Anyway, Hollander's aiyassa is a big boat for a river sailing craft -- the big ones weighed in at over 100 tons. They sported huge lateen rigs, with the tip of the boom soaring 100 feet in the air. They also carried a mizzen -- the word for the mizzen, by the way, being the same as in English, since it was an Arabic term to start with. The mainsail rig weighs close to a ton, and in The Last Sailors, it took four men a half hour to raise it, using tremendously crude machinery. In the author's observation, everything aboard was in a constant state of disintegration, and this is borne out by Mertes' photos, which show every bit of the rig pieced together with innumerable, horribly unshipshape knots and splices. There is no pride of seamanship or sentiment here -- the boat being viewed simply as an inexpensive tool with which to do a job.
Aiyassas carry bulk goods like hay and bricks. In 1984, the "upriver" (i.e., north-bound) trade in finished goods had dried up, being overtaken by road and rail transport, so the boats would travel upriver empty, and only return to Cairo with cargoes. They would sail north on the prevailing breeze, and drift south with the current, essentially out of control, moving astern, abeam -- however the current wished to take them. Extremely beamy, the craft are regularly loaded to the utmost limits of their capacity, so that they ride with literally just a few inches of freeboard. Since they're drifting downstream when laden, there seems to be little or no chance of heeling and shipping water over the gunwale, but in the "old days," when they ran upriver laden and under sail, this may not have been the case. They are, however, extremely beamy, providing a great deal of heeling resistance, even with their huge rigs.
Most boats, it seems, were owned by small merchants in Cairo, in fleets of a few boats. Crews were paid $114 a month -- not crew members, but the whole crew? (On the boat described, there were four crew, including the captain.) Even in 1984, they were being displaced by diesel-powered, steel-hulled boats called sandals, and now I can't find anything about aiyassas by Googling, or on Wikipedia. Hard to believe they've disappeared not only from the river but also from the written record, so I have to presume that they're also known by another name, whether or no they're still in use. Can't even find photos by Googling "Nile Sailboat"-- only lots of photos of feluccas, which are much smaller craft. If anyone can point me to a good photo that I could borrow without infringing somebody's rights, please let me know and I'll post it here.
Finally, don't be misled by the ancient Egyptian boats in the links below -- they are unrelated to the aiyassa, but pretty interesting nonetheless.