Maintenance on Electric Fins stabilizers

[KnotYet]

It is the compressibility of a fluid medium that creates the lag versus the instantaneous change of direction in electric direct driven fins or rotors. It seems like nothing, but isn’t.
The phenomenon is more apparent in rotors because you do not wait for the change in defection to go from positive to negative as the forces on the vessel change. just and instantaneous change in direction of rotation.
I currently own neither.

I see two errors in your statement.
Unlike gasses, liquids do not compress. This makes for a very linear control of liquid flow.
A hydraulic system can be designed to have the degree of instantaneous motion wanted.
Likewise, an electrical actuator can be designed to have any change of direction or speed.
The mechanical limitations of the system may limit how abruptly you want to move the fins,
but either hydraulic or electric actuators and their power supplies could be made to do it.

 

[Mambo42]

I see two errors in your statement.
Unlike gasses, liquids do not compress. This makes for a very linear control of liquid flow.
A hydraulic system can be designed to have the degree of instantaneous motion wanted.
Likewise, an electrical actuator can be designed to have any change of direction or speed.
The mechanical limitations of the system may limit how abruptly you want to move the fins,
but either hydraulic or electric actuators and the power supplies could be made to do it.

Basically it does not matter to me what gives me stabilisation at rest. That can be either hydraulic, pneumatic, gyro or electric. The only part that was (and is) important to me is that I can run electric fins off my batteries and no other system can do that.
For any hydraulic or pneumatic system I would need a heavy pump running which draws enormous amounts of energy. That can be a PTO on an engine or on a generator or it can be a large capacity compressor. That means I have to have some sort of motor running and that is something I did not want. With gyros it is even worse, they guzzle so much energy that I would actually need to buy a new generator in order to run a gyro in my boat.
Can hydraulic stabilisers keep a boat stable at anchor ? Probably can, but the trade off is such that it does not make any sense anymore. What is the point of having a heavy hydraulic or pneumatic pump running continuously while the system is only part of the time really needing that capacity ? To me that is not efficient.

At the moment I am lying on the town quay in Nydri, Greece. Boats pass by every now and then. So sometimes the stabilisers have to work hard to keep the boat stable, rest of the time they are doing nothing, drawing no electricity whatsoever. If I would need to have an engine running 24 hours per day to keep the hydraulic pump working, that would not be a good solution for me.

 

[KnotYet]

Now that there are options like zero speed stabilization, electric is the way to go if the rest
of your electrical system can support it. Flopper stoppers are very effective and quiet also.

 

[Gypsy Island]

Basically it does not matter to me what gives me stabilisation at rest. That can be either hydraulic, pneumatic, gyro or electric. The only part that was (and is) important to me is that I can run electric fins off my batteries and no other system can do that.
For any hydraulic or pneumatic system I would need a heavy pump running which draws enormous amounts of energy. That can be a PTO on an engine or on a generator or it can be a large capacity compressor. That means I have to have some sort of motor running and that is something I did not want. With gyros it is even worse, they guzzle so much energy that I would actually need to buy a new generator in order to run a gyro in my boat.
Can hydraulic stabilisers keep a boat stable at anchor ? Probably can, but the trade off is such that it does not make any sense anymore. What is the point of having a heavy hydraulic or pneumatic pump running continuously while the system is only part of the time really needing that capacity ? To me that is not efficient.

At the moment I am lying on the town quay in Nydri, Greece. Boats pass by every now and then. So sometimes the stabilisers have to work hard to keep the boat stable, rest of the time they are doing nothing, drawing no electricity whatsoever. If I would need to have an engine running 24 hours per day to keep the hydraulic pump working, that would not be a good solution for me.

Running a hydraulic engine driven pump all the time isn‘t necessary as you can add a pressurized hydraulic tank and an electric pump. I‘m seriously considering this for the future but first there are other points on the list.
And my compressor on board could easily run pneumatic stabilizers, it has a tank and shut‘s off, so the only problem could be the size of the stabilizers not being sufficent for at rest stabilization.

The question is if it‘s really worth the effort and money?

 

[twistedtree]

Another consideration is how proven various products are, or are not. There are many very well proven hydraulic stabilizer products out there. Electric stabilizers are new to this market, and it will take time for them to gain the same level of customer confidence as their hydraulic counterparts. Some I expect will prove very good, and others will belly-flop like Humphrees.
We all have different levels of patience for experimental tech on our boat. If I have learned anything about boats, it's that most new products do not live up to expectations.

 

[twistedtree]

As for power consumption, the energy needed to counteract roll on a boat is the same regardless of whether it's a hydraulic or electric drive fin, or a gyro. Granted, there will be differences in the idle load, and I can see how electric actuators might be lowest with fewer parasitic loads. But I'd be slow to judge how much lower.

