Haven't tried but would be even easier than tuttle as the embedded nut is in the thickest part of foil.
I wonder if these Gong foil mast heads could be a good platform to build off?
www.gong-galaxy.com/en/products/gong-foil-allvator-v2-tuttle-connection?srsltid=AfmBOoqw_AuhATANrR7_pSV1bX-evj0RSnEh8VzlP7T-lPg7U86mLTfX
Select to expand quoteAUS 814 said..
Has anyone tried printing a 3d power box weed fin ?. I'm guessing the problem with it being only the one bolt it might be difficult to join the base to the fin?
It should not be a problem. Using Flex's embedded threaded rod with poured resin technique, I don't even bother with an embedded nut. The grip of the resin on the thread seems to be immense. When I made a mistake, I tried to rotate a rod out of set epoxy resin. I just twisted the rod to destruction. I would imagine a single rod embedded down into the body of the fin will have plenty of retention.
(I should add, that while I haven't had any failures, all the fins have a fillet that helps to distribute some loading.)
Select to expand quoteGrantmac said..
I wonder if these Gong foil mast heads could be a good platform to build off?
www.gong-galaxy.com/en/products/gong-foil-allvator-v2-tuttle-connection?srsltid=AfmBOoqw_AuhATANrR7_pSV1bX-evj0RSnEh8VzlP7T-lPg7U86mLTfX
Nice find - that's a nicely resolved design. 
Select to expand quoteFlex2 said..
The main objective was to see if one could make a board using this technique and appears the infill required to get a strong result is around 4-5%. Assuming you can get the foam to expand enough to get close to 35Kg density, means a 100 litre board would use 3.5Kg foam (cost $105 for 4 litres). A board printed at 4% infill and 1mm wall thickness should use 7.88Kg of PETG filament (cost $181 AUD using Bambu refill PETG). Actual consumption would be higher as would need alignment/strengthening carbon rod stringers to join sections and solid epoxy filled areas around fin/straps and mast. If allow +1.1kg +$50 for this, a board should weigh about 12.5Kg and cost $336 cheaper than what I paid $350 2nd hand for it).
Making a board in such a way seems a bad idea to me. On a 25x25cm printer you will need something like 40 parts. And a huge amount of printing time + personnal work... Al this for a questionnable result.
Among things that can be done with a printer are cool harness lines:
A french guy is kind enough to put his invention on thingiverse. The EZ-trim.
www.thingiverse.com/thing:6015244
Select to expand quoteFranckG31 said..
Among things that can be done with a printer are cool harness lines:
A french guy is kind enough to put his invention on thingiverse. The EZ-trim.
www.thingiverse.com/thing:6015244
A key part of this is the v-jammer block which isn't easy to source at a reasonable price
You should be able to find these for around 10$ ...
The Wichard version is around 17?...
Select to expand quoteI asked Chatgpt to create a file for a super cavitating fin and it has provided me with the STL file, have you guys tried using AI?
Key Design ConsiderationsHydrodynamic Profile:
The fin must achieve supercavitation at the desired speeds while maintaining enough control to avoid catastrophic instability. A wedge-shaped or stepped cross-sectional profile, similar to supercavitating propellers or torpedoes, is critical.Surface Treatment:
The leading edge and other critical areas may require coatings or materials to encourage bubble formation and sustain cavitation.
Material:
Use lightweight, high-strength materials like carbon fiber composites or titanium to handle the stresses at high speeds.
Compatibility:
The fin must integrate seamlessly with the board while balancing lift, drag reduction, and maneuverability.
Preliminary Design SpecificationsLength:
~30-40 cm (to maintain control and provide adequate lift). Shorter than typical fins due to lower drag under supercavitation.
Chord Length:
~10-15 cm (at the base) tapering towards the tip to reduce drag.
Cross-Section Shape:A wedge-shaped profile with a sharp leading edge (angle ~10-15?).The back edge is blunt to allow the cavity to close smoothly.Angle of Attack:
Optimized for ~3-5? relative to the water flow to ensure stable cavity formation.
Trailing Edge:
Blunt and thickened to facilitate cavity closure without turbulence.
Ventilation Channels (Optional):
Grooves or channels along the fin surface to introduce air and promote stable cavitation.
Material:Core: Lightweight carbon fiber for rigidity.
Coating: Hydrophobic material to reduce wetting and encourage cavitation.
Attachment System:
A reinforced fin box system to withstand forces at extreme speeds.
Critical ChallengesStability:
Supercavitating fins are notoriously unstable due to reduced water contact. Control systems (manual or automated) may be needed.
Low-Speed Performance:
Supercavitating fins are inefficient at sub-cavitation speeds, so planing and acceleration might be difficult.
Testing and Refinement:
Designing the exact shape requires computational fluid dynamics (CFD) simulations and prototype testing under realistic conditions.
To create a 3D model of the supercavitating fin suitable for 3D printing, we need to export the design into a 3D modeling format like STL (StereoLithography). Here's the plan:
Define the Fin in 3D: The fin has a wedge-shaped leading edge, a tapering thickness, and a blunt trailing edge. We'll include the base attachment system for mounting
.Export to STL Format: This format is commonly used for 3D printing.Let's create the 3D model and generate the STL file for printing.
The 3D model of the supercavitating fin has been generated and saved as an STL file. You can download it using the link below:
Download Supercavitating Fin STL FileThis file can be imported into a slicer (e.g., Cura, PrusaSlicer) for 3D printing. Let me know if you need further modifications or assistance! ?
Choco, damm you... I hadn't till you mentioned it...boy, that opens a can of worms. I asked chat GPT to design a fin that doesn't spinout, then a fin that can do 60kts....then down the rabbit hole from there. A couple of very interesting new concepts I'd not heard about or considered were introduced....a few appear to be easy to model/3D print1) V-shaped cuts in the leading edge at base of fin on each side at an angle of between 20-40deg. Purpose: The V-shape helps improve stability by creating a more defined leading edge flow path. This makes the fin less likely to veer off course or experience drag when turning into the wind or changing direction (as in tacking).
The cuts also reduce the amount of water contact at the base, which helps keep the fin clean and efficient in turbulent water.
I can't find any examples/images of this but attached image is what I think it means...anyone have a clue?
2) Apply sharkskin texture to the surface. Purpose: Adding a shark-skin-like texture to the leading edge of the fin could reduce drag and turbulence, helping the fin remain efficient at high speeds and prevent spinouts when you're pushing hard.
3) Winglets or bulbs. According to ChatGPT bulbs at the tip of the fin increase low speed stability whilst winglets increase high speed stability.
4) Applying washout along the length of the fin (i.e. Prandtl)
There are harder to implement suggestions like variable rake and variable angle of attack fins using foot strap pressure.
Interestingly 1,3&4 are recommended for a windsurf fin capable of above 60kts. Instead of Sharkskin texture suggests applying a hydrophobic coating like NANOMYTE? SuperCN
Way back, I converted a MUF Delta to a super cavitating design. In my hands and with my skill level, it was a rank failure. The issue being there was so little lift generated from the design at lower speeds, and its handling was so bad, it was impossible to sail well enough to get up to a high enough speed where the fin was at all effective. A more skilled sailor may have better results, perhaps.
My thoughts at the time were; SC fin only ever operates on its high pressure side, so there is little low pressure lift. The fin needs to have a bigger surface area than a standard to provide some low Reynolds number lift. The drag from the extra surface area may be greater than any benefits.
The SC fin has a very narrow AoA range. Operating outside this range causes the sharp leading edge to cavitate, with sheet cavitation following almost immediately.
A pure SC fin design seems only to be an option when it is not required to provide lift/counter forces at low Re numbers. A hybrid design like Flex's above might be completely different.
Just as aside, shark skin surfaces do not provide much benefit, if any, at the Re numbers at which speed windsurfing fins function. One of the hydrodynamic boffins once described the high Re flow to be almost inflexible pipelines of fluid, not the delicate streamlines we imagine. At the speeds at which we sail, in the split second the water is in contact with the fin, there simply is too much inertia and too little time to for the water molecules to do any fancy gymnastic manoeuvres. That is, you can bend the pipes, but don't break 'em.
I spent some time interrogating a 'higher' level AI about all the improvements mentioned above. The AI was forthcoming with a very similar bunch of strategies. I asked for a diagram and got something that looked like it was out of a 1800's novel on whale internal anatomy - bizarre! Anyhoo, when push came to shove and I asked the AI to provide links to the research that proves the suggested methodologies on a hydrofoil operating at Re 4x10^6 or greater. The reply from the AI was that there isn't any, and we should do some research to validate its suggestions.
