Difference in size of ship on Transatlantic

[Leni]

We are thinking of doing a TA on the Vision of the Seas next year. We have taken TA's before but they have been on larger ships such as the Liberty of the Seas, Mariner and the Equinox. This would be a real change in size of ship. I would appreciate any comments or thoughts.

[navybankerteacher]

We are thinking of doing a TA on the Vision of the Seas next year. We have taken TA's before but they have been on larger ships such as the Liberty of the Seas, Mariner and the Equinox. This would be a real change in size of ship. I would appreciate any comments or thoughts.

 

Size is relative - we have done T/A's on Noordam, Mariner of the Seas , and Queen Mary 2 - greater displacement but comparable passenger loads - which to us is more important in feeling the "size" of a ship. This October we will do one on Prinsendam, half of Vision's displacement and a third of the passenger load - and are really looking forward to the smaller ship feel.

[John Bull]

In heavy Atlantic weather a good big 'un is always better than a good little 'un.

But Vision is no minnow.

 

I like Vision, just my size - small enough to be friendly & "personal".

Very adequate amenities but of course a lot fewer than her big sisters.

 

Sea days bore me, wouldn't want a trans-A on any ship.

But your preferences are clearly very different. ;)

 

JB :)

[BlueRiband]

We are thinking of doing a TA on the Vision of the Seas next year. We have taken TA's before but they have been on larger ships such as the Liberty of the Seas, Mariner and the Equinox. This would be a real change in size of ship. I would appreciate any comments or thoughts.

 

On a transatlantic crossing size matters. Even the venerable QE2 - a thoroughbred ocean liner - pitched more and had more motion than her much larger and newer sister QM2. Although ships of various sizes make repositioning cruises a smaller ship will have a rough ride in storm conditions. Nobody can predict the north Atlantic weather regardless of the time of the year.

[NMLady]

We are thinking of doing a TA on the Vision of the Seas next year. We have taken TA's before but they have been on larger ships such as the Liberty of the Seas, Mariner and the Equinox. This would be a real change in size of ship. I would appreciate any comments or thoughts.

 

All of our ta's have been on what could be considered smaller ships. No problem. We've had some choppy seas but the ship handled them well.

[bbwex]

The thought that size is a controlling factor is not quite correct. Of course, we are not comparing a little charter fishing boat with a cruise ship, and we are not comparing a cruise ship to a fully loaded oil supertanker either. By any real standards, Vision of the Seas is not a small ship, and the comparison with one of the larger cruise ships is what matters here (and even some of the smaller cruise ships as well).

 

A given sea state will affect different ships differently, and not necessarily so that the larger ship has an easier time. There are many factors: recent storms, wind speed, wind direction, wave frequency, wave height, how many different wave trains are involved, relative wave direction, waterline length of the ship, position of the Center of Motion of the ship, ship's sail area, ship's speed, ship's bow design (particularly heading into the seas), etc., etc., etc. In a given situation, the 78,000 ton Vision of the Seas might have an easier time than one of the larger ships you mentioned. Of course, it could have a worse time as well. But then it might change speed or direction and reduce the effect too.

 

The bottom line is that Vision of the Seas is large enough that you need not worry that you went "too small." And the effect of any given sea state is too complicated for anyone short of a naval architect to calculate. The seas could be calm during your crossing, or they could be anything else too. Relax, and get ready to enjoy your T/A.

[Leni]

Thank you to all who responded so quickly. I feel much more comfortable now with the thought of the Vision of the Seas . We had a rough two days on the Brilliance sailing from Iceland to Boston last year. However,the Vision is taking a southern Atlantic route from Tampa to the Mediterranean so that should not be as rough as compared to a more northern route. I hope !:)

[mimsymarie]

If you decide to book, come join the roll call.

[dorisis]

Thank you to all who responded so quickly. I feel much more comfortable now with the thought of the Vision of the Seas . We had a rough two days on the Brilliance sailing from Iceland to Boston last year. However,the Vision is taking a southern Atlantic route from Tampa to the Mediterranean so that should not be as rough as compared to a more northern route. I hope !:)

 

Spring weather is usually better for TA crossings. Fall is hurricane season.

