fitzgerald : the drifta - hocker : concaves and fin boxes, 1981
Fitzgerald: Drifita III
||Rod Hocker: Concaves -They're Functional||Rod Hocker: Fin Boxes- Fine Tuning Surfboards|
By mid-1981, the Mark VI saw the
rail-fins removed, the centre fin box featuring an upright blade
See Surfer, Volume 22 Number 6 page 9, below.
HB 5'9" MK III HB 6'2" MK III
Putting together any new surfboard trip,
people naturally are very critical especially if you are
sacrificing personal performance in the short term for long
term overall development.
Going backwards in your personal surfing to eventually go forward in both boards and surfing, and understanding the value of going to extremes to find a medium value is difficult.
The results to date with Drlfta development have more than justified the bullshit that has floated around.
Thanks Steve, Nick, Barry, Linda, Greenie and the customers.
There's more to come.
Drifta Mk III (Tri-fin)
Centre fin: 7.5 x 4.5 b @ 4.5 inches (estimation), laminated fibreglass.
Rail fins: 2 x 2.5 b @ 8.5 inches (estimation), laminated fibreglass.
Design by Terry Fitzgerald, Hot Buttered Surfboards, Brookvale.
Note that the Drifta Mk3 rail fins are flat on the outside and foiled on the inside, reversing the common design.
Terry was a smart guy (he went to university) and he did his homework- "technically," this should be the correct foil template for rail fins.
HB MK III - VI - VII - 8 Drifta Models, June 1981.
point to consider about channels is that they are
derived from power boat planing hulls.
I'll leave the above paragraph open for debate by the general public or advocates of channel bottoms; so write in with opinions, but please be concise.
Now to get to the theme of this article.
The new breed of concave, that is, a full nose to tail concave, does not track due to flat planes running along the rails.
These planes give the flat bottom feel.
They increase trim speed due to their ability to sit higher in the wave face, just like a fine pintail.
Another advantage is that wider tails can be used for manoeuvrability but still have loads of top speed because they can sit higher in a given wave.
They are faster on takeoff due to hyro-planing action.
Because of their natural ability to hold or compress water they give more drive through turns in any wave conditions.
The same applies on takeoff, you can set your rail a lot earlier because of the excellent rail hold due to concave through tail.
After eight years of development in trying to obtain the same basic flat bottom surfing characteristics, I have finally developed the present day contours which allow flat bottom performance along with the added extras mentioned above.
The bottom shape I have developed is completely functional in all aspects from production to surfing.
All the bugs have been ironed out and the concept suits any outline, twin or single.
Of course you can vary any or all of the integral planes to derive any response you want.
For larger surf set the fin closer to the tail, which increases hold and to a degree eliminates spinouts, when one is powering into a bottom turn on an eight foot wave.
Move the fin further forward to lift the tail so turns are looser in the small stuff.
Cutbacks are easier and an increase in trim speed is noticeable.
Ever had the hassle of your new rocket sticking in the top of a wave?
Fin box is the answer, move your fin slightly forward till you find out where you like it for your style and conditions.
Soon you will pull up at your favourite break, check out conditions, adjust your fin and go out and carve it without the hassle of feeling too stiff or loose.
So what does it all mean?
Instead of you adjusting yourself to the way your new board wants to go you can (within reason) — make your new board perform the way you want it to.
I personally feel that twins or singles without boxes are too limited in functions.
Australian Unorthodox : The Religion of Oz Design
Dougal Walker : The Tri-Fin - Did God Mean It To Be?
Terry Fiztgerald : Drifta III
Rod Hocker : Conaves and Fin Boxes
Geoff McCoy: Design
Mitchell Rae: Tails
Phil Byrne: Clinker Bottoms
Col Smith: Conaves