I've used Purpleheart for the outer stems and spacers for scuppered inwales on a canoe project I'm just about done with. The color of the outer stems, glassed, is a deep, deep red. It's not the purple you get when almost burned from machining but it looks good and it is frighteningly strong. Not sure how long it takes to oxidize because I milled up the pieces, put 'em on, shaped and glassed. The spacers for the Canarywood inwale were milled a few weeks before using and I didn't notice any oxidation.

Would you use the PH for the vertical components of the coaming? Or the rim? You could get it to bend that much if you laminated it, probably a 1/16th would work. I did 1/8th inch laminations for the stems and ended up breaking a few.