A pressure release hole is essential, for the bulkheads, usually 1/3 down from top, to prevent water transfer, if you capsize. Proper method is to drill 1/4" hole, fill w/ epoxy, then re-drill through the epoxy only, with a 1/16" hole, leaving the wood sealed. this should be done before coating the bulkhead with epoxy, but it can be done after, as long as you get a good seal with the two epoxies.
Does the Borealis normally have a rudder? I haven't seen one in a couple of years, and have forgotten, though I didn't think it did. I've always been of the opinion that a rudder on a single kayak was only employed by boat builders who lacked the skill, or were to lazy, to design the hull properly, but that may be due to the fact that I only build, and paddle sof, and it's almost impossible to efficiently install a rudder on one of them, nor have I ever felt the need.
David Mills