What is Ships: Definition and 83 Discussions

A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying goods or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished from boats, based on size, shape, load capacity, and tradition. In the Age of Sail a "ship" was a sailing vessel defined by its sail plan of at least three square rigged masts and a full bowsprit.
Ships have supported exploration, trade, warfare, migration, colonization, and science. After the 15th century, new crops that had come from and to the Americas via the European seafarers significantly contributed to the world population growth. Ship transport is responsible for the largest portion of world commerce.
As of 2016, there were more than 49,000 merchant ships, totaling almost 1.8 billion dead weight tons. Of these 28% were oil tankers, 43% were bulk carriers, and 13% were container ships.

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  1. K

    B Time and right angle traveling twins paradox

    So in scenario in which two ships(A and B) are moving relative to each other, and towards each other; each ship will measure the other to have a velocity. Within special relativity no observer himself moves. Do you agree? If you agree, assume each of the above two ships sends out shuttle along...
  2. D

    B Does Pushing a Ship from a Ramp Affect Its Movement?

    If you push a floating object from land, the object should move away. If you push a floating object from the floating object, the force should be equal and opposite, and floating object won't move. What if you push a floating object from a ramp, where the ramp is connected to the floating...
  3. H

    B Some Questions About Drag (for ships in water and airplanes in air)

    I'm interested in the very basics of drag, both for ships in water and airplanes in air. Here's what I have so far : Flow of the medium can be laminar or turbulent. As the relative speed of the vessel increases, the more likely the flow is to be turbulent. Laminar drag increases linearly...
  4. Strato Incendus

    Writing: Input Wanted Captain's choices on colony ships

    In order to discuss several questions regarding my generation-ship story in parallel, without making a single thread go all over the place, this is one thread (of most likely several ones) that I'm opening in parallel. This one is less about technical questions per se, but rather about tactical...
  5. kyphysics

    Would You Ever Buy a Computer That Ships by Mail (Fear of Damage)?

    I've seen Amazon/Fed Ex/etc. drivers fling packages. With Cyber Monday coming up, I'm wondering if it'd be safe to buy a computer and have it mailed/shipped to me vs. buying in person?
  6. E

    This is a 3D model I made of the Edmund Fitzgerald great lakes ship

    These are images of a 3D model I made of the legendary Edmund Fitzgerald, a great lakes bulk carrier ship, which famously sank in lake superior in 1975.
  7. DartomicTech

    Any books that just have blueprints of buildings, ships, etc?

    Sorry if I am posting in the wrong area. Like the title says, are there any books that just have blueprints of buildings, ships, etc? Pretty much just blueprints on structures that are places. I use them for memorization when I study, and books of blueprints would be a lot more convenient than...
  8. P

    Jupiter's Gravity: How Many Ships in the Queue?

    Imagine you are in the universe of the Expanse book. First of all, you want to speed up your spaceship to reach the alien gate. And you will use Jupiter's gravity. But there is a queue of spaceship wanting to go to the gate, and they all use Jupiter's gravity to accelerate. Suddenly Jupiter...
  9. O

    B How can two ships pass each other twice at the same moment?

    The moment when T of ship1 is lined up with N of ship2 must be the same moment in both frames of reference because there is only 1 moment when this occurs. At this moment, for someone at N of ship1 to see T of ship2 they have to look in 2 different directions simultaneously. This is impossible...
  10. xyz_1965

    MHB Distance Between Two Ships

    Points P and Q are in the same vertical plane as an airplane at point R. When the height of the airplane is 3500 feet, the angle of depression to P is 48° and that to Q is 25°. Find the distance between the two ships. Round the answer to the nearest 10th of a foot. Solution: From R, I will...
  11. G

    To find the closest approach of two ships

    Could I please ask for help regarding the last part of this question: At a given instant, a ship P revelling due east at a speed of 30km/h is 7km due north of a second ship Q which is traveling x degrees west of north at a speed of 14km/h, where tan(x)=3/4. Show that the speed of Q relative to...
  12. G

    The closest approach of two ships

    Could I please ask for help with the following question: A destroyer moving on a breaing of 30 degrees at 50km/h observes at noon a cuiser traveling due north at 20km/h. If the destroyer overtakes the cruiser one hour later find the distance and bearing of the cruiser from the destroyer at...
  13. brotherbobby

    Two ships - will they collide?

    There are two ways to solve. My problem is, when I apply the two, I end up with a contradiction. Method 1 : Conclusion - Ships will not collide . Imagine the ships collide after a time ##t##. Since they both start at the same time, the distances traveled by them would be ##3t## (A) and ##t##...
  14. wolram

    Generation Ships: Would You Go On One?

    I have just been reading this https://arxiv.org/pdf/1901.09542.pdf It makes me wonder if anyone would go on a generation ship, What about you? I would not.
  15. diogenesNY

    Naval Engineering 19-20c: Fun with numbers

    I have been reading the book _Able Seamen: The Lower Decks of the Royal Navy 1850-1939_ by Brian Lavery, Naval Institute Press 2011, and I came across an interesting paragraph regarding engine efficiency (and labor requirements) as steam began to replace sail. I reproduce the relevant...
  16. K

    How is DWT in container ships achived?

