Nordhvn 51 stabilisers

[nigel52]

My brother in law in Phuket is buying a Nordhvn 51 and needs advice on stabilisers. It looks like between CMC & Humphrey’s.




i am told that we should be able to install electric Stabilizers on board your N 51. Drew has provided two manufacturers that we could use, CMC and Humphree. See the attachment for the CMC’s and the link below for the Humphree. Also, per Drew’s comments below, he estimates the CMC up charge would be about $ 25,000 more and the Humphree could be and additional $ 10,000 to $ 15,000 above that. Please let us know if you have a preference as to which stabilizer manufacturer you would like to


Here is CMC. I don’t know what model Humphries we would use. I need to get that from the yard.



Humphree website: https://humphree.com/boat-fins-and-stabilizers/

 

[mvweebles]

I can't speak to either brand, though having gone through install of hydraulic fins, I am very much intrigued by electric actuators given their small size due to no hydraulic oil tank.

I looked at the Humphrees site. One caveat is the examples they emphasize are planing boats. I'd make sure they have good reference customers on displacement boats such as a Nordhavn. Nordhavn have installed a LOT of ABT systems, and ABT are legendary for their customer support. Something to think about as your BIL makes decisions on kit.

Peter

 

[sunchaser]

There must be a reason that the new 51 design has adopted Humphree electric stabilizers. Nordhavn - PAE- should explain their reasons to prospective new buyers after hundreds of Nordhavns have been built with hydraulic stabilizers.

Personally, I'd do a deep dive into the 24 volt design for redundancy between each JD 6068 and the genset.

 

[twistedtree]

There must be a reason that the new 51 design has adopted Humphree electric stabilizers. Nordhavn - PAE- should explain their reasons to prospective new buyers after hundreds of Nordhavns have been built with hydraulic stabilizers.

Personally, I'd do a deep dive into the 24 volt design for redundancy between each JD 6068 and the genset.

The explanation I heard was to try to simplify the systems on the smaller boats. Getting rid of hydraulics was one of them.

 

[rslifkin]

I'd think having redundant electrical supply to the stabilizers is easier than redundant hydraulic supply. And there should be less failure points with electric stabilizers as well.

I remember seeing something about ABT-TRAC coming out with electric fin actuators, so some of the big, long term players are taking that route too.

 

[sunchaser]

The explanation I heard was to try to simplify the systems on the smaller boats. Getting rid of hydraulics was one of them.

Makes sense, which ties in with Humphree's sales promos. Clean sheets have been adopted for the Turkish built Nordhavns, not a bad thing.

 

[Retriever]

A few months ago I replaced a Naiad 302 system with Humphree 14 square foot fins on Starr, a Northern Marine 77. Then I took it from Seattle to Hawaii in November to give it a good test. The Humphrees proved reliable for that trip and worked better than the Naiads ever did. I was worried about the ability of the electric motors to stabilize a 100+ ton boat, but they never showed any signs of stress, even with a fishing net wrapped around one fin.

The real magic is at rest. No hydraulic whine, no generator noise, very little servo noise (although you do get the occasional clunk). The stabilizers run for many hours off the 24v house bank. It’s a total game changer for anchoring around Hawaii…quiet, effective, push button at-rest stabilization.

When we had to stop mid-Pacific and dive to clear a net, the Humphrees did an amazing job of making life aboard tolerable.

We like that the Humphree fins spin 180 degrees and pull back on the anchor, rather than swimming the boat forward, especially since Starr has a bulbous bow that could grind against the chain.

Because the fins rotate 360, they may extend beyond the hull side and below the keel. Care must be taken to ensure they don’t actuate in a situation where they’d contact something.

My only real concern is what happens when they break. The servo unit is a total mystery and the manual is pretty sparse on troubleshooting details. With a Naiad or ABT system, I knew where to start looking if there are problems; not so with Humphree.

We added a second 24v 175A alternator to ensure plenty of power for the stabilizers and everything else.

No hydraulic fluid is a HUGE plus in my opinion. Hydraulics need cooling, they leak, fluid has to be replaced, they’re relatively noisy. Just yesterday I blew the seals out of a Naiad cylinder on my own Nordhavn 50. What a mess!

 

[sunchaser]

Retriever
Great post. You touch on the controls, which some (expensive?) spare parts may help on.

