Well, I had read just in casual discussions back when the Allure had the azipod issue that affected our sailing that there had been other issues with the pods on other ships or even the same ship previously...something about the design or something like that. So then in late 2013 it wasn't unheard of or even surprising to some of those discussing the mechanical things. Now less than 2 yrs later I'm reading of another ship in their fleet with propulsion issues. I think there was mention this one was a damaged prop? Either way, I'm curious how frequent these issues arise. I've never even heard of one of the Disney ships having propulsion issues but then I've not been cruising all that many years either. It's just a question. Is it fairly normal for ships to have various propulsion issues?
On 1 particular pod maker, even with the "fix" they are still encountering issues. Depending on who you ask its either a poor design or the fact that a very narrow part of the bearing takes more pressure then the rest of the bearing, promoting uneven wear or failure. Pods are only designed to last for about 5 years before overhaul. Why some are failing early is anyones guess.
Disney has had propulsion issues before. More often then you would think. Rumor has it that prior to 2010, the Magic had a main fail for some odd reason. The main was out of service for several months before being replaced in her 2010 or 2008 dry dock, I forget which off hand. Also, The Magic ate one of the channel marker poles at Castaway Cay damaging her port running gear. There was some pretty good vibrations on her until she got to drydock in Oct of 2010, and a lot of experimenting on how fast that shaft could turn with out too much vibration. So, they have had there share of issues, just not to the extent that other lines have had with the pods. Theres also been a few instances of a ship with reduced power for several hours, until the issue was fixed and was back to normal.
Keep in mind this also. Almost all ships that carry passengers, and there might be a few that differ, use electricity to turn the actual motors that turn the props. Whether its a azipod that are favored by lot of lines, or the traditional prop and rudder arrangements. The way it works is this. Theres 4 parts to the system. A diesel engine, a attached generator,( called a genset) the drive motors and power distribution system. When a ship is designed, someone figures out that the ship will need a total power capability of say 50mw of power. The marine engineer will sit down and say, this ship needs 6 diesel generators, 4 at 15mw capability and 2 at 20mw. The 4 15mw engines provide power most of the time under normal circumstances with the 2 20s as a back up. All of the power goes into a big box, (theres usually 2 jic) and the chief engineer on the ship decides what engine will run, while another may be down for routine maint. So Eng 1,3 and 4 may be supplying power to the ship, while 2 is resting or getting pm. The ships computer will pretty much dictate how many engines need to run, and monitor there performance etc. While the ship is in port, the ship may only need 1 main running so they may run 2, and 1,3 and 4 may rest for a while, with 5 and 6 for a reserve. On occasion, one of the back up gensets may run wile the normal mains are down for whatever reason. While at sea,typically 1 genset will be dedicated to each drive motor. On say Allure, that has 3 pods I believe, 3 engines will be dedicated to power the 3 pods. Additional gensets will power the ships needs, like hotel services. On the DCL ships, they use 2, 1 for each drive motor, with additional gensets for hotel services. In either case, based on electrical demand, will dictate how many other gensets will run.
So, in reality, a ship could have issues, and no one would know, unless the actual drive motors or pods are the issue. In which case, at sea or in the water there is nothing that can be done unless its a simple fix like a collector ring or connection that needs to be changed. Theres very little on a electric drive motor or pod that can be fixed in the field. It usually requires a drydock and removal or extended down time with heavy equipment and specialists to repair.
