Hybrid Wave-and-Current Through-Channel Propulsion Concept – Engineering Feedback Requested

Hello everyone,

I’m looking for engineering feedback on a wave- and current-driven propulsion concept that I have developed and published openly (DOI below).

The vessel uses a set of cylindrical through-channels built into the hull. Waves and horizontal ocean currents pass directly through these channels. Inside each channel there is a lift-based screw rotor designed to extract energy from both oscillating wave motion and steady current flow.
The cargo is transported beneath the surface unit as stable ballast, unaffected by wind and waves.

The screw rotor can operate in two ways:

1. Energy extraction mode – working as a lift-based turbine in both directions of flow


2. Active propulsion mode – where external torque drives the screw and produces thrust inside the channel

This means the system can function as a hybrid wave-, current- and screw-based propulsion unit.
Its purpose is not only to harvest energy but also to provide forward thrust with relatively high efficiency in a confined tube.

The concept also includes:

a linear impulse system that handles short, high-energy wave pulses and stabilizes the rotor

a wall-integrated generator ring embedded in the channel walls

a passive hydrodynamic stabilisation system designed to keep the rotor precisely aligned

an active ceramic composite surface coating for extremely low roughness and antifouling


I would appreciate technical feedback on:

flow behaviour and pressure patterns inside a through-channel with wave and current input

lift and torque characteristics of a screw rotor in this environment

thrust potential when the screw is used actively as a propeller

losses, swirl and backpressure in a cylindrical duct

how the stabilisation and surface-coating concepts may affect performance


The full technical report is openly published on Zenodo DOI (EU/CERN-funded research infrastructure):

DOI:
Zero-Emission Wave-Energy Vessel with Lift-Optimized Archimedes Screw Turbines, Ultra-Durable Marine Coating, and Passive Mechanical Rotor Stabilization https://doi.org/10.5281/zenodo.17552757

Any constructive engineering input is welcome. Thank you for your time.

— Göran Skoog

 

I recommend you do the views and downloads here. I don’t want to download stuff to my devices for cursory review.

When I look at your device; it doesn’t fit with modern cargo loading facilities. It seems to me this would be the first place to start. Then adapt the propulsion power systems. Engineering is hard, because we have to work oftentimes within process constraints (like a shipping container offload). It ain’t painting a new picture on a new medium to paint on.

Perhaps I missed liquid only cargoes? Or perhaps the vessel is only the propulsion unit?

Anyhow, I’m not really the best person to engage with you on the design, but can offer you need to make the files available here for others as well.

The concept is very interesting and may have other applications; so keep after it.

 

Thank you for your response and your encouraging words.
The logistics have been carefully thought out and explained in the report, and they work with today's technology.
In all paradigm shifts, some changes need to be made. Among other things, the draught needs to be increased in some ports.
The cargo is transported under the surface unit, which acts as ballast for the vessel.

 

I read the report. It has a lot of claims, but no experimental proof or theoretical calculations at all. If a boat is adrift, the waves are not going to provide energy to move a vessel at the speed you claim, if any at all. The current will provide zero energy to a drifting vessel that moves at basically the same speed as the water. In short, there is nothing that is technologically feasible.

 

Thank you for taking the time to read the report and for commenting.

Just to clarify an important point:
The vessel does not drift with the water. It operates by continuously adjusting its heading and angle to the incoming waves and currents. This controlled motion increases the flow through the internal channels, which is the basis of the energy extraction.

So the system is not dependent on a free-drifting hull moving at the same speed as the surrounding water mass. The submerged module and the controlled cross-angle create a constant relative flow through the channels — even when the vessel’s overall speed is low. This is fundamental to the concept.

I agree that experimental data and theoretical calculations will be needed in later stages. Publishing the concept openly is a first step to gather perspectives, questions and criticism so the next stages can be developed in the right direction.

I appreciate your feedback and welcome any further thoughts you might have.

— Göran

 

So, just a dumb guy question. Almost all boats are affected by windage and current. Almost all boats get abeam in the wind (at drift).

And depending upon the hull shape, similar expectations from current.

What happens to this vessel under windage?

Under current?

Have you tank tested?

In order for the propulsion system to work; the vessel cannot turn sideways it seems.

I understand the design of the propulsion system is to be heading into the currents, but 3 weeks ago when I was out wind and current were opposing, what then?

 

Thank you for the questions — they’re not “dumb” at all. They go straight to the practical side of the concept.

About windage:
The vessel is affected by wind, like any other hull. But the design includes a submerged cargo module that provides a large part of the total mass and damping below the surface. That means the wind has much less leverage compared to a normal surface vessel.
So instead of being pushed abeam easily, the vessel keeps a more stable forward orientation.

About current:
The submerged module and the channel geometry create resistance against drifting with the current.
The vessel therefore does not simply “go with the flow.”
This controlled resistance is essential, because it maintains a relative flow through the channels, which is what drives the screw units.

Regarding turning sideways:
The system does not rely on sailing straight down the waves.
It operates by crossing waves and currents at controlled angles.
So it does not lose function if it is partially sideways — in fact, part of the design is based on adjusting the heading to get the best flow through the channels.

Tank tests:
Not yet. This stage is conceptual. The reason I published it openly is to gather feedback that helps shape what the next-step physical tests should look like.

I appreciate your questions — they highlight the practical concerns that will matter when moving from concept to prototype.

— Göran