Jury rig for halyards

[Brion Toss]

Hi there,
Seems to me, the right question is, " Why don't I have internal halyards?". That way, the same four masthead sheaves could fit four halyards, instead of two, so if you broke or skyed a halyard, you'd have a spare. You'd also have less windage, vastly easier belay and winch layout, less slapping on the mast, and half the chance of skying a halyard in the first place. It's not too late to change, unless you have a wooden mast.
But if you must stay with external, it were best if there's a web on the aft face, suitable for drilling a hole in to hang a block from. It has to be far enough aft to clear the head of the main, but, since it is off to one side, can be closer than if it hung from a transverse pin. This "earing" style is also useful for topping lift pendants.
Use the smallest, strongest block you can find, again to keep it away from the primary halyard. A fair lead on the mast could conceivably make for a better lead to the head of the sail, but I think that reefing would accomplish the same thing, if it's needed.
Fair leads,
Brion Toss