twin-fins-or-more-on-a-race-board/so it begins

[Larry Allison]

Larry W. Allison
40 mins ·
Since the Explanation Videos about Allison Probox Race Twins a few weeks back by Paddlesurf Warehouse started. Then the results of Allison Probox Race Twin tests verses a Single Sup Fin from Doctor Bryce Dyer, PhD in Sports Technology / Senior Lecturer at Bournemouth University confirming what alot of us already learned and experienced in the last 8 years it has been crazy in LA's world. So I thought it's time to get in depth what goes on in a Probox Race Twin World with the overwhelming calls and emails from consumers and other board brands coming into market using the Allison Probox Race Twin Concept.

Here in picture 1: I created a lay-out diagram showing what I have learned that Allison Race Twins are doing. Using a Starboard All-star as a example.

First off notice looking down over the Rail Twin Fin that the rail side of the fin which is flat runs parallel to the center fin. This is so the fin does not interfere with the water flow coming from the nose to tail. The Twin Fins also creates a water snake that gives better release over a Single Fin on a Square tail board that sticks to the water.

Now looking at the inside of the Rail Twin Fin, notice the foil (curved inside surface) front edge where the Red Arrow is pointing. The front edge of the fin is piercing the water from a small point to back 40 percent to the widest point of a Quarter Inch thickness fin tapering off for release This preforms one of the tasks of the Twin Fins in directing water flow to the center of the Board's tail.

The other major task of the Twin Fin is that it stabilizes the board wobble from rail to rail especially in Narrow Higher Volume Boards and aids in bringing the board back to center instead of throwing the paddler off the board. Which is a most common event to happen to a Paddler from a balancing Act of riding A Single Fin.

Another task of the Twin Fin is taking the pivot point out of the tail which minimizes the zig zag effect ( yawing) and aids in better tracking which translates to faster speed. Along with a easier experience in pivot turns.

Keep following as I add more information about the function of Allison Probox Race Twins.

[Larry Allison]

Larry W. Allison
5 mins via Instagram ·

Now here in Picture 2 I will explain and show you the negative effects of installing your Allison Race Twins the "WRONG" way compared to the "RIGHT" way in Picture 1.

The main thing to understand here in Picture 2 is how you see more of the inside of the Twin Fin. Along with notice the top of the Twin Fin how close it is to the rail line of the board tilted out (which is a term we call CANT). This is one of the biggest mistakes people make in understanding multiple fins being reactive.

What I mean by reactive is, looking at Picture number 1 with the Twin Fin in a Vertical position with the flat side out you hardly notice the fin in the picture. Then looking at Picture number 2 with the Twin Fins tilted (CANTED) out still with the flat side out you can clearly see alot of fin, which means water recognizes that also. Now your board feels like you are towing a Anchor.

This is also a great feature in using Probox Finsystems which allows you to set your fins in multiple tilts (CANT) to best preform in the right position by a patented interchangeable CANT insert.

In Picture 3 I will show and explain the same Probox Twin Fins in a Surfboard position which is even a more common mistake. This really kills the drive and glide of a Sup Board of any style.

[Larry Allison]

Larry W. Allison
4 mins via Instagram ·
Here in Picture 3 and final post, the Twin Fins are set the same as a Surfboard would be used with the flat side facing in.

Notice the Twin Fin is vertical but look at the front Red Arrow pointing to the leading edge of the point of the fin facing inward which becomes reactive with water that now hits the outside of the front of the fin toward the the rail. Water moving from nose to tail will hit the outside acting like you are towing a Anchor even more then the Negative feel of CANTED fin position.

Hope these 3 pictures clear up any misunderstanding of the function of Allison Probox Race Twins which are again NOT LIKE A SURFBOARD.

Please feel free to ask any questions.

[Bean]

Great explanation Larry, you are a true guru!

[Larry Allison]

Great explanation Larry, you are a true guru!

Thank you Bean,

[burchas]

Larry, have you been hired by Starboard? Everything I've seen from you recently are Starboards. At this rate, most Starboards on the west coast will be 4 fins.

[JEG]

Probably because the allstar is tippy and you the 4 fins to make it go fast and stable and did I guess that right?

[Larry Allison]

Probably because the allstar is tippy and you the 4 fins to make it go fast and stable and did I guess that right?

Yes my friend, Mahalo

[gone_foiling]

Probably because the allstar is tippy and you the 4 fins to make it go fast and stable and did I guess that right?

Allstar is not a tippy board quite the opposite. Well, unless you are 225+ on 22.5"wide - then anything will be tippy.

[Larry Allison]

Probably because the allstar is tippy and you the 4 fins to make it go fast and stable and did I guess that right?

Allstar is not a tippy board quite the opposite. Well, unless you are 225+ on 22.5"wide - then anything will be tippy.

Mostly 24.5 wide with a few 23.5 wide my friend. Mahalo