We upgraded our Nordhavn N3520 with a stabilizer!

[Circumnavigator]

Each stabilization method has its pros and cons. A gyro takes a lot of power and a long time to activate.]


About as much power as AirCon. Ten minutes to partial, half an hour to full effectiveness.







[Also very heavy, and maintenance can be expensive.]


1,000 pounds for the one on Morning Light -- a quarter the weight of a full load of fuel.. Maintenance on a Quick gyro is greasing every 2,000 hours -- far less maintenance than an engine.





[A gyro puts a big hole in the boat with a stick attached to it.]


I don't understand this -- the gyro is a 2 foot cube and a separate control box -- no "big hole in the boat with a stick attached".





[There are versions that work at anchor.]


As far as I know, they all work at anchor.





In theory, the Magnus should be manufacturable for a lot less than the currently offered versions suggest.

Perhaps, but until that happens why would you buy one, particularly for use in waters with pot buoys.



Jim

 

[DDW]

I wasn't clear. The Magnus rotor puts a big hole in the boat with a stick attached. There are Magnus rotors which work at anchor.

1000 lbs on an already heavy boat, if there is space to locate it somewhere in the middle isn't a big problem. On a lighter boat, where the lazarette is the only place it can go, that can be a problem. It was a problem looking at my boat for sure. 1/2 hour to full power up may not be a problem for some, but is for others. I don't know about there Quick, but for the Seakeeper, there is a maintenance schedule they require, has to be done by them, and is somewhat expensive. The Magnus rotor also requires some maintenance, and one thing that put me off of the DMS is again they require their techs (from Europe) fly over and do it.

 

[chanprr]

I've opted to have a dual rotor system on the H46, my second Helmsman new build. I am fully aware of the indigenous salmon fishing operations, the crab pots and logs in the waters of the PNW. Helmsman/Waterline are now the agents for MagnusMaster in Seattle. My 46 will be the third Helmsman to have rotors installed using a local yard under the guidance of a MM factory tech. Local experience for installing and servicing the rotor systems is happening at the local yard. I am very confident that service and maintenance of MM rotors will not be issue in Seattle, with the kind of after-delivery service which Helmsman is known to provide.

 

[Mambo42]

That's more than twice the price of the Quick gyro we installed in Morning Light, which is a 42' Webbers Cove single screw trawler displacing 38,000 pounds. The gyro has nothing outside the boat and can be installed anywhere you have a cube two feet on a side. It does require 3kW at 120 or 240VAC and is simpler mechanically -- effectively only two moving parts. It works at any speed, including at anchor and does not slow the boat. And, of course, it runs all the time you need it -- no turning it on and off for fear of pot buoys.


Jim

That's more than twice the price of the Quick gyro we installed in Morning Light, which is a 42' Webbers Cove single screw trawler displacing 38,000 pounds. The gyro has nothing outside the boat and can be installed anywhere you have a cube two feet on a side. It does require 3kW at 120 or 240VAC and is simpler mechanically -- effectively only two moving parts. It works at any speed, including at anchor and does not slow the boat. And, of course, it runs all the time you need it -- no turning it on and off for fear of pot buoys.


Jim

3 Kw all the time is a bit too much for me. I would not be able to run them on the solar panels, nor on the battery. Also, I have a 6 Kva generator onboard, and more than 50 % of that capacity would be required to run the gyro ?
Just for comparison, my boat is fully stabilized, both underway, on anchor and in a marina / port, but the good part is that the stabilizers only function when required. In other words I just have them switched on, place them in the proper mode and as long as there is no disturbance they don't use any electricity. When there is a disturbance the fins will react with an output of the motors so that the boat returns to it's stabilized state. That reaction is instant, so even if there is a large disturbance the fins will fight that disturbance immediately. So it is not that you are slammed into the side of the boat before the fins react.