    Hi there, in martime terms DWT includes the containers weight as well. What i don't understand is how is it achieved? All ships specifications of container capacty has higher weight than the DWT.
  17. FactChecker

    Damage height versus waterline when ships collide

    I am curious. There have been two collisions recently between a military ship and a large commercial ship. Both times, the military ship was damaged at the waterline and the other ship was damaged far above the waterline. How does that happen?
  18. L

    Special Relativity -- two ships moving in one dimension

    Homework Statement You approach an enemy ship at a speed of 0.5c measured by you, and the ship fires a missile toward your ship at a speed of 0.7c relative to the enemy ship. What speed of the missile do you measure, and how much time do you have measured by you and the enemy ship before the...
  19. HyperTechno

    Arthur C Clarke's space ships -- propulsion discussion

    I've read Sir Arthur C Clerk's space odyssey series and curious of the propulsion technologies used in those ships. Ships like Universe and Galaxy of space odyssey 2061 use just water. The fiction speaks of "muon propulsion" too. The main spacecraft s that we see in his 'space odyssey' series...
  20. Noisy Rhysling

    Destination for "Passenger" ships?

    Just wondering if anybody had a clue as to candidate stars for the ship, Homestead II, in this movie.
  21. Ghost117

    Gravity Defying Ships Cause Time Dilation and Paradoxes?

    If a ship could cancel out the effect of gravity, wouldn't it be able to pass through the event horizon of a black hole, and take a tour of the singularity, and then just report back with its observations? Also, if a ship had the capability to cancel out the effect of gravity, wouldn't this...
  22. Noisy Rhysling

    Generation ships v. hibernation ships?

    I'm a fan of hibernation ships because the crew that is selected to go is the crew that lands on the new world. I have a tough time seeing a crew that is 222 generations removed from the original crew being ready to investigate and develop a new planet. However, I'm open to other views, so...
  23. DHF

    Writing: Input Wanted Designing a space ship and with the dust shield

    Hello everyone, I am designing a ship for my sci fi story and I need input regarding the shield. I am trying to make my story as hard sci fi as I can get away with. The story takes place a few centuries from now and details the first expedition to Alpha Centuri. The ship will have a cruising...
  24. L

    Advanced Vector Problem: Ships

    Homework Statement Three ships A, B, and C move with velocities \vec{v_{1}} \ \vec{v_{2}} \ \vec{u} respectively. The velocities of A and B relative to C are equal in magnitude and perpendicular. Show that \left | \vec{u} -\frac{1}{2}(\vec{v_{1}} + \vec{v_{2}}) \right |^{2} = \left |...
  25. Buckethead

    How Does Doppler Shift Affect Light From a Shuttle to a Mother Ship in Space?

    Imagine a mother ship traveling away from Earth at .5c and a shuttle takes off from the mother ship in the same direction of travel at .5c relative to the mother ship. The shuttle fires a blue laser (400nm) to a transparent screen mounted on top of the mother ship as it is traveling away. Due...
  26. B

    Speed of Ships -- Special Relativity

    Homework Statement Galaxy A moves away from galaxy B at 0.650 c0 relative to B. A spaceship leaves a planet in galaxy A traveling at 0.550 c0 relative to galaxy A. If the direction in which the ship travels is the same as the direction in which A is moving away from B, what do observers in B...
  27. P

    Why Ships Float: Displacing Water vs Weight in Air

    Does the amount of water displaced by an object needs to be greater than its weight (in air) for it to float in water? Say a bowl of 5 kg displaces 4 kg of water - will it float or sink? If it sinks the if it had displaced 5 kg of water would it float? That is the volume of water displaced by...
  28. N

    Word problem two ships departing -- One north the other west....

    Question: Two ships leave port at the same time. One travels north at 80 knots (that is, 80 nautical miles per hour), and the other west at 80 knots. The distance between the ships increases at a constant rate. At what rate is the distance between the two ships increasing?The Attempt at a...
  29. J

    Special relativity -- 2 parallel space ships & time perception....

    If two people are in in space ships traveling next to each other at the same speed and they are going close to the speed of light they see each other expiriencing time more slowly. Why does this happen?
  30. M

    Is there a benefit to having holes in sails and rudders on Chinese junks?

    I have read articles regarding Chinese junks which utilise rudders made of rubber, and they usually have diamond shaped holes in them. These articles claim that the holes provide better handling of the junks compared to a full rudder without holes in them. What are your thoughts regarding how...
  31. ManicPIxie

    Bernoulli, Fluid Dynamics, and ships

    Homework Statement The Plimsoll line is a line marked on the side all ships that effectively indicates the safe maximum load the ship can carry in that type of water at that temperature.You have been asked to stand on the dock and collect the tickets of the passengers boarding a cruise ship...
  32. I

    Exploring Relativistic Compression: What Happens to the Space Between Ships?