With a gyro the parasitic load is keeping the gyro spinning at high speed, plus electronic control operation, and hydraulics for the actuator. With hydraulics it's a motor driving a pump, but the pump will not be loaded when idle so motor load would be minimum. With electric actuators there may be nothing more then control electronics power when the fins aren't moving, but I expect there is still a bit of draw on the actuators to hold the fins in position.

Aside from idle/parasitic loads, if one system consumes less power, then it's because it has less righting force, and will be less capable, and should be judged/compared accordingly.

 

[Mambo42]

Another consideration is how proven various products are, or are not. There are a few very well proven hydraulic stabilizer products out there. Electric stabilizers are new to this market, and it will take time for them to gain the same level of customer confidence as their hydraulic counterparts. Some I expect will prove very good, and others will belly-flop like Humphrees.
We all have different levels of patience for experimental tech on our boat. If I have learned anything about boats, it's that most new products do not live up to expectations.

Electric fins have been around since 2008 (first installation), but obviously it has been in development a lot longer. We have seen huge improvements in electric cars over the last 20 years, you cannot compare the first electric cars with the current electric cars. On the forefront of the electric car development is a company called RIMAC, not well known, but that is the company that develops most of the electrical components car manufacturers use.

Electric motors for electric fins are not anywhere close to the motors for cars, after all, they don't need to go around in circles all the time. Basically they need to move the fins back and forth all the time, that is it. They can go 360 degrees if you would want them to do that, but it is not functional.
The heart and soul of electric fins however are not the electric motors, it is the software behind the system itself. Once the software figures out how to stabilize the boat it is just a simple set of commands to the electric motors. Those commands are not much different than what a hydraulic fin gets in commands. Only difference is that most hydraulic fins are not suitable for zero speed stabilisation, mostly because of mechanical shortcomings, after all the software can be changed. E.g. DMS creates new control boxes for hydraulic fins companies that are no longer on the market. I recently visited a boat that has Voiper fins (hydraulic), but the control box is no longer functioning. That renders them inoperable, so the solution used to be to get complete new fins. Nowadays you can change the control box, get new software and make them work again.

The statement that electric fins are new to the market is factually incorrect, unless you want to call an almost 20 year presence on the market 'new'. Unkown would be a better description of electric fins.
The reason why many new players on the electric market do not succeed, like Humphree and Chinese products, is that they have to work around patents that belong to one company, CMC, at the moment. And that company (CMC) is the company that invented the electric fins and the software that goes with it. But that company also has the worst marketeers in the whole business. The fact that the marketing department does not do a good job has not a lot to do with equipment being good or bad. And even with poor marketing, CMC still holds about 25 % of the large yacht market (over 30 mtrs). For some reason that is the market that they aim for, apparently they are not interested in the small boat (40 - 100') market.
Do I have experimental tech on my boat ? Not really, it has been perfected over a period of almost 2 decades and it works flawless. In all the time that I have been using them I have not had a single fault (mechanical, electrical or software). And from what I understand from the dealers of CMC I am putting more hours per year on the clock than anyone else. When I tell them I have 12.000 hours on my clock in a little over 2 years they are astonished. I also don't expect anything less than perfect performance, that is what I paid for and that is what I expect. When I hear of the problems Humphree created for its customers I can only wonder why a company would do this to its customers, because bad publicity usually means lower sales.

 

[Mambo42]

As for power consumption, the energy needed to counteract roll on a boat is the same regardless of whether it's a hydraulic or electric drive fin, or a gyro. Granted, there will be differences in the idle load, and I can see how electric actuators might be lowest with fewer parasitic loads. But I'd be slow to judge how much lower.

With a gyro the parasitic load is keeping the gyro spinning at high speed, plus electronic control operation, and hydraulics for the actuator. With hydraulics it's a motor driving a pump, but the pump will not be loaded when idle so motor load would be minimum. With electric actuators there may be nothing more then control electronics power when the fins aren't moving, but I expect there is still a bit of draw on the actuators to hold the fins in position.

Aside from idle/parasitic loads, if one system consumes less power, then it's because it has less righting force, and will be less capable, and should be judged/compared accordingly.

The gyro was, for me at least, the most aestatic solution, after all, you don't see anything sticking out of the boat, but when they told me the power consumption I was shocked. When the boat is not moving it does not take a lot of energy to keep that gyro spinning (perhaps 1 kw for the gyro in the size for my boat), but as soon as the boat needs to be stabilised that quickly jumps to 4 Kw and that meant that my 6.5 Kva generator would solely be used to run the gyro. On top of that, the generator cannot react that fast to changing loads so I would actually run into more problems.

