What is the optimal board shape?

I am currently designing the board itself and I am wonddering about the best shape. I am cutting the blank on my CNC, so the shape can be as complicated as I like. Since we are not turning with the hull in the water, should it not be optimized for straight line speed? I guess that the rounded back of a surfboard is only for turning. Would a catamaran shape be usefull to reduce drag and get up to speed easier?

Here is an inital draft. The volume os about 87l at the moment.

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I would add a little nose rocker to help before flying in choppy water
Are you using the sculpt fonction in fusion? I have played with it last night and my board looks real bad compare to yours

No I am doing a parametric design. I start with a box and chop away what is unnessasary from all three sides (front, side, top).This is very easy and quick. Its cheating in a way. but doing free form modeling is hard.

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Here is the same as above just as a catamarn. What do you think?


Hi @MaxMaker,
maybe its of some use to you.
Here is what I have come up with based on Goldy’s Templates: Fusion
I converted his pdfs to transparent pngs and arranged them in CAD. (side: Fusion top: Fusion CAD:Fusion).
I freehanded the back and front crossection and lofted those through guide rails on the mirror plane through the center of the surfboard. The last guide rail I got from a surfcace. I have some problems with 3D Sketches in Fusion.
I will look at your way of shaping the board.
Is your plan to mill the board in one go or will you cut individual sections and then glue them together?

That shape looks very cool. What is the idea behind the bottom shape?

I am trying to keep my nose quite flat. For safety reasons, but also to make it easier to apply fibre glass. The cloth needs less relief cuts if the nose is straight vs curved.

I will mill everything in one go. My CNC can handle 156 x 52cm. The height is a bit more difficult. Normally I cut 20cm high aluminium or wood. The foam will be 12mm high. I can take off my Z-axis though and attach it hire up. I need to buy a loooong bit though.

The shape is really the result of the Lofting (‘Erhebung’ in Fusion) operation. I thought it looks interesting, but I don’t have any experience making boards for surfing.
I’m definetly interested in how your board turns out. I think I will focus on my propulsion development and use my decades old board as testbed.

What are you doing in with regards to where the batteries and electric will be? Are you having a hinged lid with a water tight seal around. What are your thoughts?

I am going to use a waterproof case that gets strapped into a cavity. All waterproof hatches that I could find cost about the same, so I am getting a full box. I will also switches and displays to that case. The ESC will get its own case from aluminium.

so the waterproof box will be open so you can step on it?..like what pacifmeister has got?

Yes, but sunk in the deck. Its a “heavy duty” camera box. I don’t think I need to step that far forward though.

No experience either haha.

If you want the board to float while standing on it in the water there’s a relationship:
board volume (L) = your weight incl HF (kg) + 30 (to 40)
Example: you weight 75kg, your hydrofoil 10kg
Minimum Board volume if you want to stand on it = 115 litres.

For me, the Montague shape is a good start with plenty of volume and stability during take-off.

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How important is having it float? I could make it thicker, or cut it in two pieces that get joined. Should I make it wider or longer? At the moment its 156x52x13cm.

Hi, Can anyone advise me on what epoxy resin i need to use to glue my foil mount into the board after i router out the board. My board foam is high density foam

Hi Maxmaker,

I like your design process. I am a windsurfer from Hamburg and in the planing stage. So my thoughts on the ideal shape are biased towards multi use, but maybe intresting for your pupose too:

Shape for lift/planing would be a “planing straight” (no rocker from the back to the middle) maybe combined with a concave bottom. I think your catamaran thought goes in that direction. Here are some pictures with the terminology of all kinds of shapes: http://www.carbonartwindsurf.com/design/boardology/

Nose Rocker: For windfoiling it is often recomended to have a bit of a nose-rocker epecially for the learning phase: If you nose-dive and have a bit of rocker the board will deflect itself upwards again instead of coming to a full stop. Looking at your design, it might be enough for that.

SUP-Stability /or being able to stand on it without stability through propulsion:
The width is important here as well as the volume. Here is another example of a maximum recomended ridersweight given those two factors: https://surfer-world.com/naish-hover-foil-sup-board?gclid=EAIaIQobChMIrcrA8pOU2AIVhkAbCh0orw8NEAQYAiABEgLfJ_D_BwE