There is a reason why you were able to find availability on these aft cabins at the last minute.
A function of speed - that is, how hard the engines are working - but, yes, it's a real issue. Fantasy and Dream both are flawed ships when it comes to speeding up. Dream doesn't have to speed up, so it never comes up.
The scenario where you will most likely feel the aft vibrations is on the Eastern Caribbeans itineraries in the rougher winter waters between St Thomas and
Castaway Cay.
We were on the fantasy last week and I actually asked one of the officers during the captains party why the fantasy vibrates so much worse than the Dream and he said it’s only really bad when they have to run all 4 engines. (When they are going fast). He said the dream will vibrate too under the same conditions but the dream very rarely has the need to go fast so they rarely run all the engines together.
Not sure how much of this is true and how much of this is a “Disney answer” but I thought I would share.
Ive been trying to wrap my head around the issue for a few days now, as this subject came up somewhere else.
I know for a fact that the issue exists, as I experienced it on the maiden, and have seen reports that it seems to vary, but what I am seeing is that people are confusing normal operating vibrations with the consistent vibration on the Fantasy. What I mean by that is all of the ships have some kind of vibration on them when coming into port. This is from the thrusters as they work to turn the ship or try and keep her in the channel. Sometimes they will work harder then normal, some officers have a heavy hand on the thrusters. We were on the Magic once, and pulling away from PC, the officer using the thrusters spooled them up so fast, the ship actually rocked coming off the dock.
The issue on the Fantasy, and Ill say the Dream does not have the same issue or at least to the same degree, relates to something in the drive train. (Why do I say that? Easy, coming home from CC the ship is running at or near full speed to make it to PC on time. If the Dream had the same issue to the same extent, someone should have noticed by now. She also runs pretty quick to Nassau from PC) If it were bearings, they would have been corrected by now, as the ship has been out of the water already. Shafts, prop alignment, nicked blade, out of balance, that would have been corrected also in water or at her drydock.
I do not think its the mains, (theres 5)as the mains are all constant speed diesels, that turn generators. Typically they will rotate the mains so they can do maintenance on them, and also even out the hours on them. The power, for those that dont know, goes into a switchboard, and a computer decides how much power goes where etc. and track the usage, and will recommend starting or shutting down additional engines. They spin at the same rpms, whether they are supplying 100% of the ships rated power, 10% of the ships rated power, or sitting in standby mode running. Typically when moving, 2 mains are dedicated, 1 to each drive motor and additional mains are started based on power usage. So in theory at any given time at sea, probably at least 3 mains are running at any time.
The only thing I can come up with, is its something in or with the electric drive motor, that is connected to the shaft. These will turn at different speeds, based on need. Which would mean that the issue is more or less noticeable, and theses engines will work harder or easier based on sea state current direction etc. IIRC the issue seems to be more on the starboard side then port, which to me, seems like there is something not quite right with the stbd drive motor. It could be something internally not balanced right, or some balancer may be bad. To me, this is the most likely issue, as who gets to pay for the fix? If it was there from day 1, and they signed for the ship, its Disneys problem now. If its a manufacturing issue, then it falls to the maker. If MW didn't install it correctly, its on them. Its entirely possible, that in the last drydock, they did find an issue, but these motors are not off the shelf, and sometimes the fix isn't easy. It could be that if something internally is bad on the motor, and needs to be replaced, either there looking at a very lengthy time frame to acquire the replacement part, or it could be the whole unit needs to come out of the ship, and it was something that the yard and
DCL weren't ready for. Its doable, but its not like changing a car engine where you can be done in a day. I saw a documentary where they added a genset (diesel main) to a cruise ship and it took them like 5 days from the time they drained the dock, cut a hole in the side of the ship, removed all of the obstacles, like pipes, wiring, walkways, put in the new support deck, slid the engine in, closed up the ship, and had the engine ready to run.