# Wave powered shipping

I agree some piezoelectric device may provide some extra power. How much I don’t know. I doubt it would be as much as I am proposing because it would still involve pushing wave energy to the sides instead of behind the ship. Perhaps the two methods could be combined.

Water has the big advantage over gases in that in that it’s energy can be easily stored as potential energy. Simply blocking the flow converts kinetic energy to potential energy.
Pressure energy and potential energy refer to the same thing. If you have a column of water and increase its height that will increase its potential energy and also increase the pressure at the bottom of the column

Peleeze…Regurgitating basic physics principles and formulas available in classroom textbooks over and over like a mantra without proposing solutions doesn’t advance the discussion.

I think my idea is based on basic physics principles and logic.
As regards your suggestion of using bladders and compressed air, that may capture some wave energy but I think would be much less efficient. Air heats up as it is compressed and to repeat myself there is no energy storage.
The addition of channels to the outside of the ship means retrofitting is possible. I don’t think your idea could be retrofitted.
The channels move water around the ship so there would be less movement of the ship up and down or from side to side.

What idea? Let’s try this one more time. Regurgitating physics principles is not an idea or a solution. An idea would be proposing a possibly feasible method of converting the power of water entering channels mounted to the side of a ship’s hull into propulsive energy. You still haven’t done so.

First, you suggested water ingested through channels alongside the hull would provide propulsion by routing it without further treatment out through the stern. No explanation provided.

Second, you changed tacks and proposed storing tons of ingested water above the ship’s waterline while ignoring basic stability concepts and the source of the mechanical energy required to do so. No explanation provided.

Third, now you’ve changed tacks once again and you’re proposing that moving ingested water “around the ship” would reduce movement caused by wave action. The added weight and space used may reduce a ship’s longitudinal and lateral movement through the water but how would it noticeably contribute to propulsive power? Again, no explanation provided.

What’s next?

To recap.
Waves have kinetic and potential energy.
When a wave hits the side of the ship this kinetic energy is converted to hydrodynamic and hydrostatic pressure. This pressure forces water through the one way openings if the pressure outside is greater than the pressure inside. The pressurised water in the channel is directed to the stern where it is converted back to kinetic energy to provide propulsion.
If the rate of inflow of water is greater than the rate of outflow pressurised water can be stored as potential energy in the channel and other suitable places.
This movement of water of water through the channel reduces movement of the ship because it reduces the pressure outside the ship.
The one way openings ensure flow in one direction.
It really is simple logic.

I think if you had a ship with angled sides, the waves would hit the angle sides and impart a force on it pushing it forward. Of course the angle that waves hit the ship is continuously changing, so you need movable ship sides to get this energy.

Also, catch the water up high and use its weight to turn a turbine, as mentioned in this thread.

I wonder if we can also capture the power of the wind to move a ship?

Here is an idea that can easily be tested out and implemented on existing OSVs with retractable Azimuth thrusters:
When transiting leave the thruster down, facing Fwrd.
The forward motion of the OSV cause water flow that turn the propeller.
The drive motor becomes a generator, thus producing power that can be used to supply hotel load and more.

High powered AHTS can obtain the same by steaming on one engine and let the other prop drive the shaft generator for the same purpose.

PS> Whether the additional drag will exceed the power gained can easily be determined by trial and error over a period of time.

blah blah blah

What!? Ah man, that will never work. What’s next, engines without spark plugs?

1 Like

Blocking the flow of a moving fluid takes energy. If you are running at me and I throw five gallons of water at you and it splashes off, it may affect your forward progress but not to any great extent. If I throw a five-gallon bucket of water at you and you attempt to catch it, it will definitely have a negative effect on your forward travel because it takes energy on your part to stop the inertia of the water. If you subsequently throw it behind you, there is no net positive, and in fact there is likely a net negative due to the energy expended by temporarily moving that extra mass on your body.

The water isn’t pressurized. Allowing a wave to enter a channel is still water at atmospheric pressure, it is just a flowing fluid. Neither re-directing that flow in channels nor stopping its flow will “pressurize” it in a meaningful way. And “directing to the stern” means it is moving and therefore not potential energy. You are not converting anything unless you have stopped the water, which again, takes energy.