For the hydraulic system it is possible to store some hydraulic pressure, but the moment a disturbance is detected that stored hydraulic pressure get depleted real fast, requiring a high capacity pump to quickly bring the hydraulic system back up to pressure. So that would either be a heavy electrical pump (4 Kw or more) or an engine needs to be running all the time.
I was looking at a trawler (terranova 68) that does have hydraulic zero speed fins (4 of them), but for that system to operate one generator needs to run 24 hours per day. That results in a significant fuel consumption and thus heavy operating cost.

When my fins are not moving they are in the neutral position, which does not require any electricity. If I switch them on or off (when there is no disturbance) I don't see any increase or decrease in the AC loads. Can I move the fins by hand when they are in neutral ? Perhaps, but I never tried, I would have to move the fins against a 2 Kw electric motor and the moment I would try that the system would detect a disturbance and start an opposing force.
The fins in neutral means that the water has equal pressure on both sides of the fin, so no energy is required to keep the fins neutral (the water pressure remains identical after all).
If there is a disturbance it is not the fins that get moved by the waves, the boat gets moved out of the stable position (detected by a small gyro on the fly bridge) and only then will the fins move to counter that disturbance and that is when electricity gets used.
When they start operating I will see an increase in the AC loads, but that differs all the time. The software tells the fins to react faster or slower, with more or with less deflection. In other words it can order the fins to move at full speed to max deflection or it can order the fins to move at a slow speed to full deflection or at full speed to e.g. 10 degrees or at low speed to 10 degrees. That is all decided by the software and it does a great job in stabilising the boat in any type of sea. I can be in a long swell or short choppy sea, the fins will react differently, but the result is the same, the boat is stable at zero speed.

The conclusion that a system is less capable because it consumes less energy is not a correct statement. If you would look at the pure mechanical force required to bring a boat back to stable condition then you are correct. Unfortunately the efficiency of the subsequent systems results in completely different power consumptions.
My electric fins are in neutral when there is no disturbance, but will react when needed. That is an electric motor connected directly to the fins, there is no gear box, there is no shaft sticking out of the boat.
Hydraulic fins have a hydraulic pump which does not have 100 % efficiency, then that fluid needs to be moved through hydraulic lines, which also take a percentage (by expanding and creating friction) away from the efficiency. After that the hydraulic fluid goes into cylinders, moves pistons, creates heat through friction, thereby loses efficiency and then there is finally the gearbox assembly which also takes efficiency away from the whole system.

In the end a hydraulic system may need 20 or 30 % (or more) extra energy to overcome all the inefficiencies, where an electric motor may need 5 % extra energy to overcome its inefficiencies.
But the biggest power consumption is not when operating the system, the biggest difference in consumption is when the system is in idle, waiting for a disturbance. In idle a hydraulic system will always lose pressure, so therefore it needs to be brought up to pressure again. Same is for a pneumatic system and even more for a gyro.
An electric motor on the other hand is just doing nothing, not consuming anything.

 

[Mambo42]

Running a hydraulic engine driven pump all the time isn‘t necessary as you can add a pressurized hydraulic tank and an electric pump. I‘m seriously considering this for the future but first there are other points on the list.
And my compressor on board could easily run pneumatic stabilizers, it has a tank and shut‘s off, so the only problem could be the size of the stabilizers not being sufficent for at rest stabilization.

The question is if it‘s really worth the effort and money?

I also looked into pneumatic stabilisation when i was deciding on which system to choose. The compressor and tank that I needed was massive, I basically had no idea where to put that thing, it had the size of a 50 gallon oil drum, it was absurd. Then there was all the extra equipment that was needed, such as pressure regulators, water oil separators with filters, long pneumatic lines, connectors etc, in other words, so many points where that system could fail. And the moment that the system would start to work that 4 Kw (220 V) compressor would start to work and would not stop working until the disturbance was gone and the tank was at full pressure again. It basically meant a 4 Kw or 18 amps (at 220 V) or 180 amps (at 24 V) all the time. That requires heavier wiring, heavier fuses and again a dedicated generator, basically running all the time. Unless of course if you are willing to get out of bed each time to start the generator when the compressor starts to work.

With a hydraulic tank it is basically the same. The moment the stabilisers will start to work the pressure in that tank will start to drop and that means the pump will need to start working, creating a heavy draw on your batteries and the generator will need to start working.