 

[twistedtree]

I haven't looked at it much, but the power requirements are non-trivial. I saw AC electric fins that were in the 10kw, range, and DC fins in the 2-3kw range. There is no free lunch with stabilization. It takes energy to counter roll, and on first approximation, the same amount whether hydraulic, AC electric, or DC electric. If something is notably less power, then I think you can expect lower performance too. I'm not saying they aren't good or won't work, just noting that there is no magic involved either, and that any electric system may require more electric capacity than you would otherwise have.

 

[Retriever]

I haven't looked at it much, but the power requirements are non-trivial. I saw AC electric fins that were in the 10kw, range, and DC fins in the 2-3kw range. There is no free lunch with stabilization. It takes energy to counter roll, and on first approximation, the same amount whether hydraulic, AC electric, or DC electric. If something is notably less power, then I think you can expect lower performance too. I'm not saying they aren't good or won't work, just noting that there is no magic involved either, and that any electric system may require more electric capacity than you would otherwise have.

You’re right. Each servo can draw ~100 amps at 24v. The load really jumps around and I think it’s tough on alternator belts. Overall the load doesn’t seem that bad (I’d like to quantify it over hours at anchor on of these days), but there are very big peak loads. Power draw is dramatically higher at rest than underway since the fins rotate through a much larger arc.

The Humphree fins rotate amazingly quickly…about 1 second to rotate 90 degrees.

I ran 4/0 cable from the battery bank to each servo, about 200 feet total. That was a project!

 

[Intrepid]

Look into the magnus stabilizers.

 

[sunchaser]

TT &Retriever
You are correct about the power, it has to come from somewhere. With a battery (house or start)is this sufficient buffer for the load the alternators would see?

Does Don’s NM have a hydraulic windlass and a hydraulic warping drum? Presumably the N51 does not thus an all electric mechanical system results.

 

[Delfin]

A few months ago I replaced a Naiad 302 system with Humphree 14 square foot fins on Starr, a Northern Marine 77. Then I took it from Seattle to Hawaii in November to give it a good test. The Humphrees proved reliable for that trip and worked better than the Naiads ever did. I was worried about the ability of the electric motors to stabilize a 100+ ton boat, but they never showed any signs of stress, even with a fishing net wrapped around one fin.

The real magic is at rest. No hydraulic whine, no generator noise, very little servo noise (although you do get the occasional clunk). The stabilizers run for many hours off the 24v house bank. It’s a total game changer for anchoring around Hawaii…quiet, effective, push button at-rest stabilization.

When we had to stop mid-Pacific and dive to clear a net, the Humphrees did an amazing job of making life aboard tolerable.

We like that the Humphree fins spin 180 degrees and pull back on the anchor, rather than swimming the boat forward, especially since Starr has a bulbous bow that could grind against the chain.

Because the fins rotate 360, they may extend beyond the hull side and below the keel. Care must be taken to ensure they don’t actuate in a situation where they’d contact something.

My only real concern is what happens when they break. The servo unit is a total mystery and the manual is pretty sparse on troubleshooting details. With a Naiad or ABT system, I knew where to start looking if there are problems; not so with Humphree.

We added a second 24v 175A alternator to ensure plenty of power for the stabilizers and everything else.

No hydraulic fluid is a HUGE plus in my opinion. Hydraulics need cooling, they leak, fluid has to be replaced, they’re relatively noisy. Just yesterday I blew the seals out of a Naiad cylinder on my own Nordhavn 50. What a mess!

Their brochureware asserts pitch control. Can you confirm that versa the Naiads, and effectiveness?

 

[Mambo42]

I have the CMC Stab 25 and am absolutely happy with them, they work flawless and consume very little energy.

I installed them last year and my search for stabilizers took about a year. Spoke with almost every stabilizer provider and put all the pros and cons in an Excel sheet.

My demands were very specific, since we live basically 8 to 9 months per year on the boat.
I wanted the following:

1. Stabilization while underway
2. Stabilization on anchor and in port
3. Use as less energy as possible
4. I don't want to run an engine or generator to be able to power the stabilizers, in other words I need to be able to run them off the batteries
5. Easy maintenance

What did I find ?

