Understanding Mainsail Roach

Mainsail Roach is the area outside of a straight line that connects the
mainsail clew with the mainsail head. The more roach that a mainsail has
the more espertise must be exercised by the sailor. On the sail layout we
identify the roach that we are using for your sail based on what we call
an RF factor. Below is how we normally build mainsail's. We are happy to
adjust Roach as you may wish.

RF107   Partial Batten Cruising - Good performance great pointing easy sailing
RF109   Partial Batten Racer/Cruiser
RF110   Full Batten Cruiser
RF112   Full Batten Racer/Cruiser

Areas over 10 or 12 percent (RF110 or RF112) start to become very close to
the backstay and sailors need to provide the distance from the mast to the
backstay at boom level. This provides us the triangle we have to work with
in designing roach.

Areas above 12% often require a special rig or even a sail that exceeds the
backstay. In other words, when tacking, the sail may hit the backstay.

On Sails we sometimes build extreme roach. Extreme roach can go anywhere from
20 to 50% additional sail area defined as roach.  If a sailor asks for extreme
roach, we normally set it up at 35% or RF135. About the largest roach we build
is 50% RF150 and this is an extreme roach that requires a great deal of skill
in handling.

In summary, you do not get a better sail by having more roach, you get a
different sail that requires a different set of sailing skills.

Sail makers often define the look of the sail by MGM and MGU. These stand for
mid-girth middle and mid-girth upper. Please see that helped topic.

Sail performance is best enhanced by having the three points of the sail clearly
and properly defined. Namely, tack cut back and tack cut up (A&B) and clew cut up
and cut back, (X&Y).