HOW TO TUNE YOUR RIG
Without a properly tuned rig, you won’t be able to control your mast’s behavior over the full range of conditions. Fortunately, rig tuning is a straightforward step by step process for both masthead and fractional rigs.
The goals in rig tuning are the following: (1) Eliminate side bend and lean, (2) Set mast rake for proper helm balance, (3) Set pre-bend to match the mainsail design, and (4) Control mast bend and headstay sag.
Here are a few definitions and explanations to get us started.