A highly skilled rider is able to exploit the capabilities of a given surfboard, by knowing how to tap into the energy of the wave. Positioning on the wave is everything. That said, I’ve always believed in having the most highly tuned equipment possible. You can only do what your skill, and equipment will allow you to do.
A video offered as simply a point/counterpoint to some of the very first comments in this thread and the last comment by Mr. Thrailkill.
In this discussion the assumption is of a very pre-defined type of surfing, which seems to be a limitation of many surfers to totally think outside that box and explore other options.
A clip of Derek Hynd finless at Jbay, how does this finless example play into the equation in this discussion?
http://youtu.be/3du0vEJM5yY?t=6s
“A highly skilled rider is able to exploit the capabilities of a given surfboard, by knowing how to tap into the energy of the wave.”
There are SO many areas to explore with fins that have barely been scratched. To assume the standard dolphin fin with minor chord/foil changes is the pinacle of fin evolution is leaving SO many options on the table. Things like MVGs, super low aspect ratio keels, inline fins, foils (as in hydrofoils) etc.
Just wanted to throw a wrench in things so we all realize how myopic our worldview is when it comes to surfboards and fins. We (a collective we) as surfers aren’t very willing to stray too far from the norm, but there’s validity in a lot of designs that lie WAY outside what most of us are comfortable with.
Surfmats are extremely fast down the line, yet they have no fins. Fins provide crisp directional control. They aren’t necessary for down the line speed. They do provide crisp directional control through their drag/lift. So the real point of discussion in this context should be more around what role the fin plays in directional control and how to minimize it’s losses to drag during turns. I’m curious as to chord thickness and leading edge radius in that role.
Hope that’s not too much of a tangent for this discussion.
Gotta say this problem of figuring what makes good fins reminds me of a talk I went to by an antenna design engineer. Basically he was given an antenna design problem, that to work out the “physics of it” by solving exact equations was nearly impossible due to the amount of variables involved. He basically did some random initializations of the antenna design based on some general constraints, and optimized the particular design.
He ended up with an antenna that looked ridiculous, but performed beyond expectations. I think everyone can agree the picture of the antenna I attached would not be arrived at using conventional design.
Now I am not saying make a fin that looks like that wire, but I think lawless has a pretty good point, in that we need to try some truly jacked up designs, and evolve through lots of surfing. I definitely agree equations aren’t going to get us very far in that there are so many variable in board design, that it is pointless. In particular, we have to start with a particular shape, i.e., singlefin noserider, high performance thruster, 9’ sunset gun, etc… , then from there test a series of fins and placements.
I watched that Derek Hynd video, and found another one too I originally wanted to say that fins help you draw lines that you can’t on a finless board, but he proceeds to draw way more lines then I will ever. oh well:)
That is my 0.02, and I volunteer to test anyone’s crazy fin designs:)
The Sailfish seems to maneuver well. It does not achieve its top speed of 68 mph by increasing drag – it retracts fins to reduce drag.
What are the thickness, flex and foil of its fins?
http://www.igfa.org/Images/SpeciesID_Images/sailfish_Pacific.png
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Hmmm. Retractable keels? Pressure on back foot (turning) extends them, and pressure towards front foot (down line speed) retracts them.
Derek’s riding boards with special bottoms and outlnes like the mirandon porpoise
they have the same effect as fins just less physical impact
you end us driving off the rail line versus the fin
another “style” of surfing to master
i hate those spinning 360’s though unless it’s functional
for show it just reminds me of a kid playing on a paipo at the wall in the 60’s
we are’s ice skating or are we?
Derek’s riding boards with special bottoms and outlnes like the mirandon porpoise
they have the same effect as fins just less physical impact
you end us driving off the rail line versus the fin
another “style” of surfing to master
i hate those spinning 360’s though unless it’s functional
for show it just reminds me of a kid playing on a paipo at the wall in the 60’s
we are’s ice skating or are we?
Derek’s riding boards with special bottoms and outlnes like the mirandon porpoise
they have the same effect as fins just less physical impact
you end us driving off the rail line versus the fin
another “style” of surfing to master
i hate those spinning 360’s though unless it’s functional
for show it just reminds me of a kid playing on a paipo at the wall in the 60’s
we are’s ice skating or are we?
“i hate those spinning 360’s though unless it’s functional”
That’s a pretty interesting statement. The act of surfing is inherently non-functional. It’s a selfish pursuit of personal pleasure. It serves no other functional purpose, so why should any aspect of it be constrained to a “functional” action?
