Stabilizers - Gyro vs Electric Fin

[Salty Pelican]

I have experience with the MagnusMaster from DMS. Great product, very good support. Our 41 feet coaster/inland motor yacht is equipped with one. We added it to allow us to do longer travels, specifically at sea, where bigger waves creates a bit too much rolling in our boat to be comfortable.

Now, there are a few things to consider. First, I have heard RotorSwing might be less reliable, both engineering-wise and in service and support.

Secondly, the MM and RS add substantial drag. On my 17 metric tonnes motor yacht one MagnusMaster rotor sufficed. But - in rest - it eats away a kilometer on my top speed. Was 16,75 km/h before installation, now it is 15,75. With the rotor swing deployed 15,2 km/h is the max my boat can muster.

Thirdly, when in use, these rotors swing out. Depending on where you boat, this might cause issues, as they might "collect" nets, debris, etc.

Fourth, they break away easily. This is a build-in feature to prevent the very expensive rotating disc from being damaged. The break away rotor is - via a line - still attached to the boat, so might be put back in place, but in a location with logs, well, maybe not the best solution, since they can easily be damaged.

Finally, even though I love the amazing roll dampening that they offer, the ride can - at times - feel somewhat artificial. A little bit jerky, if that makes sense.

Regards, Edwin.

 

[Jolly Ogre]

I wish that were true; and it might be true in Florida. But I assure you that when cruising along the Pacific Coast, the vast majority of anchorages are open roadsteds that frequently have a swell running through, often that refract off whatever land is nearby. Setting a bridle just doesn't do the trick.

Right now, my boat doesn't have her outriggers on. My bride's first question when she saw it was "Where are the flopper stoppers? You are putting them back on, right???"

Peter

Ok I will give you that.. I have no experience with the Pacific coast only the Caribbean, Bahamas, Gulf Coast and the loop. There the only time stabilizers are really needed is when moving and then only in blue water.

 

[BandB]

Ok I will give you that.. I have no experience with the Pacific coast only the Caribbean, Bahamas, Gulf Coast and the loop. There the only time stabilizers are really needed is when moving and then only in blue water.

I don't agree at all. I would absolutely want stabilizers on the NP 45. Many have found them beneficial and even in Florida. Just the boat wakes can be anough to need them. Many trawler type boats rock terribly in waves and wind. Even boats like Hatteras need stabilizers You may be used to rocking but that doesn't mean most are and you bring a guest aboard without them and you may end up with a seasick guest.

 

[mvweebles]

I don't agree at all. I would absolutely want stabilizers on the NP 45. Many have found them beneficial and even in Florida. Just the boat wakes can be anough to need them. Many trawler type boats rock terribly in waves and wind. Even boats like Hatteras need stabilizers You may be used to rocking but that doesn't mean most are and you bring a guest aboard without them and you may end up with a seasick guest.

I agree - stabilization of some sort is highly desireable even outside of blue water. Like most who have owned a stabilized boat, I would never go back. Heck, I've been known to flip-on the fins when I see a ferry/wake coming, then turn-off.

The OP is certainly sold on stabilization. His question is what kind for his type of cruising - a great question. Specifically because he wants active mechanical stabilization at-anchor ("Zero Speed"). Given stabilizing an anchored 45-foot boat is fairly easy and inexpensive with flopper stoppers, hard to imagine going the extra effort with Seakeepers or the Wavelength gizmo, but maybe I'd be a convert if I gave it a try.

I wonder what type of response there'd be to a thread "Zero Speed Stabilizers: Do they work? At Anchor???"

Peter

 

[jimdavi]

I studied this for quite some time as I wanted stability in my NP45. Ultimately went with Keypower fin stability. Boat at yard getting fins installed. PM me if you would like to discuss.

 

[twistedtree]

So....I went on RotoWings URL. Lots of videos of pretty girls effortlessly tapping away on their PC in motionless bliss. And several exploded diagrams of the machinery (including the belt-drive internals). But not a single useful item on how these things work. Would be interested in seeing that.

I have to say, having a Euro-centric device on the boat seems like a recipe for frustration if (when??) you need repair or service. Might be a bit early in the product lifecycle for Americans.....

Peter

Sounds like 90% of the product web sites these days. The only thing you can learn is that if you buy their product, you will be happier, younger, and more attractive than you are today. Cool, I'll take two....