Do you need zero speed stabilisation ?
That is only a question you can answer. When I see the videos of BC and I see the flat calm waters in the many fjord there, you basically don't need zero speed stabilisation.
But when I look at e.g. the Bahama's in strong winds (25 - 30 kts) you will be happy to have zero speed stabilisation in a small boat. If you have a heavy 70 or 80' boat you may not need it, but for a boat my size (50') it is necessary if you want some comfort onboard. And here in the Med it is necessary if you want to be able to anchor out during the season. They are also charging you 50 euro a night to be on your own anchor if you are in protected bays, so if you want to avoid that you need to be in more unprotected waters, which means waves and swell. Nice for 1 day, but not a whole season. Going into a marina is not really an option. At 140 - 180 euro per night I would spend between 33.000 and 43.000 euro each season, just in marina fees. That is not really affordable, so anchoring out is the only way to limit the cost and then zero speed stabilisation is very welcome, especially when the price difference between hydraulic fins and electric fins was almost nil. Hydraulic fins could not give me zero speed, electric fins could and I can run them off my solar and my batteries. Made it an easy decision.

 

[twistedtree]

The gyro was, for me at least, the most aestatic solution, after all, you don't see anything sticking out of the boat, but when they told me the power consumption I was shocked. When the boat is not moving it does not take a lot of energy to keep that gyro spinning (perhaps 1 kw for the gyro in the size for my boat), but as soon as the boat needs to be stabilised that quickly jumps to 4 Kw and that meant that my 6.5 Kva generator would solely be used to run the gyro. On top of that, the generator cannot react that fast to changing loads so I would actually run into more problems.

Just as a comparison, your STAB 25 jumps to 3kw

For the hydraulic system it is possible to store some hydraulic pressure, but the moment a disturbance is detected that stored hydraulic pressure get depleted real fast, requiring a high capacity pump to quickly bring the hydraulic system back up to pressure. So that would either be a heavy electrical pump (4 Kw or more) or an engine needs to be running all the time.
I was looking at a trawler (terranova 68) that does have hydraulic zero speed fins (4 of them), but for that system to operate one generator needs to run 24 hours per day. That results in a significant fuel consumption and thus heavy operating cost.

This is another example that is 4kw vs your 3 kw, just to keep everything in perspective. One way or another, they all need to be powered.

When my fins are not moving they are in the neutral position, which does not require any electricity. If I switch them on or off (when there is no disturbance) I don't see any increase or decrease in the AC loads. Can I move the fins by hand when they are in neutral ? Perhaps, but I never tried, I would have to move the fins against a 2 Kw electric motor and the moment I would try that the system would detect a disturbance and start an opposing force.
The fins in neutral means that the water has equal pressure on both sides of the fin, so no energy is required to keep the fins neutral (the water pressure remains identical after all).
If there is a disturbance it is not the fins that get moved by the waves, the boat gets moved out of the stable position (detected by a small gyro on the fly bridge) and only then will the fins move to counter that disturbance and that is when electricity gets used.
When they start operating I will see an increase in the AC loads, but that differs all the time. The software tells the fins to react faster or slower, with more or with less deflection. In other words it can order the fins to move at full speed to max deflection or it can order the fins to move at a slow speed to full deflection or at full speed to e.g. 10 degrees or at low speed to 10 degrees. That is all decided by the software and it does a great job in stabilising the boat in any type of sea. I can be in a long swell or short choppy sea, the fins will react differently, but the result is the same, the boat is stable at zero speed.

Yes, that's how stabilizers work - all of them.

The conclusion that a system is less capable because it consumes less energy is not a correct statement. If you would look at the pure mechanical force required to bring a boat back to stable condition then you are correct. Unfortunately the efficiency of the subsequent systems results in completely different power consumptions.

I think I said the same thing.

My electric fins are in neutral when there is no disturbance, but will react when needed. That is an electric motor connected directly to the fins, there is no gear box, there is no shaft sticking out of the boat.

The STAB 25 is not an electric motor directly connected to a fin, at least not accrding to CMC. It has a brushless AC motor, coupled to an epicycloidal gearbox, which is a fancy name for a planetary gear. There is no shaft, but a protruding fin just like any other fin system. I'm not sure its structural makeup matters much.

Hydraulic fins have a hydraulic pump which does not have 100 % efficiency, then that fluid needs to be moved through hydraulic lines, which also take a percentage (by expanding and creating friction) away from the efficiency. After that the hydraulic fluid goes into cylinders, moves pistons, creates heat through friction, thereby loses efficiency and then there is finally the gearbox assembly which also takes efficiency away from the whole system.

In the end a hydraulic system may need 20 or 30 % (or more) extra energy to overcome all the inefficiencies, where an electric motor may need 5 % extra energy to overcome its inefficiencies.