    A convoy of spatial ships leaves the Earth at a speed v. Each ship is relativistically compressed in the direction of movement. What happens to the space between the ships? Is it compressed too?
  33. A

    Spec-rel, two ships accelerate away from each other

    Hi all, this is a follow-up variant to an earlier post https://www.physicsforums.com/showthread.php?p=3804580#post3804580 In that post, I wanted to know what an Earth observer would see for a ship some distance off accelerating towards Earth and then reaching constant velocity. For the...
  34. M

    Real-world application of Active Stabilization Tanks in Ships

    Does anyone know any specific examples of real world application of Active Stabilization Tanks in a ship? I just need a link to an article or just a name of ship IF one exists. I have been doing some research into A.S.T's and I am desperate to find out if the concept has been manufactured. I...
  35. R

    Resolving the Twin Paradox: Clock Readings on Space Ships in Relative Motion

    This has bothered me for a long time. I understand that time varies with velocity relative to the observer. But what about this case -- Suppose we have 3 space ships: A, B, and C. They are spaced widely apart with B in the middle and A and C at opposite sides to B. A and C are moving towards...
  36. karush

    MHB Distance between ships at 4 pm

    wasn't sure but made the \frac{da}{dt} negative since the ships are drawing closer to each other at least before 4pm
  37. nearc

    Two ships again [lets beat that dead horse]

    Two ships are traveling fairly close together side by side heading the same way on parallel paths near the speed of light [lets say v=.999C]. From the internal frame of reference [people in the ships] they can consider themselves as equivalent to being stationary, however from an external...
  38. W

    Space ships turning+time dilation

    I am planning a hard-ish science fiction novel and I was wondering about space ships turning when going at extremely high speeds (in my case .33c). My question is can ships going this speed turn without sending the crew through the windshield so to speak? If its a stupid question let me know...
  39. D

    I am doing a science experience prooving giant ships can float

    I am trying to prove why ultra large crude carriers and other kinds of ships can float, and why they are stable in water? The experiments need to be simple and doable at home. I also could use some formula for stability and dead weight and so on. Could someone please help me, maybe point me...
  40. B

    Special relativity:2 ships pass eachother

    Homework Statement Two space ships A (90m long) and B (200m long) travel towards each other. The person in ship A observes that it takes 5x10-7s for the tip of ship B to pass his ship. What’s the relative speed of the two ships? How long does a person sitting at the tip of ship B observe for...
  41. Astrum

    Related Rate - Rate of The Change in Distance of Two Ships

    Homework Statement Ship A is 100 km west of ship B. Ship A is moving at 35 km/h (west), ship B is moving at 25 km/h (north). Find the rate of change of the distance between the two ships after 4 hours. Homework Equations The Attempt at a Solution the distance between the two ships is shown by...
  42. K

    Understanding the speed of light between 2 ships racing away from each other

    I'm not sure if this post belongs with general physics or relativity, so feel free to move it. I am trying to get a better grasp of special relativity and I think the following scenario will help. Say rocket X moves at -0.51c and rocket Y moves at +0.51c and they take off from point Z. When...
  43. H

    Calculating how fast distance changes between ships

    Homework Statement At noon, ship A is 50km west of ship B. Ship A is sailing south at 30km/h and ship B is sailing north at 20km/h. How fast is the distance between the ships changing at 4:00pm in km/h. Homework Equations The Attempt at a Solution...
  44. P

    What is the distance between two ships and the correct solution to calculate it?

    Hello, I'd like to verify whether my solution to the problem as described below is indeed correct. Ship A is traveling east at a constant velocity of 30km/h. It notices ship B 15 km away and 30° from the north. Ship B is traveling at a constant velocity. 20 minutes later ship A notices...
  45. A

    Energy, Non-coplanar solar system orbits for space ships

    Hi all, As many of you have seen, I am thinking about spaceship trajectories. This next question falls under the same subject, but it is an entirely different question from the previous questions I have asked. Spaceships of the near future will fly in the plane of the solar system. Suppose if...
  46. T

    How many years until Ion Plasma thrusters are used on space ships?

    Thanks, just curious ever since I watched Prometheus.
  47. J

    What is the likelihood of a hijacked ship sinking from an unrelated incident?

    I belong to a group of people who, inter alia, (try to) apply Bayesian Theory to miscarriages of justice eg the recent spate of medical staff arrested when rare (but to be expected eventually) clusters of deaths occur in hospitals. A somewhat opposite case has recently arisen which has generated...
  48. A

    Relativistic Space Matter Flows over near light speed ships

    Does anyone know if any work, no matter how speculative, has been done on the following: Assume a ship (or any vessel) travels through space with a Gamma of 10-100. As the ship travels through the interstellar medium, there is a constant barrage of nuclear explosions over the tip of the jet...
  49. Biosyn

    Water Supply on Cruise ships

    Do cruise ships store clean water aboard in tanks or do they use desalination systems? Or do they take on water from their destination ports? I did a search online and I couldn't find any reliable sources. Is it any different on an ocean liner?