1. All the hydraulic and pneumatic stabilizers need some type of equipment to be able ot operate. That is either a hydraulic pump or a compressor. Both use a lot of energy and/or require an engine or generator to run. And that took them out of the equasion

2. Humphree and other rotorsystems, plus most of the hydraulic and pneumatic systems cannot operate while on anchor. They need a speed of 3 to 4 kts in order to function. They don't have the response time of electric stabilizers. So that took them out of the equasion.
Since that time Humphree has also entered the electric fin market, but I don't have enough knowledge of the ins and outs of that system.

3. The only electric one left is the Gyro, made by multiple producers. The gyro does do a good job, both underway, on anchor and in port. However, it takes about 30 - 45 min to spool up, which means if you have it switched off and you encounter a sudden storm........too bad, there is nothing that can be done. The only solution then is to leave them on all the time, but now you bring in the biggest problem of a gyro and that is the electricity usage. These things guzzle electricity and that means you need a generator running all the time. If you have a generator running all the time then it is not a problem, but be aware they can take about 3 Kw per hour and that is a lot.
On top of that, the gyro's are kind of bulky, so you will need to have space for them. Also, at the time I was searching you needed to change the bearings every 3000 - 5000 hrs and that means taking the whole thing apart. We spend about 5600 hours each year on the water, so somewhere in the season (every year) we need to do a complete rebuild.
Based on the above the gyro's went off the list.

4. So I was left with electrical stabilizers. Nowadays there are a few more producers who have started making them, but when I contacted CMC they were basically the only ones and they were the ones who basically invented them.
Good part is that the fins are screwed onto the motor. if you hit anything underwater not a lot will happen. The fin may break off, but the motor will be unharmed. Within a couple of days you can have a new fin again.
Another good part is that the motor itself does not get in contact with water at all, is physically impossible.
But best of all is that the actuators, the motors, fit in extremely small spaces. They are about 15 cm high and that is it. There is an electricity cable connected to it and that leads to a control box in the ER. There you will find the fuses, print plates etc. In the pilot house you will then have a small control box that powers the screen and that is it.
I have the main control panel in the pilothouse and a smaller, waterproof, panel on the flybridge.

In the end I installed one size larger than was required for my boat and that was based on a tip I got from someone who has Naiads and does about the same speed as I do. Our speed is about 5.5 - 7 kts, while the size of the stabilizers is calculated at 10 kts. A slower speed means less efficiency, so they sized up and I basically followed their advise.
CMC told me that, since the stabilizers are electric, it does not really make a difference. Electric fins can vary the speed and force at which they react, thereby making up for smaller fin size. I could have used the Stab 20, saved myself 14.000 euro, they would have worked a bit more, which means a slightly higher electricity usage. But I did not want to gamble, so decided to take the one size larger.

Question of course is: 'how much electricity do they really use ?'

Mine are officially rated for 2 Kw per fin, which sounds like a lot of electricity (that is 220 V, not 12 of 24 V).
In reality however I normally see between 200 and 300 W for the 2 of them combined and that is only when they are operating (on anchor). That is about 10 - 15 Amps at 24 V per hour, which is next to nothing. I have 1400 Ah of Lithium onboard, which means I can run them all through the night without a problem.
Of course, if you get into a sudden storm, they will increase their usage, but I have seldom seen over 500 - 600 W (for the both of them combined, at 220 V).
Underway the batteries get charged anyway, so I basically don't care how much they use. Only once, when we were caught in a storm and were beam on, I saw 1 Kw (total for the both of them, at 220 V).
So although they can draw 2 Kw at 220 V, I have absolutely never ever seen that. In other words, this system uses very little energy.

The system has a very clever way to save energy. You can reduce the sensitivity of the whole system, which means that it won't react to small disturbances. In other words if it is OK to move a little bit you set the sensitivity to minimum and you will see the electricity usage drop drastically. We normally put the system on minimum sensitivity while on anchor in a calm bay or in port. System will still react to large disturbances, but small disturbances will result in a slower reaction.

Another good part about CMC are the added features, which we use on a daily basis. You can opt for some extra software and that will cost you some money, but absolutely worth it.
The standard modes are Navigation and Anchor, which in itself are fine. In both modes you can set the sensitivity from minimum to maximum by pressing the screen.

