on reduced diameter masts... The new trend in wave gear is reduced diameter masts, or RDMs, also known as "skinnies". These masts are smaller in diameter and have thicker walls their largest single advantage is their resistance in white water RDMs last! Conventional wisdom says that these masts are not as responsive as normal diameter masts: thinner mast walls in a larger diameter are thought to be faster in reflex return. This may be true for racing and the large sail sizes associated with Formula and slalom. RDMs are presently wave masts, presently manufactured in shorter lengths; 370cm, 400, 430 and 460cm. RDM masts normally include the necessary shim to make your current boom fit properly. My experience is that RDMs are a definite plus for wave sails. RDMs give the rig a softer feel, slightly more power and a larger trim range. Reducing mast diameter essentially results in added shape, added from the sail’s front edge! Compared to “normal” masts, RDMs require generally 2+cm more outhaul tension to set the sail correctly due to the reduced diameter. I believe that the effective use range of the rig is expanded as the rig becomes more elastic from the RDM influence. Softer feel, expanded range, and reliability in surf are strong arguments for the extra cost of RDMs. I even prefer our O2 5.9 with a 430 RDM, but at the 460 length (O2 6.6) I windsurf with “normal” diameter masts.