Matt made the correct call: you do not have a H16 mast. Looks like a monohull/dinghy mast that fits in a mast step and does NOT rotate. Cat masts rotate and have a hemispherical knob on the bottom of the mast base for use with a teflon chip (H14, H16) or have a hemispherical cavity that rides on a plastic ball on the dolphin striker/cross beam (TheMightyHobie18, H20).