Olimpic Sails 420 Radial Plus Mainsail This sail is a bit more powerful in the top section compared to our previous RDL model. This prevents the leech from opening too early in winds over 15 knots. As the shape of this new main is very similar to our previous STD (x- cut) model, we suggest that all sailors that were confident with the old model should switch to it as we are planning to discontinue the STD model soon. As with all Radial designs, this Main is more sensitive to trimming, with small adjustments generating bigger changes in shape compared to the cross-cut. Helmsmen, therefore, need to gain experience and sensitivity to obtain the best performance from this sail. The overall shape is more stable and the sail is longer-lasting. It requires a little more work and attention to mainsheet, cunningham and outhaul to produce the best shape for the various and changing conditions.