They typically have cabins, but are designed for racing, excellent low-wind characteristics, large sail plans, and to have decent weight of crew-members to control heeling of the boat under medium winds, and higher.
For many centuries there have been canoes, proas and the like in the South Pacific and other places, with similar displacement in proportion to the sail area and hull length.
Racing dinghies, or dinghy-like modern offshore racers, so common today, are typical examples of the same principle.
In all instances the combination of the major design features: displacement, sail area, length and stability [i.e. —] power to carry sails effectively, is radically different from the combination found in the traditional seaworthy and wholesome yachts.ULDBs are competitive, even after 35 years with open ocean racing participation and podium finishes even today.
The relative low cost to obtain, tough construction and readily easy modifications make an Olson or a Hobie an extremely competitive and fun boat.