to try before exploring quobba, can never have too many!

Shaped a couple myself enjoy the journey!

Tardy
4104 posts
3 Sep 2021 11:35AM
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welcome to the forum damandan, not every board surfs well with quads ,some suit the thruster set better ...
I use both ,but with my wider board I prefer quads ,and narrower board thruster ...so don't be disheartened by liking one or the other .
hope to see your video ,first you have to load it to youtube then copy then paste the link then it just magically appears .You can't post videos straight to seabreeze ...one day maybe ..it would be easier ...

colas
4345 posts
3 Sep 2021 1:50PM
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Select to expand quote
Kovert said..
I have a set of AU fins to try before exploring quobba, can never have too many!


Ah, interesting, I did not know them, but they seem to aim at the same thing as the quobba: generate a vortex near the board to reduce drag.

pro: they have a screw-less FCSII compatible system

con: they do not offer any solution for centre fins efficiency



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"Quad vs Thruster same board same day" started by damandan