Hot answers tagged

25

A specific reason for doing this is simply when there isn't enough room to do a bow or stern first launch. This is often the case when a ship or boat is built in a yard on a river or canal either because the hull is especially long or the channel it is being launched into is narrow. There is also the consideration that a sideways launch can be done from any ...


12

It's a heavy-lift vessel, carrying four identical structures as cargo. It's very likely they are jacket foundations for offshore wind turbines. The excellent 4C Offshore has a database of such vessels used on offshore wind farms. It also has a list of all offshore windfarms under construction by country, and tells you which vessels are working on it, so ...


9

Carriers are ships intended to project power. The USA sits on a continent without any nearby enemies. So, American military doctrine is expeditionary in nature. The assumption is that if America fights a war, it will be abroad and therefore it needs the means to project force abroad. Therefore, a strong navy with a nuclear powered carrier element was seen as ...


8

Shame on the physics SE for closing it. No tacking required, although it is optional. The vessel is going directly down wind, not up wind. There is a factor called the speed ratio (SR), which is the boat speed divided by the true wind speed (TWS). TWS is the scalar difference between the wind velocity and water water velocity. And there is the associated ...


5

In short, because steel is less expensive on a strength per dollar basis of anything else, and for large structures, it's less expensive to work, again on a strength per dollar basis. That's why steel construction predominates in cars, too. For small boats, the cost equation leans more toward the ease of manufacture of that size of structure out of ...


4

Anything is possible and lowering the lightship weight (LS) of ships will save fuel, but the key issue would be any change must not reduce the seaworthiness of ships. This question is very broad. Regulations have been established for commercial steel ships (DNV GL, Lloyds, ABS, individual countries). These regulations take into account the harsh marine ...


4

Carnival Splendor is an example of Concordia class ships. From Costa Concordia deck plans: Costa Concordia (built 2006, scrapped in 2015) was the first of all five Concordia-class liners operated by Costa Cruises - together with the sisterships/fleetmates Costa Serena (2007), Costa Pacifica (2009), Costa Favolosa (2011) and Costa Fascinosa (2012), plus the ...


3

These ships can be loaded/unloaded: from a dock Figure : Loading/unloading from a dock (source Youtube) but they also have they have the ability to submerge in order for their cargo to be loaded/dropped off Figure: Loading Unloading from subversion (source Youtube) After a small search you can see that using the submersible ability those ships where ...


3

Engineering is a knowledge of physics and a game of economic tradeoffs. I have not designed any watercraft, and have less knowledge this specific wreck than the OP, but I can explain some of the engineering design process and business management that results in situations like this. A cruise ship is basically a small city and this massive project is ...


3

Regarding the first question: why 1 ship is more efficient that 100 smaller ones. if you did some research I'm sure you'd find that one large ship probably uses about the same steel than a 10 smaller ones capable of carrying the same load. See evolution of container ships. A ship 200x20x10 meters could transport about one tenth of a ULCS (which is 400x59x16)....


3

Ship-to-ship combat is now restricted to the internet's various fandoms. If you are close enough to launch a massive projectile to a nearby ship, you are close enough to get hit by one of it's lighter guided missiles. Those guided missiles tend to be more accurate over distance and much lighter to carry. Missiles can also do the penetrate and then explode ...


3

The USS Nimitz is nuclear powered, whereas the Allure of the Seas is not. Nuclear reactors are not cheap. Also, the USS Nimitz, like all aircraft carriers has a catapult to help launch aircraft off the decks. The Allure of the Seas does not have a catapult. Catapults are expensive. The USS Nimitz has kevlar armor over vital spaces, but civil cruise ships ...


3

End to end, it would bend and snap in half under its own weight. I know it's just a movie, but watch "Titanic" for a visual. The support required otherwise would be huge and expensive. A boat/ship will naturally rock side to side without breaking. Impact with the water will act as a brake and keep it from rocking too far. The weight of the ship will cause ...


2

You intend to submerge a rectangular concrete section in a fairly corrosive environment (ocean water). The section is 11.5" wide and 18" deep. During the 20 year life span of the boat, you anticipate 6 heavy impact events. The concrete keel is intended to act as a beam which is to spread the impact load evenly onto the laminated wood hull to such an extent ...


2

This gives a complete analysis of how to calculate : http://web.mit.edu/13.012/www/handouts/propellers_reading.pdf


2

They are HF radio masts that are hinged down for flying operations. My initial thoughts they were radio direction finders or airframe recovery booms, but my research does not support it. In port they are up. With planes in the air, they are down. Four port, four starboard. Two forward, six stern. They are connected by cables. From the-blueprints.com. ...


