SUP fin on a modern longboard. Kook or not kook?

[noformalites]

So I recently transitioned to my first glass top long board, reduced 20L, and 2+1 fin set up to a single fin.
HOWEVER, when paddling the tail of my board has been feeling very squirrelly despite having placed the fin at the very end of the slot for more stability.

I considered the FCS 2 fatboy, but instead I did something radical and bought a SUP fin from Danny Ching.
Kook or not kook?

[dtc]

Squirrely when paddling? Or when surfing?

SUP fins are slightly different to surfboard fins, as SUP has more emphasis on stability at slow speeds (standing), whereas surfboards only require stability at faster speeds (actually on the wave). But different fins work for different people - if what you buy works for you, then it works and who cares what it is designed for or what it looks like

[noformalites]

Squirrelly when paddling prone, having my knees bended with my toes pointed towards the sky helps a bit

[waikikikichan]

I considered the FCS 2 fatboy, but instead I did something radical and bought a SUP fin from Danny Ching.
Kook or not kook?

KOOK. Throwing money at a problem, when you do not know the true cause of the problem.

The Danny Ching fin in Orange has a huge base. The black hatchet fins on the left will be hard enough to turn for a beginner.

Why don't you try putting the fin in the middle of the box ( which you should always do with a new fin and then adjust back or front ) and see how it goes ?

[dtc]

If its squirrelly when paddling, that’s sort of odd. People can paddle a finless board. If anything you need more weight on the fins/rear to engage the fin, but lifting your legs is the complete opposite to that.

Do you mean side to side balance, or the board won’t go in a straight line when you are paddling? Either way it doesn’t sound like the fin is to blame

[noformalites]

It does feel very odd, I don't think it's my balance? I'm in appropriate position on the board when paddling, but the tail feels like its tipping side to side.

[noformalites]

I considered the FCS 2 fatboy, but instead I did something radical and bought a SUP fin from Danny Ching.
Kook or not kook?

KOOK. Throwing money at a problem, when you do not know the true cause of the problem.

Screenshot 2020-11-15 at 1.45.59 PM.png

The Danny Ching fin in Orange has a huge base. The black hatchet fins on the left will be hard enough to turn for a beginner.

Why don't you try putting the fin in the middle of the box ( which you should always do with a new fin and then adjust back or front ) and see how it goes ?

It totally slipped my mind, but do you think it can do with riding a round tail versus a square tail? Would this make a significant difference?

[jaffa1949]

I would suggest you look at your paddle stroke and leg positioning.
If you paddle with your arm movements splaying out from the board instead of straight down beside the rails each stroke will pull you sideways and down on that side and alternately with your legs in the air you reinforce the wobble as your legs try to act as a counter pendulum.
Put your feet down, together on the board , not splayed to the side as attempted outrigger ( a very unsuccessful but common mistake).

[waikikikichan]

It totally slipped my mind, but do you think it can do with riding a round tail versus a square tail? Would this make a significant difference?

I was going to ask you about that, but glad you got to thinking about what might be the cause of the problem. Yes, it could be the tail but more so the thickness of the hard board tail compared to the boxy rails on your previous board which I assume was a sponge board (?)

Can you post a photo of your current board included how you have the fin installed.

[noformalites]

This is the fin that came along with the board (Paragon nose rider 8") Thanks a lot for your help! I have a hard time flushing the fin to the box!

[waikikikichan]

Could you measure the fin’s height from the bottom of the board to the highest point on the fin vertically. Doesn’t seem to be an 8” fin.

Your sponge board was a round tail 2+1 fin setup ?

[noformalites]

ごめんなさい, the more I talk with you the more I feel like a kook. The danny ching I bought was a 9" (in transit), I know the general rule is if you have an 8" board, you get an 8" fin, but I just did it anyways. Yup! I transitioned from a 2+1 setup soft top/ round tailed to a squash/square tail. If I measured correctly, from the bottom of the board to the top of the fin vertically, it is 9". Did you mean bottom of the board e.g., the tile floor? or just the dorsal side of the board?

[waikikikichan]

Measure from the base of the fin to the highest point of the fin ( which the trailing tip may not be the highest point ). The base does not include the part that down inside of the center box, just from the surface of the board.

[noformalites]

It's a 9" fin. Is that excessive?

[waikikikichan]

It's a 9" fin. Is that excessive?

All the way back in the box it is.

[noformalites]

Where would it be ideal?

[waikikikichan]

Line up the slot of the fin box with the center of the base of the fin. If it feels "too stiff" when you are riding the wave, move it FORWARD 1 cm at a time until it feels okay. If it feels "too loose" when you are riding the wave, move it BACK 1 cm at a time until it feels okay.

( this is not adjusting the fin for paddling, but actually when you are standing up and surfing the wave )

[dtc]

As to the paddling I think jaffa is right. You are paddling in an unbalanced way, probably swinging your feet (when they are flat) over to the side you are paddling as you pull back. Maybe for some extra effort or whatever. Or, I suspect, your hand is way too wide/far from the board. So you pull your legs over to make the stroke a bit easier and maintain balance

When you lift your feet, you are maintaining your balance through a counter balance (feet going the opposite direction), so your body is much more static

So it’s your body/legs that is causing the swaying back and forth. At a guess for a solution, try to paddle with your hands much closer to the board, elbows bent, hands come down right alongside the rails