[navybankerteacher]

Spring weather is usually better for TA crossings. Fall is hurricane season.

 

The North Atlantic in Spring has not warmed from the winter and is, in fact, subject to occasional storms. While hurricane season extends through November, the most active period is over by mid-October - while most westbound trans-Atlantics sail in late October through November. Even if there is a hurricane, they are well plotted and avoidable. Because they are quite rare, the fact is that October and November weather in the Atlantic is better (and a whole lot warmer) than April and May weather.

[sullaRaffaello]

Crossed the Atlantic on the Seabourn Legend in 2010 and encountered force 10 for a few days. Even though it was definitely rough, I thought she handled it quite well for such a small ship, i.e., 440 feet long, 10,000 tons.

[Leni]

Thank you everyone for your advice....I booked the cruise:).

[Galveston Cruiser]

The North Atlantic in Spring has not warmed from the winter and is, in fact, subject to occasional storms. While hurricane season extends through November, the most active period is over by mid-October - while most westbound trans-Atlantics sail in late October through November. Even if there is a hurricane, they are well plotted and avoidable. Because they are quite rare, the fact is that October and November weather in the Atlantic is better (and a whole lot warmer) than April and May weather.

 

We have completed 9 TA's; agree 100%:)

[A2Mich]

As far as ship size, many transatlantic liners back in the day were in the 20,000-30,000 ton range. Also, a contributing factor to ship stability is the ship's draft. Most cruise ships on the market today are generally shallow draft ships. Today's 200,000 GRT monsters draw less water than her deeper-hulled 25,000 GRT ocean liners of years past. From what I've been able to gather, all other things being equal, a ship with deeper draft can handle rougher seas than with a shallow draft. One thing that possibly chengkp75 can answer more accurately is how much difference the bulbous bows of today's ships make overall than the straight stem bows on older ships. I understand the purpose and general design of the bulbous bow, but don't know if it's design is dependent on the actual wave size it cuts through for optimum stabilization, or if the wave size doesn't have a major impact on the wave cancellation effects.

Edited April 14, 2014 by A2Mich

[chengkp75]

As far as ship size, many transatlantic liners back in the day were in the 20,000-30,000 ton range. Also, a contributing factor to ship stability is the ship's draft. Most cruise ships on the market today are generally shallow draft ships. Today's 200,000 GRT monsters draw less water than her deeper-hulled 25,000 GRT ocean liners of years past. From what I've been able to gather, all other things being equal, a ship with deeper draft can handle rougher seas than with a shallow draft. One thing that possibly chengkp75 can answer more accurately is how much difference the bulbous bows of today's ships make overall than the straight stem bows on older ships. I understand the purpose and general design of the bulbous bow, but don't know if it's design is dependent on the actual wave size it cuts through for optimum stabilization, or if the wave size doesn't have a major impact on the wave cancellation effects.

 

You caught me on a slow day. The older "liners" are actually not any deeper than the new mega-ships. The United States draws 31 feet, and the Allure does to. Now, that same draft is supporting much more weight these days; Allure at 225,000 GT, while the US is at 53,000 GT. Mostly, this is due to an increase in beam, from 101.5 ft (Panamax) for the US to 154 ft for the Allure, and an increase in length (990 ft to 1187 ft). Because today's ships have much more "sail area", they require the stabilizers to counteract wind heel, which affected the smaller liners less.

 

The ability to "handle rough seas" is dependent on length to beam ratio (the older liners and the new Cunarders are much slimmer), beam to displacement ratio, and most importantly the "metacentric height". There are two points inside a ship (hopefully inside the ship, or it isn't real stable) that accounts for the stability of the ship. The center of buoyancy is located somewhere down below the waterline, and represents the point where the force of buoyancy can be considered to act on the hull. The center of gravity will be somewhat higher in the ship, and represents the position where all the various weight of the ship would be concentrated in one point (weight versus distance). Now when a ship rolls, the center of gravity is fixed in the ship, but the center of buoyancy moves (rolling to starboard submerges more hull on the starboard side, less on port, so the center of buoyancy moves to starboard. Now, since the buoyancy acts in the up direction, and the gravity acts down, you now have a force couple which will force the ship to roll back to port. The metacentric height is the distance between these two centers. The greater the metacentric height, the more righting moment will be generated, and the quicker the roll period will be. Very small metacentric height, will result in less righting, and more sluggish rolling. Cruise ships tend to have high metacentric heights, and would "snap roll" without the stabilizers and anti-heeling systems to modulate the roll. Sorry.

