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Old 11-29-2013, 12:50 PM   #1
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RotorSwing stabilizer system

I posted the introduction of the "Jetten 50 MPC". As a standard option Jetten Yachts can equip the yacht with the RotorSwing Stabilizer. For who never heard of this system here some info.

RotorSwing "The World's First Retractable Magnus Effect Stabilizer"

RotorSwing is the first fully electrically driven, non-hydraulic roll damping system for yachts up to 30 metres based on the Magnus effect. Instead of traditional fins, the system uses rapidly rotating cylinders which, subject to the direction of rotation, generate an up or downward pressure.

The biggest advantage of RotorSwing in comparison to a fin driven conventional system, is the greater roll damping at lower speeds. To achieve effective roll damping with fins it is necessary to reach a substantial speed through the water. This is partly due to the fact that often, the surface of the fins have been designed to be as small as possible to reduce the risk of damage. In shallow water, protruding fins are, in particular, very vulnerable.

RotorSwing features retractable rotors, eliminating the risk of damage. The retracted rotors remain largely within the turbulent boundary layer1 of the vessel so that any resistance is negligible.

If the rotors are in use in the “Drive” position, they can protrude outside the hull of the ship. However, should the engine be put in to neutral, the rotors automatically retract. This prevents damage during maneuvering and berthing at quays, in locks and ports.

The rotors do not have any effect on the steering and therefore, unlike fin based systems, can be mounted at a position of choice. For the majority of yachts, this is likely to be dictated by the onboard available space for the compact electric motor. It is even possible to mount the rotor at the stern which, in particular for fast-moving yachts, may be preferable.

RotorSwing is the first fully electrically driven, non-hydraulic stabilizing system based on the Magnus effect. No expensive, vulnerable hydraulic pumps, cylinders or high pressure lines and no risk of oil leaks on board. RotorSwing is a product from RotorSwing Marine, founded by Theo Koop. Theo, the founder and owner of the former KoopNautic Holland, is, for good reason, known as “the Godfather of stabilizers”.

Link: RotorSwing

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Old 11-29-2013, 01:43 PM   #2
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Very interesting. Thanks for posting this. Just a month ago, I saw something like this sticking out of the hull of a big Krogen while it was being slung. I couldn't get close enough to see if this was the device or not.
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Old 11-29-2013, 02:14 PM   #3
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This would sure be better than fins if it worked as well but it is a power hungry device. The specs say each rotor requires 1500W of 230 VAC power and averages 1000W of power. I assume you need 2 rotors so that would mean running a fairly good size generator when you need the stabilization.

I would sure like to see some independent reviews but can't find any.

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Old 11-29-2013, 02:25 PM   #4
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This would sure be better than fins if it worked as well but it is a power hungry device. The specs say each rotor requires 1500W of 230 VAC power and averages 1000W of power. I assume you need 2 rotors so that would mean running a fairly good size generator when you need the stabilization.

I would sure like to see some independent reviews but can't find any.

Ron
I would suggest to power them with Hydraulic Motors with the Hydraulic Pump mounted on the main engine.
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Old 11-29-2013, 02:47 PM   #5
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You mean these things?



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Old 11-29-2013, 03:50 PM   #6
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This would sure be better than fins if it worked as well but it is a power hungry device. The specs say each rotor requires 1500W of 230 VAC power and averages 1000W of power....
Please excuse my slope-foreheaded, uni-browed, knuckle dragging incompetance in all things electrical, but isn't that pretty much equivilant to turning on ten 100 watt lightbulbs per rotor? An alternator wouldn't even break a sweat, would it?
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Old 11-29-2013, 05:19 PM   #7
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... isn't that pretty much equivilant to turning on ten 100 watt lightbulbs per rotor?
Or, since everyone loves talking about horsepower, they average around 1.35 hp to run but evidently can consume up to a whopping 2 hp!

For the torque aficionados among us, that is a gut wrenching, steel bar twisting, rotate your world, about 7ft lbs or for our metric friends, about 9.5 Newton meters.
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Old 11-29-2013, 06:09 PM   #8
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Please excuse my slope-foreheaded, uni-browed, knuckle dragging incompetance in all things electrical, but isn't that pretty much equivilant to turning on ten 100 watt lightbulbs per rotor? An alternator wouldn't even break a sweat, would it?
Based on wattage, it would take the entire capacity of a 240 amp alternator to drive both of them at peak power consumption. This may not take into account peak draw in motor start up.

