What size flex fin?

[Loganw]

Hi all,

I have a 7'6" Bing collector, and I want to experiment with a flex fin. I'm 5'9", 155lbs, tail width on my board is 14.5" (pintail). My main mode of transportation is a 9'8" log/10" D fin and I absolutely love it.

I have my eye on a 9" Greenough 4a flex fin. Is that too long? Help...

[saltydog]

I've wondered about single fin size for mid length boards too. As far as I can find from various forums people ride fins about 1" longer than 1" for every 1' of board rule. i.e. 8.5" fin for 7'6 board. Greenough 4a seems like a great all around fin. I have a 7' pintail egg w/ an 8" el cheapo plastic fin and not bad. Hope someone w/ more experience can jump in.

[dtc]

Old school is put the base of the fin on the stringer approx. where you plan to put it in the fin box and you should have (depending on who you listen to) 1/2 inch or 25% of the fin extending beyond the rails of the board. However, this focuses on tail width rather than length so I'm never really sure if it works.

The best way, for most people, is to just use whatever fin you have laying around and - having moved it around the fin box - decide if it works for you. If it doesn't, what is the problem (eg tracking too much, too loose, whatever) and then then adjust up or down in length or flex or rake or whatever. If it does work, then use it - who cares if its 8.5 inches on a 7ft board or 6 inches on a 7ft board.

If you don't already have a fin, I think for a 7ft board a 7 1/2 inch or an 8inch will probably be fine, just move the fin back or forward in the fin box a bit more to compensate for the length.

[Big H]

Well documented on this site, the rule of thumb/starting point for single fin is 1" for every foot of board.....9' board gets a 9" fin.............

I have a 7'8" single fin that is a rounded pin that I ride in overhead conditions....I use a 8.5" greenough 4a and it works great. I have a 7.5" 4a as well and have used it in conditions that were less powerful and it worked fine, but I like the larger size in the bigger waves I use the board in....in bigger surf is when that particular board turns on; not really special in smaller sized waves.

[saltydog]

Thanks, doc and Big H. Will play around with the fin placement first and go from there.

[dtc]

1 inch per foot works fine for longer boards but for mid lengths, say single fins under 7'6, it starts to break down a bit ie you usually want 1 inch plus a bit. So a 7ft might use a 7.5 inch fin. But obviously fun style, area and placement plus wave size and riding style can influence it

[saltydog]

Thanks, doc and Big H.

I meant dtc and Big H. Stupid autocorrect.

1 inch per foot works fine for longer boards but for mid lengths, say single fins under 7'6, it starts to break down a bit ie you usually want 1 inch plus a bit. So a 7ft might use a 7.5 inch fin. But obviously fun style, area and placement plus wave size and riding style can influence it

Single fin length for mid length boards demystified!