The extra modes are
- Dock
- Flip
- Slow speed (MSS)
- Center

The dock mode is what you use in port or in a marina. It limits the movement of the fins, so they cannot get outside the hull range, which means even when you are tied to the dock you can still have the stabilizers on. We have been in ports where ferries and other boats pass by at high speed. The whole port was rocking and rolling, we were lying steady as a rock

Flip mode is what you can (if you want) use while on anchor and basically it turns the fins 180 degrees. As a result the boat will keep tension on the chain and you won't drift over your anchor, reducing the risk of pulling your own anchor out of the ground. This mode I use when there is no wind, but when there is wind I just keep them in the normal anchor mode, which actually reduces the tension that the wind puts on the chain.

MSS mode is something you use while you are maneuvering at low speed. Normally the system will put the fins in center position when the speed drops below 4 kts. It assumes you are in close proximity to the shore, so just to make sure you don't forget to switch them off, the system will center them for you.
However, it can be bad weather or rough in the port / marina or anchorage, so that you do want stabilization in order to keep the crew safe while they work the lines or fenders. Then you select MSS and the fins will work like they do in Dock mode, so limited movement of the fins.

All these options basically enable you to operate the fins under all conditions and that makes them ideal. In fact, I don't understand why anyone would want to have any other system.
E.g. why would you want to go hydraulic when you then have a less responsive system and have all the risks of leakages, plus problems with pumps ? I can only understand it if you have a 100 mtr boat, then you will need hydraulic, otherwise the electric motors will become massive.


Lastly, installation of the system takes about 20 days in total (if you have an existing boat). If the boat is still under construction it is of course much easier.

It was a long story, but this is in detail what CMC is all about and to be honest I think that for the size of boats most of us have, electric fins are the way to go.
No need for hydraulics, pneumatics or electricity guzzling systems. They take up almost no space and use very little energy.
If you happen to have solar panels and a large battery bank (like I do) you can run them all day long without even thinking about them. They will keep doing their job.

 

[READY]

Thank you Mombo42 for that very informative post!

 

[Retriever]

Their brochureware asserts pitch control. Can you confirm that versa the Naiads, and effectiveness?

The control panel allows for adjusting sensitivity of pitch control, but I don’t think it works with just fins. Maybe if you had a larger install with 4 fins, but my sense is the pitch control is geared towards fast boats that are using the fins and interceptors together and the interceptors are doing the pitch control.

 

[nigel52]

The explanation I heard was to try to simplify the systems on the smaller boats. Getting rid of hydraulics was one of them.

I must admit adding electrical redundancy should be easier than hydraulic redundancy. I know when I helped my brother in law (BIL) take delivery of his Halberg Rassy 55 in 2005 our first trip offshore and some of the hydraulics failed on the mast. Luckily I could jury rig other alternatives. Even if the genset failed at least the engine alternator should drive the electric stabilisers.

 

[nigel52]

Wow, what a useful comprehensive reply and much appreciated.

 

[finatic2002]

My brother in law in Phuket is buying a Nordhvn 51 and needs advice on stabilisers. It looks like between CMC & Humphrey’s.




i am told that we should be able to install electric Stabilizers on board your N 51. Drew has provided two manufacturers that we could use, CMC and Humphree. See the attachment for the CMC’s and the link below for the Humphree. Also, per Drew’s comments below, he estimates the CMC up charge would be about $ 25,000 more and the Humphree could be and additional $ 10,000 to $ 15,000 above that. Please let us know if you have a preference as to which stabilizer manufacturer you would like to


Here is CMC. I don’t know what model Humphries we would use. I need to get that from the yard.



Humphree website: Boat fins and stabilizers

Nigel, if you have an AC genset onboard, opt for CMC, which is equipped with AC servo motors and drives. They're more robust, durable, and quieter than the DC technology. You'll also benefit from being able to use significantly smaller power cables! There's no need for cooling, and they're more compact inside the hull for the same fin size. Given their quick movement at anchor, their smallest size should suffice for you. By the way, I believe they have at least two service dealers with experience in Phuket. Please keep me updated on what you decide, and enjoy your cruising, regardless.

