Ship size measurement?

[CRUISING71]

How do you compare size of ships? Is it by tonnage? The bigger the tonnage the bigger the ship?

 

For example...we wonder how much bigger the Splendor to the Spirit? A lot bigger or not noticable? Splendor is 113,00 tonage and Spirit is around 88,000 tonnage?

 

Thanks

[*Mach*]

Gross tonnage can be deceptive... it's not a measurement of weight, it's measurement of volume.

The Splendor is 952 feet long with a beam (width...) of 116 feet. The Spirit is 960 feet long with a beam of 106 feet. The narrower beam allows her to transit the Panama Canal.

You may remember that the Splendor did a 47 day 'round the horn adventure to reposition to the west coast.

:)

[CRUISING71]

Thank you Host Mach...

 

Let assumed we hit turbulance water...would the ship with the most gross tonnage (like the Splendor) rock less than the ship with less tonnage (like the Spirit)?

 

Thanks,

Tibbie

[*Mach*]

Thank you Host Mach...

 

Let assumed we hit turbulance water...would the ship with the most gross tonnage (like the Splendor) rock less than the ship with less tonnage (like the Spirit)?

 

Thanks,

Tibbie

 

 

All modern cruise ships are quite stable and resistant to roll as they're equipped with 'stabilizers'... wing like structures that extend from the hull. For higher speeds the stabilizers are retracted. They cost about a 10% penalty in fuel.

On a Conquest class ship the stabilizers are about 15 feet long, very similar size for the Spirit class.

Unless the seas get fairly high the roll and pitch of the ship is pretty much nill...

 

By the way, it's Mach... the host thing is just a title... kinda...

:)

[PunkinsDad]

To muddy the waters even more, passenger vessels, such as cruise ships, are measured by Gross Registered Tonnage (GRT). GRT is actually determined by the interior volume of the ship, with no direct relationship to the actual displacement (weight) of the vessel.

 

Cargo and naval vessels are measured by Dead Weight Tonnage (DWT) which is a measure of the actual weight of the vessel at full load, determined by the amount of water displaced by the hull.

 

While in your example of the Splendor and the Spirit, the Splendor undoubtedly actually weighs more, the difference in actual weight is far less than it would be between two cargo ships of the same general dimensions.

 

But Mach is right, as always, cruise ships are incredibly stable. It takes pretty serious waves to get them to move a whole lot. I'm one of those weirdos that actually likes it when the ship is "rocking and rolling"!! :D

[2Ports]

A Gross Registered Ton is about 100 cubic feet - goes way back to the 19th century when they used BF barrels for stuff. It's a measure of volume. More important than the size of the stabilizers is the hull shape - the Spirit class is much more "seaworthy" or "stable" than the Conquest class or the Fantasy class - personally I like the feel of the ship moving.

[CRUISING71]

More question on these ships...speed.

 

How come it goes so slow? Top speed for Splendor was only 22 knots. With ship that size...couldn't they go faster?

[caribsun]

http://www.nauticalcities.com/compare.php

 

And i believe the SS United States holds the record for fastest liner crossing the Atlantic at 37 knots.

[Livin4Real]

More question on these ships...speed.

 

How come it goes so slow? Top speed for Splendor was only 22 knots. With ship that size...couldn't they go faster?

 

You answered your own question "with a ship that size". Cruise ships are massive steel structures that push a huge bow wake. The amount of resistance is huge. It takes a massive amount of power to move that massive amount of steel, 22 knots is a good amount of speed for something that big. There's about 2 stories of ship below water that you don't even see.

[*Mach*]

More question on these ships...speed.

 

How come it goes so slow? Top speed for Splendor was only 22 knots. With ship that size...couldn't they go faster?

 

 

Hydrodynamic drag... to buy and additional knot in speed would require an additional fuel burn on the order of 10 to perhaps 15%.

It's for that reason that you'll rarely see a ship at it's rated cruise speed. Expect to see 15 to 17 knots under most conditions.

Remember, these ships are moving at whatever speed 24 hours a day. Even 15 knots over 24 hours is quite a bit... 360 nautical miles, 410 statute miles...

:)

[*Mach*]

You answered your own question "with a ship that size". Cruise ships are massive steel structures that push a huge bow wake. The amount of resistance is huge. It takes a massive amount of power to move that massive amount of steel, 22 knots is a good amount of speed for something that big. There's about 2 stories of ship below water that you don't even see.

