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.
