Foot length of mainsail from tack to clew. Distance
from the tack to the black band at the end of boom,
so long as the sail does not extend beyond the band.
Otherwise, use the length of the foot when outhaul
is fully taut. In the event the clew of the mainsail
is carried below the top of the boom where it intersects
the mast (boom drop), measure E along the slope of the mainsail.
The foretriangle height measured along the foreside of the
mast from the main deck "datum" to the top of jib halyard
sheave. Note: the height of the deck used as datum for this
measurement shall be taken as 4% of beam above the shear
line abreast of the mast.
Distance from the foreside of the mast to the point where
forestay attaches to the deck or bowsprit, in a direction
level with the waterline.
Luff length of mainsail from tack to head. Distance from
the tack to the black band at the top of the mast, so long
long as the sail does not hoist above the band. Otherwise,
use the top of the main halyard sheave.