chengkp75

The stabilizer will produce force in opposition, but it does so about 1/4 out of phase with the wave roll, so the sine curve gets a "bump" in it part way up or down the slope, which changes the roll period slightly. Ocean wave period is never steady. Technically, all "azipods" provide propulsion and steering. A "fixipod" is fixed straight ahead to only provide propulsion. The two center pods on the Oasis class ships, and the center pod on RCI's Freedom class ships are "fixipods". Apparently, having the two center pods only provide a straight fore/aft waterflow prevents the course control problems of QM2. All ships with azipods experience the "azipod shimmy" to some extent (a port/stbd yawing motion aft) caused by the water flow coming into and leaving the propeller being swept back and forth as the pods make small corrections to keep course. Having 4 large pods doing this, obviously caused large problems. Many believe that cruise ships are "top heavy", but it is because the ships have so much "metacentric height" (so the center of gravity is actually lower than most think) that they are considered "stiff" vessels, with great stability. However, as your research will show, a stiff vessel "snap" rolls, and this is uncomfortable, so the stabilizers were added to slow the roll period.

The stabilizers require a small amount of rolling motion to start reacting. Their purpose is to change the roll period, by introducing force at a different time than the wave. An interesting note regarding the QM2, is that after sea trials, where it was found that the 4 azipods did not provide any lateral stability (ability to keep to a steady course) in following seas, that the ship went back into dry dock, and a "skeg" or wedge shaped extension was added to the after end of the keel, to provide the needed stability.

Stabilizers do nothing for pitching, and do not stop rolling. Stabilizers are designed to slow the ship's rolling motion to a more comfortable speed. The thought that 4 small stabilizer wings could counteract the rolling force of 80,000 tons of ship is just not realistic.

Since a Great Circle path is defined as the shortest distance between two points on a sphere, there is only one Great Circle route between two ports. Between NYC and Southampton, the Great Circle route takes you very far north.

Well, the record for a manned free-fall lifeboat drop is 40 meters, and the record for dropping a boat, without personnel is 60 meters. The boat flipping over is a result of there not being enough "ballast" (the crew) inside the boat. If you google the highest lifeboat drop, you will see that with only 10 men in the boat, and dropped from 40 meters, it does not exhibit that behavior. When free-fall boats were first introduced, a regulation was enacted that the release mechanism be tested every 3 months. This meant that ships were dropping their boats every three months. This was recommended by the boat manufacturers not to be done, as it was subsequently found to overstress the boats from impact. Subsequently, testing rigs were made that allowed the release hook to release the boat, but a hydraulic cylinder only allows the boat to slide down a couple of inches. Note that everyone in a free-fall boat is strapped in with a six-point harness, not only for the fall, but because keeping the weight in the seats if the boat rolls over, will automatically roll the boat back upright.

No, but I would trust maritime accident investigators, who also interviewed passengers, and with a mandate to find the truth, over a 60 minutes interview with a mandate to sell commercials. I have read the report, several times.

Have you read the official report?

Every 5 years, the boats, davits and wires are weight tested. They don't use people, they use water filled bags to equal the weight. The SOLAS weight of an individual is 87.5kg (192.5lbs), and the boats are loaded to 110% of the capacity for the test. Any time repairs are made to the boats or davits, a weight test is required. The wires are renewed every 5 years. For a lifeboat like Quantum's, that is actually 78,000 lbs. The boats have to be lowered, stopped, hold the load for a couple of minutes, and then they can be lowered to the water and the releasing gear is tested with the overload weight. 370 people will fit in a boat marked for 370 people, but even if everyone was the standard weight or less, it ain't gonna be comfortable. This is tested prior to a manufacturer's boats gaining approval.

Well, I'm always in a minority here on CC, but as someone who has done emergency drills on ships for decades, has experienced real emergencies on ships, who has run cruise ship muster drills and fire and boat drills, and who has had the required training in crowd and crisis management, no I don't believe it would be complete chaos.