I agree with you about most of these alternative fin stabilizers, i.e. all the non-gyro variants. Hydraulic fins are very well proven and reliable, and available from a multitude of vendors. With such a critical system, and a system who's installation is essentially irreversible, the threshold for trying something "new" like a magnus effect rotor or electric actuators is very high. If for any reason they don't perform as expected, you have made a colossal, irreversible mistake. So the advantage has to be VERY compelling compared to the well-known and lower risk approaches, and I just don't see it in either of these other approaches. At best I see equivalent performance using a different approach. So why risk it.

 

[mvweebles]

Sounds like 90% of the product web sites these days. The only thing you can learn is that if you buy their product, you will be happier, younger, and more attractive than you are today. Cool, I'll take two....


I agree with you about most of these alternative fin stabilizers, i.e. all the non-gyro variants. Hydraulic fins are very well proven and reliable, and available from a multitude of vendors. With such a critical system, and a system who's installation is essentially irreversible, the threshold for trying something "new" like a magnus effect rotor or electric actuators is very high. If for any reason they don't perform as expected, you have made a colossal, irreversible mistake. So the advantage has to be VERY compelling compared to the well-known and lower risk approaches, and I just don't see it in either of these other approaches. At best I see equivalent performance using a different approach. So why risk it.

I wish TF had a special place for posts that provide a difinitive, respectful, and highly informed position on a topic. If there were, this would be filed under "When topic of stabilizers comes up....."

Peter

 

[Hippocampus]

Problem is without early adaptors we’d all be sailing or rowing.

 

[mvweebles]

Problem is without early adaptors we’d all be sailing or rowing.

Hippocampus - I know of no one who has done more research on stabilizers than yourself. I had never heard of Magnus Effect systems before you brought them to light on TF and I am truly curious. What do they do that hydraulic fins don't? I understand the possible benefits of direct-drive/brushless electric actuators, though reliability and serviceability would need to be established. For SeaKeepers, I understand the perceived benefit of no appendages and at-anchor stability.

But there are other systems on the market that I simply do not see a demonstrable benefit. Pneumatic instead of hydraulic seems like an incremental tradeoff. And the Magnus Effect system I searched (RotoSwing) gives zero information on how they work and why they are better.

I'm all for early adopters when there are benefits. But many ideas have died on the vine. In the end, there has to be a problem that is being solved - a value proposition. What is the gap in stabilization that Magnus Effect systems are solving?

Peter

 

[twistedtree]

Problem is without early adaptors we’d all be sailing or rowing.

But this is the key to innovation. The new thing needs to provide a compelling advantage, and when it does, the "thing" likely becomes successful. Gyros, for example, provide a number of advantages in a variety of circumstances, and as a result they are gaining traction. But it's not a hands-down better approach, so they have had limited success in displacing fins, and instead have opened new markets like smaller boats, and drifting/trolling boats, and have complemented fins in other applications to provide at-rest stabilization.


LFP is another example. There are clear and compelling advantages, so it's gaining rapid traction, and as costs and system integration improve, I expect will completely obsolete lead acid.


If a Magnus fin, just to pick an example, were twice as effective, or half the cost, or in some way compellingly better than the alternatives, I think you would see more market traction.

 

[BandB]

Problem is without early adaptors we’d all be sailing or rowing.

But very few are cut out to be early adapters. I'm sure not.

 

[DDW]

The Magnus effect, or it's use in stabilizers isn't "new". Older, lower tech than gyros for sure. There is a fair amount of technical info on the Rotorswing or DMS websites, though you have to click on the Technology tab to see it.

The Magnus effect, first described in the mid 1800's, is the creation of lift by a rotating cylinder. It is what makes a curve ball curve. The control system for Magnus rotors or fins is similar, in a Magnus rotor it changes the rotation of the cylinder rather than angle of the fins. They have some geometric advantages as they can be mounted to maximize roll moment and minimize steering moment, and they can therefore be mounted much further aft if layout demands it. They can be much smaller in area because the lift coefficients available are much higher. Drag is probably about the same though.

Certainly fins are the better worn path. Between Magnus rotors and gyros, not sure there is much to chose in terms of technology risk. Magnus rotors are much less likely to punch a hole in the hull, though that is a low risk in any case.

And I'll admit, "My name is DDW, and I am an early innovator...."

