A lot of fascinating material about traditional Vietnamese boats can be found at the site of the Vietnam Wooden Boat Foundation. Based in Port Townsend, Washington, this not-for-profit's purpose in life is to preserve the traditional boating heritage of Vietnam before it becomes extinct as, almost everywhere else, the traditional types are being rapidly supplanted by modern ones, and the experienced builders are fast dieing off.
The Vietnamese developed several unique and/or unusual methods of construction. These include several types of sewn-plank boats and boats woven from narrow strips of bamboo. Some of the sewn-plank boats appear to be built with extraordinarily heavy planking. I believe that buffalo dung is used to waterproof the woven boats.
The VWBF has an ambitious program of projects, including the building of a Ghe Nang, which it describes as "a graceful Vietnamese 3-masted sail-powered fishing boat typically built with a woven bamboo hull fitted to a wood top shelf. She was from the region around Danang in central Vietnam and was considered the fastest sailing craft in Vietnam." The organization plans to locate some of the elderly builders of the type, construct a 30' to 36' example, film and document the process, test sail it, and ship it to the U.S. for display. Estimated cost: $75,000.
Other projects include: the translation of J.B. Pietri’s Voiliers d’Indochine into English (completed and published as Sailboats of Indochina, link below) and Vietnamese; and the creation of a maritime heritage museum in Vietnam -- both worthy pursuits.
I don't know anything about the sampan below except that the photo was taken in Hue, and I find high, inboard-sloping bow transom a fascinating feature.All photos used with the kind permission of the VWBF.