 

 

Nearly three... most Carnival ships draw about 27 feet of water...

:)

[joebat1]

How do you compare size of ships? Is it by tonnage? The bigger the tonnage the bigger the ship?

 

For example...we wonder how much bigger the Splendor to the Spirit? A lot bigger or not noticable? Splendor is 113,00 tonage and Spirit is around 88,000 tonnage?

 

Thanks

 

Remember Regulation 7(3), the next time you are wondering about the "size" of the ship:(3) The calculation shall be sufficiently detailed to permit easy checking.. so there should be no problem checking the "size" of the ship.....LOL

 

The current method is based on an Convention, adopted by IMO in 1969, was the first successful attempt to introduce a universal tonnage measurement system.

 

Previously, various systems were used to calculate the tonnage of merchant ships. Although all went back to the method devised by George Moorsom of the British Board of Trade in 1854, there were considerable differences between them and it was recognized that there was a great need for one single international system.

 

The Convention provides for gross and net tonnages, both of which are calculated independently.

 

The rules apply to all ships built on or after 18 July 1982 - the date of entry into force - while ships built before that date were allowed to retain their existing tonnage for 12 years after entry into force, or until 18 July 1994.

 

This phase-in period was intended to ensure that ships were given reasonable economic safeguards, since port and other dues are charged according to ship tonnage. At the same time, and as far as possible, the Convention was drafted to ensure that gross and net tonnages calculated under the new system did not differ too greatly from those calculated under previous methods.

 

Gross tons and net tons

The Convention meant a transition from the traditionally used terms gross register tons (grt) and net register tons (nrt) to gross tons (GT) and net tons (NT).

 

Gross tonnage forms the basis for manning regulations, safety rules and registration fees. Both gross and net tonnages are used to calculate port dues.

 

The gross tonnage is a function of the moulded volume of all enclosed spaces of the ship. The net tonnage is produced by a formula which is a function of the moulded volume of all cargo spaces of the ship. The net tonnage shall not be taken as less than 30 per cent of the gross tonnage.

 

The used formula to fiqure the Gross tonnage:

 

The gross tonnage (GT) of a ship shall be determined by the following formula:

 

GT = K1V

 

where: V = Total volume of all enclosed spaces of the ship in cubic metres,

 

K1 = 0.2 + 0.02log10V (or as tabulated in Appendix 2).

 

Regulation 4

 

Net Tonnage

 

(1) The net tonnage (NT) of a ship shall be determined by the following formula:

 

NT = K2Vc 4d2 + K3 (N1 + N2),

 

3D 10

 

in which formula:

 

(a) the factor 4d2 shall not be taken as greater than unity;

 

3D

 

(b) the term K2Vc 4d2 shall not be taken as less than 0.25 GT; and

 

3D

 

© NT shall not be taken as less than 0.30 GT, and in which:

 

Vc = total volume of cargo spaces in cubic metres,

 

K2 = 0.2 + 0.02 log10Vc (or as tabulated in Appendix 2),

 

K3 = 1.25 (GT + 10,000)/10,000

 

D = moulded depth amidships in metres as defined in Regulation 2(2),

 

d = moulded draught amidships in metres as defined in paragraph (2) of this Regulation,

 

N1 = number of passengers in cabins with not more than 8 berths,

 

N2 = number of other passengers,

 

N1 + N2 = total number of passengers the ship is permitted to carry as indicated in the ship's passenger certificate; when N1 + N2 is less than 13, N1 and N2 shall be taken as zero,

 

GT = gross tonnage of the ship as determined in accordance with the provisions of Regulation 3.

 

(2) The moulded draught (d) referred to in paragraph (1) of this Regulation shall be one of the following draughts:

 

(a) for ships to which the International Convention on Load Lines in force applies, the draught corresponding to the Summer Load Line (other than timber load lines) assigned in accordance with that Convention;

 

(b) for passenger ships, the draught corresponding to the deepest subdivision load line assigned in accordance with the International Convention for the Safety of Life at Sea in force or other international agreement where applicable;

 

© for ships to which the International Convention on Load Lines does not apply but which have been assigned a load line in compliance with national requirements, the draught corresponding to the summer load line so assigned;

 

(d) for ships to which no load line has been assigned but the draught of which is restricted in compliance with national requirements, the maximum permitted draught;

 

(e) for other ships, 75 per cent of the moulded depth amidships as defined in Regulation 2(2).

