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Old 02-18-2014, 08:06 PM   #1
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Gyro stabilizers

Anyone here used or considering installing a gyro stabilizer on their boat?

The units I am talking about are like those made by Seakeeper, Veems, and a couple of others.

Opinions, general thoughts about them?
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Old 02-18-2014, 08:12 PM   #2
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Anyone here used or considering installing a gyro stabilizer on their boat? The units I am talking about are like those made by Seakeeper, Veems, and a couple of others. Opinions, general thoughts about them?
Have a friend that just got one on the brand new viking he captains and loves it.
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Old 02-18-2014, 08:22 PM   #3
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Gyros

From what I understand they have limitations as how rough the conditions are before you have to shut them down. The same applies to paravanes. They take some time to spool up and need about 2500 watts to run. I looked at a installation in a Azmuth. My first thought was what an incredible load it must put on the stringers. If you run your genny full time anyway why not. Less drag than paravanes or fins, nothing to foul on crab pots. My two cents worth.
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Old 02-18-2014, 08:50 PM   #4
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Greetings,
Mr. RickB. My only concern would be what would happen if the flywheel ever let go. Spinning at, say, 10,000 RPM and weighing several hundred pounds an errant mass of metal that size and with that amount of kinetic energy could wreak havoc. My $.02.
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Old 02-18-2014, 09:39 PM   #5
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I considered them on my Grand Banks, but went with ABT fin stabilizers instead. Having to run the genny all the time ruled them out early in the process. If you run your genny all the time anyway, then that's less of a concern. They are also quite large. Advantage is that you get stabilization at rest too, but that's available on the ABT fins now too. Both require full time power of one sort or another. I've also heard there are corner cases where they don't quite behave the way you'd like. Someone mentioned having to shut them down if the seas get too rough? Sounds like just the opposite of what you would want.
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Old 02-18-2014, 10:00 PM   #6
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Looked at the Mitsubishi model and elected for ABT for these reasons:

1. 3kw to run. Not that tough, but that's a lot of juice
2. Size of the unit inboard rather than outboard
3. Less effective than active fins - 80% or so?
4. In really nasty conditions, their slower response rate means they can aggravate the roll, not decrease it, requiring shut down when you really need it.
5. Spool time - delay in effectiveness

Don't know if that is reason enough but it was for me.
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Old 02-18-2014, 10:29 PM   #7
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I could have installed a Seakeeper for the same price as Naiads, but the drawbacks were the 2.5kW power, size and weight for a retrofit of gyro. I am glad I made that choice, the Naiad's are trouble free and brilliant at keeping the boat flat as far as roll goes.

Talking to Navigator about a year ago, he said the gyro they had used to make his wife seasick. The gyro would create a snap back of the roll, with short period. It wasn't a Seakeeper or Mitsubishi, not sure if they would be better. Perhaps the one he had was undersized. But I doubt that he would ever have a gyro again based on the conversation we had.

The gyros will resist the start of a roll but I suspect that they will create stronger counter force as the roll progresses? With my Naiads, the accelerometers detect the start of a roll and give strong fin deflection before the roll actually progresses very far at all. They have very strong countering force right at the start of the roll. Fin deflection then lessens, giving a tapering off of the counter force. This way there is little impact on the natural roll period, but a big reduction is roll amplitude. One of the Naiad user controls relates to roll period so that you can better sync with differing conditions, such as following sea versus quartering head seas. I dont think the gyros have the same capacity to be tuned to conditions, and although they obviously reduce roll amplitude reasonably well, they also shorten the roll period and that can cause issues for some people.
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Old 02-19-2014, 05:53 AM   #8
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My only concern would be what would happen if the flywheel ever let go. Spinning at, say, 10,000 RPM and weighing several hundred pounds an errant mass of metal that size and with that amount of kinetic energy could wreak havoc. My $.02.

This fear is why they are not used in passenger cars.
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Old 02-19-2014, 06:49 AM   #9
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Spinning at, say, 10,000 RPM and weighing several hundred pounds an errant mass of metal that size and with that amount of kinetic energy could wreak havoc.
I witnessed an 8 (or was it 10?) test-tube centrifuge let go in a biochemistry prac during my uni days. Was like a bomb went off. Luckily it was unnattended and over in the empty half of the lab. I shudder to think what FF's scenario would look like.

Having said that - has anyone heard of a boat gyro ever coming unstuck?

