From the Newcastle Courant 8 December 1843:
WARLIKE PREPARATIONS. — The Penelope steam-frigate has arrived in Kingstown harbour, loaded almost to the water’s edge with large gun-boats. They are intended for the Upper [ie non-tidal] Shannon, and the large lakes formed by that river in its progress towards the lower branch. A considerable number of persons were collected on the banks of the canal to witness their being towed to Portobello from the basin at Ringsend. They are immense boats, with great beam, capable of carrying two guns, and accommodating a large body of men. They are double banked, and each pulled by twelve rowers. As floating batteries they are most formidable, and furnish an important, as well as a novel, addition to the armament already existing in this country.
Irish waterways history 