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Old 11-29-2013, 06:35 PM   #9
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Based on wattage, it would take the entire capacity of a 240 amp alternator to drive both of them at peak power consumption. This may not take into account peak draw in motor start up.

Ted
Ahh, there we go, something I can (sort of) wrap my head around. Thanks Ted,

Murray
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Old 11-29-2013, 06:56 PM   #10
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Based on wattage, it would take the entire capacity of a 240 amp alternator to drive both of them at peak power consumption. This may not take into account peak draw in motor start up.

Ted
Even if you ran them with a 12V motor (a really silly idea) they would still only consume about 80 amps each.

When operated at the 230VAC designed for they consume about 4 amps.
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Old 11-29-2013, 08:34 PM   #11
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Even if you ran them with a 12V motor (a really silly idea) they would still only consume about 80 amps each.

When operated at the 230VAC designed for they consume about 4 amps.
As they are 230VAC each and you would have to run the 12 volt DC output of the alternator through an inverter to convert it into 230VAC. After you factor in line loss and inverter conversion loss, 2 of these units that run at a maximum of 1500 watts each will likely consume all of the output of a 240 amp alternator.

1500watts per unit maximum multiplied by 2 units divided by 12 volts equals 250 amps.

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Old 11-29-2013, 08:37 PM   #12
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OR you can go with active fin stabilizers
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Old 11-29-2013, 10:11 PM   #13
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They sound interesting. But for once, i would like to see a promo video of a stabilizing system operating out on rough water; Maybe with a 4 ft beam sea, rather than a 1 foot wake in flat water.
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Old 11-29-2013, 10:30 PM   #14
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They sound interesting. But for once, i would like to see a promo video of a stabilizing system operating out on rough water; Maybe with a 4 ft beam sea, rather than a 1 foot wake in flat water.
Bingo!

You'd think, after all that sweat equity and personal commitment to bring this to market, that they would want to show it off in all manner of gnarly following and beam sea conditions. Then again, maybe they don't
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Old 11-29-2013, 10:42 PM   #15
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OR you can go with active fin stabilizers
I gave my Naiad active fins quite a workout yesterday. My boat was put back in the water at Bulimba after Norman R Wright's had repaired the damage from the Canadian stevedores mismanagement of the slings. Wrights did a magnificent job of the repair.

So I had little choice to head back up to my berth at Newport Marina with a strong wind warning in effect, and seas 1 to 1.5m. Wind was up to 30kn, but mostly in mid 20's. The Naiad's kept the boat perfectly level port to starboard, and I was quartering the seas for most of the way. I was amazed that there was virtually no roll. And delighted. The fins were getting to maximum quite often, and moving/adjusting all the time. The control box has accelerometers in it and they sense movement very early and hence the flat ride.

Fore and aft pitching was a different story! Every now and then there was a significant rise and plunge. I decided it was best to keep up a bit of speed, and did most of the 25 nm trip at just under 10 knots. Sure, I got a fair bit of spray on the flybridge but it was still a pretty good ride. Little slamming, and momentum helped the ride I'm sure.

Contrary to an erroneous claim above, a good active fin installation will be designed to be effective at low speeds. I have 7.5 sq ft fin area. I get good response in the 5-6 kn range. Its true that at greater speeds they give more countering force, and I think I probably benefited from that yesterday. And good design/installation means that they don't protrude outside the hull sides, or anywhere near the depth of the keel. You would have to work hard to scrape them on anything. Although debris in the water can bump them.

I'd like to see some good tests of the cylinders the OP talks about. I would be curious about the snap-back effect. A friend had a powered gyro on his boat and the snap-back to correct a roll was sufficiently quick to ensure his wife got seasick. It was not a gentle roll correction at all. But that might also be because it was 'generic' gyro, and not the highly regarded SeaKeeper system. What would be really good is to have some hard data on all of these systems roll, measuring their damping/correction over time, to quantify the modified roll period.
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Old 11-29-2013, 10:55 PM   #16
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I've often wondered if trim tabs could be equipped with fast acting cylinders and a motion sensing control to act as roll stabilizers. Bennett has a sensor that will level a boat but I don't think the tabs react fast enough for true roll control.
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Old 11-29-2013, 11:07 PM   #17
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.............................I'd like to see some good tests of the cylinders the OP talks about. I would be curious about the snap-back effect. A friend had a powered gyro on his boat and the snap-back to correct a roll was sufficiently quick to ensure his wife got seasick. It was not a gentle roll correction at all. But that might also be because it was 'generic' gyro, and not the highly regarded SeaKeeper system. What would be really good is to have some hard data on all of these systems roll, measuring their damping/correction over time, to quantify the modified roll period.
RotorSwing’s History and Design Background

The intent of Theo Koop was to create something unique. Theo wanted to make the world’s first electric Magnus effect stabilizer that was not only electrically powered, but also retractable. Theo had a big challenge ahead of him, to make stabilizer fins that protrude from the boat, are relatively easy to install, and are also kept safe from vulnerabilities in shallow water. The new RotorSwing system was the optimum solution; quiet, safe, and extremely effective, even at speeds around 4 knots.

