Even without electronics, unless the tell tales are flying to perfection you wont get any optimization of sail trim.
This includes dead downwind sailing where one uses the tell tales to 'balance' the drag forces (non-aerodynamic sailing) although your description highly suggest you were sailing in aerodynamic conditions.
In 5-7 kts, there isnt much 'energy' that can be transferred from the wind to the sails, plus the sails will VERY easily develop an invisible separation stall, especially if the sails are not 'flattened' to prevent this 'separation' stall. Without shaping to FLAT sails in 'light' winds you risk the deadly 'separation stall' ... and the boat will almost come to a dead stop - only a FULL set of tell tales (luff, mid cord, and leeches) will show exactly what going on.
In such 'light' conditions the only 'real' way go downwind is to SAIL the boat downwind by 'tacking downwind' to keep the apparent wind as high as possible (Stu's reply). If you 'parachute' instead of aerodynamically having the increase of apparent wind all youre going to get is .... nowhere. For light winds, shape is more important than trim, and the shape you need for 'light' is FLAT simply because the wind doesnt have enough energy to stay 'attached' to the sails. Midcord tell tales (and an accurate speedo) will tell you how much draft (outhaul and fairlead position) you need.
FWIW, in light winds and when beating, the clew of the jib/genoa can be brought in toward the mainsail by a considerable amount (barberhauler, etc.); 1. since the main is or should be more flattened and 2. with less draft the 'slot distance' can be 'closed' .... just until the point that you see so-called 'backwinding'.
;-)
This includes dead downwind sailing where one uses the tell tales to 'balance' the drag forces (non-aerodynamic sailing) although your description highly suggest you were sailing in aerodynamic conditions.
In 5-7 kts, there isnt much 'energy' that can be transferred from the wind to the sails, plus the sails will VERY easily develop an invisible separation stall, especially if the sails are not 'flattened' to prevent this 'separation' stall. Without shaping to FLAT sails in 'light' winds you risk the deadly 'separation stall' ... and the boat will almost come to a dead stop - only a FULL set of tell tales (luff, mid cord, and leeches) will show exactly what going on.
In such 'light' conditions the only 'real' way go downwind is to SAIL the boat downwind by 'tacking downwind' to keep the apparent wind as high as possible (Stu's reply). If you 'parachute' instead of aerodynamically having the increase of apparent wind all youre going to get is .... nowhere. For light winds, shape is more important than trim, and the shape you need for 'light' is FLAT simply because the wind doesnt have enough energy to stay 'attached' to the sails. Midcord tell tales (and an accurate speedo) will tell you how much draft (outhaul and fairlead position) you need.
FWIW, in light winds and when beating, the clew of the jib/genoa can be brought in toward the mainsail by a considerable amount (barberhauler, etc.); 1. since the main is or should be more flattened and 2. with less draft the 'slot distance' can be 'closed' .... just until the point that you see so-called 'backwinding'.
;-)