2

If you consider the base concept of material used versus available volume for transport, a smaller vessel will have a poorer result. A water craft capable of carrying one container will use a certain amount of material, call it c and assign the value of one. This imaginary assignment is containers divided by material, equal to one in this example. The next ...


2

I'm not an expert on this so this is an "educated guess". It boils down to what the advantage of nuclear power is. To laypeople it sounds cool, but for the military you need a tangible advantage. That advantage is (see the Wikipedia article on nuclear submarines): The performance advantages of nuclear submarines over "conventional" (...


2

Answer: Gantry cranes with submersible dry dock. It has to be a crane because we have to accurately place one hull on another. Vessel is Blue Marlin. Load has been described as 22 barges. There are barges there to allow hulls to be transported, but mainly inland ship hulls with super structures on top of hulls. Destination was Veka shipyard Lemmer, which ...


1

"as much power as possible (not necessarily speed)" is a weak Specification "More Power." I'm not sure what this means. Power means the rate of doing work. At face value it would mean to me the ability to carry the maximum amount of sail, since that's where the power will come from. I'm not clear this has anything to do with hull ...


1

The gravitational force and the buoyancy force create what is known as a moment couple (or sometimes just couple). Essentially they are two equal (because buoyancy and gravity should be equal in a boat), parallel and opposite facing forces, when have a zero translational effect and produce only rotation. See the following example For the above example it ...


1

Of the 5,211 container ships of 2018, 19 <500GT, 2,213 between 500≤GT<25.000, 1,538 between 25.000≤GT<60.000 and 1,441 are ≥60.000GT.  Source: Equasis.  So the majority of container ships (72%) were below 60,000 DWTs.  This comes down to supply and demand. No point in sending 11,000 TEU vessel to ports with 1,000 TEU requirements.   Feeder container ...


1

No, because the relative directions of forces and travel are wrong Consider your diagram. In order to change the frame of reference, the current would have to be pushing the boat left to right, in the opposite direction to the arrows above the green dots. The result of this would be an "apparent wind" creating the force in the direction shown. ...


1

There was a wonderful article in the American Institute of Aeronautics and Astronautics (AIAA) journal (80s? maybe 70s?) envisioning a sailboat that was nothing but an airfoil (the sail) connected to a water foil (the keel). Based on the density ratio, the airfoil should be 80 times larger (IIRC) than the water foil. It then imagined people who live on ...


1

Probably yes. To a sailboat, there's no difference between floating in a river surrounded by stagnant air, and floating in stagnant water surrounded by moving air (wind). The boat will "feel" a relative wind in both cases. The only question is whether or not a sailboat could sail upstream faster than the water is flowing downstream. The relevant ...


1

River water flow creates hydrodynamic pressure which is equal to $$ P_{hydrodynamic}=1/2 \rho v^2$$ If we can tap this pressure to do work it is possible to use it to move the boat upstream. One practical solution would be to have a paddle wheel like those used on riverboats turn a winch winding a cable that is anchored to the shore upstream at the desired ...


1

There is no one way to do things. Ship design is continually evolving. In general, cargo ships are low and slow, as in powered by large 2-stroke diesel engines with big propellors and slow speeds. Higher speed vessels use smaller 4-stroke engines with smaller propellors and higher speeds. Traditionally, propulsion has been diesel, but as ship sizes get ...


1

The water stream flow on the back of ship depends on two main factors, ignoring waves and possible wake shock. The shape and curve of the wet surface on that section. The more streamlined, the less turbulent flow and ideally less rushing of the water. The depth which causes larger hydrostatic pressure. That is the reason they avoid creating a bulkhead at ...


1

If you know the Froude efficiency $\eta_{\text{Fr}}$ and assume a constant velocity $u$ for the ship. Then you can calculate the thrust $F_{\text{T}}$ for given power at the shaft $P_{\text{S}}$ as $$F_{\text{T}}=\eta_{\text{Fr}}\frac{P_{\text{S}}}{u}.$$ There is also a dimensionless thrust coefficient $C_{\text{T}}$ which is defined as: $$C_{\text{T}}=\...


1

Most navy ships require very high redundancy of all critical system (Propulsion computer, navigation etc), the material specs are also usually very tight, meaning more costs, for example the paint used on some of the new carriers alone was a multi million dollar project to withstand the F35 Jets.


Only top voted, non community-wiki answers of a minimum length are eligible