Yep.
I just draw length, New centre width, either + or - , Same widths at nose and tail.
The nose and tail widths change slightly.
I usually make templates 4" longer or shorter.
So @ 4" the width changes 1/2".
Nose and tail change naturally as I follow the same curve.
When widths were increased by 1/4" for every 2.0" of length from 72" to 78", widths ranged from 20"- 20.75" (basic math based). I got this overlay:
.
Eh,
I may joke
But in all seriousness
Just went thru this dilemma!
Stretching a template.
As sadly follows
Two build sheets and basic photos of the product.
Came down to experience and eyeball.
BTW, when I was a lad, it was numbers and battens.
Good worthy templates came at a price.
If it were simple, well just
Rejoice in the craft…
No offense intended. A template re-size is only as good as the original template, the cutting of the new template and the final template sanding.
Sometimes computers draw and print curves that I cannot draw nearly as clean or smooth.
Sometimes I let the computer make the curve, others I do not.
Scaling a board up or down is always going to be a compromise, there is no way that every feature gets scaled equally, otherwise fins and fin boxes would have to come in infinite gradations, that would be silly! Rocker, plan shape, curves, fin placement, it all gets fudged to make it work. Mathematical proportions are a starting point, and valuable. But aesthetics, common sense, intuition, and experience all have to factor in too. When I scale a board up or down, I just draw it up new from scratch, but its different if you had a customer who wanted “this specific board” but a different size. Kudos to guys like Mattwho and Barry Snyder who work this kind of magic.
double post.
There are many ways to get the job done.
I suspect you used coordinate geometry to paint that surf mural on the side of a house.
Aesthetics are as much a part of generating computer shapes as for math based and hand drawn shapes. I find all useful .
This thread is about a simple method to adjust length and/or width of a template using basic math.
Accept. Reject. It does not affect me…
Cool sounds good. Thanks Barry!
I see it is quite a while ago this thread was alive, but i was wondering if you could post the rest of the details, spesifically those about the rail and rocker outline, on Steve Lis’ original scetch?
Start on page 62 at this link:
http://www.hollowsurfboards.com/documents/38-SurfboardDesignandConstruction-ByJimKnistle1977.pdf
This thread was one of the true “nuggets” of golden information here on Swaylocks. And mucho Kudos to Mr. Stoneburner and others for their contribution. Stoneburner’s Math helped me greatly in another thread as well when I attempted to put my Spin on a “Moonbeam” that required resizing. This is where someone who has the analytical mind and can do the Math can contribute greatly to something as simple as shaping a surfboard. High regard Stoney. Lowel
Thanks for the kind words McD.
I have gleaned some technical build pearls from you as well…
abfab, thanks a lot!
Thanks very much for the link.
I am completely new to surfing and to this (shaping), but considering my history of skateboarding and snowboarding here in norway, when I friend had moved out west where there were waves, I guess I got smitten.
I work with wood, so I downloaded some templates from blendingcurves, having no real clue what I was doing in terms of surfboard design, and made two boards from local wood based on morgan surfboards youtube video on chambered wooden surfboards.
I guess I was kind of lucky that the things worked at all in the waves, but of course there are many more things for me to learn, especially about how different board features impact performance in the wave.
So, to get to the point of all this.
My friend suggested I try making a fish-type model for my next board and since I now had learned a little more about surfing and about shaping, the idea was that I wanted to make a traditional fish-model.
thanks for pointing me in the right direction, but there are a few things I think i perhaps misunderstood from the drawings or perhaps simply did wrong.
The reason why I think this is because I thought the shape I got when I plotted the numbers from the Steve Lis fish simply turned out strange.
So, in the column for the rocker table, it has a dash for ‘tail’ and then as far as I understood at 37" it is up 1/4" from flat/zero etc. Does this mean that in this rocker template the first 37" are flat? I hadn’t seen that before, and I see that more of the other rocker outlines have the same, quite a long flat section at the towards the tail, is this correct?
Secondly, when I plotted in all the numbers, and drew the line, all the way up at the nose the curve didn’t simply seem to flatten out, but to almost slope downwards again, and I couldn’t work this out to be correct. At 63" it says gives a lift of 3" and at ‘nose’ which at 5’ 5" should be 66" according to my calculation (another challenge is that I am not so familiar with feet and inches as all building work in norway is done in meters, centimeters, and millimiters, so I have to convert all numbers to double check). When I plot these numbers down on paper I get a funny looking rocker outline, have you any experience with drawing this out on paper?
I am also asking myself whether I am reading these tables all wrong, but since I have gone through it a few times and am not happy with the result, I see no other option than to ask here, as there are no experienced shapers in the middle of norway I can ask!
Sorry about such a lenghty verbal elaboration, but I’m in a bit of a shit here…
the thought was, as I said, to learn to shape by making some ‘standard models’ and learn from that, but no other fish rocker outline I have found are completely flat toward the tail.
the first picture is of the rocker near the nose as it falttens out, the second is the result of my first efforts and attempts with epoxy, which I think was problematic directly onto the wood with no cloth.
thanks to anyone who can help
david h.
Norway
Those illustrations are from 35+ years ago and reflect a design that was 10+ years older than that. Certain limitations in the renderings would be nearly inevitable.
Others will disagree but IMO, the numbers are the result of the curve, not the other way around. Perhaps better to chase the curve you’re after than to fall into the trap of being a slave to the numbers. Most people making that design today are using somewhat different curves for the bottom anyway. Not radical differences, but differences nonetheless.
This mirrors one of my axioms of shaping. ‘’ Let the ideal curve dictate the numbers. Don’t let the ‘‘ideal’’ numbers dictate the curve.‘’ Good call, gdaddy.
@ OneH20
I used those old Lis Fish graphics to demonstrate how length/width ratios could be changed to re-size a surfboard template. I have used that planshape outline as a “guide” for generating a template.
You asked for rocker numbers for that specific template. However those numbers are for a “curve” with a more gradual sloped curve. Linking those points with straight line segments eliminates the curve. If you want to use those numbers, you should probably use them to plot a best fit curve.
I use two different half-ellipses to design rocker curves.
Here are some links to other Fish templates:
More modern:
Retro:
From this thread:
