Making A Triangular Sail

[micheus]

I've had good success getting the outer shape by starting with a cone, flattening it in half on the z axis, but what I'm aiming for is having the inner curve exactly match the outer, so that the thickness of the sail is constant.

The fast way is to create a mold/shape (something you already did) and select the faces to be used and apply the Shell Extrude command - moving the mouse to set a small thick to your sail. When you finish the command a new object will be created and you can delete or hide the "mold".

I've tried this approach ... https://youtu.be/se9bF_XiFXM ... but the sail wall thickness varies because it's a manual process to adjust the inner curve.

As amfitrione already showed you that approach is waste of time since you can just use one command: Intrude.