Howdy Partner!

Originally I though to make the partners more/less match the curve of the mast.  At first blush, that seemed like the right answer.  Why not minimize Spar-Tite, or whatever gap might allow water intrusion.  I wasted some time carefully tracing the outline of the mast butt, including the aluminum forging that holds the ram, and transferred it into Rhino using the all-in-one printer, and scaling the scan.  I printed some templates and dug out some MDF to make a mold.  

Then a dim flicker of idea crept into my brain, and I hit the brakes.

After making a couple phone calls, I confirmed my suspicions.  There is a real good reason to make your partners generally rectangular.  If you want to play games with your side bend, and your rake, say to spoon the mast aggressively in light air, or to increase rake in a blow, having an elliptical hole in your deck is a problem because you can't use the same blocks and wedges throughout the range of settings.  If the hole is rectangular, you have a nice flat surface to press against, whether you are in the forward or aft position.

Once I decided on the length and width of the rectangle, I taped some paper templates to a chunk of MDF and cut out 6 slices with the jig saw.  After the simple glue up, I sanded things smooth, and wrapped the form in PTFE mold release tape.  

For layup, I burned up a pretty solid amount of scrap carbon by winding it around the form.  I knew that layers would buckle when bagged, as a result of the circumference reduction, but since I was really just making a thick wall hoop without much worry about strength, I kept it simple.  I wrapped 5 layers of breather atop the peel ply to soak up the liberal amounts of Pro-Set used during wet-out, bagged it, and cooked at 125F.

To tackled the challenge of the geode that I created, I started by slicing off all 6 sides with the chop saw, bag, breather, and everything.  Following that, I went after the wrinkles with the angle grinder.  

To remove the part from the mold, I had the pleasure of employing the rarely used press at work which worked even better than anticipated.