 

[Hippocampus]

At one point thought to replace the boat we had built for us with another boat we’d have built for us. Although specing a new boat is a major PIA it’s an education and most satisfying. However lead time to finished vessel, heart to heart with the admiral and economics suggested not a good move a this time. During that exercise took a look at the two major vendors of Magnus effect . Came away impressed by two of Quantums products.
The dynafoil which is a retractable active fin and the magnalift which is a retractable Magnus effect device. Both are in active service for ice class and military vessels. Depending upon hull they can be within the hull envelope so decreased risk of injury. The Magnus ones outer half detaches if seriously struck but also retracts automatically if struck. Both work at rest. Unlike gyros with their limited precession both continue to work in an sea state. Draw is comparable to fins and is instant on.
Hence for a boat that will need to work both in skinny water and deep, open clear water and full of debris or clear, wants draft restricted, wants device to work in any sea state think these two devices deserve a close look. Totally agree for a exclusively ble water boat given the refinements of current generation fins they east the list. But do see significant benefits to Magnus in certain settings.
Peter- my limited understanding-take any horizontal cylinder immersed in a fluid and spin it. Now move it in the vertical plane. The side in the lee of the movement will develop augmented negative pressure hence lift. The downside relative to the vertical movement will develop augmented positive pressure hence more lift. On the cylinder on the opposite of the boat if spinning around in the opposite direction the contra positive will be occurring. So both rotors will be try to restore the boat to level. Simple physics. Which way the cylinder needs to spin is determined by if it’s rising or falling when moving forward. You want the bottom of the cylinder moving against the direction of boat motion.

 

[bowball]

I think the new Flemings at least the 65 is specifying Humphree.

 

[mvweebles]

I think the new Flemings at least the 65 is specifying Humphree.

Okay, what are Humphree?

 

[BandB]

I think the new Flemings at least the 65 is specifying Humphree.

We have a complete Humphree system on an AB 116, stabilizers and interceptors. So much for not on fast boats.

 

[SANAUH]

https://humphree.com/boat-fins/

An all electric fin (24VDC) that can also rotate 360deg and provide stabilization while at anchor… similar to the CMC Waveless fins.

 

[Salty Pelican]

We are adding Humpfrees to the LM65h expedition yacht we are designing as well. Electric, on the move and at achor, and in cas of collision they break away. As important: in the simulations we did, they show about 90% roll reduction, which is pretty impressive.

Regards, Edwin.

 

[mvweebles]

https://humphree.com/boat-fins/



An all electric fin (24VDC) that can also rotate 360deg and provide stabilization while at anchor… similar to the CMC Waveless fins.

Website shows mostly larger, fast boats such as a Sunseeker. Compact design would really benefit small boats such as mine (hydraulic tank takes up a fair amount of space). Any sense if there are electric actuated fins that scale down? When I replaced mine, Wesmar and Naiad were the only options.

I would also think installation would be less expensive, especially on a smaller boat that frequently does not have a PTO of the generator or engine.

Peter

 

[Salty Pelican]

CMC - up until now - has mostly targeted bigger boats. They now also want to enter the market for smaller yachts and trawlers. They have a great reputation, but the support in terms of analysis of what they can do for those smaller boats still needs improvement, in my opinion. Makes it difficult to build a case for 'm yet.

Regards, Edwin.

 

[mvweebles]

CMC - up until now - has mostly targeted bigger boats. They now also want to enter the market for smaller yachts and trawlers. They have a great reputation, but the support in terms of analysis of what they can do for those smaller boats still needs improvement, in my opinion. Makes it difficult to build a case for 'm yet.

Regards, Edwin.

Thanks. For what it's worth, I had a lousy experience with Wesmar support when I purchased their system a couple years ago. That leaves Naiad for fins for small boats so there may be fertile ground in the market. Appears Helmsmen and North Pacific are going gangbusters. Might be worth CMCs effort to at least have a chat. A couple of well placed ads, maybe an influencer type YouTube, and they might be on to something credible. All assumes the technology scales, which I suppose isn't a problem.

Peter

 

[rslifkin]

Thanks. For what it's worth, I had a lousy experience with Wesmar support when I purchased their system a couple years ago. That leaves Naiad for fins for small boats so there may be fertile ground in the market. Appears Helmsmen and North Pacific are going gangbusters. Might be worth CMCs effort to at least have a chat. A couple of well placed ads, maybe an influencer type YouTube, and they might be on to something credible. All assumes the technology scales, which I suppose isn't a problem.

