In the deciding to build submarines in Manitowoc, several obstacles had to be considered. One of the early doubts that Navy officials had about building submarines at Manitowoc concerned the sideways launching, required because the river there was too narrow to permit stern-first launchings. All previous vessels built at Manitowoc had been launched in this matter. However, a submarine’s low stability and circular hull presented unique problems.  The design of the launching ways had to be considerably altered in order to permit safely launching submarines.
Another obstacle was that of getting large ships to sea from the Great Lakes. There were three main routes available for reaching the ocean. The main route was via the Saint Lawrence river, but this was before the construction of the Saint Lawrence Seaway. The series of locks between Cornwall and Lachine on the Saint Lawrence River were only 270 feet long and had only 14 feet over the sills; these dimensions restricted this part of the route to small vessels. Another route was the Erie Canal, but the combination of shallow depths and clearance under fixed bridges eliminated this route.
The route via the Mississippi River to New Orleans required entering the Chicago Sanitary Canal by way of the control lock at Lake Michigan, then passing into the Chicago River and thence to Lockport, Illinois, where vessels entered the Illinois River. From the Illinois River, ships passed into the Mississippi River at Grafton, Illinois, about 38 miles above St. Louis, and then on to New Orleans and the sea. The obstacles on this route were the depth of the Sanitary Canal, the many bridges that crossed it, some of which were fixed, and the controlling depth of water at Chain of Rocks Channel in the Mississippi River about halfway between Grafton and St. Louis, which was 9 feet. In order to overcome this obstacle, Manitowoc Shipbuilding developed a plan to use floating drydocks to lift the submarines out of the water and traverse safely that 9 foot-deep stretch of the Mississippi River.
After Manitowoc boats had completed their trials on Lake Michigan, they sailed under their own power to Navy Pier in Chicago. The boats were then prepared for the trip through the Chicago River and the Chicago Sanitary Canal. What follows is a typical experience for those boats making the transit from Manitowoc to the port of New Orleans.
The boats were towed by two tugs, one on the bow, and one astern, through Chicago to Lockport in order not to foul up the engine circulating water systems. There were also some very tight turns and the river had very little maneuvering room. Furthermore, while lift machinery had been installed on nearly all the bridges that had previously been incapable of opening, there were still some, such as the railroad bridge at Western Avenue, for example, that couldn’t be opened at various times.
At Western Avenue it would be necessary to trim the submarine down in the water in order to pass under this bridge, and in order to minimize the pollution of the trimming tanks as much as possible, the boat was partially trimmed down to about 19 ft. 6 in. draft while in the outer harbor alongside the dock. The tugs would then pull away from the dock and head for the Control lock that had to be passed through before entering the Chicago River. The tow would enter the river at 6:10 a.m. This early transit of the Loop District was, of course, planned so as to interrupt traffic in the heart of the city of Chicago as little as possible. It was a thrilling sight in the misty predawn to see the nine bridges in the Loop District raise in sequence on a time schedule as the tow approached. It was also an experience to transit this narrow cut between the tall buildings on either side of the river. The tow would proceed and enter the Sanitary Canal just before reaching the railroad bridge at Western Avenue. The clearance under this bridge was extremely critical. The tow was stopped and lay-to while calculations were made. The clearance of the bridge above water level was obtained by reading the gauge on the bridge and then a determination was made as to the draft of the submarine that was required to enable it to pass under. This draft figured to about 21 ft. 6 in., so water was flooded into the trimming tanks to obtain exactly this draft. With the boat trimmed to this draft, the stability was very touchy, particularly fore and aft. During this passage the personnel on board were forbidden to move in order not to disturb the fore and aft balance of the boat, and the tugs had to operate very carefully in order not to dip the bow of the submarine. As the tow passed slowly under the Western Avenue bridge, there was a clearance of about two inches with the bridge and the clearance under the keel was about six inches! This evolution took about one-hour to accomplish.
After all the bridges over the Chicago River had been renovated as necessary, so they could be opened, these delicate procedures did not have to be followed for future boats. After that, the boats were able to be quickly towed through Chicago to Lockport, thence to the drydock waiting down river. The trip from the lock at Chicago to the drydock was a distance of about 34 miles, and some 51 bridges had to be passed through or under. On arrival at the trimmed-down drydock, the submarine entered the dock, was centered on the blocks, and secured. The dock was then pumped dry, the submarine braced, and the tug made up to the dock. Then commenced the 1,500 mile journey to New Orleans, a journey that consisted of numerous narrow twists and turns of the rivers, many bridges, several locks, and shallow spots (at times, the tow would have to be tied up to a tree on the riverbank while waiting for some dangerous situation ahead to clear up).
(Above Information Courtesy of Les Guille, Menhaden's Last Commanding Officer, who visited the Manitowoc Maritime Museum in Manitowoc, Wisconsin, in August of 1999)
USS Menhaden (SS-377) in the floating drydock on the Illinois River near Lockport, Illinois, on July 16th, 1945.
(Photo Courtesy of John Mansfield, RM2(SS), Menhaden, 1963-65)
Front Cover of Captain David H. McClintock's Transit Procedure Manual
(Manual Courtesy of David H. McClintock, Jr., son of Captain David H. McClintock, Menhaden's First Commanding Officer)