# Questions tagged [marine-engineering]

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### How to calculate the force required to tip a floating dock

If I have the following I'd like to determine how wide the base of a floating dock would need to be to prevent tipping under certain weather conditions (wind & waves) I'd like to build a modular ...
76 views

### How much longer could Titanic have remained afloat if it had gotten rid of its anchor and chain right after hitting the iceberg?

I am wondering how much longer the RMS Titanic could have remained afloat if the crew had allowed the ship's anchor and anchor chain to fall to the bottom of the ocean immediately after the ship had ...
854 views

### Sea waves: Having trouble visualizing the difference between group celerity and celerity

What I know, if I'm not mistaken, is that group celerity is the speed at which the energy is transferred and celerity is the speed of the waves themselves. Since sea waves basically transfer energy ...
191 views

### Disposition of the generators on the shipwrecked Costa Concordia

Recently I have been reading about the shipwreck of the Costa Concordia, unfortunately what I read is not online, so I have no links, but it raised a lot of questions. A rock hit by the ship tore a 50-...
76 views

### Computation of the moment of restoring forces for a floating vessel

Some slides associated to the book Handbook of Marine Craft Hydrodynamics and Motion Control (2021 edition) are provided by the author of the book here. At page 12 of the slides for Chapter 4, the ...
71 views

### How do cracks form on a ship's hull?

The oil spill in Mauritius would be caused by cracks in the hull. How can this happen? Is it possible to be caused solely by rough weather?
274 views

### Why did the Soviet Alfa-class submarines have a titanium hull?

My limited knowledge in engineering tells me: Titanium is expensive, stronger and heavier than aluminium, lighter and weaker than high yield steel. The most significant advantage of titanium is the ...
4k views

### X-form and cross-form rudders in underwater control

What are the advantages of using X-form rudders in comparison to cross-form rudders? Why do some submarines, torpedos and underwater autonomous vehicles use X-stern control? X-stern: Cross-form:
114 views

### How does a cable-laying ship retrieve a partly-laid cable?

I was reading an article in the press this week about a project to lay an undersea cable across the Tasman Sea. The ship had had to return to port for repairs and return to complete the job later. ...
669 views

### How to design a reinforced concrete ship keel?

I am building a small ship (or very large sailboat) that will have a concrete ballast at the base of the keel. I am looking to increase the weight of the concrete (lb/ft3), but I also want to maximize ...
8k views

### Purpose of spheres and fins on submarine propeller

On a recently launched Russian diesel-electric submarine, the rear propeller has two distinct features. You can see spheres at the base of every propeller blade: Also, the trailing edge of the shaft ...
61 views

### What is the best practice for ensuring the best possible connection between a battery cable and a battery terminal

I've seen a number of opinions on conductive gels to ensure the best conductivity between battery terminals and battery cables. I'm interested in knowing an expert's opinion on the matter. I'm ...
2k views

### What are the 'poles' off the side off this aircraft carrier's flight deck?

Looking at a model of the HMS Ark Royal I found myself intrigued by the prominent 'poles' lining the flight deck. Some investigation on Google reveals that they can apparently be lowered to lay ...
238 views

### Auxiliary engines on cargo vessels, what types are used for what purpose?

On large cargo ships (dry bulk carriers, or tankers) there are main and auxiliary engines. Auxiliary engines can be internal or external combustion (generators vs boilers) and generate electricity to ...
52 views

### How the design of ship help to survive in the water

I have seen bigg cargo, and other ships, and I like their structure very much., a question come sin my that why the ship structure is like this. Can anyone explain what was reason for this. I am not ...
2k views

### Preheating Diesel before injection?

Significant amount of heat is lost from an engine by various means, so to recoup the energy, is it possible to increase efficiency via heating of diesel fuel prior to injection using waste engine heat ...
2k views

### What is it about the cabin electrical supply on cruise ships that makes surge protectors dangerous?

Surge protectors are banned on cruise ships, and so are confiscated during boarding. Extension cords and cube taps etc. are discouraged, but not banned. I'm asking specifically about surge protector ...
50 views

### Is the metacentric height independent of heel angle?

when the sides of a pontoon are verticle, BM(distance between center of buoyancy and metacenter) is given by I/V As well as for a small angle that expression is true. But when the heel angle ...
511 views

### Will this water jet propulsion system design produce any forward thrust?

I am interested in building a very basic water jet propulsion system for a toy boat. Before I build it, I would like to know from a conceptual standpoint if this design of a water jet propulsion ...
43 views

### Finding phase velocity for froude number scaling

So I am calculating phase velocity of a wave for Froude number scaling for model testing of a boat. I got data from Lloyd's Rules saying for the specific sea area I did $H_s=3.6\text{ m}$ and \$T_z=6.8\...
432 views

### Detergency and dispersancy

Abstract:The detergency property in oil comes from a chemical additive called detergent which has a property of preventing the deposition of carbon deposits and wash it away. There is also this ...
444 views

### Boat Hull Drag in Shallow Water

I paddle several different types of small craft in the ocean and bays near my home. One phenomenon I've observed is beyond my understanding of drag on a narrow displacement hull. When paddling in ...
885 views

### Hydrogen in submarines: "keep below 8%" rule of thumb?

In the book "Against the Tide: Rickover's Leadership Principles and the Rise of the Nuclear Navy", Rear Admiral Dave Oliver (Ret.) narrates some of his experiences in the USS George Washington Carver, ...
595 views

### How Big can Hydrofoils get?

Is there a limit to the size of ships that can have hydrofoils (would an aircraft carrier work)? Would there be cavitation if the load was high enough, and to what extent would using larger foils help,...
114 views

### What mechanism in the radar that enables the switch between transmission and reception?

I think there is a mechanism that switches off the transmitter in order to turn on the receiver in the antenna. Do you know the technical terms by which this is done?