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Upright fin drive

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Created by surfmore 28 days ago, 12 Jul 2022
surfmore
25 posts
12 Jul 2022 1:11AM
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does a more up right fin have less drive compared to a more raked fin?

I know a more up right fin is more pivoty by was wondering about drive.

Hoppo3228
VIC, 598 posts
12 Jul 2022 1:58PM
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More to do with fin base. Simply put, the larger the base, the more drive. See C-Drives as an example.

Also read up here: www.boardcave.com.au/the-surfers-corner/the-surfboard-fin-guide

colas
4589 posts
12 Jul 2022 2:37PM
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An example of upright fins with no rake, the fins made by Cheyne Horan:

www.cheynehoran.com.au/fins/



(I used the starfin as a single fin, but alas never tried my EZ3 thruster set, as I had discovered the Quobba and had no motivation anymore to test non-Quobba fins. Plus my EZ3 set was in an awful soft plastic)

Compared to a raked fin:
- they will be more efficient: the raked tip has a long surface, which is hard to foil properly, hence lots of friction and more fin is in a turbulent wake.
- they will engage in the turn more suddenly and frankly
- at the end of the turn, they can feel twitchy, as they lack the "damping" of the raked part that kind of prevent a sudden stall, transitions are more progressive. This was a drawback of the famous "spitfire" fighter places in WWII by the way. This is why they can feel lacking drive: this "twitchyness" can make you oversteer or stall at the end of the turn, killing your speed.
- when you push on them during the turn, their center of resistance is closer to the board (less torque on the ankle) and stays forward. A lot of people like to feel they can leverage on the raked part

My opinion is that they are quite unique - and tricky - to ride as single or twin fins, but the "twichyness" is countered when used as thrusters or quads. The rear fins act as "stabilisers", replacing the role of the rake. This is why you see some quad sets having no rake on the rear fins, what is called a "controller" setup. The rake on the front fin gives you the traditional positive feel underfoot to push on, while the rear fins let the tail loose to make the board more lively.
So, basically, single of twin upright fins not so much lack drive than can feel unpredictable in hairy situations.

I even cut out the raked part of my rear Quobba fins to end up with the best quad setup I ever had: my tail is then so much looser that I can easily put the board on the rail with no latency:

supthecreek
2371 posts
13 Jul 2022 5:24AM
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Select to expand quote
colas said..
An example of upright fins with no rake, the fins made by Cheyne Horan:

www.cheynehoran.com.au/fins/



(I used the starfin as a single fin, but alas never tried my EZ3 thruster set, as I had discovered the Quobba and had no motivation anymore to test non-Quobba fins. Plus my EZ3 set was in an awful soft plastic)

Compared to a raked fin:
- they will be more efficient: the raked tip has a long surface, which is hard to foil properly, hence lots of friction and more fin is in a turbulent wake.
- they will engage in the turn more suddenly and frankly
- at the end of the turn, they can feel twitchy, as they lack the "damping" of the raked part that kind of prevent a sudden stall, transitions are more progressive. This was a drawback of the famous "spitfire" fighter places in WWII by the way. This is why they can feel lacking drive: this "twitchyness" can make you oversteer or stall at the end of the turn, killing your speed.
- when you push on them during the turn, their center of resistance is closer to the board (less torque on the ankle) and stays forward. A lot of people like to feel they can leverage on the raked part

My opinion is that they are quite unique - and tricky - to ride as single or twin fins, but the "twichyness" is countered when used as thrusters or quads. The rear fins act as "stabilisers", replacing the role of the rake. This is why you see some quad sets having no rake on the rear fins, what is called a "controller" setup. The rake on the front fin gives you the traditional positive feel underfoot to push on, while the rear fins let the tail loose to make the board more lively.
So, basically, single of twin upright fins not so much lack drive than can feel unpredictable in hairy situations.

I even cut out the raked part of my rear Quobba fins to end up with the best quad setup I ever had: my tail is then so much looser that I can easily put the board on the rail with no latency:



Thanks for this clear explanation colas!
I don't know squat about fins and why they do what they do,
but... I know what I like, and this helps me understand why I like certain set-ups.

I finally got my Quobba set while I was in Florida, but couldn't really feel the magic until I got home and got waves where I could feel the fins more.

My video on the 8'8 SP25, I was using the Quobba's and the board blew me away.... on my 8'9 Kanga the day before, I used a standard set of fins because the Quobba's didn't slip in the fin box easily and I was in a hurry.
The standard fins I used let me down.
I will have to retest the 8'9 Kanga with the Quobba's.

