The hull is between 75' to 100' long, and 25' to 28' wide, with a draft of 3'. Loaded, the vessel weighs about 200 tons; it can carry about 50 tons of cargo and passengers. Crew consists of a captain, helmsman, 2 deckhands, cook/steward, engineer, 2 mechanics, and 2 stokers. Bench seats for a dozen or more persons are provided on the canopied upper deck; dozens more can sit or squat on the decks. Primitive cabins are provided for the crew, but none for the passengers (though many similar vessels might erect a deckhouse on the upper deck, with half a dozen cabins). If need be, up to about 250 persons could be packed aboard.
A cord (2 tons) of green (freshly-cut, soft) wood will supply the boiler for about 5 hours; top speed is about 10 knots. Steam can be raised from "cold" in about 3 hours.
No weapons are normally fitted, but military expeditions have successfully mounted minor weaponry on the decks of this type of vessel -- at most two machine guns on each side of the upper deck, and a cannon on the prow. Heavy wooden bulwarks, or sandbags, are usually fitted if the vessel expects to come under fire, providing a "midships" armor value of 1 (18 DEF in Hero terms).
Hull size 2, engine size 5 (50 tons), fuel bunker 10 (100 tons = 50 cords), mass number (4). Cost, about £10,000 on Earth; if constructed on Mars, with machinery and other iron parts imported from Earth, the cost is about £15,000.