Freedom Vibration

[FLchick3]

Hi All,

 

A couple of years ago I sailed Freedom in the starboard corner aft Deck 7 and felt no vibration at all. I just got off the Freedom. I stayed in the portside corner aft Deck 7. The vibration in the bed was very, very intense!

 

I have a few guesses as to why the vibration was so strong, but I’m not sure. Any feedback was would be appreciated.

 

1. The Captain noted in a video that the stabilizers had been upgraded.

2. The seas were not super smooth.

3. We had an itinerary change and the Captain said he’d go at full speed the entire way to Grand Cayman (instead of Coco Cay). He may have been going full speed the entire trip.

 

I love the corner aft, but I can honestly say I don’t know if I’d book it again. It was very difficult to sleep at night with that much vibration.

 

Any idea as to the cause?

 

Thanks!

[atnolan94]

I've heard afts tend to have vibration issues from the props. it was likely worsened because he was pushing it to Grand Cayman.

Edited November 4, 2016 by atnolan94

[Merion_Mom]

Free Magic Fingers!!!!

[FLchick3]

Atnolan – thank you.

 

Merion Mom – yup! I told guest services it felt like someone had put a quarter in the slot.

[chengkp75]

The stabilizers would have nothing to do with vibration.

 

The weather, however, definitely would, as would the speed of the ship. Any ship will vibrate differently on any given day, depending on the propeller speed and the wave period and direction. Freedom, not having azipods, does not suffer from the "azipod shimmy" where the stern oscillates horizontally as the pods steer the water flow one direction to another. This is generally increased with following seas, as the directional stability of the pods is lessened.

 

What happens with a propeller and rudder ship like Freedom is that at a certain propeller rpm, the passage of the propeller blade tip close to the hull (at the top of the propeller's arc) causes a pressure wave in the water, and this wave is in harmonics with the natural frequency of the hull (the hull, as an empty box emits amplified vibrations just like a guitar body emits amplified sound from the strings). This harmonic vibration feeds off itself, and becomes stronger and stronger. And again, this frequency can vary with the sea condition. Most times, the ship's officers will note the vibration and speed up or slow down the propeller by a couple of rpm, and this takes out the harmonics. Sometimes, due to schedule, this cannot be done, and the vibration is minimized as best as they can and keep the required speed. I have been on some twin screw ships where the blade passage of the two propellers needs to be offset to keep the vibration down, and there will be special automation to keep the props "out of synch".

 

Edited to note I brain farted and thought this was Carnival Freedom, not Freedom of the Seas, so yes, it does have azipods, and all of the above, including the "azipod shimmy" holds true.

Edited November 4, 2016 by chengkp75

[FLchick3]

chengkp75-

Thank you so much for the detailed explanation. As soon as I heard the Captain say he was planning to go top speed, I knew I was in trouble! I did not plan on getting off at any ports, but I do understand the Captain wanted to make sure we did have 2 ports during a 5-day cruise. The weather was too rough at Coco Cay to allow tenders.

I won’t be doing aft cabins again.

I did read that props tend to vibrate more with age. RCL Freedom is now 10 years old. In addition, the beds shook a lot more than the floor…..which leads me to believe the bed frames may not have been as sturdy as they were a number of years ago.

All in all it was a great cruise and the RCL staff was awesome. I think all crew were excited and happy as this was the final cruise after 7 years in Port Canaveral. The ship is headed to Barcelona.

[songbird1329]

So he did make the port change?

 

We were on the cruise before yours, and had bad weather the whole time. The captain mentioned he might make a port change because of the bad weather.

 

And yes, we felt the motion of the ship during our cruise, he was going top speed most of the time.

[FLchick3]

Songbird - the Captain used the word horrible (or terrible?) when describing your weather in the video. I'm sorry you didn't have better weather! Hopefully next time.

[Queen of Oakville]

When we sailed FOTS, it was a few years ago and we had the forward most cabin on deck 6 or deck 7. I recall lots of vibration.

 

I find the same thing on Oasis.

 

I'm sensitive to the vibration myself, and it gives me headaches or sea-sickness like symptoms. When the vibration is really bad, I take some gravol and hope for the best.

 

Don't think it would bother me at night, and I would probably sleep through it.

[FLchick3]

Thank you for the feedback.

[fletch1027]

So he did make the port change?

 

We were on the cruise before yours, and had bad weather the whole time. The captain mentioned he might make a port change because of the bad weather.

 

And yes, we felt the motion of the ship during our cruise, he was going top speed most of the time.

 

I was on that sailing as well. He made the change because he knew we would end up missing Coco Cay and he wanted us to have a 2nd port day as opposed to only one port day on a 5 night cruise. Captain was awesome! I love Grand Cayman!