Questions tagged [marine-engineering]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
13
votes
1answer
171 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 ...
0
votes
0answers
30 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 ...
5
votes
3answers
410 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 ...
0
votes
1answer
23 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\...
1
vote
2answers
104 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 ...
2
votes
2answers
130 views

Why had the Alfa submarines 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 ...
2
votes
3answers
2k views

X and Cross-from rudders in underwater control

What are the advantages of using X-form rudders in comparsion to Cross-form rudders? Why some submarines, torpedos and underwater autonomous vehicles use X-stern control? X-stern picture Cross-form
3
votes
3answers
980 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 ...
1
vote
0answers
164 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 ...
1
vote
3answers
284 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 ...
3
votes
0answers
615 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, ...
0
votes
1answer
167 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,...
2
votes
1answer
429 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 ...
0
votes
2answers
79 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?
13
votes
5answers
5k 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 ...
2
votes
1answer
170 views

How to divert solids from a downward vertical pipe

I am an electronics engineer trying to build one small underwater mechanical device (about 12 cubic cm) as part of a personal automation project. I have figured out the electronics for this, but I am ...
12
votes
4answers
1k views

Below what Froude number can I neglect wave-making resistance on a vessel?

I want to do some very simplified drag calculations on a vessel. My hope was that calculating the skin-friction resistance would be enough to get a good estimate of the surge resistance. Because wave-...