Surfboard Geometry

I have a system of designing surfboards automatically on 3D engineering CAD by using the dimensions of a board, length, width and thickness etc and choosing the style and then turning those dimensions into cylinders and variations of cylinders and slicing them up to get the lines of intersection and then projecting those lines of intersection to make surfaces and intersecting those surfaces to create the lines that make a 3D surfboard. From there I can come up with Gcode for CNC machines to cut them out … or I can send you plans … so you can make them by hand. … maybe!

Thought I’d see if anyone is still interested in the idea, I did post a bit a few years ago on a thread some one else had started. Today I started a blog, and I will use the guidance from you guys (if anyone comments) to develop the blog further.

Hey, I tried for months to post on Gnargnar’s thread "Surfboard Calculus: and I couldn’t, if you can’t post on this thread please let me know with private message.

Hi Malaroo,

I love your design priciples! A perfect example of out-of-the-box thinking and parametrization.

I’d love to see you using OpenSCAD in these series. OpenSCAD is a free parametric solid modelling tool: . To me, it seems like the perfect tool to demonstrate the simplicity of your ideas (take a look at the cheat sheet to get an overview of the functionality: ).

This way, pleople without expesive CAD licenses can start playing around with your ideas.

And we might create a github repo later, to share designs.



Hi Hans

Great to hear from you … and I love the work you have done in the past. I am honoured to hear from you again. I will have a good look at openSCAD and see if we can get it happening. Give me a few days to sort myself with it. It would be so good if we can get this stuff to anyone anywhere that wants it.

If you send me a specific geometry desciption, I can create an OpenSCAD file following that description.

This will get you started faster :wink:

Always easier to learn from example.

hi Hans

Ok I will send you a step by step description of the most basic classic design. It’s a great board, but works best with a length that equals the circumference of the circle that represents the width … I’ve attempted to load a picture of it in this reply … the history of the dimensions is that I made a short one 4’11" x 20.75" and the guys said make it a bit longer, 5’10" then they said make it shorter, 5’4" then longer 5’8", then shorter 5’6" and slightly wider … (yes they drove me mad and cost me a fortune) and I realised the relationship … 5’7.5" x 21.5 x 2+5/8" … made some and they ripped. This is a board I would like to get out to the world. 

The calculations with a 1/4 relationship are as follows … length 5’7.5" = 67.5" divided by phi 3.14 = 21.4968 (width 21.5") divided by 2 = 10.75" (centre line to widest point) divided by 4 = 2.6875 (thickness of board-it can be + or - ) so … 2"+5/8th.

metric equivalents

length 67.5" =  1714.5 / width 21.5" = 546.1 / thickness 2+5/8" = 66.675

OK, I am loading two pics, one of the board and another of the frame used on CAD, See if you can create the frame on CAD to the dimensions I have listed above.

I tried to download openSCAD and it wont work on this old MAC computer … but I do have a windows 7 pc … (not connected to the internet yet) that I will try.

Good fun Hans!

pic of the board

pic of the CAD frame


Hi Malaroo,

The whole thing sounds really interesting. I am not seeing the picture in #7.


Hi Jrandy

I will try it in some other formats, that was a gif file, this next one will be a jpg, let me know if it shows … confusing because I can see it, so I will not know if jpg solves your problem unless you tell me. It should work because the others are jpg.

Malaroo, I can see the JPEG file, thanks. -J

I do not really understand what you want to achieve.

I’ll try to model this in OpenSCAD:

When driving home with train today.

You might then take it on from there?

This is very interesting to me, I’ve just started learning parametric modeling. I have found it difficult to get decent results designing boards using solidworks.

My avatar is my first attempt at designing something like this and I think it’s too blocky, I’m trying to learn surfacing because it seems to be the best way to produce shapes that flow, but I have a ways to go before I gain any proficiency at it…

If it’s not too much trouble is it possible to explain to a nube how your method works without a lot of math? 

The last pic you posted helps a little but I’m still not quite getting it.

Do you plot the dimensions inside the cylinder and then use them as control points for splines for surfacing or is it more complicated than that?




Hi Hans

These next few pics for woodave might help you see the next steps, but I will give them to you in detail as you go.

Hi Dave

I learn’t to do this on a 1996 CAD system where I worked, little did I know at the time that the system of that old CAD was so user friendly for the type of concept I was pursuing. Last year I started learning Solidworks through an online University module. I couldn’t work out how to do the boards … and I invented the board system … one day a few weeks ago, I was so frustrated, I decided to do it the same way I did it on the old CAD, step by step and did each step in every possible way. So I created the frame as pictured, with Solidworks that means those lines will have to be drawn over again and at the same time in the surfacing section I created a cylinder. I’m no expert in Solidworks, but I found that I could extrude cut on the boss/base (Solidworks talk) and with the convert entities tool (more solidworks talk) get the line of intersection to respond and be used. I couldn’t get that from the surface section … but that’s just me, I am an absolute beginner at Solidworks. Here’s some pics, see if you can create these steps. If not I might create a step by step tutorial for you. Trouble is as a beginner I might be teaching you a really stupid way of doing it … I don’t know.

In response to your comments: When you understand it, it’s so simple it’s a joke, No maths except, measurements. No splines, no creating anything except slices and using the intersection lines for the next step. This is baby CAD stuff, honestly, the difficulty was working out how to do the steps and the different models and what works and doesn’t work … that took me years. 

Hi Dave the first of 5 Solidworks pics


pic 2

pic 3

pic 4

pic 5

hi Dave and Hans

There is more to this than just an outline, we will create a whole board. we will continue to use each part we create to create the next part.