Molding part the "wrong" way (Annular foil)

[ziper1221]

Hello, I had the idea to make an annular rudder for a foiling dinghy, both for induced drag reduction and for safety reasons. However, I couldn't come up with any east to make the part. To mold it the typical way, it would take (by my count), no less than a 6 part mold. If it were to be made with the parting line along the line of max thickness instead of along the chord line, it could be made with only a 2 part mold, CNC'd from foam. Pictures attached for your viewing pleasure. The section is exaggerated.

Note that the actual section would be much thinner (~8% of chord) and minimally cambered. The part would be solid carbon, no core.

My concerns are that:

1. The trailing edge would be too fine. the mold would be difficult to machine, difficult to keep release agent on it, and difficult to pack with fiber.
2. The draft angle would be too small, and the part would fail to release from the mold.

Those issues could be solved with either using a sacrificial mold, or using the mold to make an oversize billet and then machining that down.

Is there a better way to make this that I am not seeing, or is this my best option? Thank you for your responses.

 

[BrissoDamo]

make a solid core cnc machined and coat it

 

[fallguy]

Oversize and machine is my vote, but I am an amateur.

 

[DogCavalry]

Why mold it at all? The plug to form the mold on will take the same amount of time and effort, as making the part. Or almost as much. Much less than making a plug, making a mold from that, making the blank in the mold then machining it down to the final form.