Another 25 Seafari goes under the knife

[Bushwacker]

. . . Could you use patching plaster instead of clay for the radius? I`m about to make my first mold.

Sandy, I think plaster tends to shrink as it dries out, especially if it gets too thick. Also fairly brittle when dry. I'd be worried about cracks, both in the thickest parts of the fillet, and at the bond line. Sounds like clay will work fine if you just keep an eye on the details (adequate mold release agent/PVA and cure time, etc.)!