For frames, I don't know, but tempered glass panels can be obtained in most major cities (Buenos Aires might be closest). If they have the dimension drawings, then getting a fabricator to extrude the aluminum frames should not be hard, bronze might be a bit more difficult. It is getting the installers to the ship that could be another problem. I suspect that some of the "nordic balconies" will become "interior" cabins with steel plate over the windows.

And, another example of PR for the passengers. Marine engineers live by the old US Navy SeaBee slogan "the difficult we do immediately, the impossible takes a little longer". The engineers will try their darndest to fix anything that breaks, but there are some things that require a part that cannot be fabricated onboard. We come up with "innovative" "outside the box" or just plain "nuts" solutions that work, but I can guarantee that there could be situations on both of these expedition ships that the engineers could not repair, only patch until port. And, I've worked many years on the same ship, in fact taking it from the builder's yard, so I knew everything about that ship, and there were things we couldn't do.

Andy, diverting to the Zodiac incident, this sounds like it was something under the deck, where are the fuel tanks located? Could a combination of fuel leak and non-functioning bilge blower have resulted in an explosion? No real experience with RHIBs, so just speculating.

Andy, I did a quick read on the training requirements for the Polar Code last night, and I thought I saw that 2 or 4 (can't remember which) of operational experience in polar waters was required for certification.

Under international law, not any US state, ships have a zero tolerance for drugs. While CBD products have THC levels within state or federal guidelines, there is almost always a detectable level. I have had knee pain for years, but while I was working on ships, I never considered using a CBD product, as there are documented cases of crew who used CBD having a positive drug test while onboard.

I believe that they are controlled similarly to the Celebrity "Infinite balcony" windows, where the bridge has a complete override of the window controls.

At the time it happened, "rogue waves" were considered to be "old salt's tales", and I was not on the bridge at the time. The bridge watch described it as two 15 meter seas hitting the ship from different directions at the same time. Was this a rogue wave? Can't say. I will say that it stopped a RO/RO cargo ship doing 10 knots dead in the water. It lifted the stern out of the water, and tripped the starboard engine on overspeed as the propeller came out of the water. It also fractured a salt water cooling line in the bow thruster space. This was in the North Atlantic in winter. Busy night for the engineers.

While it's true that no one will likely know, it is illegal on all ships.

Portland and Sebago.

Unless there is a lawsuit, no one other than Carnival will see it, and even then it will up to each legal team to determine whether to make it public or not.

Using average statistics, anyone less than 5'10" (for a male) has their center of gravity below the top of the handrail, so he would have had to hop up while leaning over to fall over the rail. That is why the rail heights are set that way.

Then again, the NCL Dawn hit a rogue wave, stove in some forward cabin windows, and flooded 62 cabins, a good number of insides.

Did the Hanseatic ever get hit by a rogue wave? Was the Hanseatic alongside the Polaris when the wave hit the Polaris? As I've said, from 46 years at sea, unless you have two ships in the same location, at the same time, heading in the same direction and speed, you cannot say how the two ships would perform compared to each other. Why does the NHTSA use identical tests to compare car safety? Because that is the only way to do it scientifically, rather than emotionally.

I believe that the next cruise has already been cancelled. Again, you cannot make something that never fails. How many tons of force do you design for? How much does this affect the vessel's stability, or operational ability? Do you design ship's balconies so that no one can ever jump over the side?

It is still required that each boat be lowered to the water and exercised monthly.

I'm very surprised that any ship still has an aerator in the hot tubs. Back in the early 2000's, we were directed to disconnect them on NCL. The reason is that the temperature of the water in the hot tub is the optimum breeding temperature for legionella bacteria (Legionnaire's disease), and since this is an aerosol disease, creating air bubbles in this potentially dangerous environment just provides the optimum transmission vector to get the bacteria into your lungs.