Oasis of the seas speed and turning ability

[Clovis8]

I don't want to derail the other thread about the overboard incident so I'm starting a new thread.

 

I find the idea a ship as big as Oasis can turn fast fascinating.

 

I'm curious what would define a fast turn though? How long would it take Oasis to do a 180 for example?

 

If someone has a source for the nautical technology I would love to read it.

Edited November 7, 2015 by Clovis8

[chengkp75]

I don't want to derail the other thread about the overboard incident so I'm starting a new thread.

 

I find the idea a ship as big as Oasis can turn fast fascinating.

 

I'm curious what would define a fast turn though? How long would it take Oasis to do a 180 for example?

 

If someone has a source for the nautical technology I would love to read it.

 

As I said over on the other thread, this is not real common public information. Not classified, just not something that would be of interest.

 

Every ship has a "pilot card" posted on the bridge, that gives any visiting pilot information regarding the ship's handling characteristics. This will include full speed, stopping distance, and turning circle diameter for various conditions. It also includes things like the blind spot distance directly in front of the ship (not usually a problem for cruise ships, but can be several hundred yards on large container ships).

 

While most ships I've been on give the turning circle as being the diameter of the turning circle at full speed and full helm (35* or hard over), I can't say whether or not this is the case for cruise ships.

 

Cruise ships have high tech steering capabilities that most ships do not have. Either use of azipods giving direct thrust lateral motion, or for ships with propellers and rudders which will have Becker rudders (with a small "trim tab" on the trailing edge like an airplane's aileron) which produce lateral "lift" like an airplane wing, these devices are designed to assist with lateral and rotational control while docking, at minimal speed. Most ships do not have these devices, and rely on tugs and thrusters for docking. Conventional rudders lose all effect under about 3 knots of forward speed. The drawback to these steering devices is that their effect is magnified greatly as the speed increases, and therefore this turning force acting on the ship creates "an equal and opposite reaction" meaning the ship heels (lists) away from the turn. At speed, and full helm, this can be truly frightening. As I've said, the Norwegian Sky did this, and heeled over 30-35*.

 

Because of this, I would believe that the pilot card information for a cruise ship would note the turning circle for a reasonable amount of helm that would not create more than 10-15* of heel. Of course, the less helm used, the larger the turning circle.

 

Also along these lines, thrusters become nearly ineffective above 3 knots, which is why some large cruise ships have doors that close the thruster tunnels off when underway, to improve hydrodynamics. So thrusters cannot assist in turning while moving at speed.

 

My feeling, and this is somewhat of a SWAG (scientific wild ass guess) would be that limiting the ship to 10-15* heel (which would frighten most passengers, but is common on ships), the Oasis would take several hundred yards laterally to complete a 180* turn.

[Clovis8]

Very Interesting thanks.

 

I can't believe how nimble it is. Really impressive.