macgregor boating
- sail calc


I = Height of headstay termination above the sheer line

J = Distance between the headstay termination at the deck and the front of the mast at the sheer line.

P = Distance between black bands on the mast, or the maximum luff length of the main.

E = Distance between black bands on the boom, or the maximum foot length of the main

PY & EY are similar to P & E, but indicate mizzen dimensions

(Please note that the measurement rules for rig dimensions vary from class rule to class rule, and from measurement rule to measurement rule. Many yacht designers use different definitions as well. These definitions are general enough to provide guidelines to approximate your sail area. None of the information here is guaranteed to be accurate, as manufacturers often change rig dimensions without notice. You should physically measure your boat and record precise measurements to calculate accurate sail area figures.)