In most cases “Tonnage” is not exactly weight. Displacement measures weight of a volume of water displaced, not the vessel’s absolute weight in pounds put on a scale. It should not be confused with other measurements of volume. Since we don’t usually have water in space. . . values are slightly different. The Zuku’s from the desert planet of Blarb might have a different measurement.
Merchant ships on the other hand are usually measured based on the volume of cargo they can carry.
One Displacement Ton is roughly the equivalent of 13.5 kiloliters of volume. This can be solid metal OR a wide open area.
Real world the International Space Station is 419,455KG, which in some books is about 419 metric tonnes (or 924,739 pounds). The habitable volume is 388 cubic meters (13,696 cubic feet). Pressurized volume is 916 cubic meters. This equates to about 2.1 cubic meters of livable space per tonne. Overall the ISS is larger than a six bedroom house with 6 crew, or 152 cubic meters per person. Sounds spacious, but it isn’t. The ISS is spread out over the size of a football field.
By comparison a nucleur submarine has a crew of 14 officers, 18 chief petty officers (senior enlisted) and 109 other enlisted men and pretty much everyone works a lot more than 8 hours a day. A ‘day’ onboard a submarine is 18 hours, not 24. This equates to three different six hour shifts, so someone works 6 hours and then is off for 12 hours. One side effect of this is that three crewmen share the same rack.
Now. An Ohio class submarine is 16,764 tonnes surfaced. 18,750 tonnes submerged. The length is 170 meters (560 feet) and about 13 meters tall (42 feet) and about 10.8 meters wide. So using raw numbers that is 23,868 cubic meters, but because of the dimensions (not a perfect box) we will shave off some space and call it 18,000 cubic meters which includes everything from engines to toilet water. If we are generous and say 1/3 of that is actually habitable space (I’ve been on subs and it might actually be a lot less than that), we are down to 6,000 cubic meters of ‘livable’ but very cramped and claustrophobic space. So. . . Playing the numbers game that is about 42 cubic meters per person and about 1 tonne per cubic meter.
International Space Station and an Ohio Submarine Comparison
| ISS | Ohio Sub | |
| Crew | 6 | 142 |
| Tonne (Metric) | 419 | 18750 |
| Length | 51 | 170 |
| Width | 109 | 10.8 |
| Height | 73 | 13 |
| Pressurized Volume | 916 | 6000 |
| Cubic Space Per Person | 152 | 42 |
| Tonnage per Cubic Meter | 2.1 | 1 |
| Tonne per Person | 70 | 132 |
Below is a list of modern warships. Note that the Zumwalt is one of the most advanced and most automated ships currently produced.
Modern Warships
| Ship Class | Tonnage | Crew | Role | TonePerCrew | Length(m) | Beam(m) | Draft(m) |
| Shchuka | 704 | 38 | Submarine (Medium) | 19 | 57 | 6.2 | 3.78 |
| Flower | 1036 | 85 | Corvette | 12 | 62.5 | 10.1 | 3.51 |
| Barracuda | 1179 | 37 | Submarine(attack) | 32 | 59.77 | 7.49 | 4.39 |
| Whisky | 1350 | 54 | Submarine(Coastal Patrol) | 25 | 83.3 | 6.5 | 4.9 |
| Dekabrist | 1354 | 53 | Submarine (Diesel) | 26 | 76 | 6.5 | 3.8 |
| Gleaves | 1630 | 276 | Destroyer | 6 | 106.15 | 11 | 4.01 |
| K-Class | 2600 | 67 | Submarine (Cruiser) | 39 | 97.65 | 7.4 | 4.51 |
| Hamilton Class | 3250 | 167 | Cutter | 19 | 115 | 13 | 4.6 |
| Golf-class | 3553 | 83 | Submarine(Ballistic Missile) | 43 | 98.9 | 8.2 | 8.5 |
| Anzac | 3600 | 163 | Frigate | 22 | 118 | 14.8 | 4.35 |
| Kilo-class | 3950 | 52 | Submarine(Diesel) | 76 | 74 | 9.9 | 6.5 |
| Adelaide | 4100 | 198 | Frigate | 21 | 139 | 14 | 6.7 |
| Oliver Hazard Perry | 4100 | 235 | Frigate | 17 | 138 | 14 | 6.7 |
| National Security | 4600 | 113 | Cutter | 41 | 127 | 16 | 6.9 |
| Virginia | 7900 | 135 | Submarine(Attack) | 59 | 115 | 10 | N/a |
| Arleigh Burke | 9800 | 303 | Destroyer | 32 | 155 | 20 | 9.3 |
| Ticonderoga | 9800 | 400 | Guided Missile Cruiser | 25 | 173 | 16.8 | 10.2 |
| Sea Wolf | 12139 | 140 | Submarine(Nuclear Attack) | 87 | 108 | 12 | N/A |
| Zumwalt | 14564 | 140 | Modern Destroyer | 104 | 180 | 24.6 | 8.4 |
| Minotaur | 14800 | 802 | Cruiser | 18 | 158.2 | 22.7 | 7.9 |
| Lord Nelson | 18106 | 800 | Battleship | 23 | 135.18 | 24.23 | 8 |
| Ohio | 18750 | 155 | Submarine(Ballistic Missile) | 121 | 170 | 13 | 10.8 |
| Invincible | 20750 | 1000 | Battle Cruiser | 21 | 173 | 23.9 | 9.1 |
| New York | 28367 | 1042 | Battleship | 27 | 175 | 29.03 | 8.7 |
| Alaska | 34253 | 2251 | Heavy Cruiser | 15 | 246.43 | 28 | 9.68 |
| Essex | 36380 | 3120 | Aircraft Carrier | 12 | 270.7 | 45 | 8.4 |
| Typhoon | 48000 | 160 | Submarine(Ballistic Missile) | 300 | 175 | 23 | 12 |
| Iowa | 58000 | 2250 | Fast Battleship | 26 | 270 | 33 | 11 |
| Montana | 70965 | 2572 | Battleship | 28 | 280 | 36.93 | 10.97 |
| Nimitz | 94781 | 5828 | Aircraft Carrier | 16 | 332.8 | 76.8 | 12.5 |
| TI-Class | 517660 | 20 | Super tanker | 25883 | 380 | 68 | 24.5 |
| Seawise Giant | 646642 | 40 | Super tanker | 16166 | 458.45 | 68 | 24.6 |
REFERENCE:
International Space Station
https://www.nasa.gov/mission_pages/station/main/onthestation/facts_and_figures.html
http://iss.jaxa.jp/kids/en/station/03.html
Submarine OHIO
http://en.wikipedia.org/wiki/Ohio-class_submarine
Cruise Ships
https://en.wikipedia.org/wiki/List_of_the_world%27s_largest_cruise_ships
