I don't understand the word "tunnels" in the context of the vibration she had. I think what the person in the original article wanted to say is that the Roger Blough had a half-tunnel installed on the underside of the stern, above the propeller. That was installed in August 1972 at AmShip Lorain. The skewered-propeller was added in the 1990s.Duluth guest wrote: November 3, 2025, 11:55 am One thing Capt. Cooper might have been referring to is vibration issues the ship had early in its career.
The following quote from the Shipwatcher News' Great Lakes Ships histories page for the Blough:
The entire history can be accessed at https://greatlakesships.wordpress.com/roger-blough/The Blough suffered from vibration issues due to lack of water flow to her propellers. Throughout the 1970’s, engineers studied the vessel and worked out a solution to these problems. Tunnels were added in her stern to improve water flow. Her original propeller was eventually replaced with a skewed propeller to help smoothen her ride.
Here's a some pictures of the propeller and half-tunnel: https://www.behance.net/gallery/2039778 ... er-Blough#
The Roger Blough had a reputation for springing, more so than other ships, perhaps that is what Capt. Cooper was talking about. She was instrumented with hull stress gauges through most of the '70s, along with several other ships as part of a study on revisions to Great Lakes Vessel Strength Standard, that both the US and Canada were undertaking at that time. I'll see if I can find some papers on the subject, along with screen grabs.
Vibration on the transom stern vessels was a big problem in the early years, especially when operating in deep water. Early in it's career, the captain of the Charles E. Wilson (now John J. Boland) entered his quarters one time only to see his brand-new color TV vibrate off a table and on to the deck, destroying it.