 

[JOHN CLAYMAN]

We have been using the Magnus Master electric stabilizers for quite some time from DMS Holland. The no. 1 in stabilisation for yachts DMS has a network of installers around the country. They have been installed on some Nordhavns.
We have vast experience with other systems and find that they work much better than active fins on trawlers. The electric draw is minimal and they retract when not in use.

 

[Mambo42]

I know DMS well and spoke with Patrick and his guys at length when I was researching stabilizers. At that moment the Magnus Master was only for stabilization while underway. So that was the reason I did not choose them.
Now they do have the Magnus Master where the arm moves as well, like a fin, thereby making the on anchor stabilization possible. I don't know if the system performs well, I have no idea, so that is something for the OP to check.
I also don't know how much electricity the moveable Magnus Master uses when it is in operation. Also that is something for the OP to find out.
What I do know is that I can run my CMC stabilizers off my solar panels during the day and off the batteries at night. That was important for me, since I did not want to have the generator running all the time.
If the Magnus Master can also do the same then I guess it comes down to the question: 'with which company do you have the best communication and do you feel the best'. I can only say that Patrick and his company (DMS) have been very professional, welcoming and helpful. I would not have a problem working with them.
The same I had with CMC and so far the system functions flawless.
In other words, OP has to do his research and decide what is important for him/ her.

 

[nigel52]

First of all thank you all for your comprehensive replies. A huge cross section of views and experiences. I’m sure you inow the first Nordhavn 51 has recently been launched and the owner a New Zealander is documenting it on YouTube. I’m very much the intermediary as it is my brother in law who is due to take delivery of hull number 3 early next year.

 

[Mambo42]

I have seen the videos of the first 51' and kind of funny, they are now in Bodrum and we are right next door in Kos. He has hydraulic stabilizers though.
If your brother wants to pass by in Greece to see our CMC stabilizers in real time he is welcome. Can also visit our instagram, I have a video there of the stabilizers when they are working in port. Had to create some instability by hand, since it was flat calm that day, but you can get the idea. mv.endless.summer on Instagram.

 

[tonykool]

I realize this thread is a bit old, but I thought I would ask @Mambo42 what the maintenance of CMC stabilizers has been like. I realize there hasn't been much time go by yet, so maybe to early to tell. What is the recommended maintenance?

Your post was very thorough and I got a lot out of it. Thank you!

 

[Mambo42]

I realize this thread is a bit old, but I thought I would ask @Mambo42 what the maintenance of CMC stabilizers has been like. I realize there hasn't been much time go by yet, so maybe to early to tell. What is the recommended maintenance?

Your post was very thorough and I got a lot out of it. Thank you!

Yearly we put about 5000 hours on the stabilizers, so when we did our first maintenance we had around 5600 hours on the clock.
Did not have a single failure or other issue with them, was all fine, but you need to change 2 seals on both sides after 5000 hours and for that the boat needs to be out of the water. Those are the seals that keep the water from entering the boat, so basically have nothing to do with the motors themselves.

Basically what you need to do is loosen up 8 bolts on each fin, take the fin off, then loosen up the bolts that hold the stainless steel ring which covers the seals and once the ring is off you can take out the seals. Taking them out what easy, they simply drilled a hole in the seal, screwed a long screw in the seal and pulled the seal out. Then with a drill and brush they cleaned the housing of the ring, once that was done the new seals were lubricated and pushed into the slot. After that the stainless steel ring, which covers the seals, was put back on and after that the fins went back on. For the fins new bolts were used, but for the stainless steel ring they used the old bolts again, does not seem to be a problem.
Complete maintenance was done in 1 day.

