question re: "tonnage" on ships...

[MamaParrotHead]

here's an obscure question for those of you who are good at digging up this kind of info. I was reading about the "tonnage" of each of the ships...I'm assuming that's minus all cargo and passengers. does anyone know, or can anyone guesstimate, what the additional weight is with those figured in? just curious. :)

[runner15km]

Question: How is the weight of a ship determined and what is gross tonnage?

(courtesy of daveandzeen)

 

Answer: It has been said that the measurement of tonnage is as much an art as a science. As soon as a new regulation is brought out myriad Naval Architects, Engineers, Designers, et al, immediately see how they can get around it to their benefit.

 

The word 'tun' was originally used to describe a size of wooden cask in which wine was shipped from Iberia (Spain & Portugal) to England, and in 1347 a tax of 3 shillings a tun was imposed, and this was called 'tonnage'. A ship's size became known by the number of casks it could carry, and gradually the word tonnage superceded the word burthen which had used previously. It was found that with the design of ships in those days that if one took the length x the breadth x the depth of the hold under the deck and divided it by 100 it was close to the number of casks carried. Hence we have the "Measurement Ton" of 100 cubic feet per ton still in use today.

 

Gross Tonnage - the one most commonly quoted in the cruise industry because it makes ships seem bigger - is the internal volume of permanently enclosed spaces in cubic feet of the ship minus certain spaces above the main or tonnage deck, which are called "exemptions".

 

Net Registered Tonnage - this one the Ship Owners like to keep as small as possible as it is commonly used for for things like harbour dues and other taxes - is the Gross Tonnage less certain non earning spaces and allowances which are called "deductions".

 

Displacement Tonnage - is the actual weight of the water "displaced" by the ship and is usually quoted in long tons of 2240 lbs.

 

Light Displacement Tonnage - this is when the ship is built with nothing in it.

 

Loaded Displacement Tonnage - this is when the ship is fully loaded to the maximum and is on her Summer draft in salt water.

 

Deadweight Tonnage - is the difference between Light and Loaded Displacement Tonnage....the Actual carrying capacity of the vessel.

 

Panama & Suez Canal Tonnages - these are different to the International ones. There used to be a lot of variations between countries and they thought they were being conned, so they came up with their own for everyone.

 

Other tons in common use are the "Short Ton" of 2000lbs, particularly in the US, but not much at sea. The "Metric Ton" or Tonne which equals 2204 lbs and this is becoming more used.

 

So, we have different "tonnages" for different uses. Passenger ship owners like like a large Gross to make their ships appear bigger than the competition, and a small Net to save money. Tanker owners use Deadweight tonnage to show how many actual tons of oil the ship can carry, and the World's Navies use Displacement as their ships weigh heavy for their volume, and to impress or lie to their friends and enemies.

 

I have just got back from the Sea Princess so I thought that these figures for her will help illustrate what I said before.

 

Gross Tonnage 77,499 tons

Net Tonnage 44,193 "

 

Panama Gross 88,788 "

Panama Net 63,441 "

 

Suez Gross 83,502 "

Suez Net 72,538 "

 

From the above it can be seen that Panama and Suez allow almost no Exemptions to the Gross Tonnage and a lot less Deductions to get the Net Tonnage. Dues are usually collected at least partially based on Net Tonnage.

 

On a maximum draught of 26' 7.5" she has a Displacement Tonnage of 39,997 tons (remember this is in actual weight... Metric tons which = 2016 lbs.)

 

Her Deadweight Tonnage is 8,293 Metric tons. ( this is the actual weight she can carry - the difference between Empty as built and a Full load of everything...including bodies.

(courtesy of Peter/Gohaze)

 

 

 

--------------------------------------------------------------------------------

 

Answer: Tonnage is often completely misunderstood and is a constant source of confusion. It all started in ancient Greece when taxes were introduced on shipowners bringing their ships into port, measured against the earning capacity of the ship. They decided the size of the hold by the number of TUNS of wine could fit into the hold and this was called the TUNNAGE. Obviously a measure of volume, this eventually became the mixed in with the weight measurements which confusingly were tons.

