Standard diameter (SDM) or reduced diameter (RDM)?
RDM – Advantages:
•Thinner in the hands, many prefer this feel in transitions where the mast is held.
•Thicker wall, more durable
•Relatively softer in the middle for a springy feel
•More suited to wave & freestyle applications
SDM – Advantages:
•Lighter for a given stiffness
•Range of top section stiffness available for speed/slalom applications
•First choice for camber induced sails
•More locked in feel with better top end performance
•More suited to freeride, slalom, racing and speed applications.
•Floats better for easier water starting
Generally speaking it’s obvious that the SDM is the natural choice for larger sails, for speed, slalom, and light/medium wind freeride. Conversely, the RDM is popular with wave and freestyle sailors.
Lifted from Tushingham site !!!