Being able to regulate the output of the motors does limit the electricity usage drastically. On anchor we won't use more than perhaps 300 W (220 V) when the fins need to react, but most of the time they use much less or nothing at all. Even if they would do 300 W all the time we are still talking only 15 A (24V) per hour for the fins and about 5 A for the control boxes. That is a total of 20 A per hour while on anchor and since I have 1100 Ah available in my batteries for real time use I simply don't need to run the generator at all.
My generator uses about 3 ltr per hour and at 24 hours per day that would be 72 ltr and per month that would be over 2100 ltr and in a season that would be more than 17.000 ltr. At 1.45 euro per liter I would spend over 25.000 euro in order to have the boat stable.
With my electrical fins and battery bank (plus solar panels) it does not cost me anything whatsoever. In other words, each year I save around 25.000 euro and that quickly pays back the investment in batteries and solar. On top of that, we don't need to sleep with a running generator.

I don't contest the fact that other stabilization systems can do a very good job, I simply say that moneywise and result wise (having stabilization at all times) it just does not make sense to have anything other than electrical fins.

 

[Hippocampus]

Has anyone done a service life cost (including energy and servicing) comparison for
Gyro-SeaKeeper and Quick
Magnus
Active fins=electric and hydraulic
Would think for all costs would dramatically decrease if using flopper stoppers at anchor.
So far it’s been very rare we’ve needed to turn on our SeaKeeper at anchor. Given we are now coastal on a SD hull we rarely turn on the SeaKeeper when underway. It’s simpler to just speed up a bit when it’s just chop. Of course when heading into or directly away from the waves you just get pitch not roll and none of the systems except multiple pairs of fins or Magnus help with pitch. Also none help with heave. It’s not practical for a small to moderate sized boat to have multiples.
So in our actual use stabilization goes on for ~10~20% of the time we are on the boat. We do run in skinny water or with debris so very much appreciate a protected single screw and nothing sticking out. All boat decisions are compromises.
Would note anything sticking out from the hull creates drag so even when not in use if you are underway you are using more fuel. Perhaps with two sets of Magnus you can raise the boat enough to decrease wetted surface enough to not be using more fuel. But with electric or hydraulic fins you have more drag so more fuel usage or you are going slower.
Personally think if the boat is large enough retractable Quantum fins maybe the best of all worlds. For smaller and lighter boats retractable Magnus Master.

 

[rslifkin]

Some of the fin setups are fairly low drag so that wouldn't be a huge concern in my mind. Paravanes or even Magnus rotors strike me as higher drag than many fins.

At least for my current boat, my ideal combo would be fins plus flopper stoppers at anchor (we already have a rudimentary setup for this but want to upgrade). To some extent the best choice depends a bit on the boat in question, as sometimes one option clearly fits better (in the sense of physical installation) than the others. I'd struggle to install a gyro in my boat, for example, as there's not really anywhere to put one that wouldn't severely restrict engine access. Yet there's good access to an area that would be suitable for fins (both structurally and from a placement perspective).

 

[NSM]

I wondered bout the fuel hit from the DMS and did a quick check of speed and fuel burn penalty when deployed. The average was 0.21 knots slower across 900-1900 rpms. Fuel burn increased by up to 0.1 gallons per hour with the higher fuel burn at higher rpms (not surprisingly). At the 1500 rpm I usually run I get ~2.90 gph stowed and 2.96 gph deployed, running around 7 knots.

 

[Mambo42]

Has anyone done a service life cost (including energy and servicing) comparison for
Gyro-SeaKeeper and Quick
Magnus
Active fins=electric and hydraulic

I have done a cost calculation for the Gyro and the hydraulic and electric fins as far as operating cost.
Maintenance cost I have only calculated for the gyro since that was the only one (next to the electric fins) that could give me what I wanted (stabilization underway, on anchor and in port / marina).
At the time of my investigation / research I spoke with seakeeper and also gyrogale, both told me the gyro needed to be taken apart in order to exchange the bearings after roughly 3000 - 5000 hours. The difference was more based on who you were talking to then on something anyone could show me on paper. They never gave me an exact figure, but by telling me they basically had to take the whole thing apart, lift it out of the boat, change the bearings, lift it back in etc I could figure out we were talking anywhere between 15.000 and 20.000 euro in labor, parts and dry dock fees.