 

If you'll bear with me for a second then, this is the situation as I understand it:

 

Gross Tonnage - varies slightly to how it is measured according to the rules of the flag state but is the capacity in cubic feet of the spaces in the hull and enclosed spaces above, available for cargo, stores, passengers and crew (i.e. her earning capacity) divided by 100. Therefore 100 cubic feet of capacity is 1 gross ton. Metricization now means it is measured in cubic metres but I'm not sure of the conversion.

 

Net tonnage - is found by subtracting the working spaces of navigation and machinery, crew and fuel from the Gross tonnage.

 

Displacement tonnage - is the weight of water displaced by the ship and is effectively the entire weight of the ship and all that is in her.

 

Deadweight - Is the weight in tonnes of cargo, fuel, stores, fresh water, crew and passengers carried by the ship when she is down to her marks.

 

The other tonnages are Suez and Panamanian when they measure the earning capacity of the ship by their own rules.

(courtesy of Gerry Ellis)

[big_duck]

Ya had to ask.

 

I think we have another candidate for the Loyal Order of Derf. (not links though tsk, tsk).

[AppleValleyCruisers]

Ya had to ask.

 

I think we have another candidate for the Loyal Order of Derf. (not links though tsk, tsk).

 

I was thinking the EXACT same thing, Don;)

[Chucksta63]

Ya had to ask.

 

I think we have another candidate for the Loyal Order of Derf. (not links though tsk, tsk).

ROTFLMAO :D:p:D:p

 

Sorry Mama p,,, great question, but what an answer!!!!!! lol

[jgmpuma]

I love telling my wife about this kind of stuff when we are on a cruise, and seeing how long it takes before she starts to roll her eyes.

 

The last time out, we were standing on the funnel deck (no nudes there at the time) and I was enlightening her on how to calculate the distance to the horizon. She didn't last long.

[derf5585]

Question: How is the weight of a ship determined and what is gross tonnage?

 

You are now in the "Loyal order of Derf"

 

The Science of Really Gross Things

from

http://www.grossology.org/

 

Terry Gross, NPR Biography (I work with her)

from

http://www.npr.org/templates/story/story.php?storyId=2100593

[smeyer418]

I love telling my wife about this kind of stuff when we are on a cruise, and seeing how long it takes before she starts to roll her eyes.

 

The last time out, we were standing on the funnel deck (no nudes there at the time) and I was enlightening her on how to calculate the distance to the horizon. She didn't last long.

Ok I'll bite how do you calculate the distance to the horizon...inquiring minds want to know or is that inquiring mimes...I never get that right :)

[derf5585]

Ok I'll bite how do you calculate the distance to the horizon...

 

How Far is the Horizon?

from

http://www.boatsafe.com/kids/distance.htm

 

The observer's astronomical horizon is the dashed line through O, perpendicular to the Earth's radius OC. But the observer's apparent horizon is the dashed line OG, tangent to the surface of the Earth. The point G is the geometric, or geodetic, horizon.

from

http://mintaka.sdsu.edu/GF/explain/atmos_refr/horizon.html

[Codfish]

Why is the sky blue?

 

Who's burried in Grant's Tomb?

 

How much wood could a woodchuck chuck if a woodchuck could chuck wood? :rolleyes:

[richfret]

Since we are webbing about ship tonnage (notice my newly invented computer word), thought you might find this fact interesting. The Conquest, Glory, Valor and Liberty are designated as 110,000 gross tons. During the 1960's, I was stationed on the USS Boston, a WW2 heavy cruiser, and the weight of that ship was approximately 35,000 gross tons. Hard to believe that a current cruise ship can be 3 times the size of a WW2 cruiser. By the way, don't be fooled by the term "heavy" cruiser since it refers to the size of the guns and not the weight of the ship. Interesting, eh?

[mikayla73]

Why is the sky blue?

 

 

basically it be because of refracting light .. but here is what I found for an "scientific" answer ..

The sun's rays hit the Earth atmosphere, where the light is scattered by nitrogen and oxygen molecules in the air. The blue wavelength of this light is affected more than the red and green wavelengths, causing the surrounding air to appear blue. At sunset, the sun's light passes farther through the atmosphere, deflecting and decreasing the blue in the air. Scattering by dust particles and pollution in the air causes the sunset to appear red.

 

 

 

http://www.sciencemadesimple.com/sky_blue.html