Underwater Propulsion: Pumping Out Water for Acceleration

In summary, the conversation discusses the possibility of using water pumped outwards from a submersible object to provide acceleration while underwater, and whether this method is practical. It also mentions the invention of the Hamilton Jet in New Zealand, which is a classic example of this technology. The conversation also touches on the technical aspects of how a pump-jet works and the potential use of water flowing within the system for intake. The idea of using water jet propulsion is not new and has been used in various applications, such as in lifeboats.
  • #1
RICKYtan
23
0
Can water inside a submersible object be pumped outwards to provide an acceleration while underwater?
 
Physics news on Phys.org
  • #2
Squid?
 
  • Like
Likes fresh_42
  • #3
RICKYtan said:
Can water inside a submersible object be pumped outwards to provide an acceleration while underwater?
Isn't this exactly what a propeller does? If you like, you can put the whole system in a tube through the inner of the object, but why?
 
  • Like
Likes russ_watters
  • #4
If you mean can water from a tank inside be pumped out to produce thrust then answer is yes but in practice this method of producing thrust is not very practical.

Generally better to use the water from lake or sea and pump it through or around the submersed object .
 
  • #5
Nidum said:
Generally better to use the water from lake or sea and pump it through or around the submersed object .

invented in my home country, the Hamilton Jet is the classic example of that
https://en.wikipedia.org/wiki/Jetboat
 
  • Like
Likes Nidum
  • #6
At least they are fast!
https://www.ngva.eu/worlds-fastest-high-speed-ferry-propelled-by-waertsilae-technology
 
  • Like
Likes Nidum
  • #7
This is the UK version built by Dowty under license from Hamilton :

 
  • #8
Technical :

 
  • Like
Likes davenn and fresh_42
  • #9
Can someone explain how the intake works and the work necessary? Also, can intake be supplied by water flowing inside the system at a location on the system that is "in front of" the moving system, a system which can travel any direction underwater?
 
  • #10
RICKYtan said:
Can someone explain how the intake works and the work necessary?

The wikipedia article is a good starting point for an overview of a pump-jet: https://en.wikipedia.org/wiki/Pump-jet

If you're planning to build one then you'll have to get into the technical literature, as teaching you the details would be beyond the scope of this forum.

RICKYtan said:
Also, can intake be supplied by water flowing inside the system at a location on the system that is "in front of" the moving system, a system which can travel any direction underwater?

I'm sorry but I can't make heads or tails of this.
 
  • Like
Likes davenn
  • #11
Perhaps Google Bow Thruster?
 
  • #12
I visited the RNLI Lifeboat museum Pool, UK last year and saw an ancient (1950's?) lifeboat which used water jet propulsion. Nothing new under the Sun. Great for shallow water use.
 

FAQ: Underwater Propulsion: Pumping Out Water for Acceleration

1. How does underwater propulsion work?

Underwater propulsion works by using a mechanism, such as a propeller or jet, to create a force that pushes water in one direction and propels the object in the opposite direction. This is based on Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction.

2. Why is pumping out water important for acceleration?

Pumping out water is important for acceleration because it reduces drag and increases the efficiency of the propulsion system. When water is pumped out, there is less resistance for the object to move through, allowing it to accelerate more quickly.

3. What factors affect the efficiency of underwater propulsion?

The efficiency of underwater propulsion can be affected by various factors such as the shape and design of the propeller or jet, the power and speed of the motor, the weight and size of the object being propelled, and the density and viscosity of the water being moved.

4. Can underwater propulsion be used for long distances?

Yes, underwater propulsion can be used for long distances. However, the efficiency and speed of the propulsion system may decrease over larger distances due to factors such as energy loss and resistance from the surrounding water.

5. Are there any environmental concerns with using underwater propulsion?

There can be environmental concerns with using underwater propulsion, especially if the system is powered by fossil fuels. This can result in water pollution and harm to marine life. However, there are more eco-friendly alternatives such as using renewable energy sources or improving the design of the propulsion system to minimize environmental impact.

Similar threads

Can someone explain the vacuum pressure created by water pressure on waders?
Replies
9
Views
4K
I In a closed loop system with a pump, how can we control the pressure?
Replies
26
Views
5K
I A specific case of an exception to Archimedes' Principle?
2
Replies
40
Views
3K
Mammals deep underwater, water pressure, & implications
Replies
18
Views
2K
I Find Best Water Nozzle Type & Pressure for Longest Distance
Replies
32
Views
4K
One submersible water pump and two tanks?
Replies
9
Views
6K
Need stress value of aluminium for project work
Replies
5
Views
1K
Help understanding how my "magic" siphon works....
Replies
17
Views
3K
Apparent depth of an object underwater
Replies
3
Views
1K
Water all around when air stays upside down
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top