: ...sticking up at the left rear corner of the cockpit?

That there is a gen-u-wine hydration port. He has a platypus bladder in the day hatch area, and built a custom grommet with PVC pipe and rubber membrane to keep the day hatch dry. You can pull it up as far as required to get a drink. I imagine he has included the details in his plans.

Not that the King is so tippy it needs the bladder on the very bottom of the hull. Seems like a great idea for a surf ski!

If you like performing paddlefloat rescues, that "roller's recess" is dead flat, and a paddle shaft sits very nicely behind the coaming. It also sits quite well in those bungies, but I'm one who prefers to do my p'float rescues with the paddle clamped to the coaming with my hand.

Carved turns are super, too.

Joe has done a lot of "thinking" with this boat.

Shawn