New Halyard

[Brion Toss]

Hi there,
The good news is that all of your questions are answered, in exquisite detail, in my new book Rig Your Boat. The bad news is that I haven't finished that book yet, though I have been gnawing away at it for years. So meanwhile the short form is: if the halyard goes into the mast in front, it should come out of the mast in front. That way it will have the fairest lead, and the least likelihood of encountering throughbolts, other halyards, and any other obstacles. This method also makes it easy to figure out whether a line is a jib halyard or a main, because the jib, for instance, is in front, and that's where the halyard exits.
And if that halyard exits in front, then it will lead fairest to the starboard winch; if you brought tit out on port, from an exit towards the front of the mast, you would have to deflect it aft, to get a lead to the winch, which would make for a foul lead. And one sees precisely this a lot, because people are still fixated on the "main on starboard, jib on port" mantra, which was evolved specifically for external halyards. Actually it goes even deeper than that, back to the days of external halyard blocks and the first, jib-less sailboats. The point is that rig layout should reflect rig traffic patterns, and inverting the traditional patterns makes sense with internal halyards.
There are refinements, like optimizing relative leads based on load and frequency of use. For that, I fear you will have to wait for the book, or take one of our classes.
Fair leads,
Brion