I think we are saying the same thing, though I didn't make up numbers. BTW, CMC claims 85% efficiency, not the 95% that you guessed. Regardless, without guessing at numbers, I do believe that electric is better than hydraulics in this regard.

But the biggest power consumption is not when operating the system, the biggest difference in consumption is when the system is in idle, waiting for a disturbance. In idle a hydraulic system will always lose pressure, so therefore it needs to be brought up to pressure again. Same is for a pneumatic system and even more for a gyro.
An electric motor on the other hand is just doing nothing, not consuming anything.

Actual numbers on hydraulics would be interesting. Other than very low end system, the hydraulics use variable displacement pumps so are not moving any oil when idle, other than for lubrication. So power consumption is pretty low.

 

[twistedtree]

Electric fins have been around since 2008 (first installation), but obviously it has been in development a lot longer. We have seen huge improvements in electric cars over the last 20 years, you cannot compare the first electric cars with the current electric cars. On the forefront of the electric car development is a company called RIMAC, not well known, but that is the company that develops most of the electrical components car manufacturers use.

I didn't make any comparisons like this.

Electric motors for electric fins are not anywhere close to the motors for cars, after all, they don't need to go around in circles all the time. Basically they need to move the fins back and forth all the time, that is it. They can go 360 degrees if you would want them to do that, but it is not functional.

Going around in circles is exactly what the CMC fin motors do, coupled to the fin via a planetary gear. The more goes around and around in one direction, then around and around in the other direction.

The heart and soul of electric fins however are not the electric motors, it is the software behind the system itself. Once the software figures out how to stabilize the boat it is just a simple set of commands to the electric motors. Those commands are not much different than what a hydraulic fin gets in commands.

Agreed, this is no different from any other fin system

Only difference is that most hydraulic fins are not suitable for zero speed stabilisation, mostly because of mechanical shortcomings,

What limitations? The hydraulic fin companies I'm familiar with offer fins specifically designed for zero speed. If you are talking about retrofitting zero speed to an existing fin system, then sure, there might be limitations. But that's because it's a retrofit, not because it's hydraulic vs electric.

after all the software can be changed. E.g. DMS creates new control boxes for hydraulic fins companies that are no longer on the market. I recently visited a boat that has Voiper fins (hydraulic), but the control box is no longer functioning. That renders them inoperable, so the solution used to be to get complete new fins. Nowadays you can change the control box, get new software and make them work again.

OK, but I don't see how that's relevant to this discussion.

The statement that electric fins are new to the market is factually incorrect, unless you want to call an almost 20 year presence on the market 'new'. Unkown would be a better description of electric fins.

That's not what I said. I said they are new to "this" market, i.e. small cruising boats like most of us have here on TF. The CMC small boat product line has been out for 5 years, not 20 years. Perhaps CMC has hit the nail on the head with their offering and it will prove to be bullet proof. That would be great, and make them one of the few to accomplish that. But I'll also remind everyone about carbon foam batteries that were goign to change the world, worked great, then a few years later have all been removed from boats because they didn't hold up. Humphrees seems to have issues with their planetary gear. Will CMCs be trouble free? Only time will tell.

The reason why many new players on the electric market do not succeed, like Humphree and Chinese products, is that they have to work around patents that belong to one company, CMC, at the moment.

People throw out the "patent" argument all the time. I'll pay attention if there is a specific patent where another company's work around caused a problem, let along a company failure. I doubt any CMC patent is the root cause of anyone else's planetary gear problems.

And that company (CMC) is the company that invented the electric fins and the software that goes with it. But that company also has the worst marketeers in the whole business. The fact that the marketing department does not do a good job has not a lot to do with equipment being good or bad. And even with poor marketing, CMC still holds about 25 % of the large yacht market (over 30 mtrs). For some reason that is the market that they aim for, apparently they are not interested in the small boat (40 - 100') market.
Do I have experimental tech on my boat ? Not really, it has been perfected over a period of almost 2 decades and it works flawless. In all the time that I have been using them I have not had a single fault (mechanical, electrical or software). And from what I understand from the dealers of CMC I am putting more hours per year on the clock than anyone else. When I tell them I have 12.000 hours on my clock in a little over 2 years they are astonished. I also don't expect anything less than perfect performance, that is what I paid for and that is what I expect. When I hear of the problems Humphree created for its customers I can only wonder why a company would do this to its customers, because bad publicity usually means lower sales.

It's great that yours are working well, and I hope that continues. There are definitely benefits to electric stabilizers, but let's not get too starry-eyed about it

 

[Retriever]

I'm glad your CMC system has performed well, and regret not selecting it myself.

We put a Humphree electric stabilizer system on a boat I ran and it has been a disaster. The've clunked loudly since the beginning and they began leaking water into the boat after less than two years. Parts and service are very difficult or impossible to get.

