The original trailer for Chessie (a Core Sound 20 Mk 3) carried her (1" yellow pine keel w/SS half-oval) on three hard-rubber rollers.  The side bunks were adjusted to carry loads just enough to keep her balanced at the verticle.  That arrangement concentrated her load on just three places and, over many miles at highway speeds, the stresses caused by potholes, RR Xings, unseen speed "humps," etc., -- caused the rollers to be severely damaged at their centers (the only load-bearing part).  Note