Allowing additional waves to push through your check valve (one way opening?) could possibly increase the pressure of a volume of water in an otherwise closed container, but by doing so you have allowed the stopping of the inertia of that flowing water, at a detriment to the motion of the ship. Further, since water is not compressible, any increase in pressure of the trapped volume would also result in the majority of the wave being directed back to sea. If you are not stopping the flow of water but merely redirecting it out the stern, then it is simply still a flowing fluid at no greater velocity or mass then when it entered, and it will not provide any propulsive effect.

The rate of inflow of a fluid into a space cannot be greater than the rate of outflow unless it is an open system. And if it is an open system then there will be no stored energy.

Please explain what pressure you think this water will be stored at and how that pressure is achieved at anything other than a net loss to the vessel.

1 Like

Wait for it: “Just to recap…”

1 Like

This is turning into “one of those” threads

Anti-gravity anyone ?
Perpetual motion ?
Pyramid power !

If that’s the case it should be pretty easy to work out the equations to show it works.

And let’s not forget that pesky Newton’s 3rd law…

Newton’s 3rd law of physics? That must be in the next chapter in my Physics 101 text book. Well anyway, you see, water is heavier than air and gas heats up when compressed. In other words, air is lighter than water so if you scoop up the waves that are above sea level before they sink, a ship will move by itself. Simple. It’s pure science. Why are you against progress?

As you might expect I disagree with shipengr.
Water entering the channel from the side does not increase drag but does give pressurised water to be redirected to the stern to provide thrust.
I agree water coming from straight ahead provides drag. I accept that storing this energy may increase drag more than pushing the water to the sides. But for half the wave cycle no pressure or drag is exerted. The stored energy will then provide thrust whereas water pushed to the side will not. So overall when waves come from straight ahead I think there will be a less energy loss by storing the energy compared to pushing waves to the sides.
You seem to be assuming all waves come from straight ahead and ignoring energy gains from waves coming from the sides.
Waves exert pressure. Water will enter the channel if the pressure outside is greater than the pressure inside. This pressure is higher than atmospheric pressure. There is a flow of pressurised water to the stern. Pressurised water contains energy. If the rate of inflow is greater than the rate of outflow the energy surplus can be stored as water with potential energy at a higher level.
As per my previous post i estimate pressures of 60,000 Pa for a typical wave and 150,000 Pa for large waves. If waves come from straight ahead these pressures will be higher.

I

I suggest you build a proof of concept model to demonstrate the validity of your ideas. Get back to us when you have data to share. Don’t forget to file your patent application.

1 Like

Ship engineers, pfft…

Potential energy is E = mgh E is in joules, m in kg, h in meters. For a first approximation make some assumptions about how much water is stored at what height above the water line, efficiency of the conversions to useable energy convert joules to kwh and compare to engine power.

Whelp, I shoulda seen that coming…

Pro Tip: if you are failing to make a logical argument, simply repeating the same illogical sentences over and over doesn’t suddenly make them logical nor overcome the laws of physics or fluid dynamics of a ship’s hull movement.

Not sure why I’m bothering but, you keep using the term “pressurized” like it means something it does not.

I recognize that solids and fluids are different, but for the purpose of trying to get this through to you…If you are driving forward in a car and someone else drives into the side of your car, there is a pressure at the interface which is the force exerted over the area of impact…however the t-boning car is NOT “pressurized”. Even if that car were a fluid, and you were capturing the fluid in a channel on the side of your car, the pressure of the captured fluid is not equal to the impact force over the area.

Likewise, you could measure the pressure of the force of a wave over the area of impact on the side of a ship, which you appear to be trying to do in pascals. Let us for one second assume you can capture this water in a closed-end channel. 150,000 Pa is what, 22psi? Even if you doubled that, tripled it, heck times ten. That would be the equivalent of pointing a fire hose off the stern and thinking it will make you go faster. The mass of water you are talking about, at the pressure you are thinking of, at the velocity that could possibly exit astern, is insignificant.

Further you are talking about essentially the peak of a wave acting on a mysteriously located channel above waterline. I say mysteriously located because waterline is not a constant on a ship and depending on the vessel loading and the sea-state there is a high likelihood that this non-smooth surface will periodically and frequently be below waterline and create significant drag while the vessel is moving forward.

There is a reason hull shape is tank tested and studied with regard to wave action and period. Over a few hundred years of hull design, it’s pretty well studied. Spend a decade, a hitch, or even a day on a commercial ship and you’ll understand how inefficient and detrimental your idea would be.