Best Mainsail Halyard Material

[Brion Toss]

Hello,
Ah, a good halyard challenge. You want something that is inelastic enough to give that good design a chance to sail up to its potential, yet not "crazy expensive." I don't understand why coming down a size would make the sail easier to raise; care to elaborate? In any event, the most halyard for the money would be a blended core, like New England's VPC. It stretches, about half as much as double-braid Dacron of the same diameter, and is only about 30% or so more expensive, depending on where you get it. If 7/16" is right for your boat, no harm done. But if it isn't, then stay with half. Have you run any numbers on halyard loads?
Another option would be (mostly) uncovered Spectra, spliced to a fat Dacron tail. This would minimize stretch and weight aloft, and wouldn't be a whole lot more expensive, even including the joining splice.
Get back to us about those halyard loads.
Fair leads,
Brion Toss