Put simply the shape and surface area that is required to achieve "plane" places great restrictions on other areas of the performance perimeters of a sailing craft, so that when comparing a planing hull to an efficient, light weight displacement (sailing) hull the trade offs and compromises between the two when all are considered tends to place the light weight displacement hull at the fore. Remember that to "plane" the hull has to reach a pre determined speed to generate the required "lift" to get up on plane, before it achieves that required speed it is acting as a less than efficient displacement hull, and if it is designed to be able to plane at very low speeds the hull shape is a very uncomfortable (non "sea kind") riding hull as its speed increases. A planing hull is best suited for boats that have relatively "large" amounts of "constant" power available to motivate them (ie power boats) and they suffers appreciably when their "power" supply is inconsistant and the attitude of the hull to the surface of the water varies dramatically with pitch and roll. Look at power boats that plane, a very flat bottomed "ski" boat performs extremely well on very flat protected waters with a relatively "small" amount of horse power. but put that same boat in an ocean swell with just moderate chop and it is a very uncomfortable (unsafe?) craft. To plane a boat safely and comfortaby in "sea" conditions require an entirely different shaped hull which require considerably more horse power (relative to its displacement) to be able to "handle those rougher conditions. Planing hulls sound great for sailing in theory but, for every type of water borne craft there are always compromises that have to be made between the theory and the practical. the theorically "best" shape tested in a controlled environment often neglects to (or is unable to) take into consideration fully the variations of the full range of actual wind and water conditions that it will be subjected to "in real life" and although it may appear "wonderful" in theory, when the practical trials occur different results are regularely encountered.

As to "Kaffamorans" Mary, there are many references to the "tribes bordering the Red sea" and twin hulled sailing craft predating the "polonesians" in various historical/geographical/social texts, and I have read several references in sociological texts on the peoples and cultures of the islander peoples of the pacific and indian oceans (Melenesians as well as Poloynsians) that refer directly to the Red sea as the origin of "multi hulled" sailing craft.