|I measure mast rake to a datum set on the stern of the hull. Each boat and rig is different hence knowing what works and being able to measure it and get back to it is more important than knowing what is level etc. Use a good fibre glass tape measure secured to the halyard hauling the halyard up into the turning block. Remember that if you change the length of the shackle or knot on the halyard it changes the measurement hence include the lengths of the shackle and knot in your records and a good description of the datum on the stern. |
While your measuring, check your rig is even port to starboard. It happens.