Okay.
Sails work using a differential in air speed and therefore pressure, between the 2 sides of the sail cloth, the front more curved side, air speeds up and loses some pressure, the rear theoretically flat side, the air speed remains constant and so does pressure.
This results in the higher pressure side being pushed towards the lower pressure side, giving the sail drive. In an airplane this force is called lift.
In order to generate this drive we must place our sails at a certain "angle of attack" relative to the true wind direction. We can't push the wind around, so we haul our yards and booms, into the right positions, to get the right shape into our sails for power.
Oh, were are my old theory books on aerodynamics?
In all sailing craft, the standing rigging that holds the mast(s) in place, can interfere with gear movement. In a square rig, the yard-arms can only move a certain distance before being stopped by the "shrouds", the big stays that hold the mast(s) side to side. This is not so in a fore and aft rig like a staysail.
A fore and aft rigged vessel can be brought up to tack closer into the "eye of the wind" than a square rigger, because her sails are on her center-line not across it.
It is here, Shorty realises he really must find diagrams.
Thumbnail dipped in tar, does not seem to translate from floor to ether very well.
More to follow.
Sail theory 101 will resume, after this short station identification break.
101-1 a quick diagram to show drive generated. All sails work the same.
101-2, an attempt to show the difference in a rigs ability to bring the ship herself into the wind. In a square rigger, the sails may be as close into the wind as any sail can be, but, the rig itself won't let the
ship get up into the wind.
A fore and aft rig can be hauled right in to the center-line, and driven hard up into the winds true direction, instead of having to sail across the face of it.
Angle of attack.