Below are the assumptions we make about windships in our interpretation of the world of Talislanta...
First off, don't believe everything you read (i.e., we deviate from the main Tal books). Alas the propagandists in Cymril have hidden the true source of many of the windship technologies. Many cultures have found ways to improve upon the great invention, the windship. Here are some of the facts we've uncovered...
Windships aren't very durable. Sure they can take a few hits from a heavy ballista or hurlant, but let's face it... windships are transports first, combat vessels second. Defenses and armament have not evolved much since the days the Phantasians ruled the skies. The ballista, hurlant, archers, and skyfire chute are still the most common weapons of choice. Magics have become common in aiding propulsion, but wind and weather still have the greatest impact on the use and survivability of a given ship. Due to the lightness required for lift, armors are notoriously minimal the Protective Rating of windships is more a function of the fact that they are made of certain woods, and not that they have actual armor.
The Sindarans invented the "catch-sail" as a means of catching more air for forward movement, but with steerable poles to aid in cutting the wind in unfavorable conditions; combined with these Aeriad "flex-poles" (a touch-sensative living pole, that bends on touch, developed by a windship-loving botanomancer) they form an excellent rudderless steering system, that requires less crew to handle.
Cymrilians have minimally refined Phantasian shipbuilding techniques, but in true Cymrilian fashion, most improved on the magics used in levitational and propulsion systems. The annual Windship Regatta held in Cymril has aided in further advances in hull design; most notable are the angular, but windcutting Dracartan hull designs that have won many times.
Similarly, far off in the Kang Empire, a fusion of Sunra boat building & sail design, along with Vajra engineering have produced some amazingly rugged vessels albeit at a higher construction and maintenance cost than some deem practical for large production. The Farad and Kasmirians haven't improved on the ship design, but have developed interesting security solutions.
Other inventions have been created on an individual basis, but haven't yet been adopted by the major Talislantan windshipwrights. The future of windships looks bright.
Lighter Than Air:
One of the consistent characteristics of windships (in our Tal universe) is they never touch the ground, but instead dock by floating 5' - 15' off the ground (tied or anchored somehow); some designs do allow for 'landing' on ground or in water, but very few. This is due to the mass of a ship. Levitationals allow the vessels to magically rise and fall, however because of the mass a wooded ship has, unless the maker's willing to forgo strong construction (i.e., anything with armor above +1), they need to also use some lifting magics (in addition to the levitationals), to give the ship 'lighter' qualities. The Phantasians rely on dream mists that surround the hull with lift magic, whereas most Seven Kingdoms made ships rely on Aeriad lift resins applied over the hull. Other creative methods of elemental magics also work. Other hull materials have been tried, but wood (in its many varieties) is still the most practical.