They are so bad that the owner plans to throw them away and replace them with something else when the boat is back in the USA.

I wouldn't wish Humphree on anyone!

 

[Mambo42]

I didn't make any comparisons like this.

Going around in circles is exactly what the CMC fin motors do, coupled to the fin via a planetary gear. The more goes around and around in one direction, then around and around in the other direction.

Agreed, this is no different from any other fin system

What limitations? The hydraulic fin companies I'm familiar with offer fins specifically designed for zero speed. If you are talking about retrofitting zero speed to an existing fin system, then sure, there might be limitations. But that's because it's a retrofit, not because it's hydraulic vs electric.

OK, but I don't see how that's relevant to this discussion.

That's not what I said. I said they are new to "this" market, i.e. small cruising boats like most of us have here on TF. The CMC small boat product line has been out for 5 years, not 20 years. Perhaps CMC has hit the nail on the head with their offering and it will prove to be bullet proof. That would be great, and make them one of the few to accomplish that. But I'll also remind everyone about carbon foam batteries that were goign to change the world, worked great, then a few years later have all been removed from boats because they didn't hold up. Humphrees seems to have issues with their planetary gear. Will CMCs be trouble free? Only time will tell.


People throw out the "patent" argument all the time. I'll pay attention if there is a specific patent where another company's work around caused a problem, let along a company failure. I doubt any CMC patent is the root cause of anyone else's planetary gear problems.


It's great that yours are working well, and I hope that continues. There are definitely benefits to electric stabilizers, but let's not get too starry-eyed about it

There is a lot to react to, which is almost impossible, but I will focus on the more important parts.

It is true that the stab 20 was introduced in 2019, but this was just a continuation or development of the earlier series, the stabilis electra. The soft ware basically did not change a lot, it was just the miniaturisation of the electric motors.

But for anyone who has doubts on the technical workings of these electric fins I have some interesting stats.
Prior to zero speed stabilisation there was basically only underway stabilisation. And here in Europe it is calculated that the average boater uses his or her boat around 50 hours per year. Take a few people who use the boat more than that and let's say they use their boat 400 hours per year. The stabilisers therefore only make those 50 to 400 hours per year.
In comparison, my stabilisers have now done over 12.000 hours in 27 months. For a hydraulic underway system to get to 12.000 hours it would need between 30 and 240 years. That is a lot of years and I doubt they will never see any problems during that time. In my 12.000 hours I have not seen any problems or faults arising at all. And if it would be a hydraulic zero speed stabiliser I still would need to see it last for 12.000 hours, because I have the idea pistons and cylinders will be worn out well before those 12.000 hours.

I guess that is also the reason why more and more stabiliser producers are introducing their own version of electric fins.

 

[KnotYet]

Zero speed stabilization is a comparatively low power mode meaning low wear and tear.
I would expect similar low wear and tear for both hydraulic and electric fins used that way.
The same amount of forces and stresses are passing through either system.

 

[Retriever]

Zero speed stabilization is a comparatively low power mode meaning low wear and tear.

It’s actually just the opposite. Zero speed stabilization requires much MORE power. Fins must be larger and they must move faster the slower the boat goes, all the way down to zero speed.

This is really apparent with the Humphree electrics…we see current draw of more than 100 amps (at 24v) per side routinely at rest, and more like 30 amps per side when underway.

I’ve just spent some time with ABT looking at their offerings, including a visit to the first boat in the USA with their 240v fins. If I went electric again it would be with ABT, largely because their support speaks the same language as I do and it’s relativly easy to move between DC electric, AC electric, and hydraulic actuation.

 

[KnotYet]

It’s actually just the opposite. Zero speed stabilization requires much MORE power. Fins must be larger and they must move faster the slower the boat goes, all the way down to zero speed.

This is really apparent with the Humphree electrics…we see current draw of more than 100 amps (at 24v) per side routinely at rest, and more like 30 amps per side when underway.

I’ve just spent some time with ABT looking at their offerings, including a visit to the first boat in the USA with their 240v fins. If I went electric again it would be with ABT, largely because their support speaks the same language as I do and it’s relativly easy to move between DC electric, AC electric, and hydraulic actuation.

That is interesting and somewhat counter-intuitive to me, a newcomer to fin stabilization.
Thank you for that correction.

Also, I was recently on the phone with Inov8v Marine, the parent company for ABT and
TRAC stabilizers, to troubleshoot an electrical problem I had with my hydraulic fin system.
This was late afternoon on the East coast but within minutes I was talking with a seasoned
engineer familiar with the issue I was having. We diagnosed my problem in a few minutes.
I have nothing but praise for that level of customer care for the 3rd owner of a 25 year old system!

 

[DDW]

There are now Magnus rotors with zero speed stabilization. I don't know how much power is used in them, but they are typically electric.

 

[Mambo42]

There are now Magnus rotors with zero speed stabilization. I don't know how much power is used in them, but they are typically electric.

Many companies now offer electric stabilisation, in many different forms. The Magnus effect however does need movement through the water, so what some companies have come up with is moving the whole rotor back and forth to create water flow over the rotor. To me that does not make a lot of sense and uses more electricity than necessary.

 

[sunchaser]

My 20 year old Wesmar hydraulic fins gave few if any problems over a 4,000 hour cruising regimen. Like KY’s they are powered off the port engine PTO via a Vickers pump. The fins get pulled every 4-5 years for seal PM. That’s it, but I seldom anchored where at rest rolling was a issue.

Based upon my 50+ years of (very large) hydraulic and electric actuator systems I struggle with the notion that electric actuators will wholesale replace hydraulic pumps and actuators in a damp salt water environment. One look in one’s ER could sway my thinking however. Zero rust anywhere, a bone dry bilge(s) and perfect wire runs would be my target for electric actuators.

When all is said, whether electric or hydraulic, the initial setup combined with varying degrees of maintenance and one’s stabilization needs will determine the ultimate success.

 

[DDW]

Many companies now offer electric stabilisation, in many different forms. The Magnus effect however does need movement through the water, so what some companies have come up with is moving the whole rotor back and forth to create water flow over the rotor. To me that does not make a lot of sense and uses more electricity than necessary.

The way zero speed fins work is by moving the whole fin back and forth to create water flow. Hydrodynamically, there is reason to believe the Magnus rotors would be more efficient in this use than fins - but I don't know from experience, we'd need to see some data.

 

[Mambo42]

The way zero speed fins work is by moving the whole fin back and forth to create water flow. Hydrodynamically, there is reason to believe the Magnus rotors would be more efficient in this use than fins - but I don't know from experience, we'd need to see some data.

I spoke with DMS at length before I decided which stabiliser I was going to install and they told me that I would need a speed of at least 4 kts for the Magnus master to work. The Magnus effect only works when there is water flow over the rotor.
So when a boat is stationary there is no water flow (unless you have a current of 4 kts, in which case you won't have a lot of waves either), so now you have to create that water flow. That means moving the rotor back and forth the whole time and that is a separate motor, which means more electricity usage.

The fins don't create water movement to become effective. What they do is use the friction of the water (read: the opposing force of the water) to push the boat in the other direction. So when the boat wants to roll to the left the fins will also move to the left to use the opposing force of the water to push the boat back upright again. No movement of water over the fins is required.

 

[DDW]

If there is no water movement over the fins, there is no force on the fins. In fact both fins and rotors work the same way, by creating lift (or drag) from movement. When the boat is still, the fins work like a paddle, pushing water through movement. Their coefficient of drag is pretty inefficient but still something. Magnus rotors move on the folding axis pretty much normal to the roll, so don't do much at all through drag. But they do create lift perpendicular to their motion if the cylinder is rotating, and that is how they work when the boat is still. They spin the cylinder, then rotate the folding axis to create motion through the water, and therefore lift counteracting the roll. The fins are creating force like a parachute does, and the magnus rotors more like a helicopter. It isn't at all obvious which will be more efficient, and no reason to assume that the electric fins would be.

 

[Mambo42]

If there is no water movement over the fins, there is no force on the fins. In fact both fins and rotors work the same way, by creating lift (or drag) from movement. When the boat is still, the fins work like a paddle, pushing water through movement. Their coefficient of drag is pretty inefficient but still something. Magnus rotors move on the folding axis pretty much normal to the roll, so don't do much at all through drag. But they do create lift perpendicular to their motion if the cylinder is rotating, and that is how they work when the boat is still. They spin the cylinder, then rotate the folding axis to create motion through the water, and therefore lift counteracting the roll. The fins are creating force like a parachute does, and the magnus rotors more like a helicopter. It isn't at all obvious which will be more efficient, and no reason to assume that the electric fins would be.

I was not talking about the boat being stable. When the boat is hit by a wave, the boats will start to roll and when it rolls there will be a force on the fins. But that is not what stabilises the boat. The fins will move in opposite direction of the roll and use the water as sort of like a wall to push against (as if you would do when you push yourself away from a wall).
Since the fins are connected to the boat almost at the front of the fin, which means that this the turningpoint of the fin it will push the water also backwards, thereby creating a forward motion of the boat. For that reason you can 'flip' the fins 180 degrees so now the boat will 'swim' backwards and not over the anchor.
The swimming motion of the boat however is minimal. When I am lying stern to, as i am now, the fins don't have enough strength to tighten the shore lines. At anchor I will need to pay attention of swimming over the anchor when there is absolutely no wind. If I have 5 kts of wind the boat will not swim over the anchor due to the motion created by the fins. So the forward motion, created by the fins, when they keep the boat stable at anchor is almost nil.