This was kind of my point in my long-winded comment above, surfing has really constrained itself to a pretty tight little box of what’s considered “functional”, and anything that falls outside of that is dismissed. I think we’re all doing ourselves a disservice by limiting how far out we go on the periphery to find our sources of enjoyment. We tweak an 1/8" here, a 1/4" there and cut off a few inches and call ourselves enlightened. Talk about a Counterintuitive Concept. If you’re pushing the limits wouldn’t you want to play well outside the defined box in order to do that instead of constraining yourself to just the corners of the box?
Lord Board from Hydrodynamica on Vimeo.
Hey Stoneburner -
It’s been a while since I studied up on the physics of this, so I have question: Is the acceleration from centripital force turned into an actual increase in speed/velocity, or is it, as I’ve teased friends, when they say they like the speed they get from the sharp bottom turn on their thruster, more like g-force - I tell them they think they are going faster, becuase they feel it in their body, but actually they look like they are dumping some speed as the change direction? Then again, there’s that whip effect you get when you have an eight man skateboard catamaran, and the guy on one end hits the curb, then the guy on the other end gets whipped a lot faster towards said curve - simialr to roller derby?
this is how you surf a finless
I love this kid…
Rabbitsfoot + Ryan Burch Section - Almost Cut My Hair from Ryan Lovelace on Vimeo.
but then the crew in hawaii has been exploring the same subject for the past 3 decades
The centripetal force/centripetal acceleration concept is abstract. The source of confusion is usually the definition of velocity. Velocity has two components, speed and direction.
Speed is the change in distance an object travels over time. Direction is the path/vector the moving object follows over time (up, down, north, south, east, west, left, right, forward, backward).
Acceleration is the change in velocity over time. For an object traveling in a straight line, acceleration is the change in speed over time. For and object traveling at a constant speed, acceleration is the change in direction over time. Acceleration can be caused by changing direction, changing speed, or both; over time.
For an object traveling in a circular path at a constant speed, the direction of travel is constantly changing over time – causing acceleration.
In order to continuously change direction about the radius of a circle’s center, there must be a force pushing the object toward the center of that circle. This is centripetal force.
Force is mass times acceleration. So for centripetal force, there must be a centripetal acceleration. Centripetal force is also the product of mass times acceleration. Centripetal acceleration can be defined as a function of “velocity” and the radius of the turn – which can be proved with the math/geometry of circles and right triangles.
So, if acceleration is only a change of direction over time while traveling in a circular path, the speed remains constant (no change).
In “general,” the sensation we feel in a cutback or turn is mostly the G-Force, the apparent change in our weight.
My favorite part of surfing and riding other vehicles that lean is the hard lean turns/cutbacks and that sensation of “slingshot acceleration” coming off the bottom of that turn/cutback.
But to be accurate, the force exerted on a surfer is a combination of Gravity and Centripetal force where both speed and direction can change.
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Cut your hair. Nothings more redundant than a hipster doing the same move in the same way on every wave over and over. Thank god for fins!
Thanks Stoneburner -
I think that supports my position to some degree - I think the lay person equates the word acceleration with going faster/more speed, which clearly in not neccessarily the case.
I remember some threads years ago from someone from Great Britain, I think, working on a phd around fins, and it was serious intense stuff just to quantify one aspect of what is going on… Multiply that times the many other aspects of a boards function, and… Ha!
those stand-up boogie board videos are the best thing in this thread! thanks for posting them. it’s so cool to watch them shred finless foamers
Yes. People often think velocity is the same as speed and that acceleration is increasing speed.
Other points to consider:
Deceleration is negative acceleration. Common causes of deceleration are traveling in the opposite "direction" of gravity and drag/friction.
The direction vector has "3-dimensions (3-D)**.**"
**...**
This thread got me thinking about what performance might be missing when using a thruster rear fin which is half the thickness that it should be (as I believe all “off the shelf” rear thruster fins are). Took me a while, but I finally got this built with a 15% chord ratio and will hopefully test it in the next few weeks. I’ve also left it textured - laminated and un sanded 4oz cloth finish.
nice , Rohan !
is it paulownia ?
will you get a chance to surf it tomorrow ?
let us know how you like it , eh ?
fellow vicco ‘redboards’ commented that he ’ preferred thicker fins ', when he was looking through my collection …so , I ‘may’ have a pair for him , I think ?! 
enjoy tomorrow , eh mate ?!
cheers !
ben
is that a single or a twinny , herb ? I like the outline , I had a similar one [and colour] in 1975 , a kneeboard , that I enjoyed standing on as a 16 year old …