Had a 'bit-too-big' fin on last weekend and as soon as I was overpowered, the board lifted and tail-walked...which is a fair effort seeing as I'm 105kgs!

I'm not 100% sure why, but I know that if I use the right fin, with the right size sail, in the right conditions...It feels awesome! Wrong size fin and it ruins the experience...

eckas, trust me, you will know when your over finned you will know in a few seconds.
The first symptom is that your on the edge of "out of control, and cant get "downwind" (home), board tail walking and all sorts of problems. Your pushing hard out on the back hand trying to take the drive off the sail, and its still driving upwind and all your thinking is "I wana get back to start point..... now)
Example, was last weekend, I ran a 6.2 Hellcat in a good Westerly down at Bunbury, with a 33 Choco weed fin. When it all went pear shaped, I could have dropped board size down from the 110 to a 91, but was too buggered to change over, so went for a 28 weed fin, and regained some level of control for rest of session. You can drop sail size, but if your experimenting try the smaller fin first.
Mineral

crazyjockey said...

You'll realise you're over-finned when you get moving and all of a sudden the board tries to jump out of the water and attack you.

Exactly, no need to know more.

Sailhack said...

Had a 'bit-too-big' fin on last weekend and as soon as I was overpowered, the board lifted and tail-walked...which is a fair effort seeing as I'm 105kgs!

I'm not 100% sure why, but I know that if I use the right fin, with the right size sail, in the right conditions...It feels awesome! Wrong size fin and it ruins the experience...

You don't have to ask about it. You will know when you are over-finned and quite happy to make it back to the launch in one piece. Usually people pick the right fin for normal sailing conditions so they experience the symptoms of being over-finned when they are over-powered. However, some times they pick the wrong fin for the board and blame the symptoms on the board not the fin. In those cases, it's not so obvious that you have the wrong size fin as the symptoms are mild.
However, now that I have experienced tail-walking and railing up on two different occasions, I was wondering why one and not the other. I figure tail-walking is a fin-sail mismatch while railing up is a fin-board mismatch, but it also has something to do with where the footstraps are located. If they are out on the rail, you can counteract the railing up and force tailwalking. In those cases, the board must be rather wide and the tailwalking rather horrible.

so .. useing my 21wave fin on a 75lwave .. would i need a smaller or larger fin as my sails are 5m/4.2m/ 3.7m .. would u 21 suit the 5m and buy a smaller fin for the 3.3m or is it the other way around ??

nick0 said...

so .. useing my 21wave fin on a 75lwave .. would i need a smaller or larger fin as my sails are 5m/4.2m/ 3.7m .. would u 21 suit the 5m and buy a smaller fin for the 3.3m or is it the other way around ??

Generally, larger sail, larger fin. BUT, changing from a larger fin to a smaller one can feel like changing down a sail size and can turn an overpowered set-up into something sweet. I guess it's basically adjusting and matching the lift you get from the water (fin) vs the lift from the air (sail) to get a controllable balance.

I'd guess that a 21cm fin would be a bit small for a 5.0, but probably OK for the 4.2 or 3.7, but there's plenty of factors that go into deciding what is appropriate.