Rigging my 15' Bob Special canoe for sail, I'm about to cut the dumb sheave (for the halyard) in the top of the mast for a 35sq ft. lateen. Should this slot be cut in the mast aligned with keel line or perpendicular to it? I don't recall seeing this particular detail illustrated. Does it matter? Hoping maybe Todd or other canoe sailors will weigh in on this. Thanks.