Hi all, good day.

Cannot find if long ago, already posted about this. Memory fading fast. Am unable to create an animation, or ask 'artificial intelligence' to make such animation or prove the concept. Please lend me your brains and skills to confirm if am wrong..

A boat with a rope at the keel near its bow. The rope tied forwardish of a submerged plane-form (not airplane form !) ballast. Rising sea surface waves make the rope tension pull up and glide forward the ballast because of its fixation angle point. Next the boat descending into the valley of the seawave surface allows the slack ballast rope to descend aiming downwards pulling also forward.

Can the up/down motion = glide of the ballast be tailored to pull the boat forward ? Am I having another mental fart ?

-Please correct poor terminology-

This is another animal, a sea 'parachute' anchor that if was ballasted+shaped as glider wing; could be similar to the proposed :

17 hours ago, Externet said:

Hi all, good day.

Cannot find if long ago, already posted about this. Memory fading fast. Am unable to create an animation, or ask 'artificial intelligence' to make such animation or prove the concept. Please lend me your brains and skills to confirm if am wrong..

A boat with a rope at the keel near its bow. The rope tied forwardish of a submerged plane-form (not airplane form !) ballast. Rising sea surface waves make the rope tension pull up and glide forward the ballast because of its fixation angle point. Next the boat descending into the valley of the seawave surface allows the slack ballast rope to descend aiming downwards pulling also forward.

Can the up/down motion = glide of the ballast be tailored to pull the boat forward ? Am I having another mental fart ?

-Please correct poor terminology-

This is another animal, a sea 'parachute' anchor that if was ballasted+shaped as glider wing; could be similar to the proposed :

In your diagram, why does the ballast object not just hang down vertically beneath the vessel? At the moment I don’t see what would make it move forward.

Wave on water (often) does not move a tons of water (in direction it goes), instead just transfers momentum between particles..

If you go with the sea current, you don't have to do anything, it flows beneath you, but when you fight against the current, things get rough.

For modern means of transport, such transport is too slow.

In different regions of the earth, the sea current flows in opposite directions, so the first explorers of America could sail with it (rather than against it) and reach America (or return), but they had to use it, not fight it.

When you fly airplane from the US to the EU, and vice versa, you either fly with the wind and your actual speed is much greater than the speed of sound, or you fight against the wind and your journey takes much longer. It depends on how the wind is blowing and whether the pilot has flown into the right zone.

https://edition.cnn.com/travel/article/jet-stream-flights-speed-of-sound

If someone wants to achieve good speed on the water or underwater, they strive to minimize resistance between the vehicle and water molecules.

If someone wants to achieve good flight speed, they strive to minimise resistance between the vehicle and air molecules.

If this resistance cannot be avoided, water currents or air currents are used, which flow wherever they want.

Before the invention of steam engines, in the age of sail, this meant that you sailed where the sea current took you, which meant that you did not sail the shortest possible route in a straight line.

Today, the same applies to aeroplanes, only much more dynamically, because at different altitudes you can have winds blowing in opposite directions.

(which looks funny in films, because you have a cloud flowing in +x, and at a different altitude a cloud flowing in +z, etc.)

Perhaps in order to appreciate my statement, you need to know the speed of an ocean current?

https://www.google.com/search?q=sea+current+speed

Edited November 1Nov 1 by Sensei

6 hours ago, exchemist said:

In your diagram, why does the ballast object not just hang down vertically beneath the vessel? At the moment I don’t see what would make it move forward.

Thanks. On a flat sea, it would be just hanging down vertically. Drawn affected by the waves.

The ballast having a plane or wing shape; when pulled up by a wave peak rising the boat, it glides upwards + ahead. When the boat descends to the valley of the wave, the ballast sinks gliding + pulling ahead.

Like a glider airplane lifted by a helicopter, the angle of attack determined by the rope fixation point when being pulled up makes it tilt to rise + forward. When released, descends gliding forward.

What the rope tension does is changing the angle of attack of the ballast 'wing' making it rise or sink + advance forward. Reciprocating motion into linear motion.

Sensei :  This has nothing to do with sea currents nor wind nor their direction nor speed.  In about converting up/down motion to linear motion, no matter if slow.

Edited November 1Nov 1 by Externet

An equation is bi-directional, right ? If a wing has such a direction of flight, it will lift. If lifted, will move in the direction shown.

12 minutes ago, Externet said:

An equation is bi-directional, right ? If a wing has such a direction of flight, it will lift. If lifted, will move in the direction shown.

But this wing is being held rigidly at a certain angle to the medium. In your scenario that is not the case, surely?

2 hours ago, Externet said:

An equation is bi-directional, right ? If a wing has such a direction of flight, it will lift. If lifted, will move in the direction shown

In your diagram

The lift arrow represents a force

The direction arrow represents well a direction or a velocity.

You can't add a force to a direction or velocity, tempting though the diagram makes it seem.

Further the thrust force, which aligns with horizontal only in level flight, is developed by another agent, not shown on your diagram.

In the case of an aircraft, the wing is rigidly connected to the rest of the aircraft meaning that both positive and negative changes to the lift force are transmitted to each.

In your case the rope can only transmit tension and goes slack if the wing if lifted up.

Hydrofoils are rigidly connected to a boat for this reason. And of course for shaped hulls the force acts directly on the boat.

It is however true that in flight gravity must also be taken into account and this force can often be greater than the actual thrust.

3 hours ago, exchemist said:

In your scenario that is not the case, surely?

Thank you all, gentlemen. Held by a rope (not rigid) that 'pivots' at one tailored/calculated/chosen point along the 'wing' allows the angles of attack upwards or downwards. If pulled up by a wave peak, aims as to climb with motion. If left to slack by descending to a wave valley, aims down as to sink.

Am having difficulty expressing the expected behavior.* The ballast wing stays horizontal in calm sea. If the rope is pulled up, its leading edge is the one rising as the pivoting/holding point is towards its leading edge front. When slack by a wave valley, its weight moves the nose down and sinks forward.

*Perhaps instead analogy to an helicopter lifting a glider held to a hooked point that pulls its nose up when being raised. At certain altitude, if the helicopter releases the glider, the nose goes down and descends advancing while gains speed. Feel free to say it in other words to improve mine.

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Imagine you are holding with a rope, a heavy 'wing' near the bottom of a pool. Stays horizontal. Pulling the rope attached not at its center, will tilt and propel the 'wing' in a direction influenced by the position the rope is attached to.

Nearing surface, slacking the rope the 'wing' will nose down, sink, and travel in a certain direction. Does not move vertically in either case; it glides.🤔

@Externet I think the basic idea does have enough merit to deserve a closer look - but does the underwater water motion in the opposite direction to the wave actually move "backwards" (in an absolute sense) or is it more a case of moves forward with the crest but closer to stationary in reverse?

Engaging my brain a bit longer suggests it must move in reverse - net water motion = zero - therefore, yes, I think you could extract some propulsion that way. Whether that could be practical is different question.

Edited November 1Nov 1 by Ken Fabian

Good evening, Ken.

It would be better if you chose a more accurate numeric model for this.

Here is some actual marine data.

Note how the size of the circulation dies away with depth and the relationship between wavelength and rotational diameter.

You can definitely convert the up an down of waves into forward motion with a scheme similar to the OP but it I question whether it could done with enough efficiency to be practical. It doesn't seem like it would be very useful if all you get is something like a thousandth of a centimeter of forward progress per wave.

*also, it might be necessary for the "rope" to be rigid so the wing doesn't just swing back and forth under the boat.

Edited November 2Nov 2 by npts2020