 

Regulation 5

 

Change of net tonnage

 

(1) When the characteristics of a ship, such as V, Vc, d, N1 or N2 as defined in Regulations 3 and 4, are altered and where such an alteration results in an increase in its net tonnage as determined in accordance with the provisions of Regulation 4, the net tonnage of the ship corresponding to the new characteristics shall be determined and shall be applied without delay.

 

(2) A ship to which load lines referred to in sub-paragraphs (2)(a) and (2)(b) of Regulation 4 are concurrently assigned shall be given only one net tonnage as determined in accordance with the provisions of Regulation 4 and that tonnage shall be the tonnage applicable to the appropriate assigned load line for the trade in which the ship is engaged.

 

(3) When the characteristics of a ship such as V, Vc, d, N1 or N2 as defined in Regulations 3 and 4 are altered or when the appropriate assigned load line referred to in paragraph (2) of this Regulation is altered due to the change of the trade in which the ship is engaged, and where such an alteration results in a decrease in its net tonnage as determined in accordance with the provisions of Regulation 4, a new International Tonnage Certificate (1969) incorporating the net tonnage so determined shall not be issued until twelve months have elapsed from the date on which the current Certificate was issued; provided that this requirement shall not apply:

 

(a) if the ship is transferred to the flag of another State, or

 

(b) if the ship undergoes alterations or modifications which are deemed by the Administration to be of a major character, such as the removal of a superstructure which requires an alteration of the assigned load line, or

 

© to passenger ships which are employed in the carriage of large numbers of unberthed passengers in special trades, such, for example, as the pilgrim trade.

 

Regulation 6

 

Calculation of volumes

 

(1) All volumes included in the calculation of gross and net tonnages shall be measured, irrespective of the fitting of insulation or the like, to the inner side of the shell or structural boundary plating in ships constructed of metal, and to the outer surface of the shell or to the inner side of structural boundary surfaces in ships constructed of any other material.

 

(2) Volumes of appendages shall be included in the total volume.

 

(3) Volumes of spaces open to the sea may be excluded from the total volume.

 

Regulation 7

 

Measurement and calculation

 

(1) All measurement used in the calculation of volumes shall be taken to the nearest centimetre or one-twentieth of a foot.

 

(2) The volumes shall be calculated by generally accepted methods for the space concerned and with an accuracy acceptable to the Administration.

 

(3) The calculation shall be sufficiently detailed to permit easy checking.

[CapeCodCruiser]

Remember Regulation 7(3), the next time you are wondering about the "size" of the ship:(3) The calculation shall be sufficiently detailed to permit easy checking.. so there should be no problem checking the "size" of the ship.....LOL

 

The current method is based on an Convention, adopted by IMO in 1969, was the first successful attempt to introduce a universal tonnage measurement system.

 

Previously, various systems were used to calculate the tonnage of merchant ships. Although all went back to the method devised by George Moorsom of the British Board of Trade in 1854, there were considerable differences between them and it was recognized that there was a great need for one single international system.

 

The Convention provides for gross and net tonnages, both of which are calculated independently.

 

The rules apply to all ships built on or after 18 July 1982 - the date of entry into force - while ships built before that date were allowed to retain their existing tonnage for 12 years after entry into force, or until 18 July 1994.

 

This phase-in period was intended to ensure that ships were given reasonable economic safeguards, since port and other dues are charged according to ship tonnage. At the same time, and as far as possible, the Convention was drafted to ensure that gross and net tonnages calculated under the new system did not differ too greatly from those calculated under previous methods.

 

Gross tons and net tons

The Convention meant a transition from the traditionally used terms gross register tons (grt) and net register tons (nrt) to gross tons (GT) and net tons (NT).

 

Gross tonnage forms the basis for manning regulations, safety rules and registration fees. Both gross and net tonnages are used to calculate port dues.

 

The gross tonnage is a function of the moulded volume of all enclosed spaces of the ship. The net tonnage is produced by a formula which is a function of the moulded volume of all cargo spaces of the ship. The net tonnage shall not be taken as less than 30 per cent of the gross tonnage.

 

The used formula to fiqure the Gross tonnage:

 

The gross tonnage (GT) of a ship shall be determined by the following formula:

 

GT = K1V

 

where: V = Total volume of all enclosed spaces of the ship in cubic metres,

 

K1 = 0.2 + 0.02log10V (or as tabulated in Appendix 2).