Magnus rotors work basically like the principle of a wing, the water over the top goes faster than the water below rotor, thereby creating a upward force (extremely simple explained).
However, the Magnus rotor will need a water flow over the rotor to function. If the rotor would be sitting in water with no current and no forward speed, there is not going to be an upward force, it is just not going to happen. The rotor can spin around like crazy, not a lot is going to happen.
That is the reason why DMS states you need 4 kts of speed through the water in order for the Magnus rotor te become effective. Obviously, when you are at anchor you won't have that speed and thus they had to come up with a different way to create that 4 kts speed through the water. If the water is not going to move then why not move the rotor with a speed of 4 kts through the water ? And that is what they did.
The new all in one series of DMS is however back again to the fin movement, not with a rotor anymore. They still sell the Magnus rotor, but now they also have the fin that is installed on an arm at the stern of the boat.

 

[twistedtree]

Also, I was recently on the phone with Sleipner Group, the parent company for ABT and
TRAC stabilizers, to troubleshoot an electrical problem I had with my hydraulic fin system.

Something is mixed up here. ABT and Wesmar are part of Inov8v Marine, and privately owned. They aren't part of Sleipner. What stabilizer system do you have?

 

[twistedtree]

If there is no water movement over the fins, there is no force on the fins. In fact both fins and rotors work the same way, by creating lift (or drag) from movement. When the boat is still, the fins work like a paddle, pushing water through movement. Their coefficient of drag is pretty inefficient but still something. Magnus rotors move on the folding axis pretty much normal to the roll, so don't do much at all through drag. But they do create lift perpendicular to their motion if the cylinder is rotating, and that is how they work when the boat is still. They spin the cylinder, then rotate the folding axis to create motion through the water, and therefore lift counteracting the roll. The fins are creating force like a parachute does, and the magnus rotors more like a helicopter. It isn't at all obvious which will be more efficient, and no reason to assume that the electric fins would be.

^^ This. Good explanation, and not pseudo science.

 

[KnotYet]

Something is mixed up here. ABT and Wesmar are part of Inov8v Marine, and privately owned. They aren't part of Sleipner. What stabilizer system do you have?

Good catch, it had been a couple months and I misremembered that detail of the parent co.
I'll edit my post.

One thing that stood out to me was that the troubleshooting phone number in the software
on my display screen still worked 25 years after it was bought and installed!

 

[tonykool]

This video link below might be interesting to people following this thread. From reading up on this, it seems like there might be some maintenance advantages to electric stabilizers as well as the ability to rotate 360 degrees. Also, with more boats going with the new battery technology, seems like it is just a better solution. The guy in the video references energy harvesting which is also interesting.

 

[Gypsy Island]

There's a lot of selling talk, obviously the bearings should last a life long, but how long is a life to them? If i understood it correctly, you cannot change them if they are worn or water gets in , the whole unit has to be renewed - big $$$.

I like my old style fully mechanical hydraulic NAIADS, no ECU, no electronics at all just plain simple.

 

[Jklotz]

There's a lot of selling talk, obviously the bearings should last a life long, but how long is a life to them? If i understood it correctly, you cannot change them if they are worn or water gets in , the whole unit has to be renewed - big $$$.

I like my old style fully mechanical hydraulic NAIADS, no ECU, no electronics at all just plain simple.

I agree. No bearings last forever. I remember when BMW released the 1200GS motorcycle. They said "lifetime final drive gear oil, never needs to be changed". A year later, they were replacing final drives on a boat load of bikes under warranty, and changed the manual advising to change it every 6 months. Problem was, they were so confident about the lifetime oil when they released it, they didn't put a drain plug on the unit. So you had to suck it out with a syringe and plastic tube. That was fun.

 

[sunchaser]

I like my old style fully mechanical hydraulic NAIADS, no ECU, no electronics at all just plain simple.

Without a control module consisting of a roll sensor, electronic boards and associated output signals, how do they work? The control logic used by Naiad, Wesmar, etc is not new technology, my first hands experiences go back more than 30 years. A few years ago I was on a 5 decade old DeFever that had a single stabilizer controlled by roll sensor with electronics based upon some aircraft instrumentation. Art tried all sorts of electronic stabilizer strategies to smooth things out on his long offshore cruises.