I have a few boards that I love and would like to make that same board bigger or smaller. I have been sketching the boards out to scale and then drawing them a little bigger or smaller, that works but I know there is a little math I can do to find the measurement I'm looking for. For instance if I have a board that is 5'10 and has a wide point that is 23" if I made that same board at 5'8 how would I figure how wide it is?
Thanks for all your help
Jesse
I almost forgot, If I change the scale of a board how would I draw it up using the same the template from the original board. I know it will not fit just right, I'm guessing that I burn/stretch a little at the nose, wide point, and tail to get the best fit.
Thanks agian
Jesse
Greg Loehr uses this cool tid bit; for every inch of length, change the width by 1/8 inch…
Divide length by width. This will give you the ratio: 3,0434782.
Divide the new length by this ratio and what you get is: 22,34".
You can do the same at different points: nose width, tail width…
Scaling is a bitch with surfboards.
Surfboard length is almost independent of width, that is maximum
width really doesn’t change much over the full spectrum of boards.
This is partially due to dynamics, or the maintaining an optimum
amount of planing surface. So you have this constraint – a
conservation of surface area, but its a little more complicated in that the constraint also involves this ability to present the surface area in a way that is conducive to surfing.
Here's a solution which I don't recommend. Chainsaw off an inch off the nose, seal it and surf it. Then do it again. If the board still works. Sketch in some new forward rails so they meet at a point... and presto, you've got you're 5'8”.
The point being that surfboard real estate is not all functionally equal, so simply scaling doesn't really work.
Actually, here's a neat way to look at it.
When you're surfing you're constantly scaling, that is the act of maintaining position or pulling off some maneuver is an act of scaling itself.
A picture might help.
As you can see it's all about the wetted area. So what are you scaling when you scale? For example , changing nothing else, that is same conditions and surfer, if you scale, you'll still need the same amount of wet area. So by simply scaling you'll literally change those characteristics that made the original so appealing to begin with -i.e. the way you were able to dynamically present surface area to the wave. All that, and then there are rails, contours etc. to be scaled.
Scaling is a bitch... than again, maybe it's just an opportunity to get creative - given you want to change the length, the questions then becomes, what do you want to conserve and then how to do it?
kc
ps
One more picture. Though it's hard to think of it in these terms, surfboard design can be viewed as starting at the tail end and moving forward. (I'm sure that's going to upset a few.)
… ah, what the hell,... a little more on scaling.
Your position/stance/posture on the board (at any given moment) is a function of conditions, planing area and, what you're immediate objectives are -i.e. are you attempting to pull off some maneuver, etc. So if you scale the planing area, your position/stance/posture stands to change. Or, putting it another way, you'll wind of surfing a different board for a given (same) set of conditions, which means position/stance/posture will change, which is likely to impact overall technique.
This is obviously also true for rails and contours, the optimum functioning of both of which are depend on position/stance/posture. So shrink your board and shrink where your hard rail begins or ends?... shrink where your contours begin?...shrink the rocker etc. relationships?
And that still leaves volume distribution unaddressed... scaling is a bitch.
Closing note
I wouldn't attribute such motives to you, but its my sense that people who seek to scale boards either way, up or down, have usually formed some sort of attachment to the “art” as opposed to the “functional” aspect of surfboards... really, they can be truly beautiful things out of the water - the "art" attachment is completely understandable.
In summary, I guess I just don't believe that a simple, or even some sort of hegded or otherwise formula scaling is possible, especially when it comes to shortboards. With longboards you may or may not be able to sneak in or remove an inch or so, it will depend on what your starting with, but even then ...
Hi KCasey -
That's a very interesting composite of the blanks. I saved it. Thanks. I think it's true that most boards are in the 14" tail width range with 3"+/- tail rocker. Assuming most shortboards have about 5" nose rocker, I wonder how the front profiles of the shortboard blanks might stack up?
Guilhem's direct proportioning method works to a point (very wide but accurate curve if lengthening by much.) Greg Loehr's formulaic scaling method changes the curve.
With those issues in mind, it's about as close if you just eyeball it with a spin template. For moderate 'scaling', eyeballing a spin template allows you to skip the math (Yeah!)
By extending the length of the template as you make it by several inches and tapering the outline curves inward where each end approximates center, you can easily shift things around and probably get what you want by eyeballing.
I.E. a few inches longer? Just spread the end points to desired length and bump the wide point out a tad. Shorter? Place your end points and shift the template in a tad.
Blank selection to approximate rocker and foil of the smaller/larger boards might save you some work too. That blank composite diagram really tells the story there.
The composite is mesmerizing…
…on lofting
I understand. However, using a spin template just preserves a curve or curves, it’s not scaling in the formal sense - that is, you’re not changing the parameters that define the curve, you’re just using a smaller or larger section of a curve(s). If that’s what surf_guru was after… I misunderstood (… something which seems to be happening more and more lately.)
Anyway, yeah, you’re approach (lofting) is generally the way to go, but you still have to address the dynamics, and I don’t mean by Math, e.g. changes in rail, rocker, etc. - and its all a personal call.
…back to composite studies
By the way, I started one of my ‘going nowhere fast threads’ a while back on the way surface area is developed starting at the tail, for each of the classes of surfboards (from fish to guns) based on this kind of data collection. The curves followed by all where pretty similar, the big difference was where they started.
kc
You guys are giving me a head ache.
…just go get some wax and go surfing.
… add some waves and light off-shores and the forum is yours.
kc
At the risk of waking the dead
…. some more nonsense on scaling and its application in design.
There
is a kind of (partial?) scaling which has obviously had some success – wings,
bumps or stingers, whatever you like to call them. The designer isn’t
exactly constrained to maintain the same template curve, prior and
post wing – but it’s often roughly the case.
Though such an experiment is unlikely, the one roughed out in the (over-simplified) illustration, at least begins to address some of the changes you might expect by simply application of the idea.
Here [in the illustration], the assumption is that if the only thing that changes is the tail area (which includes its length), but 'plane-shape' is conserved.
Dynamically. the net result being that the rider is going to be pushed to move little forward, if not in position than at least in posture. Obviously, the consequences of reducing the tail area is going to impact the bottom presentation characteristics -i.e. when turning etc. (And by the way, the designer need not even reduce the length, nor maintain plane-shape as in the illustration. I've just made the assumption here that it does for the sake of illustration.)
I think wings definitely have there role. You can ride smaller mushy conditions or sections with the same board by shifting you're stance/posture forward, less than if you did not have wings. But it's no fish, for exactly the same reasons – moving forward and change of stance/posture, which results in a different bottom presentation when turning etc.. But that's just one aspect of the application – it's all trade-offs.
So maybe in its purest form, this is a kind of partial scaling, if only a simple geometric one.
kc
ps
By the way, I could be wrong, but didn't Slater do almost the reverse on his latest 'magic' board. He took a the tail end of some fun shape or something and just stuck another the nose on it. See my intial post, it's that 'start chopping at the nose and when you've chopped enough just re-draw to connect' approach - which, and I can't believe I'm alone, is an approach that's been around for a while. Not to be confused with chopping the tail off like they did to all those poor longboards back in the 60's... a dark and perilous time for longboards... though I have to admit, I did enjoyed seeing the occasional Dextra get chopped.
... and for a real treat see my Adjustable Bottom Area Concept thread (... mind you I don't know where all the illustrations went, but some are still there in the archives.)
…hello,
the method of cut nose and tail to obtain a new smaller board doesn t work
you ll obtain the same board but worst
Doesn’t work?
You’ll wind up with something, but whether or not it works will depend on what you’re after. In a way, it’s done all the time. In part that what’s suggested by the composite image in my initial post in this thread. Admittedly, there are other aspects like a board’s balance - the feel of the board when you swing it around, etc. but there’s a lot of plug-in and play when it comes to tail sections. This is not scaling proper, but it is an attempt to conserve something functional, which as I wrote, I don’t believe is completely possible just from simple (geometric) scaling.
kc