Has to be a ballast issue but surprised they don’t have shut off valves in case one the pumps has an issue.
The valves have manual override. But depends on when it happens and how quick the crew is to get there. The stability of a ship like this when it is ballasting down is just like a drydock. Stability is directly related to the width of the waterplane. Once the deck goes underwater the GM drops significantly as the width of the waterplane is greatly reduced. If the ballast is not correct for the load and the ship lists, you get what is called the multiplication effect of all the liquid loads shifting to one side. The most critical phase of stability is when the deck goes awash but the loads are all still 100% on the ship due to blocking heights of the yachts.
I took the tour of engineering spaces on Super Servant 3 on a voyage from Nanaimo to Lauderdale. I was surprised to learn that the ballast spaces are evacuated with compressed air. There was a bank of 4-6 very large engines lined up in the forward house section that I took to be generators, but learned they were compressors. Didn't get a spec or close look, but the engines were on the order of 12-71's, or larger. There are motor driven valves for both the lower ballast discharge and upper vent valves for each ballast tank that are remotely operated from a ballast and trim control console. Just like in our favorite WW II submarine movies' they close the vent valves and "Blow the Ballast tanks" out the bottom There was a plaque on the ship that stated that it was built to submarine vessel standards in 1972 in Japan. That plaque was welded on to the bulkhead in a tunnel-like corridor that ran most of the length of the ship on the keel back to the two main engine rooms. While underway, they removed a hatch on one of the tanks and sent a crew inside for maintenance. No idea what they did, in there. Although this incident involves a different vessel, the configuration may be similar.
Took a tour and subsequently wrote a feature on Yacht Express too many years ago... https://www.yachtforums.com/review/dockwise-685-yacht-express.8995/ There's a number of pics in the review for our readers that are not familiar with these sinkers.
Supposedly, they lost power when sinking the ship and couldn't get to or reach the manual valves to close them, causing the one side to fill with ballast water and now the entire cargo has shifted. They have tugs pushing it and are afraid it will roll over without the tugs.
Hard to imagine tugs have enough force to keep it upright if it really wants to go all the way over. But I guess if it is just at zero GM or a little negative it is theoretically possible.
Quite a bit, the yachts are all leaning on top of each other. It's too early to know and the ship isn't stabilized yet as far as anyone knows. It's quite possible that it could roll over, yachts and all.
It could be ugly. At that stage of operations, all of the sea lashings have been removed, and the hull stands are still welded to the deck. Yachts shifting and floating around could hit sharp corners or edges of the stands, not to mention the boat to boat topside contact.
Unfortunately, not that simple. First of all, just getting to the tanks can be an issue. The tank lids are likely underwater or not safely accessed. Recovering this vessel safely requires a highly experienced salvage team which will include many stability scenarios and modeling by qualified Naval Architects. Otherwise you run the risk of completeley sinking the ship and having a much larger disaster.
I have a friend who is captain on one of the boats. He figured his damage wasn't terrible, and said there was only one boat that looked to be damaged more than his.