For the bag length measure from where on the pole you want the snuffer to sit. On the snu on my tiger I moved iy up 6 inches in front of the bridle. Makes snuffing easier if you start to round up. Then measure back to the end of the pole . Thats the bag length. Or you can hold your arm in a small circle and pull the spin through with the snuffer line attached. Like your arm was the mouth and find out how long you need.
Or measure from your two upper/lower-most snuffing points to the corner(s) of the spinnaker...that's bag length.
