Yes, thanks for that, it will/may be interesting to see what results I can get, as the laser beams form a circleof dots on the target and so some will fall on and some between any projections but should be esily visible around dusk. Realistically, I am only interested in how close to 35 or so feet it is, in the middle, so as to ascertain wehether or not there is any safety margin or whether the published height is actually given as the lowest point on the span which would be at the supports at each end. I have probably discounted attempting to travel with my masts fixed now but the question will not go away until I have had at least a good attempt at checking the height for myself. A single laser beam could be more accurate but I am not aware if there is a convenient source of such a calibrated item outside the military, scientific or surveying communities. It would not be likely to be affordable anyway.