Bottom line... after the session with the Quobba's, I am super stoked with these fins!!
Thanks for your help in getting them!!

DavidJohn
VIC, 17009 posts
13 Jul 2022 8:54AM
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It's my opinion that fins with drive work in conjunction with the rail of the board to allow you to drive the board through a turn without and drift or slip..

Many more upright fins tend to steer the board through a turn and sometimes work against what the board shape or rails wants to do regardless of how much base area there is on the fin..

It's tricky stuff..

colas
4589 posts
13 Jul 2022 3:24PM
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Select to expand quote
supthecreek said..

I finally got my Quobba set while I was in Florida, but couldn't really feel the magic until I got home and got waves where I could feel the fins more.



Cool!
It is true that you don't feel the "Quobba effect" in slow waves... but once you have experienced it, you are hooked!

surfmore
25 posts
14 Jul 2022 2:14AM
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where can you get Quobba fins, I'm curious.

theSeb
35 posts
14 Jul 2022 3:38AM
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Select to expand quote
surfmore said..
where can you get Quobba fins, I'm curious.


Direct from their website. They ship all over.

colas
4589 posts
14 Jul 2022 4:25AM
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Select to expand quote
surfmore said..
where can you get Quobba fins, I'm curious.


All details in www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/Quobba-Fins-?

And quobbafins.com/

PS: unlike what they say on their site, their design has nothing to do with foiling. It creates vortexes along the base of the fin, allowing water to move with less resistance (and the fin in the water), a bit like you can empty a bottle faster by creating a vortex.

colas
4589 posts
16 Jul 2022 4:00PM
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With all this talk on getting rid of the rake, I took my sander to make "finger" front fins out of a pair of Quobba L



A bit like the MUF - Maui Ultra Fins - template:



And... it works quite well in small waves! More speed (less drag), more looseness (instant response), but the magic Quobba base still provide hold and drive...

colas
4589 posts
18 Jul 2022 4:35PM
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After 3 tiny waves sessions, with the last one being hip high max but hollow and punchy (12s period), I definitely like this setup.
Noticeably less drag at low speeds, and a more immediate response. Faster and more playful.
A keeper for my small wave board.

No feeling of lost hold. I still have more hold than with normal M (orange) Quobbas.
The only drawback I saw is when the wind grew stronger, creating some chop, the board became a bit twitchy and less controllable in turns. It was to be expected since I basically went the opposite route of S-Wing fins(*) that act as shock absorbers in chop.


(*)

MangoDingo
NT, 833 posts
18 Jul 2022 10:22PM
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Select to expand quote
colas said..
. the opposite route of S-Wing fins(*) that act as shock absorbers in chop.


(*)



* @Bighugg, @Finsup - (cough) - you blokes across this?

Bighugg
NT, 463 posts
19 Jul 2022 7:33PM
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Select to expand quote
MangoDingo said..

colas said..
. the opposite route of S-Wing fins(*) that act as shock absorbers in chop.


(*)




* @Bighugg, @Finsup - (cough) - you blokes across this?


Yep.. unfortunately this trip I left my S-Wings in Alice in lieu of another Hanalei 5 fin set

colas
4589 posts
20 Jul 2022 1:27PM
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Another interesting info: A French Windsurfing fin manufacturer has a line of fins available either in raked or upright templates:





They describe the difference as: u-ride.net/actualite/matos-nouveautes-erd-fins.html (in French)

"The tests and the development carried out by Vincent show that the upright sets are much less versatile than the set with classic rakes but the upright are very suitable for onshore type spots like La Bergerie or Pozo where you need maximum speed and drive ["impulsion", in this context was when you push on the fin to get max acceleration for a jump] but without too much grip in the surf."

In a nutshell: upright = faster, looser, less control.

that guy
69 posts
25 Jul 2022 12:50PM
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drive comes from area. upright ( rake) has nothing to do with drive (except how it is applied but that is another question) and is about hook and pivot .

colas
4589 posts
Saturday , 6 Aug 2022 5:32PM
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On the subject of fins, at least I stumbled upon a well-written article.
Most of the posts about fin just regurgitates things they have read on the internet.
This one is the only one where the author seems to known what he is talking about, and has actually tried fins such as EZ3 and C-Drive.

www.swellnet.com/news/design-outline/2021/09/01/parting-the-water-part-1-fin-placement
www.swellnet.com/news/design-outline/2021/09/20/parting-the-water-part-2-fin-shape



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"Upright fin drive" started by surfmore