Lake Superior Shipwrecks
Present Description

After extensive historical research and a lengthy search using a depth sounder, divers Jerry Eliason of Cloquet, Minnesota, and Kraig Smith of Rice Lake, Wisconsin, found the remains of the Onoko in June 1988. The wreck lies in 220 feet of water, 13.5 miles nautical miles east of Duluth and 6.5 nautical miles south of Knife Island. Following their location of the wreck, Eliason and Smith made a series of visual inspections that identified the vessel as the Onoko. The surviving hull structure had been broken almost in half forward the boiler and both sections lie upside down on a mud bottom. Much of the stern is buried beneath a mound of sediment pushed up as the Onoko settled stern first into the bottom sediment. Debris from the wreck lies on the bottom in the vicinity of the break in the hull, and additional material lies off the bow.

Drawing of the Onoko wreck site; MHS/SHPO Collections

Sonagrams of the Onoko reveal that the hull lies on a north-south axis of 010 degrees with the bow to the south. Sonar records reveal that the break in the hull occurred approximately 200 feet aft of the bow. Photographs and observations provided by Jerry Eliason suggest that the hull is buried just beyond the approximate level of the deck. Near the starboard bow photographs document the wood bulwark that was built above the Onoko's iron hull structure and the mushroom anchor drawn into the hawse pipe. Other photographs reveal the forefoot and a fairlead outboard of the starboard bow timberhead. The break in Onoko's hull is approximately 20 feet in width on the starboard side, the bow and stern sections remain attached on the port side. Compression ripples in the freighter's iron skin confirm that the forward section of the hull twisted slightly as stress caused the bottom structure to fail. The interior of the hull exposed by the structural failure also reveals design and construction evidence.

underwater image 1 underwater image 2
Photo 1: Onoko wreck - inverted bow showing mushroom-style anchor and clay borrom, ca. 1990; Jerry Eliason, Scanlon, MN
Photo 2: Onoko wreck - fairlead in bulwarks of inverted hull, 1990; Jerry Eliason, Scanlon, MN

Photographs of the failed section document the double bottom and the complex of floors, longitudinal girders and ceiling that comprised Onoko's lower hull. The bottom of the ship was apparently constructed without an exterior keel. The Onoko's frames and floors were composed of plate reinforced and stiffened by angle iron riveted to one side of the floor and possibly opposing sides of the frames. Above the floors vertical plates approximately three feet in width and reinforced on the top and bottom with angle iron formed the center girder. The center girder was attached to each of the floors by vertical sections of angle iron that extended from the face of the floor to the underside of horizontal angle iron stiffeners riveted along both sides of the top of the center girder. The center girder was additionally reinforced by angle iron brackets on either side of the center girder plate that extended from the upper center girder plate stiffeners out at approximately 45 degrees to the face of the floors.

At least two and perhaps four side girders reinforced the hull of the Onoko. Like the center girder, the side girders were composed of plate approximately 3 feet in width and were attached vertically to the top of the floors. Unlike the center girder, the side girders were stiffened by angle iron riveted horizontally on opposite sides of the top and bottom of the plate. At each floor joint the side girders were attached by a section of angle iron extending vertically from the top of the angle iron stiffening the bottom of the floor to the bottom of the angle iron stiffening the top of the side girder. Although available evidence is inconclusive, it is possible that a smaller wing girder reinforced the turn of the bilge. Above and attached to the top of the center girder and side girders the Onoko was fitted with an iron bilge ceiling or inner-bottom. Above the turn of the bilge the inner-bottom and the hull appear to have formed a watertight joint to permit the inner hull to be used to carry water ballast.

Aft of the break in the hull structure the stern section is exposed for approximately 40 feet, while the rest is buried in the bottom sediment. From the point of structural failure the aft section slopes at a angle of approximately 30 degrees into a mound of sediment pushed up as the vessel settled into the bottom stern first. As no evidence of the deadrise, propeller, or rudder is exposed, it appears that more than 40 feet of the stern remains buried. A photograph of the starboard side of the hull near the point where the hull disappears into the sediment reveals a port light and plate joint that appears approximately 40 feet from the stern in historical photographs.

Debris associated with the Onoko is documented by both sonar and diver examination of the shipwreck. Examination of the site carried out by Eliason and Smith reveals that a ventilator, mast, water tank, bath tub, patent depth sounder, and other material lay scattered on the bottom surface in the vicinity of the break in the hull. Sonar reveals that additional material lies forward of the bow and aft of the point where the stern section disappears into the bottom sediment.

|--Onoko-- |--Historic Description-- |--Construction and Career--|
|--Description of the Wreck Event-- |--Present Description-- |--Significance-- |--Photographs--|
|--Minnesota Lake Superior Shipwrecks-- |
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