 

The bulbous bows are more for efficiency than wave cancellation effect. It is designed to create a lifting wave that tends to pull the ship through the water.

 

All of the above boring stuff leads to my statement that size is no guarantee of minimizing motion at sea. As another poster stated, there are a vast amount of variables, and no two ships, even of the same class, will behave exactly the same on the same day, even if only a few miles apart. But as a whole, the cruise ships of today will act similarly, regardless of size, with the exception of the Cunard ships which are designed more for their ability to sail with efficiency in the poor weather of the North Atlantic, than for the ability to pack the maximum numbers of souls onboard.

[Leni]

I have learned a lot about the architecture and the physics of a ship from the preceding comments. Turbulence in air or motion on the water are concerns. In cruising, we trust in the design of the ships and the competence of the Captains (and companies). I will try a mid sized ship on a TA and then I will be better able to compare both the experience and the environment compared to other larger ships.

Thank you again!!

[british betty]

I have learned a lot about the architecture and the physics of a ship from the preceding comments. Turbulence in air or motion on the water are concerns. In cruising, we trust in the design of the ships and the competence of the Captains (and companies). I will try a mid sized ship on a TA and then I will be better able to compare both the experience and the environment compared to other larger ships.

Thank you again!!

 

I'm not sure you'll meet such wonderful people as you did this year though ;)

 

Bernice :D

[cruising cockroach]

I understand tonnage for ships is a measure of volume and not weight. not even the volume of displaced water, these days. With lighter materials used in modern ship superstructure, ships can have the same water displacement but have much greater volume.

[keyguide]

As far as ship size, many transatlantic liners back in the day were in the 20,000-30,000 ton range. Also, a contributing factor to ship stability is the ship's draft. Most cruise ships on the market today are generally shallow draft ships. Today's 200,000 GRT monsters draw less water than her deeper-hulled 25,000 GRT ocean liners of years past. From what I've been able to gather, all other things being equal, a ship with deeper draft can handle rougher seas than with a shallow draft. One thing that possibly chengkp75 can answer more accurately is how much difference the bulbous bows of today's ships make overall than the straight stem bows on older ships. I understand the purpose and general design of the bulbous bow, but don't know if it's design is dependent on the actual wave size it cuts through for optimum stabilization, or if the wave size doesn't have a major impact on the wave cancellation effects.

You are correct about the draft ...a 20,000 ton vessel w/31' draft will ride well

compared to a 200,000 ton with the same draft(bob's like a cork)Theoretically the larger ship should have an even deeper draft but alas most ports they visit would be unable to accommodate them.

[navybankerteacher]

You are correct about the draft ...a 20,000 ton vessel w/31' draft will ride well

compared to a 200,000 ton with the same draft(bob's like a cork)Theoretically the larger ship should have an even deeper draft but alas most ports they visit would be unable to accommodate them.

 

An additional variable is the size (length and beam) of the ship relative to wave height and length. A shorter ship dealing with very long wave length seas will climb up and ride down, while a longer ship encountering shorter wave lengths will tend to knife through -- with all sorts of permutations in between.

[chengkp75]

I understand tonnage for ships is a measure of volume and not weight. not even the volume of displaced water, these days. With lighter materials used in modern ship superstructure, ships can have the same water displacement but have much greater volume.

 

Sometimes its volume, sometimes its weight.

 

Gross Tonnage is the total volume of the ship in cubic meters.

Displacement is the weight of water displaced by the volume of the ship in the water, in tons.

Deadweight is the amount of weight the ship can carry, in tons.

Lightship is the weight of the ship itself, in tons.