There is an article in the current (jan/feb) edition of 'Pacific Powerboat' magazine comparing gyros and stabilisers FYI. Not a particularly in-depth article (are any in these magazines, really?), but interesting in that it compares some of the current crop of models of both types of stabilisers.
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Old 02-19-2014, 10:58 AM   #10
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I looked int both the seakeeper and the mitsubishi gyros for my boat Vs active fins.

My problem wasn't the performance; they seemed to work fine even at anchor.

It wasn't the power draw; being able to stop roll in a bumpy anchorage is worth having to run our generator, which is super quiet anyway.

It was the size of the things.

They are approx the same size as a generator. I cannot figure out where to put the thing.

I could jockey things around to fit it, but it would take my well laid out (for maintenance) spaces and make it a nightmare.

As soon as I can find a competent outfit to do the work in my part of Alaska, or as soon as I get my boat back to Washington I'll be installing fins.
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Old 02-19-2014, 11:04 AM   #11
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Regarding power draw, would a gyro use any more power than Wesmars, ABTs or Naids? The PTO power takeoff driving a hydraulic pump is not free energy. With a 4KW or so "generator" driven off an engine when cruising, the genset use could be negated.

It all comes down to cost though, in a new build the gyro may have some real economic attraction with operating cost savings when cruising in the 12 to 18 knot range. I'd guess the target audience to be non trawler designs where stabilizers are not easily fit due to hull shape.
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Old 02-19-2014, 03:02 PM   #12
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Anyone here used or considering installing a gyro stabilizer on their boat?
Just every time I am in a big beam sea.......
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Old 02-19-2014, 03:09 PM   #13
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I looked int both the seakeeper and the mitsubishi gyros for my boat Vs active fins.

My problem wasn't the performance; they seemed to work fine even at anchor.

It wasn't the power draw; being able to stop roll in a bumpy anchorage is worth having to run our generator, which is super quiet anyway.

It was the size of the things.

They are approx the same size as a generator. I cannot figure out where to put the thing.

I could jockey things around to fit it, but it would take my well laid out (for maintenance) spaces and make it a nightmare.

As soon as I can find a competent outfit to do the work in my part of Alaska, or as soon as I get my boat back to Washington I'll be installing fins.
You will love the fins. Once you've had them, you'll never go back.

ABT or Naiad?
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Old 02-19-2014, 03:20 PM   #14
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Regarding power draw, would a gyro use any more power than Wesmars, ABTs or Naids? The PTO power takeoff driving a hydraulic pump is not free energy. With a 4KW or so "generator" driven off an engine when cruising, the genset use could be negated.

It all comes down to cost though, in a new build the gyro may have some real economic attraction with operating cost savings when cruising in the 12 to 18 knot range. I'd guess the target audience to be non trawler designs where stabilizers are not easily fit due to hull shape.

It's very true that both consume power, and let's assume for argument's sake that both consume the same amount.

At least in my case it was about where/how you get the power. While underway the main is obviously running, and adding a hydraulic pump to drive a fin system is relatively straight forward and cost effective.

Electricity for a gyro would need to come from a good sized electric source. The cheapest would be your genset, assuming you don't mind running it all the time you are underway, and that it has sufficient capacity. Under many situations, this would be the ONLY reason to run the gen, and hence becomes objectionable. If you run your gen anyway, then it's not a big deal.

An alternate source would be some sort of enlarged main engine driven alternator. Perhaps a hydraulic generator, or a beefed up DC alternator and inverter system. All are possible, with varying levels of cost and complexity.

The space thing is tough to get around. Provided you have an accessible and suitable location for the actuators for a fin system, the in-boat foot print is pretty small. But in boats under 45' or so I suspect finding a suitable location will be very difficult. The gyro's a big box. On my boat it would have completely consumed the laz. As the boat gets bigger, at some point you need two gyros, but I don't know where the break point is.

Trade-off, trade-off, trade-off. That's what makes it all so interesting.....
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Old 02-19-2014, 04:24 PM   #15
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I suggest you start by reading the Seakeeper FAQ at Seakeeper Inc. - General Facts and possibly some of the reviews such as: http://www.seakeeper.com/files/press...Maker%20Ad.pdf and Seakeeper Gyro Stabilization for Trawlers | OceanLines

To answer some of the questions or comments above. Catastrophic gyro failure and parts flying at you isn't a valid concern. Seakeeper gyro's use high strength steel forging and each piece undergoes several levels of inspection and tests to ensure it meets the design requirements. Gyro's can easily be proof tested by spinning them up to greater than 100% of the design speed. The primary loading in the spinning mass is a constant load so fatigue failure due to cumulative cyclical loading isn't a significant factor. The lack of catastrophic failures of any of the systems that have been installed and used for years should soothe anyones concerns.

