Interesting Calculation

[tripman]

I was looking at past pictures and thought of an interesting question. How much does the depth of the ship change when fully loaded as opposed to empty (passengers only, not crew or supplies). Being an engineer, I couldn't help but make a rough calculation. Assuming 2000 passengers (an average number for todays ships) at 150 lbs per person, that comes to 300,000 lbs of people. Removing them from the ship, will cause the ship to decrease its depth the amount of water it no longer needs to displace. So 300,000 lbs of water is 4,800 cubic feet of water. Assuming a 900 ft long and 105 ft wide ship, that means a depth of about 0.6 inches is required to equal 4,800 cubic feet of water. That is quite interesting, the ship is so big, 2,000 people changes the depth less than 1 inch.

[lougee1043]

i will try to remember that ---- could be worth a bet drink at one of the lounges --will bring your post with me for proof

[MikeT718]

:D Too much time on your hands...LOL :D

[wench58]

Being the daughter and mother of engineers, this type of discussion is common at our house.

 

Thank you for doing the calculations so that I will be able to appear intelligent at the next family gathering!

[tripman]

:D Too much time on your hands...LOL :D

 

Not really, it only took about a minute.

[Terpnut]

If you also consider all the merchandise, food, water and trash that is also removed from the ship, there's alot more weight to be considered!

 

BTW, don't most cruise ships have some sort of ballast control so that their waterline is always the same?

[caribbean dreams]

Also each passenger brings aprox a 50 lb suitcase onboard with them so add that to each passengers weight.

[Terpnut]

Also each passenger brings aprox a 50 lb suitcase onboard with them so add that to each passengers weight.

Looking around during embarkation, I think your estimate may be on the low side--many people easily had over 100 lbs worth of stuff! :D

[uomograsso]

Very interesting topic. Considering the weight of most cruise ships 70,000 - 158,000 tons, the 150 tons of passengers is 0.1% to 0.2% of the entire ships weight. Maybe if you got everyone to jump up all the same time you might see the ship bob up and down a little :rolleyes:

[seamama1]

Stop, stop!! My head is about to explode!!:eek:

[caribbean dreams]

Looking around during embarkation, I think your estimate may be on the low side--many people easily had over 100 lbs worth of stuff! :D

 

I totally agree, i was just trying to go off the luggage limit for the airports.

Many people bring way to much luggage.

[dkjretired]

Very interesting topic. Considering the weight of most cruise ships 70,000 - 158,000 tons, the 150 tons of passengers is 0.1% to 0.2% of the entire ships weight. Maybe if you got everyone to jump up all the same time you might see the ship bob up and down a little :rolleyes:

 

The tonage of ships does not have anything to do with weight. It is a measurement of the inside volume of the ship. Heres a good explanation.

 

Gross Tonnage. What does it mean? Tonnage is neither the weight of the vessel, nor a measurement of the amount of water it displaces, but rather a measurement of the vessel's volume. Gross tonnage refers to the overall volume of a vessel. Definition: Each gross registered ton equals 100 cubic feet of enclosed space within the ship. OR; the total cubic feet of enclosed space divided by 100. Thus a ship with 11,000,000 cubic feet of enclosed space would have a rating of 110,000 GRT.

[uomograsso]

The tonage of ships does not have anything to do with weight. It is a measurement of the inside volume of the ship. Heres a good explanation.

 

Gross Tonnage. What does it mean? Tonnage is neither the weight of the vessel, nor a measurement of the amount of water it displaces, but rather a measurement of the vessel's volume. Gross tonnage refers to the overall volume of a vessel. Definition: Each gross registered ton equals 100 cubic feet of enclosed space within the ship. OR; the total cubic feet of enclosed space divided by 100. Thus a ship with 11,000,000 cubic feet of enclosed space would have a rating of 110,000 GRT.

 

Now I know, thanks. The density of water is 62 lb/cu. ft, so depending on the displacement of the vessel (not all the enclosed space is below the waterline) the weight of the water displaced could be 434,000,000 lbs to 979,600,000 lbs for 100% to 43,400,000 to 97,960,000 for 10%. Which still means the weight of the passengers is a small percentange of the weight of the water displaced by the vessel. I would still like to find a way to get all the passengers to jump up at the same time to see if it would have any effect.:D

[Tristan]

We must also factor in the differences in weight....some passengers weigh

60lbs (children) and some weigh 360lbs.