These first wooden boats were more or less replicas of the earlier reed boats. They were built square at each end, more barge than boat. Since Egypt lacked good timber, the shipwrights devised a special technique. They used the acacia tree, with brittle wood which only comes in short lengths. But they cut planks three feet long, put together like brick, building up the hull from a central plank laid for the bottom. They would join the three foot planks together edge to edge by means of long close-set dowels, and when the hull was built up they stretched crossbeams over it. They made no ribs or frames, and caulked on the inside, using papyrus fibers.