Other things being equal, a longer board will have more glide and less yaw than a shorter board. How much does rider weight effect glide and board speed on weak waves and flat sections? A 70 kg rider on a 7'7" 100l Destroyer will be at a Guild factor of about 1.4. A 92 kg rider on a 8'5" 130l Destroyer will be at the same guild factor. Will the 8'5" board have more glide?

Using the analogy of a yacht the longer the length the faster she goes, regardless of the weight generally. It would make sense that a longer sup would glide faster than a shorter one again regardless of weight. Having said that we're going from a standing start to catch a wave, so a lighter weight of board and rider would have to get up to speed quicker from a stop but would not glide as fast at full speed.

Outline shape also makes a difference more paralell more speed