I'm not sure I wholly buy the paddlewheel (prop walk) effect. A ship loaded as heavily as Dali was, sits way down in the water. The paddlewheel effect happens mostly on ships sitting high with the top of the prop barely under the water or even with the blade coming out of the water as it makes it's turns. I've seen that on empty tankers going up the Houston ship channel on their way to get a load at one of the refineries.
On a loaded ship, sitting low in the water, the paddlewheel effect from the bottom side rotation is almost equally offset by the reverse force as the other prop blade(s) rotate across on the top side of the revolution. (I think this ship's prop has 3 blades) The 2 (or 3 if 3 blade prop) forces offset each other...




I spent several years on a low rpm tugboat and by design and ballast, I never saw paddlewheel effect. I spent 2 years in the gator Navy and never saw it there either except maybe, in small craft, under 50' long that weren't loaded down.

Now, on a Navy LCU, or newer LCM you see it but only because they had flanking rudders. Flanking rudders allow the vessel to pretty much move sideways (crab) while keeping bow and stern aligned straight perpendicular to the shore or come up adjacent to a dock and just move sideways right alongside the dock and tie up.. The main rudder behind prop controls the bow and the flanking rudders control the stern.


This ship had no flanking rudder, but did have bow thruster which would be useless above 5 knots forward speed..

Meanwhile...

As expected, the ship's owners have filed legal requests invoking a many decades old claim to limit liability.

An excerpt from a Fortune news article follows:

quote "The owner and manager of a cargo ship that rammed into Baltimore’s Francis Scott Key Bridge before the span collapsed last week filed a court petition Monday seeking to limit their legal liability for the deadly disaster. In a federal court filing on Monday, the ship’s owner Grace Ocean Private Limited and operator Synergy Marine PTE denied any fault or neglect over the collapse that claimed the lives of six construction workers. “The [bridge collapse] was not due to any fault, neglect, or want of care on the part of [ship owner & operator], the Vessel, or any persons or entities for whose acts [ship owner & operator] may be responsible,” it reads. The companies’ “limitation of liability” petition is a routine but important procedure for cases litigated under U.S. maritime law. A federal court in Maryland ultimately decides who is responsible — and how much they owe — for what could become one of the costliest catastrophes of its kind. Singapore-based Grace Ocean Private Ltd. owns the Dali, the vessel that lost power before it slammed into the bridge early last Tuesday. Synergy Marine Pte Ltd., also based in Singapore, is the ship’s manager. Their joint filing seeks to cap the companies’ liability at roughly $43.6 million. It estimates that the vessel itself is valued at up to $90 million and was owed over $1.1 million in income from freight. The estimate also deducts two major expenses: at least $28 million in repair costs and at least $19.5 million in salvage costs. The companies filed under a pre-Civil War provision of an 1851 maritime law that allows them to seek to limit their liability to the value of the vessel’s remains after a casualty. It’s a mechanism that has been employed as a defense in many of the most notable maritime disasters, said James Mercante, a New York City-based attorney with over 30 years of experience in maritime law. “This is the first step in the process,” Mercante said. “Now all claims must be filed in this proceeding.” Cases like this typically take years to completely resolve, said Martin Davies, director of Tulane University Law School’s Maritime Law Center. “Although it’s a humongous case with a very unusual set of circumstances, I don’t think it’s going to be that complicated in legal terms,” he said. “All aspects of the law are very clear here, so I think the thing that will take the time here is the facts. What exactly went wrong? What could have been done?” A report from credit rating agency Morningstar DBRS predicts the bridge collapse could become the most expensive marine insured loss in history, surpassing the record of about $1.5 billion held by the 2012 shipwreck of the Costa Concordia cruise ship off Italy. Morningstar DBRS estimates total insured losses for the Baltimore disaster could be $2 billion to $4 billion. The wreckage closed the Port of Baltimore, a major shipping port, potentially costing the area’s economy hundreds of millions of dollars in lost labor income alone over the next month. Experts say the cost to rebuild the collapsed bridge could be at least $400 million or as much as twice that, though much will depend on the new design. The amount of money families can generally be awarded for wrongful death claims in maritime law cases is subject to several factors, including how much money the person would have likely provided in financial support to their family if they had not died. Generally, wrongful death damages may also include things such as funeral expenses and the “loss of nurture,” which is essentially the monetary value assigned to whatever moral, spiritual or practical guidance the victim would have been able to provide to their children."

[This message has been edited by maryjane (edited 04-02-2024).]