 

Regulation 4

 

Net Tonnage

 

(1) The net tonnage (NT) of a ship shall be determined by the following formula:

 

NT = K2Vc 4d2 + K3 (N1 + N2),

 

3D 10

 

in which formula:

 

(a) the factor 4d2 shall not be taken as greater than unity;

 

3D

 

(b) the term K2Vc 4d2 shall not be taken as less than 0.25 GT; and

 

3D

 

© NT shall not be taken as less than 0.30 GT, and in which:

 

Vc = total volume of cargo spaces in cubic metres,

 

K2 = 0.2 + 0.02 log10Vc (or as tabulated in Appendix 2),

 

K3 = 1.25 (GT + 10,000)/10,000

 

D = moulded depth amidships in metres as defined in Regulation 2(2),

 

d = moulded draught amidships in metres as defined in paragraph (2) of this Regulation,

 

N1 = number of passengers in cabins with not more than 8 berths,

 

N2 = number of other passengers,

 

N1 + N2 = total number of passengers the ship is permitted to carry as indicated in the ship's passenger certificate; when N1 + N2 is less than 13, N1 and N2 shall be taken as zero,

 

GT = gross tonnage of the ship as determined in accordance with the provisions of Regulation 3.

 

(2) The moulded draught (d) referred to in paragraph (1) of this Regulation shall be one of the following draughts:

 

(a) for ships to which the International Convention on Load Lines in force applies, the draught corresponding to the Summer Load Line (other than timber load lines) assigned in accordance with that Convention;

 

(b) for passenger ships, the draught corresponding to the deepest subdivision load line assigned in accordance with the International Convention for the Safety of Life at Sea in force or other international agreement where applicable;

 

© for ships to which the International Convention on Load Lines does not apply but which have been assigned a load line in compliance with national requirements, the draught corresponding to the summer load line so assigned;

 

(d) for ships to which no load line has been assigned but the draught of which is restricted in compliance with national requirements, the maximum permitted draught;

 

(e) for other ships, 75 per cent of the moulded depth amidships as defined in Regulation 2(2).

 

Regulation 5

 

Change of net tonnage

 

(1) When the characteristics of a ship, such as V, Vc, d, N1 or N2 as defined in Regulations 3 and 4, are altered and where such an alteration results in an increase in its net tonnage as determined in accordance with the provisions of Regulation 4, the net tonnage of the ship corresponding to the new characteristics shall be determined and shall be applied without delay.

 

(2) A ship to which load lines referred to in sub-paragraphs (2)(a) and (2)(b) of Regulation 4 are concurrently assigned shall be given only one net tonnage as determined in accordance with the provisions of Regulation 4 and that tonnage shall be the tonnage applicable to the appropriate assigned load line for the trade in which the ship is engaged.

 

(3) When the characteristics of a ship such as V, Vc, d, N1 or N2 as defined in Regulations 3 and 4 are altered or when the appropriate assigned load line referred to in paragraph (2) of this Regulation is altered due to the change of the trade in which the ship is engaged, and where such an alteration results in a decrease in its net tonnage as determined in accordance with the provisions of Regulation 4, a new International Tonnage Certificate (1969) incorporating the net tonnage so determined shall not be issued until twelve months have elapsed from the date on which the current Certificate was issued; provided that this requirement shall not apply:

 

(a) if the ship is transferred to the flag of another State, or

 

(b) if the ship undergoes alterations or modifications which are deemed by the Administration to be of a major character, such as the removal of a superstructure which requires an alteration of the assigned load line, or

 

© to passenger ships which are employed in the carriage of large numbers of unberthed passengers in special trades, such, for example, as the pilgrim trade.

 

Regulation 6

 

Calculation of volumes

 

(1) All volumes included in the calculation of gross and net tonnages shall be measured, irrespective of the fitting of insulation or the like, to the inner side of the shell or structural boundary plating in ships constructed of metal, and to the outer surface of the shell or to the inner side of structural boundary surfaces in ships constructed of any other material.

 

(2) Volumes of appendages shall be included in the total volume.

 

(3) Volumes of spaces open to the sea may be excluded from the total volume.

 

Regulation 7

 

Measurement and calculation

 

(1) All measurement used in the calculation of volumes shall be taken to the nearest centimetre or one-twentieth of a foot.

 

(2) The volumes shall be calculated by generally accepted methods for the space concerned and with an accuracy acceptable to the Administration.

 

(3) The calculation shall be sufficiently detailed to permit easy checking.

 

:eek::confused::eek::confused: