TaylorO said… "Puts the ‘Drive’ component closer to the board where the Drive is more effective.
Is this assertion based on the structural/physical interaction of the fin base and the bottom of the board? "
Yes, I’m sure it’s the combination of the board and fin base creating the most effective setup to create drive.
It’s about effective area.
All these fins have about the same area. Area on its own doesn’t create drive, there’s more than just quantity, there’s also the quality or positioning of the area to get the right performance.
In the spirit of experimentation I’ve asked Ben Chipper to make a set of these MIDI fins where the drive area usually at the tip is now in the middle of the fin. Similar leading edge curve and base length as a AM2/G2 but the area is redistributed.
Just one is how much pressure needs to be applied to move it to the side in a turn .
This is determined by the width .
This fin pictured has a width that grows at the bottom ,moving reward , very wide -
Then radically narrows - moving forward
The amount of pressure to turn - move the base and mid section will completey overide what that upper section requires - rendering it useless in function .
Widest width tappering to the tip as it moves up and back making the most efficient use of all its area working as one .
Maurice just posted a pic of Noah Johnston on his 10’6" at jaws with C-5 fins , I must be incorrect ;-)
Imagine which template as a single fin would work best at Pipe , Lanis ,Backyards , Log Cabins and Sunset to name a few .
Greg, I wasn’t sure if this above comment was about my fin shape or not. Check these four pics that shows the width of the bottom half of the fin doesn’t vary by more than around 1/8 in. And it’s maximum width is exactly the same as a G2 base. So the base width doesn’t grow at all nor get any wider than a standard fin base, not over sized at all and it has the same height and area.
The top half narrows but has very similar dimensions as the G2, it’s just more of an upright shape.
the following pics were too large, here are the links to view them. They must be reduced to smaller size than computer screen to avoid problems for some users. - moderator
On your last pic , put a ruler at the bottom and slide it up
It will lengthen as well as move back into a higher pressure position .
Then reducing ( due to the leading edge angling rearward now ) as it goes to the corner at the back edge then drastically reduce in width with the back edge moving forawrd to a lower pressure position .
The fin shapes I use start with a width at the base and reduce in area ( in a very caculated manner) as that area moves up and back into the higher pressure area .
The G-2 fin starts wide , back edge moves forward narrowing radically then starts to sweep back while the area increases radically towards the tip .
Start at the base with a ruler and move it up and watch the area reduce , move forward , then move back and increase .
The pressure on this fin is all over the place .
All theory aside , how well do you think these shapes will go as a single fin ?
[ ~ + obj] to prepare the preliminary plans for (work):The engineer designed a new bridge.
to plan and fashion (clothing, etc.) in an artistic or skillful way: [ ~ + obj]:He designed a new dress for the fashion show.[no obj]:She designed for many wealthy clients.
[ usually: be + ~-ed] to develop, set up, and plan for a purpose: [ ~ + obj]:That scholarship is designed for foreign students.[ ~ + obj + to + verb]:She designed the scholarship to help foreign students.
[ ~ + obj] to form or make up in the mind; plan:The prisoner designed an intricate escape.
Indeed!
The difference is practical application VS. Internet knowedge.
Flying an F-14 is nothing like flying a hang glider.
Each has its own learning curve.
The principles are the same but the performance is not.
The same is true for surfboard and fin designs. Performances differ. Each design has its own unique learning curve and performance.
Some like longboards, some like short boards, some like flex, some like rigid.
Pilot preferences and abilities differ. Some have ability for one craft and none for another. Observations about performance are related to their own particular skill set and personal preferences (subjective).
A professional horticulturist relies on printed information, practice, skill and theory to remain on the cutting edge of fruit and vegetable production. Which tastes better? Apples, oranges or strawberries…
also … are you using a wood core , for lighter weight / quicker build ?
edit …
I don’t know if this will present on computer screens this size , brett , but I resized it to around 5" base [at the VERY maximum ! ] , x 4 "depth …
[ this is about the size I would try like to them at … I might make myself a wood core one , at some stage , with a smaller [narrower , too] ’ c drive’ bit . Or I may just make a wood core [smaller] ’ c drive ’ , as I am curious to ride a set [of 3] … ]
cheers !
ben
p.s. - YOUR green fins , pictured above , are in the post today . With ’ express post ', the lady reckoned you ‘may’ receive them by tuesday . Have FUN with them , eh ? [ thanks for letting me test ride them , by the way ! :) ]
Ben, I had a ride today on a test fin very similar to the ones you made and I think there’s too much area in the base so this next version needs to be a finer blend of the Red hi aspect fin (see pic below) and the Orange keel fin shape. The red and Orange outlines are to show that despite the unusual outline, it’s just a combination of fins.
My Double Base fin idea has nothing at all in common with the C -Drive fins which is its own unique concept. Mine is a combination of two very old fin designs with a similar base length / height as ordinary fins.
Greg asked how they’d go as a single and once I get the overall shape right I’ll work on a single fin version.
Riding all sorts of fins has shown me that fins with less area in the tip are quicker to turn while chunky tip fins are slower to react, but more stable.
And chunkier bases have better natural drive, not necessarily longer bases, but also wide , deep bases create lots of connection with the wave that naturally push the board further, longer.
Rake can create a similar push but also fattens the arc of any turn.
I now see why high aspect fins are deeper to compensate for less base and why more base gives drive but usually leads to a stiffer fin.
Passively…More base area naturally creates more resistance to the water flow, while more tip area creates resistance to board roll. Actively… When turning, more base adds drive, while more tip area creates more turn stability and turn direction because the area is stabilising the board by being further from the centre of the turn. It’s like waving a flag on a 2 foot stick Vs waving a flag on a 20 foot pole.
So the movement of even a square inch of fin area can make a board naturally faster in a passive mode and quicker to turn when the powers applied.
Almost all commercial fins have the same base length so these fins give a similar result but when you try fins with more base AREA like a Spitfire or Wavegrinder you notice the passive grip and drive is massively increased. The most effective area for drive is at the base while the most effective area for turning is at the tip.
I bought a pair of small Scarfini fins (rear quads which will serve as twin fins). They’re untested as yet, but combine a stiff carbon base and more flexible tip.
Similar principles, i.e different materials in different parts f the fin. I’m not sure how durable they’ll be though.
Some mind boggling combinations look possible with your fins. From the extremes something interesting may emerge.
Hi Bob, I’m testing all sorts of variations of the Double Base Area concept and it’s clear that (as you say) the initial extreme designs lead to more interesting advances.
Im building test fins by layering veneer and glass and the latest outine is a more refined version of the resistance Vs leverage concept.
