The wreck of the whaleback steamer Thomas Wilson, U.S Registry 145616, lies on the bottom of Lake Superior in the harbor of Duluth, Minnesota. The Wilson was a riveted-steel, single propeller freight-carrying steamship. Its hull was of a special form known as a whaleback. Whalebacks were designed by Captain Alexander McDougall to carry bulk cargoes of grain or iron ore economically about the Great Lakes. The majority of the hull and superstructure were built of steel with wood joinery comprising most of the remainder. A pair of Scotch boilers provided steam for the three-cylinder, triple expansion steam engine which drove a single screw propeller.
The Wilson was built of heavy steel plates double-riveted to steel angle frames. Its register length was 308 feet. It was 38 feet in beam and 24 feet depth of hold. The hull form is roughly cigar-shaped; conoidal ends with a parallel-sided midbody, a flat bottom with only a small external keel running to the stern deadwood supporting the propeller and a single balanced rudder. Three rows of half-round steel rubbing plates ran most of the length of the hull for protection while inside locks. The hull was supported by one continuous longitudinal keelson and two bilge keelsons, two hold shelfs and four longitudinal beams under the deck. Additional support was provided by eight stringers which were fastened above and tied together individual frames. A watertight double bottom rested atop the keelsons and stringers. Athwartships beams tied the top shelves together and were fastened to vertical angle-iron stanchions supporting the underdeck longitudinal beams. The bulkheads and stanchions provided the vertical members of the hull truss as well as providing some protection in the event of a leak in a smaller compartment.
Internally, the Wilson was divided into seven watertight compartments by six athwartships bulkheads. Four bulkheads help to support the conoidal portions of the bow and stern and served as collision bulkheads. The other two bulkheads separated the engine and boiler rooms and the boiler room from the hold. The bow compartment forward of the collision bulkhead contained the operating machinery for the steam-powered windlass and capstan on the decks above. It also contained a chain cable locker for the anchor cable and the crew's accommodation below decks in the forecastle. The forecastle had bunks for the crew, as well as a "dunnage room" for spare gear and dunnage materials.
A single cargo hold carried the Wilson's cargo. It had an inner surface designed to facilitate bulk cargo handling. For stability when the vessel was traveling light, water ballast could be carried in the double bottom between the ships' outer hull plating and the hold ceiling plating below the hold. The upper surface of the double bottom was covered with wooden hold ceiling planking atop the steel plates. There were no raised hatch coamings as found on most freighters. Instead, twelve flush-fitting, steel plate hatches were bolted directly to the curve of the upper deck. Some of the hatches were open when the Wilson was rammed and having no coamings to keep waves out, sped the process of flooding the holds. Later whalebacks were fitted with raised hatch coamings to avoid similar problems.
The engine and boiler rooms were aft of the hold and extended vertically up through the main deck in the two largest turrets. The two Scotch water tube boilers were arranged lengthways on each side of the keel at the forward end of the space. Each boiler was hand fired from the front with coal. The fire passed around the water in tubes to the back of the boiler and returned to the front twice before the exhaust gasses passed through uptakes and exited through the smokestack in the largest turret. Steam produced by the boilers was extracted from the top of each boiler and passed through the main steam line overhead to the engine in the next compartment. Steam piping was covered by a jacket of refractory material.
The three cylinder reciprocating steam engine produced 1200 Indicated Horsepower. The high-pressure cylinder was in the center, the intermediate-pressure cylinder was forward and the low-pressure cylinder was aft. The engine was mounted along the centerline of the engine room aft of the boilers. A surface condenser was built into the starboard support pillars of the cylinders. The engine turned a four-bladed propeller at the stern. A number of small auxiliary steam engines powered various pumps and generators. A steam reciprocating pump was mounted to starboard in the engine room and was used to fill and empty the ballast tanks in the double-bottom.
The aftermost compartment in the hull was the area where the steering gear and the tiller quadrant were located. This was a cramped area because of the upward sweep of the hull bottom at the stern. The large counterbalanced rudder was mounted behind the propeller. The upper portion of the rudder stock extended into the compartment. Steering was controlled from the pilothouse using cables running inside the turret and hull to the rudder quadrant atop the rudder stock.
The main deck was open for the entire length of the hull except for the small area covered by the four turrets. The center part of the deck was only gently crowned, but the outboard areas of the main deck curved down to meet the hull sides. To provide a modicum of protection to the crew in heavy seas, pipe rails were fitted to define the edge of the flat portion of the deck. Twelve curved steel hatchcovers were bolted to the deck along the centerline of the deck. Two smaller coal scuttle hatches provided access to the bunkers belowdecks, just forward and to each side of the stern superstructure. Three side hatches in the curving edge of the main deck gave the Wilson and its near-identical the capability to load lumber cargoes.
The superstructure of the Wilson consisted of three decks; the main deck, the cabin deck supported by turrets above the main deck and the slightly elevated wheelhouse deck with a navigating bridge atop. The four vertical cylindrical turrets provided access to belowdecks spaces and supported raised deck platforms above the main deck. The single turret forward contained the steam windlass and companionway to the forecastle. The three turrets aft provided access to the engine and boiler rooms and supported the cabin deck and wheelhouse. The top of the forward turret supported a slightly larger oval-shaped deck level with the cabin deck aft. This deck was surrounded by a pipe rail and held a capstan connected mechanically to the windlass below. A single ladder provided access from the interior of the turret below.
The cabin deck aft was supported by the three after turrets. This deck had an open outside promenade surrounding the cabin proper. The cabin deck formed a teardrop shape with sweeping curves to match the outlines stern below. Deck stanchions along the edges of the cabin deck supported the boat deck above. Pipe railing surrounded the cabin decks' edge between boat deck stanchions. The captain's cabin was right aft with the mates' and engineers' cabins to port and starboard next forward, then the dining room, pantry and kitchen port and starboard, and the crew's mess and chart room to port and starboard forward. The pilothouse was a wooden, glass-enclosed house with a flat roof elevated about four feet above the front of the cabin deck. The large wooden pilot wheel was mounted inside. The roof of the pilothouse was surmounted by a small navigating bridge equipped only with a compass binnacle.
The boat deck atop the cabins was the same size and shape as the cabin deck below except forward where it was cut away to improve visibility from the pilothouse. The deck held only the funnel, six small and two large ventilators and the single boat to starboard aft. The boat was handled by a single iron davit crane.
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|--Post-Depositional Impacts-- |--Present Description-- |--Significance-- |--Photographs--|
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