PJR discusses the matter of halyard on pages 32-37. One factor which directed me at using multi-purchase halyards rather than a winch on a single whip, was the matter of compression load on the mast: On a single part halyard the pole compression on the mast will be about twice the halyard forces on the yard. If one uses a 5-part halyard, that compression force is reduced to only 1.2 times. That means a 40% reduction of the compression forces on the mast, and my hunch is that compression forces should be kept low on an un-stayed mast.
I know, I know; the compression forces in a JR is very low, compared do those on a tuned up Bermuda rig of similar size, but still. Just a thought.
As for purchase and gearing; remember that no matter how much we down-gear our winches, and no matter how many blocks we use, the work of hoisting x kilos of sail will still be the same (plus friction work). In the last Practical Boat Owner magazine I spotted an ad, showing an affordable electrical (vertical) capstan, meant for anchor rope, which would have been perfect for saving one’s breath when raising the sail(s). I don’t know if it has a ratchet function, which would be nice to let one quickly hoist the first few panels by hand.
The Amp-hour drainage of the battery is miserably low for hoisting a sail, as it runs for such a short time. On my former boat Johanna I used an electric winch handle from Winchrite. I know I hoisted the sail six times before recharging the internal battery. It may well have taken more than that. The battery of the Winchrite is 21volt at 2.8Amp-hours, which means 58.8Watt-hours. Converted into the common 12 Volt world that is equivalent of 4.9Ah. In other words, it would take well less than one Amp-hour (in 12V) to raise Johanna’s 48sqm sail.
Arne