The hydraulic fins never came into play for me since they don't function on anchor or in port. And since that was important to me I took them out of the viable options.
However, having been a pilot for close to 30 years I know that you either need a good system with very good mechanics or you need a very simple system when you have mediocre mechanics. I have had my fair share of hydraulic problems when flying, so realizing the system needs to work flawless for thousands of hours and so much hydraulic equipment is involved.............I knew there would be problems on the horizon and those problems usually mean very high repair cost.
The required maintenance after 2 years is not that complicated for hydraulic fins, so I assumed that would be roughly the same as for electric fins, which means lift out, cleaning, taking the fin off, changing seals and bearings, putting it back on again, finished.

As far as the electric fins I basically have 2 options. Either the motor is complete crap and I need to exchange it after 4 or 5 years (just outside the warranty) or it will simply keep working. With most electrical equipment it is always a case of: 'it works when you buy it (and then it will keep working) or it doesn't work'
Maintenance is lift out, cleaning, remove the fins, change the outer seal, put the fins back on and back into the water. That is going to cost me around 2500 - 3000 euro.

Would think for all costs would dramatically decrease if using flopper stoppers at anchor.

I wish I could have installed a flopper stopper at anchor, but I would have needed to completely redesign the boat. I don't have a mast, have basically nothing that can take the force of a flopper stopper, so I had to let go of that idea. It would have been the cheapest solution by far, it would have been more than sufficient, but it would have meant saying goodbye to our sun deck, to our solar panels and I was just not willing to do that.

So far it’s been very rare we’ve needed to turn on our SeaKeeper at anchor. Given we are now coastal on a SD hull we rarely turn on the SeaKeeper when underway. It’s simpler to just speed up a bit when it’s just chop. Of course when heading into or directly away from the waves you just get pitch not roll and none of the systems except multiple pairs of fins or Magnus help with pitch. Also none help with heave. It’s not practical for a small to moderate sized boat to have multiples.

Unfortunately we cannot speed up. 7 - 7.5 kts is about the maximum we can do and then we are almost at full throttle. And bad part is that our boat really likes to rock and roll when at anchor or in port. It has been both a comical and sad view in ports and in anchorages when all boats were lying quiet while ours was rolling like it was Sea State 9. It came to the point where the admiral and the dogs were literally hanging over the railing in the port. Sometimes we just had to hang on for dear life. I don't know if this is normal for my boat or that we have a stability problem, but something needed to be done or the admiral was off the boat. And that would have meant no more boating, no more seasons on the water. So that is when I started looking for stabilization while underway, at anchor and in port.
And since we are in Greece, where the seas can be horrendous (Odysseus was based on real life sea events) there was no escaping it and we always have the stabilizers stby. Out of the blue you could be in bad weather.
This year we will go to Croatia, where the waters are much calmer, and my guess is we won't need the stabilizers that much. They will be stby, but I don't think they will need to do a lot.

So in our actual use stabilization goes on for ~10~20% of the time we are on the boat. We do run in skinny water or with debris so very much appreciate a protected single screw and nothing sticking out. All boat decisions are compromises.

Would note anything sticking out from the hull creates drag so even when not in use if you are underway you are using more fuel. Perhaps with two sets of Magnus you can raise the boat enough to decrease wetted surface enough to not be using more fuel. But with electric or hydraulic fins you have more drag so more fuel usage or you are going slower.
Personally think if the boat is large enough retractable Quantum fins maybe the best of all worlds. For smaller and lighter boats retractable Magnus Master.

It is true that we have more drag and we did lose some speed at given rpms. I would say we need about 500 rpm extra to get back to the same speed that we had before. That does give us extra fuel burn, that is true, but luckily it is nowhere near having to run the generator to run the stabilizers.
During the summer season we spend a lot of time at anchor in bays. We sometimes spend 1 or 2 weeks in the same bay, won't move at all. Then the solar panels will provide the electricity to power the whole boat, including the solar panels. I won't run the generator at all.
In the end, the trade off is simple. Every hour navigating I will spend about 1 ltr extra fuel to have complete comfort in the boat. This year we will do roughly 450 hours, which means 450 ltr, which means about 700 euro. And if I switch off 1 engine it will be 350 euro for 8 months of comfort. I think that is a small price to pay.
If I would need to run the generator it would cost me well over 25.000 euro in extra fuel.