By 1982, Theo had already designed the first line of retractable Magnus effect stabilizers with his company, KoopNautic Holland. Although his first prototypes were very effective at the time, the sealing technology against the seawater was still a challenge. A few of the initial installations that were delivered are still in operation, however, the maintenance on the rotary seals of these systems requires regular attention from the owners. KoopNautic Holland had to stop the production of the initial stabilizers due to the aforementioned sealing issues.

Since Theo’s first installations, sealing technologies have improved drastically. Having sold his stabilizer company and retiring, Theo got the urge to start again with a new stabilizer that utilizes the Magnus effect.

Theo and his business partner, Lambert Dinnissen of Quantum Controls, have proven experience and tenure in the design, development, and construction of large roll damping systems. They designed and engineered a complete line of fin stabilizers for both underway and ZeroSpeed® applications that are available for large yachts, commercial, and military vessels.

When Theo was first approached about designing and manufacturing retractable stabilizers for smaller power boats up to 20-25 meters in length, he immediately thought of the Magnus effect. Such a system for small boats had to either be retractable or swing-away in order to make the system less vulnerable to damage. The retraction of a “normal” fin system is practically impossible, because it takes up too much room inside the ship. Theo found that the Magnus effect cylinders are the answer. To simplify the installation, Theo researched the technology and created a fully electric system. There is nothing technically wrong with a hydraulic system, but it is too expensive and installation takes time and expertise.

Theo and Lambert didn’t just stop at a completely new mechanical and electrical design, they also wanted the most cutting edge electronic control technology implemented into their product. Electronic design engineer Rudolf Geurink was hired to create the best and brightest control system using the latest algorithms.

The new prototype system was built into Theo’s Linssen Grand Sturdy 430 which is a yacht that is 13.5 meters in length. The prototype was tested extensively in all kinds of weather and since then, several systems have been delivered successfully to various types of yachts. Theo and Rudolf now run the company RotorSwing Marine BV.

Quantum, the art off stabilization.

YOUR STABILITY IS OUR MISSION

20 years experience in ship motion control gives Quantum the technical edge in providing military vessel stabilizer solutions. As missions and capabilities evolve at a time of calls for increased efficiency and economy, reduced ship motion means the crew works in greater comfort, greater safety, and with more ability to focus on the task at hand as they expand the mission envelope.

Mark Armstrong will be attending upcoming Military Shows and Conferences.

Link: Quantum Hydraulic - Military Sales
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Old 11-30-2013, 06:08 AM   #18
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As they are 230VAC each and you would have to run the 12 volt DC output of the alternator through an inverter to convert it into 230VAC. After you factor in line loss and inverter conversion loss, 2 of these units that run at a maximum of 1500 watts each will likely consume all of the output of a 240 amp alternator.


Or you could put a thousand thermocouples in your exhaust and power the inverter off that voltage source. Or maybe use a windmill with belts and gears ... there are dozens of really stupid ways to drive the things. Running them off a 12V inverter is just one of them.

If you have a boat big enough to fit active stabilizers, you probably have a boat and budget big enough to fit a generator.
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Old 11-30-2013, 07:31 PM   #19
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Or you could put a thousand thermocouples in your exhaust and power the inverter off that voltage source. Or maybe use a windmill with belts and gears ... there are dozens of really stupid ways to drive the things. Running them off a 12V inverter is just one of them.

If you have a boat big enough to fit active stabilizers, you probably have a boat and budget big enough to fit a generator.
Rick, you missed the point.
The point of my post was not to suggest that you should run a set of stabilizers off an inverter, the point was to give a comparison of how much energy they require. My first response was to give the person (post 6) who was asking for something they could more easily relate to. Most of us can grasp the power output of a 240 amp alternator. For some, 3, 000 watts peak power requirement isn't as easy to relate to.

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Old 11-30-2013, 09:00 PM   #20
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Ted's right, Rick. I'm one of those stupids. Even if I do get a lot out of your posts, I sometimes need a translator.
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