The wheel-boat is an Iron Master vehicle for riverborne travel. Extremely large and impressive, especially to their primitive Mute trading partners, smaller wheel-boats are used for travel along the waterways of Ne-Issan, but the largest marques are used primarily for trade across the Great Lakes with the Plainfolk. Prior to the destruction of the Heron Pool only the Yama-Shita family was permitted to build and use the Great Lakes-class wheel-boats, but following the Yama-Shita's disgrace their allies, the Ko-Nikka, were also allowed to use them.
Although the Iron Masters gradually lost their knowledge of high technology following the War of a Thousand Suns and the edict on the Dark Light that followed it, the knowledge of steam technology remained intact, and was employed to create early, small river and ocean-going craft. The vessels developed for use on Ne-Issan's internal waterways used side-mounted paddles and were relatively modest in size, with shallow drafts to allow their use on the rivers.
When the Yama-Shita successfully secured an agreement from the Shogun to permit trade across the Great Lakes with the Plainfolk Mutes, they required a larger vessel capable of traversing the greater distances across the lakes. The result was the Great Lakes-class, an extremely impressive vessel capable of carrying hundreds of passengers and crew and armed with heavy cannon for both defence and offensive operations. The Yama-Shita have maintained this model, with some improvements to its design, ever since.
The Great Lakes-class is a stern-wheeler which employs bow-screws to aid in maneuvering. A Great Lakes-class wheel-boat also typically mounts at least half a dozen cannon on either side. Its crew and complement is unclear, but each vessel is capable of carrying hundreds of passengers.
Prior to 2990 the Yama-Shita had never lost a Great Lakes-class wheel-boat to enemy action before. However, in the Battle of Lake Mi-Shiga between the Iron Masters and Clan Kojak they lost one such vessel, followed by an additional five in the epic Battle of the Trading Post, which severely crippled their trading ability. With the subsequent outbreak of full-scale civil war in Ne-Issan, the Yama-Shita abandoned their attempts at trade and used their remaining ships on enslavement missions, capturing Mutes from the clans bordering the eastern Great Lakes and forcing them into servitude instead.