I do understand this applies to our specific situation (living 8 - 9 months per year on the boat), but for people who only spend a couple of weekends a year on the boat the gyro may be the better option. It will take you many years to get to the service level where you need to take the gyro apart. You probably will run the generator all weekend long and nothing is sticking out of the boat. No chance on leakages, no barnicles, no drag, that makes it interesting.
In other words, every type of boat use may have its best way of stabilization.

 

[Mambo42]

Some of the fin setups are fairly low drag so that wouldn't be a huge concern in my mind. Paravanes or even Magnus rotors strike me as higher drag than many fins.

At least for my current boat, my ideal combo would be fins plus flopper stoppers at anchor (we already have a rudimentary setup for this but want to upgrade). To some extent the best choice depends a bit on the boat in question, as sometimes one option clearly fits better (in the sense of physical installation) than the others. I'd struggle to install a gyro in my boat, for example, as there's not really anywhere to put one that wouldn't severely restrict engine access. Yet there's good access to an area that would be suitable for fins (both structurally and from a placement perspective).

I had the same problem with the gyro: I had no clue where to put it if I would have desired to have one. I simply don't have the space. It would have meant crawling over the gyro in order to get to vital equipment. To me that was not realistic.

Fins occupy a lot less space, that is a definite benefit, but I was lucky I could install them in my ER. I know someone else who wants to have stabilizers, but he just does not have any space in his boat at all. Engines and tanks are in the way.
However, I would have had no idea where to put the hydraulic pump for stabilizers. Again I don't have the space for such a pump and on top of that I would have had all the hydraulic lines running near fuse boxes, water heaters, water pumps, just not a good idea.
The electric fins only have 2 electricity cables attached to them and those I could put out of sight without a problem. If there would be an accident in the ER and I would pull out a cable, the fin would not function anymore, but that would be it. If I would rupture a hydraulic line it would be a different story. This week I saw a video on Youtube about the first Nordhavn 51. Had problems with the stabilizers and literally all the hydraulic oil ended up in the bilge. He was lucky the bilge pump did not start pumping all that oil overboard...............then he would have been in serious trouble.

So, on that part electrical fins are just ease of operation. It is a clean install, not a lot of lines, not a lot that can break down and if it breaks down you won't have any leakages, no high pressure hydraulics spraying the ER. In fact, if one of the fins breaks down, the other one will keep working and still provide stabilization.

 

[Hippocampus]

M thanks for explaining your situation in detail. Given those parameters sounds like electric fins make a lot of sense. Like you even after stopping voyaging still spend more time on the boat than off. Usually go up a creek or into a small bay to anchor so don’t deal with the troubles you have an anchor. Have yet to go through the C&D in spring without hearing a few bumps from dead wood. Enjoy Croatia and your new fins.

 

[Just Bob]

Magnusmaster for trawlers

The November/December issue of Passagemaker had a good article about the Magnusmaster system, which was pretty helpful in understanding how it works. It also had links to the manufacturer's web-site, where they have a tool to figure out what size is needed for a particular boat. Supposedly Elling, Helmsman and Nordhavn now offer it as an option on new boats; there may be others as well.
I have been pretty disappointed with Passagemaker recently, which used to be full of interesting technical discussions, and reviews of boats that pointed out both the good and the bad, but now they mostly seem to be an advertisement for boats that few of us will ever be able to afford. This particular article, though, was pretty good.
It has some advantages over larger active fin or gyro stabilizers, but also the disadvantage of not working at anchor, or at very low speeds. The company's web-site is "dmsholland.com"
Peter

Thank you for your comments on the article I wrote. I’m always on the lookout for more subjects like this, to share relevant technical information that appeals to a broad range of boaters.

I had the pleasure of visiting the DMS factory where the MagnusMaster’s are made. I was impressed with the company and their products. I believe you will be seeing more of them on more boats in North America in the coming years. They are currently building out a network of yards that can install and service.

