well its very simple really. i think the lightest indicators are the most effective. magnetic tape is good but i like a dart better. i like a jib bridle indicator cause its easy to look at. i have a dart made with about 8" of soda straw that uses 3" of pencil inserted into the front and a semicircular half of a styro coffee cup bottom sanded and faired for a vane. cut a 1/8" slot about 2"deep into the rear of the straw.insert the vane . tie it into place in the slot with a 4" piece of kite string looped around the front and back of the vane, insert about 1" of the pencil (sharpened of course!) into the front-should be a tight fit. find the balance point of your dart by balancing it over a pencil laid flat on your desk, melt a hole through the balance point with a large hot needle. minor adjustments can be made by sliding the pencil in or out. find about a foot of non corrosive wire, about 1/16" diameter is good. i think mine might be nickel plated steel it doesn't rust. coat hanger will do in a pinch, the thinner ones are better. bend a loop into one end that will be bolted and wing-nutted to the bottom hole of your bridle's jib shackle, pointing down. put the dart onto the wire next followed by a plastic bead, a small brass washer, and another bead. then bend the wire into a u at the bottom to capture the dart and beads. make sure the shaft wire is vertical. these lightweight darts can be so senitive they will move when you walk past. they degrade in uv, i make a new dart every few months. with one of these on the front of your boat you will know the direction of every subtle wind shift as you carve through the zephyrs and the fleet to the windward mark, and detect every nuance of shift as you religiously keep the dart perpendicular to to your boat's centerline reaching downwind...