Peter

On the hydraulic front, the Side power vector fins also come in smaller sizes. Electric would be nice though, as for some smaller boats it'll just be easier to fit.

 

[BandB]

On the hydraulic front, the Side power vector fins also come in smaller sizes. Electric would be nice though, as for some smaller boats it'll just be easier to fit.

We loved our Sidepower and will have the same on our next loop boat. Electric really isn't important to us as we're going to run the generator anytime not docked.

One thing I'd suggest to all is to speak to the boat builder about their experiences and recommendations. If they regularly use a specific stabilizer and have had good results and customer satisfaction with it, then might well be a strong reason to go with it, plus all design and drawings and architecture already done. Don't overthink this and do not reinvent the wheel.

 

[Hippocampus]

Interesting link about Magnus

https://apps.dtic.mil/sti/pdfs/ADA165902.pdf

 

[Dav]

Secondly, electric or air operated fins will not have as quick a response time as a hydraulic systems thus lowering their effectiveness. I spent over 50 years in industrial applications using all three. By far the quickest movement is via hydraulics. As example - trucks, loaders, backhoes and airplane actuators that require rapid and high power movement are mainly hydraulic.

This is simply not true.

Hydraulics is mainly used for its power density. It will never match the response time of electric drive, which can be controlled in a timescale of milliseconds, microseconds even. Heck, in this context hydraulics is electrically controlled, via solenoid valves.

Its no surprise all the modern robotics is electric drives, and direct drive taking the field very quickly, for even more precise and fast control.

I see the electric fins taking over the hydraulics ones very quickly, for many reasons. Especially when 48 VDC becomes standard onboard voltage, as it provides plenty of power and makes the installations much simpler, both initial installation and maintenance.

 

[Dav]

So my choice is go with an ABT, Naiad or Wesmar hydraulic setup that has stood the test of time. Then your onboard house electrical systems can be smaller, cheaper and working under well established conditions.

Even all these established manufacturers are bringing electric options.

Forgot to add, at anchor electric power is much easier to provide than hydraulics.

 

[Dav]

I'd think electric makes sense at the largest end as you mentioned, but also at the small end where you don't need hydraulics for anything else and the system is small enough that the power draw isn't all that huge. It's in the middle where hydraulic is almost the only viable choice.

True and agree on the first part, for a superyacht with 24/7 genset or say 40ft boat electric stabilizers are way more practical and just make so much sense.

Now that they are available from multiple vendors for any boat size, I would not claim "hydraulic is almost the only viable choice" for any size of boat. Both are options, and electric ones are taking and will take the market share very quickly

 

[mvweebles]

All I can tell you is, as the owner of a 36 foot boat with hydraulic stabilizers, the oil tank and hoses are space hogs. I would seriously consider electric drive on compactness alone. I know nothing about them, but given what's going on in electric cars, I assume there are some hi-torque, fast response direct drive brushless motors out there that could easily drive fin actuators

Peter

 

[bowball]

We have a complete Humphree system on an AB 116, stabilizers and interceptors. So much for not on fast boats.

That’s a big boat, so it’s encouraging. My next boat will have Humphree’s.

 

[Dav]

All I can tell you is, as the owner of a 36 foot boat with hydraulic stabilizers, the oil tank and hoses are space hogs. I would seriously consider electric drive on compactness alone. I know nothing about them, but given what's going on in electric cars, I assume there are some hi-torque, fast response direct drive brushless motors out there that could easily drive fin actuators

I have a slightly bigger boat, but still my hydraulics setup takes up an entire wall out of the pretty sizeable engine room. Tanks, hoses, heat exchangers, cooling pumps, valves, manifolds etc, it is a lot of stuff, not only the pump on the main and aux engine.

I bet going to electrics would free a lot of room in the engine room and make the setup much more compact, simple and elegant, and being able to run it on batteries - or genset - at anchor would be a huge bonus.

These compact, high torque, extremely quick response and high efficiency bldc motors are quickly replacing hydraulics in many fields. I bet they will quickly replace hydraulics in boats not only for stabilizers, but also thrusters and other uses as well.

Actually, a motor like the one in a stabilizer would suit perfectly for steering as well - maybe implemented as a bldc motor with two independent windings and controllers fed from independent batteries, for full shared nothing class redundancy. Backup could still be hydraulic maybe, but the steering lines would not need to run all the way to pilothouse, backup steering wheel could be in the cockpit area somewhere, in addition to emergency tiller of course.