I wanted to do this service during the winter, but the company in Italy went absolutely beserk with the price for that maintenance, came up to 15.000 euro and that was including 5 star hotels and restaurants for the workers. I declined on that one, did not even reply to them.
Next company wanted 7000 euro, but had never done the the maintenance, so declined on them as well.
Third company had done it before, wanted 3000 euro for the service and 1200 of that were the spare parts (so 1800 for the labor and VAT for 1 day work for 3 guys), so I went with them. They did it very professionally, knew what they were doing, all went fine, they were finished in a day.
Since that service we have put on well over 1200 hours again and the reason for that is that we just keep them on stand by 24 hours per day. Even when they are idle the maintenance clock is running, which means you put hours on the clock. But since they do exactly what I want them to do (keeping the boat stabilized at all times) I basically don't mind.
The way to stop the clock is to shut the main control box down, but that is in the engine room, which means I need to get in there, flip the circuit breakers and I will only do that if we leave the boat for a prolonged period of time. However, we live more or less on the boat, so we just keep them on stby. They will only use electricity if they need to work, so having them stby will cost me a few amps per hour, which is no problem.
At the moment we are in a calm anchorage, which is the port of Pula. Every now and then a boat races through the anchorage, causes a wake and then it is nice to know that nothing will happen. Don't even roll 1 degree.
Last week we were in an anchorage which was basically wide open to waves and swell coming from the East, South and West, but protected from the Northerly wind. Nobody anchored there due to some wave activity being present, but for us it was perfect. Had the anchorage to ourselves (in the bay next to us were close to 100 boats), 20 kts of wind, 100 mtrs of anchor chain and we were lying steady as a rock.

This winter we will be short of the 5000 hours, but I think I will change those seals again, otherwise I will have to lift the boat out mid season just for a seal change. This time I will do it myself. I have now seen what is required, how they do it, basically pretty simple. The warranty is finished anyway (in September we will hit the 2 year mark), so no need to have someone do this anymore.

According to CMC they have not had a customer that put so many hours on the stabilizers as we did in such a short period of time. Most boats apparently are not used 8 to 9 months per year continously.
In all, still very happy with how they function and that we did not have a single failure. If we keep this up then it will be perfect.

 

[tonykool]

Thanks for the quick, detailed response. Glad to hear they have worked so well for you. The maintenance sounds very reasonable.

 

[Ithaka7]

I always thought that the power consumption for a gyro and electric stabilizers should be similar for a given set of sea conditions. The gyro will likely use more, since it needs to spin when not doing work but I can't believe the difference is 10x (i.e. 3 kw vs 300 watts mentioned above). One can say that at rest they should be more comparable while at speed the fins have an advantage but the energy must come from somewhere (i.e. if the fins appear more efficient, this is because the engine is doing more work through the fin surface to balance the boat). I may be wrong though. I see a lot more boat with Seakeeper than stabilizers in the Med.

 

[Mambo42]

I always thought that the power consumption for a gyro and electric stabilizers should be similar for a given set of sea conditions. The gyro will likely use more, since it needs to spin when not doing work but I can't believe the difference is 10x (i.e. 3 kw vs 300 watts mentioned above). One can say that at rest they should be more comparable while at speed the fins have an advantage but the energy must come from somewhere (i.e. if the fins appear more efficient, this is because the engine is doing more work through the fin surface to balance the boat). I may be wrong though. I see a lot more boat with Seakeeper than stabilizers in the Med.

A gyro is basically a heavy weight that needs to be kept spinning at a certain rate, so for that you need a heavy motor. The gyro hangs in bearings, which cause friction and that will slow the gyro down, so basically constant electrical supply is necessary. And since that motor is quite heavy it does use quite a bit of electricity.

Electric fins however work in a different way. They only react (read: move) when a disturbance is identified. A small gyro on the fly bridge detects the disturbance and as the operator you can set the sensitivity. The lower the sensitivity the less power is consumed, vice versa. I can, next to the sensitivity, also set it on night mode, which means that the system will react slower and will allow some more disturbance. Reason is that if you are asleep you won't notice a gentle roll I suppose.

Once a disturbance is detected the software will decide how much deflection of the fins is required to stablelize the boat again. That can be very fast, but can also be a slow movement of the fins. Once the disturbance is gone the fins will go to their neutral position again and thereby don't consume electricity. If you are in an anchorage where there are constant disturbances you will see the fins making slow and not so large corrections. If however the boat is hit by the wake of some other boat you will see a very fast and large correction, but that dies down again once the boat becomes stable.

While underway the fins are more effective so less power is needed to make the boat stable.

Obviously, if you are at anchor in a rough sea the stabilizers will work hard to keep the boat stable and you will see a power increase. But the times that you are floating around mid sea are minimal. We don't fish, but if we would fish I would assume that you then would see a higher power consumption. We also don't anchor in a wide open sea, we always search for some sort of shelter.

