The rotor manoeuvring system is a good investment

Aboard Henk de Vries’s new MTS Myriam vessel, a single system attracts special attention from fellow shippers: the Rotor Manoeuvring System (RMS) developed and produced by Damen Marine Components (DMC). This active RMS improves the course stability of a vessel and reduces fuel consumption. ‘You definitely notice the effect.’

If you have been active in inland shipping for a long time, you continually see new developments coming in. If, like Henk de Vries, you have been active in the industry for almost half a century, you sometimes even see discoveries making a come-back decades later.

De Vries (69) experienced that when he supervised the construction of his latest MTS Myriam. More or less by coincidence, the RMS came up in a discussion with DMC. De Vries had known of the system since its introduction in 2000, but it had faded into the background somewhat for him since then. Yet an RMS for more course stability and less fuel consumption was precisely what he needed.

So he had not just one, but two RMSs installed into his new inland shipping tanker, which has a length of 135 metres and a beam of 17.50 metres. Now that he has been sailing with these for a while, he can conclude that they meet his expectations. ‘It’s been a good investment,’ he says.

Magnus effect
The RMS consists of a vertical cylinder of corrosion-resistant composite material. At a sailing speed of 6 km/h or more, the cylinder can submerge into the water below the vessel. The operation of the system is based on the principle of the Magnus effect, the physical phenomenon in which the rotation of objects in a liquid or in air affects their propulsion.

If the cylinder rotates quickly below the bow, a pressure difference arises in the water flowing past it between the starboard and port sides of the cylinder, with a sideways lift force or propulsion: in other words, the Magnus effect. By switching the rotation direction, the cylinder can pull the vessel to starboard or port. In this way, the bow is kept straight, so that there is no need to compensate with the main rudders, which can remain straight.

The rotor drops to a maximum of 1.20 metres below the bow, which means that the draught is very limited, and can be infinitely adjusted from an extension of 60 centimetres. Extension and retraction take place hydraulically. The rotation is controlled electrically with the aid of a 15-kilowatt electric motor. The system can be operated via an HDMI touchscreen and a handle that enables the skipper to control the speed of the electric motor.

Course stability, less fuel consumption
De Vries finds the RMS very easy to use. ‘With a crosswind, you lower the rotor a little and you can stay perfectly on course. At first, you have to find the combination with the ordinary rudders at the back, so that the bow and stern ‘communicate’, as it were. But once you have mastered that, it all goes fairly simply. When you want more propulsion, you extend the cylinder a little lower below the vessel and give the command for faster rotation. You then definitely notice the effect.’

Apart from improved course stability and, therefore, improved safety, the RMS has another major advantage for him: it saves him fuel. ‘The rudders at the stern now have little or no rudder deflection, and everyone knows that all rudder deflection causes a change in speed, which in turn costs fuel. We no longer have to deal with that now.’

Toofan Pour, senior sales engineer at DMC in Hardinxveld-Giessendam, can confirm that. ‘The rotor does not steer on the basis of resistance, as normal bow rudder systems do, but solely on the basis of the Magnus effect. So you don’t lose speed and there are no rudder movements that increase the fuel consumption.’

For every new vessel, DMC can provide a document containing proof that the RMS saves fuel. As a result, the owner qualifies for an Energy Investment Allowance, a Dutch government subsidy to stimulate investments in energy-saving equipment.

Integration with river autopilot
The RMS on board De Vries’s MTS Myriam had an extra upgrade in February last year, when it was integrated with the Alphatron Marine river autopilot, a frequently used system in inland shipping. ‘In the past, you had to adjust the rotor yourself, depending on the route,’ Pour explains. ‘Now there are two buttons on the pilot: one for the conventional pilot system, using the rudders, and one for the RMS, which leaves the rudders as they are while you steer only with the RMS.’ The new AlphaRiverPilot MFS will be on the market soon, leading to further integration, with both systems being operated simultaneously with the rudder of this autopilot.

In that way, a system that has already been around for a very long time still remains in development. In some ways, however, the upgraded version of the RMS can hardly be compared with the original. ‘In 2020, we completely overhauled the product dating from 2000, recalculated it and adapted it to modern requirements,’ Pour says. ‘That’s why we no longer talk about the old and the new version; this is the version.’

High demand
It is a version that could not have come at a better time, the demand for the RMS is higher than it has ever been. ‘There are various new vessels already sailing with it, and there will be dozens more. That’s thanks to the inland shipping culture. If you see that a fellow shipper has a system like that and ask him about it, and then get a very enthusiastic reply, you start to become curious about it yourself. It really has developed a new life of its own.’

A source of great satisfaction to De Vries, who has been active in inland shipping as an independent skipper since as long ago as 1976 and has been using the products of DMC since 1987 (when DMC was still named Van der Velden). His latest MTS Myriam is equipped with a DMC steering system, rudders, nozzles and hydraulic units. And regardless of all the benefits in the fields of course stability and fuel savings, the key issue for him is something else. ‘Sailing pleasure and enjoyment are also important to me, and systems like the RMS certainly contribute towards that.’