(illustration by Fernando G. Baptitsta; courtesy National Geographic, Click picture for larger image.)
An article in the June '09 issue of National Geographic features an early-ninth-century dhow wreck that was discovered off Sumatra, Indonesia. Loaded with Chinese trade goods, the wreck provided archaeologists with much detail about the nature of trade between China and the Persian Gulf, and about the boats that engaged in it.
About 58 feet long and 21 feet in beam, the hull was sewn, not nailed or pegged. Sewing was probably coir (fiber from coconut husks), and caulking with paperbark wadding. Planking was hardwood -- possibly teak -- and the deck was bamboo. According to the typically illuminating NG-style illustration, it had a straight keel, straight stem and sternpost (like a boom), and a steering oar a la a Viking ship. It had a keelson, deck beams that extended through the hull planking, and used lead ingots for ballast. The most un-dhow-like feature, by modern standards, were the lug sails, as opposed to settees.
It's thought that it may have been built in Oman -- a major dhow-building center right into the 20th century. The reconstruction is similar to an Omani type "known as a baitl qarib", according to the article. The book The Dhow, by Clifford Hawkins, which I've referred to in recent posts, doesn't describe this type.
A full-scale, sailing reproduction of the ancient boat, named the Jewel of Muscat, is under construction in Oman, with launching planned later this year. More on that project here. Thanks to Oman Holidays for the comment on my previous post drawing my attention to this impressive, ambitious project.