My fins are 220 V and on my Victron Cerbo I can see exactly what I am using at any given point. My normal AC equipment are freezers and fridges, they are always on and use about 200 - 300 W per hour. When the fins operate I can see the consumption go up to about 400 - 500 and in extreme cases it will go up to 800 - 900 W, but that is only for a short period of time. As soon as the disturbance is gone the total AC load will go back to 300 - 400 until the next disturbance. So in all it is a very low electricity usage.

 

[Ithaka7]

Thank you for the very comprehensive explanation. I largely agree with you but I still think that the fins power consumption is underestimated because some if the energy comes from the engine that propels the boat forward. Not important though. For me the question is, while at rest or slow speed (<6-7 knots), what is the gyro consumption vs. % of roll eliminated and the fin consumption vs. % of roll eliminated.

I kind of liked the idea to purchase a gyro and install it myself. Now since you are convincing me that fins are more efficient, I need to find a yard to do it for me. That is expensive and I am not excited about the cost .

 

[Mambo42]

Thank you for the very comprehensive explanation. I largely agree with you but I still think that the fins power consumption is underestimated because some if the energy comes from the engine that propels the boat forward. Not important though. For me the question is, while at rest or slow speed (<6-7 knots), what is the gyro consumption vs. % of roll eliminated and the fin consumption vs. % of roll eliminated.

I kind of liked the idea to purchase a gyro and install it myself. Now since you are convincing me that fins are more efficient, I need to find a yard to do it for me. That is expensive and I am not excited about the cost .

In fact the fins use most electricity while at anchor. Then the deflections need to be much more than while underway. So as a result the underway electricity usage is (most of the time) less than while at anchor.

For a gyro it basically does not matter whether the boat is underway or at anchor, the friction is identical. However, also for a gyro at anchor the deflections will be more than underway, so friction will be more at anchor than underway. No matter what, the weight of the gyro will always require a heavy motor to keep the rpm's going. Any deflection will increase friction, after all that deflection will press the axels more into the bearings and thereby the power the motor needs to put on the total weight will increase. The more rough the anchorage is the more friction and the more energy the gyro will use.

Installing fins is not too problematic, I spoke with a doctor in the US who had done it himself with his sons. The company makes it look more difficult than it really is to be honest.
Very important of course is to select the correct location and that would be between 1/2 and 1/3 of the hull length, measured from the stern.
Once identified you will need to strengthen the hull, because at anchor is when you will encounter the heaviest forces on the hull. They increased the thickness of my hull with about 2 inches in an area of approximately 30 inches to 1 yard around the hole where the fins will be installed.
After strengthening the hull a mould was used to drill the 8 holes for the bolts that hold the motor in place. Once drilled the motor is placed and the rest of the hole is sealed off to keep the water out. The doctor told me that CMC had supplied all the required material.
After the motor has been installed it becomes a matter of attaching the fins with a total of 8 bolts each.

Next thing is to install the electrical wiring.
My fins are running on 220 V, so I have a control box in the engine room where 220 V go to the fins and come from the inverter (Victron Quattro in my case).
Then you have another control box in the pilot house and lastly an inertial device as high as you can get it in the boat. It is all plug and play or pull the cable and plug it in.

The commisioning however needs to be done by CMC, otherwise you won't have any warranty.

If you call with CMC US they will be more than willing to explain everything to you. The doctor I spoke with did the job in about 4 weeks (total) with his sons and I understood they basically only worked in the weekends.
I had mine installed in Turkey, did not have to pay VAT, so that made a huge difference.
But even if I would have to pay VAT it is still simple mathematics. For a gyro I would need a generator to run basically all the time, using fuel and that would end up in about 1000 - 1500 USD per month, just in fuel. Add the overhaul of the generator after an X amount of hours and it will start to add up. I calculated I would have the installation cost back in roughly 1 year and the same is for the fuel savings in case of a gyro.

Am currently looking at a slightly bigger boat, it has hydraulic stabilizers and am actually already talking to CMC how we can take those off and fit electrical fins under that boat. Once you have experienced zero speed stabilization you don't want to go back to being unstabilized. It is an investment, but you also raise the value of your boat, so when you sell the boat you will get quite a higher price for your boat.

For me it is clear that in the future, electrical fins are the way to go. Everything else will just slowly disappear. Does not sound nice, but that is reality.