 

[Hippocampus]

Have a SeaKeeper and are delighted with it but wouldn’t install one on a new build blue water boat. Reason being in extreme conditions it will go to its stops and stop providing stabilization.

In reading the promo for any of the Magnus effect units they would seem to face the same limitations in extreme conditions. Magnus effect fails to produce stabilization once hull speed increases to a certain point. From my limited understanding that could easily be reached should a boat start to surf quickly. Even on a unpowered 40-50’ sail boat in BF 6-7 you can surf into the high teens low twenties. I think at those speeds Magnus would not be effective. You don’t need to be going downwind to surf. Can occur on the descending face of a wave as well.

My understanding is both Magnus and retractable fins can offer stabilization at rest but varying the angle to the boat. In both cases there’s water movement across the device. Believe Quantum offers this instead of paddling.

 

[Just Bob]

Have a SeaKeeper and are delighted with it but wouldn’t install one on a new build blue water boat. Reason being in extreme conditions it will go to its stops and stop providing stabilization.

In reading the promo for any of the Magnus effect units they would seem to face the same limitations in extreme conditions. Magnus effect fails to produce stabilization once hull speed increases to a certain point. From my limited understanding that could easily be reached should a boat start to surf quickly. Even on a unpowered 40-50’ sail boat in BF 6-7 you can surf into the high teens low twenties. I think at those speeds Magnus would not be effective. You don’t need to be going downwind to surf. Can occur on the descending face of a wave as well.

My understanding is both Magnus and retractable fins can offer stabilization at rest but varying the angle to the boat. In both cases there’s water movement across the device. Believe Quantum offers this instead of paddling.

All good points here. All forms of stabilization have a maximum limit of effectiveness. MagnusMaster specifically states the product is limited to displacement speeds, and does not offer stabilization at rest. I am not affiliated with the company nor promote their products, but I do know they have a gyro for vessels where that would the most effective, and they have in development an innovative stern-mounted system appropriate for boats with a wider range of speeds. I don’t now about anyone else, but if my fat displacement hull is ever surfing down a wave even in the high teens, I have much bigger problems than stability.

 

[Hippocampus]

Totally agree. Only a concern for voyaging and not even for vast majority of passage making. Still it’s noteworthy fins have more effect the faster you go.
Magnus effect can work at rest
from Quantum promo
Traditional fixed fin systems use a “paddling” action, whereas Quantum’s DYNA-FOIL™ uses the hydrodynamic lift generated by water flow over the foil from a swing action of the unit. This action creates water flow over the surface of the foil thus generating lift. The direction of swing determines the direction of lift force generated. Both the angle of attack and the swing speed are controlled variables that are adjusted to provide the optimal ship stability.

 

[long-cours.62]

If we don't find customer for our trawler probably we will ...remove the fin and put nothing more for the moment, at anchor don't need, in harbor of course don't need under way : we choose nice weather to move and anyway to became really uncomfortable it needs "some " amount of wind and wave.
We have enough place in our lazarette to fit a big gyro but we will try to got K.I.S.S. more and more.
For example at the origin our trawler had 2 gen-set, when we change them we also put two...but the smaller 9kw at anchor we use it once a week for make bread and washing machine the 17kw we ....never use it !
Probably if don't sale her we will remove also the 17kw.
If my stomach complain to much for a stab we will try to fit the model pictured : no electronic, no hydraulic very, very low maintenance

 

[Hippocampus]

Wish I could do that. Use pattern and slip dimensions wouldn’t allow it. Totally agree with KISS. Especially now as I work through the start of season hit list. Apologize for the dumb question. Is that on a hinge? If so how much extra beam when retracted?
I copied the wrong section from Quantum. But it’s the same technique. The rotor swings back and forth so there’s water flow over the rotor even at rest.

 

[DDW]

The batwing type stabilizers typically retract by swinging up alongside the rail. There are a couple of studies about their effectiveness, suggesting not as effective as an active stabilizer, but pretty good. Can be designed to break away or fold back when struck, very simple and relatively cheap.