Curves...

[Cpt.Caveman]

...on a surfboard (sorry).

I understand what each design element does in terms of outline curve, rocker curve, wide point, etc.

What I am interested to learn, is how do they all combine? I mean, does the wide-point of the outline curve have to meet up with the apex of the rocker? How does the ride change when the wide point, apex, and planshape are changed in certain ways?

Are they all independent of one another, not needing to meet up at a certain point so much?

[black duck]

Here's a good example of where wide point, rocker and outline curve marry into a deceptively subtle combination that looks like it would ride well.

tumblr_kymuni8sKy1qawtkoo1_400[1].jpg (66.2 KiB) Viewed 3316 times

[oldman]

Nice planshape, great outlines, rocker built for speed I would imagine.

Love those tight rails. Can we send that one up and down the coast for test-riding purposes.

[Natho]

Nice deep channel on that baby.

[Cpt.Caveman]

Yes, I enjoyed that a lot too, but back to the point?

[ric_vidal]

There are no rules CC, just convention if that is the right terminology.

[feraldave]

Balance is the key... Wide point forward with volume back is going to ride terrible etc. Wide point back with Volume apex in the same will be fine... Look at classic proven shapes right thru time they have a balance of all those design aspects

[dUg]

Are they all independent of one another, not needing to meet up at a certain point so much?

I have a theory on this, perhaps i even did a post on it a few years ago ( and even sent a letter to surf mag detailing it ), but here goes.

There are a load of mathematical formalae that can be used to generate curves. One of the most obvious is the good old parabolic function: y = x².

"Parabolic rails" are, in theory at least, based on this formula ( but in reality I doubt a Parabolic rail follows a perfect parabola ), but there are some other very interesting mathematical functions that generate very surfboard-like curves:

- A pursuit curve can be used to create almost any rail profile - boxy, low, neutral, pinched etc.

- A catenary can be used for rounded tails or noses on longboards, but also for foils ( rockers are often catenary curves )

- A ciscoid can be used for swallow tails, especially classic style

- A Folium traces a near perfect retro shortboard outline, with the mid point nearer the tail. The Pearls of de Sluze and Quartic functions also generate curves that will instantly make you think of plan shapes

So... if you could somehow tie all of these formulae together, it would in theory be possible to summarise an entire surfboard in terms of one, single succinct mathematical function.

I am talking everything here... rails, nose, rail, rocker, foil, outline, and tail.

If you'd like to take a look at some of these curves, have a look at http://curvebank.calstatela.edu/famouscurves/famous.htm