Gyro's work at any speed, whereas fin stabilizers effectiveness is best at their design speed. If you want stabilization at zero or very low speed gyro's are the best option. Fin stabilization may be more effective at cruising speed, but that depends on the size gyro you use.

Seakeeper Gyro stabilization takes less power to operate than fin stabilization. The Seakeeper M8000 which is suitable for vessels with displacements up to 35 tons takes 240 Watts of DC and 3 KW of AC during spool up and 1.5 to 2 KW AC steady state operation. If you don't want to run an AC generator, the Seakeeper M8000 can run off a 3 KW inverter. http://www.seakeeper.com/files/manua...%2027JUN13.pdf The steady state 2 KW of AC power, assuming 90% inverter efficiency plus the 240 Watt DC load would require 2,500 Watts of 24 volt DC power or 102 amps. This could be provided by an oversized alternator running of the main engine(s).

Fin stabilizers will increase drag, which will increase fuel consumption and reduce speed at a given power level. They claim up to one knot reduction in maximum speed.

I agree that the biggest downside of the Seakeeper gyro stabilization is finding the room to accommodate the unit. Note the dimensions of the M5500 and the M8000 are the same.
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Old 02-19-2014, 04:45 PM   #16
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Regarding power draw, would a gyro use any more power than Wesmars, ABTs or Naids? The PTO power takeoff driving a hydraulic pump is not free energy. With a 4KW or so "generator" driven off an engine when cruising, the genset use could be negated.

It all comes down to cost though, in a new build the gyro may have some real economic attraction with operating cost savings when cruising in the 12 to 18 knot range. I'd guess the target audience to be non trawler designs where stabilizers are not easily fit due to hull shape.
Not sure, but I can tell you that if I am cruising along and turn off the fins, the change in rpm is almost imperceptible and the speed doesn't change based on GPS readings to .1 knots. On that basis, I'm not sure they use much power under 'normal' conditions and have no effect on speed. I wouldn't be surprised if they actually, at least on Delfin, result in greater fuel economy since they keep her oriented in the water in a position with what I assume is the least resistance, and tracking a straighter line. Gyros need the same power regardless of the sea conditions, whereas active fins are variable depending on how hard they have to work.
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Old 02-19-2014, 05:23 PM   #17
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Not sure, but I can tell you that if I am cruising along and turn off the fins, the change in rpm is almost imperceptible and the speed doesn't change based on GPS readings to .1 knots. On that basis, I'm not sure they use much power under 'normal' conditions and have no effect on speed.
Here is a question Delfin, if you removed your fins entirely would the fuel burn go down at the same boat speed with the drag is reduced?

With my fins and twins, when I shut down the stabilizers' hydraulic pump on the port engine, there is a noticeable RPM change - by ear - requiring me to adjust throttle to get them back in ear sync.
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Old 02-19-2014, 05:36 PM   #18
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For what it's worth, I see no difference in speed or fuel burn when I turn my ABT stabilizers off. Per and post installation I saw at most a 0.5 kit max speed reduction, presumably due to fin drag.

If you really want to wallow, go to www.mvtanglewood.com and follow the link on the right to stabilizer installation.
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Old 02-19-2014, 06:25 PM   #19
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Here is a question Delfin, if you removed your fins entirely would the fuel burn go down at the same boat speed with the drag is reduced?

With my fins and twins, when I shut down the stabilizers' hydraulic pump on the port engine, there is a noticeable RPM change - by ear - requiring me to adjust throttle to get them back in ear sync.
Hard to know, but certainly the fins must contribute to some drag. How much is the question, but as Twisted Tree notes, it isn't much. In our case, perhaps because of where the fins are on our hull, I really can't see any impact on speed with them inactive but taken off altogether I doubt it would result in any more than a fractional increase in speed.
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Old 02-19-2014, 06:32 PM   #20
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Again for what it's worth, I don't care how much drag or fuel burn they cause. It's worth every drop of diesel that it takes.


Buy my comparison does show with and without fins which addresses the drag question. Turning fins on and off doesn't really address that, and it's rare to get before and after on the same boat with the same owner (I installed the fins, quite literally)
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