Gyro stabilizers

[jrudge]

Was part of the visiting crew last night.

Prices and dimensions

MC5 e14000 39x39x42 110kg
MC10 e18500 48x48x49 235 kg
MC20 e24000 61x61x63 436 kg
MC40 e52000 83x83x85 785 kg
MC80 e79900 95 x 95 x 96 1084 kg

All PLUS vat in Euros.

All the numbers refer to boat weight in tonnes - 5 = 5 tonnes etc

Install is claimed as bolt on and forget. Clearly what you bolt it to is the issue !!

A big point is that to get 20 you could use 2x10 or 4 x5

This might not seem economic but if you consider that suddenly instead of taking the boat to bits (squadron 65) you can use 2 smaller units that might fit somewhere, and dont need to be mounted next to each other it starts to make sence. This same feature may let you use 2 free spaces - bottoms of Laz and somewhere in ER for example. In a S 65 there is a HUGE space below the lower companion way in the middle of the boat. So a number of smaller units could be deployed etc and no useable space lost.

The consumption is 600w/1500w/2200w/3500w/4800w so running off an inverter was not considered practical by them. It would be like running the kettle for 8 hours !

They are working on a mod that uses an inverter to boost voltage to 400v during spin up which lops about 10 min off the spin up time.

A squadron 58 for example is 23 tonnes dry so an MC20 would sort of fit that bracket ( the next one being a 40) and if that was not good enough you could add a MC5 to the mix.

An MC20 would be E24000 + vat so about £25k plus fitting

A seakeeper 5 ( 20 tonnes also ) is $32,340 + shipping from USA and VAT. - probably £35k landed + install costs.

Weight 790 lbs (358 kg)
Dimensions 29.7 L x 30.0 W x 24.7 H (inches)
0.755 L x 0.763 W x 0.626 H (meters)

Interestingly it is lighter than the MC20. but the MC20 is smaller by 10cm in most dimensions

On the face of it you could stabilise an S58 for not much more than £30k which is starting to look attractive

 

[Deleted User YDKXO]

V interesting post J. Did they give any indication of how difficult/easy the install is compared to the Seakeeper? And do you think they have really shipped hundreds as Jimmy suggested?

 

[Nick_H]

As a general point it can only be good for us boat owners that there is someone else in the game, hopefully leading to more innovation and better pricing.

I'm struggling with the idea that the MC2 units don't run in a vacuum and don't have cooling, so AOTBE they will generate more heat, but have less capacity to dissipate it. They get over this to some extent by having heavier flywheels running at lower rpm, which of course means more weight for the same anti-roll performance.

Putting aside the weight penalty, if the gyro still has good durability without the need for raw water cooling then that is a very positive feature. I'm in the process of replacing the entire sphere of my Seakeeper due to bearing failure after 5 years, 2,000 hours. I think the cause is a generator fault I had at the start of last summer which caused the genny to shut down a small number of times whilst the gyro was running, meaning it had no cooling during the start of the run down period when the motor and bearings were at their hottest. I've had reasonable support from Seakeeper and the French installer to mitigate the costs, but it will still be an expensive exercise.

I think the precession mechanism on the MC2 is also quite neat. Instead of using hydraulic rams, they have a circular gear track and servo motor operating in the horizontal plane (because the flywheel rotates around a horizontal axis). I think this is part of the reason the unit is quite a lot smaller, as the gear track is mostly accommodated in the footprint of the flywheel housing above it.. You can see it clearly in the 3D view on the bottom right of this drawing.

http://www.itemmare.it/pdf/Ingombri_20ton.pdf

What we really need now is some user reports

edit: judging by the rudimentary website, and the fact that no-one on here has heard of the MC2 gyro before, and AFAIK no OEM offers them as an option, I seriously doubt they have already shipped hundreds of them.

 

[BartW]

The consumption is 600w/1500w/2200w/3500w/4800w so running off an inverter was not considered practical by them. It would be like running the kettle for 8 hours !

thanks, all very interesting indeed !

we run electric fin stabs from 2 x 5KW invertors (70ft - 50Ton boat)
2 x 5Kw is peak power, but average consumption is a fraction of that.
during navigation the battery's are permanently recharged from the 2 x 140Amp/24V standard engine alternators
we run the stabs at anker aprox 1 to 2 hours from the battery's,
while swimming or lunch on the cockpit, no genny running !
stabs are ALWAY'S on.

I assume that consumption from gyro's is much more stable compared to fin stabs, any details on peak / average power consumption available?
looking at the power figures, would be perfectly doable with a invertor imo
the price of invertors is neglecteable in the total sheme of a stabiliser installation, and are a nice feature to have onboard anyway.

also in my case, CMC, the fin stab manufacturer didn't consider the use of invertors, but their typical installations are much bigger than mine
so conslusion: I probably have the only invertor driven pleasureboat stabilizers on the globe

 

[jrudge]

V interesting post J. Did they give any indication of how difficult/easy the install is compared to the Seakeeper? And do you think they have really shipped hundreds as Jimmy suggested?

The install is simpler to some extent as there is no cooling and they are physically smaller. Cooling is not a major issue in my view ( issues Nick has had below aside) to install ( pump and a hole, but the smaller size and ability to mix and match will help.

Size I think is really relevant as on a S65 ( only quote that as i know it) the install cost was mostly taking the boat to bits so anything that can mitigate this is worthwile.

I would like to know that in for example a 23 tonne boat would a 20 tonne unit be fine, or is there some logarithmic type rule that says that this would be wholly inadequate to stabilise the boat.

No idea how many they have shipped and i did not hear that part of the conversation.


They will both have to be mounted in such a way that the forces can be handled. I know sea keeper have a cradle for this but have no idea how it is fitted - but i suspect the way the units are mounted to be somewhat similar - unless lots of small ones are used which in effect distributes the load (and gives you a big bill).

 

[NGM]

As a general point it can only be good for us boat owners that there is someone else in the game, hopefully leading to more innovation and better pricing.

I'm struggling with the idea that the MC2 units don't run in a vacuum and don't have cooling, so AOTBE they will generate more heat, but have less capacity to dissipate it. They get over this to some extent by having heavier flywheels running at lower rpm, which of course means more weight for the same anti-roll performance.

Putting aside the weight penalty, if the gyro still has good durability without the need for raw water cooling then that is a very positive feature. I'm in the process of replacing the entire sphere of my Seakeeper due to bearing failure after 5 years, 2,000 hours. I think the cause is a generator fault I had at the start of last summer which caused the genny to shut down a small number of times whilst the gyro was running, meaning it had no cooling during the start of the run down period when the motor and bearings were at their hottest. I've had reasonable support from Seakeeper and the French installer to mitigate the costs, but it will still be an expensive exercise.

I think the precession mechanism on the MC2 is also quite neat. Instead of using hydraulic rams, they have a circular gear track and servo motor operating in the horizontal plane (because the flywheel rotates around a horizontal axis). I think this is part of the reason the unit is quite a lot smaller, as the gear track is mostly accommodated in the footprint of the flywheel housing above it.. You can see it clearly in the 3D view on the bottom right of this drawing.

http://www.itemmare.it/pdf/Ingombri_20ton.pdf

What we really need now is some user reports

edit: judging by the rudimentary website, and the fact that no-one on here has heard of the MC2 gyro before, and AFAIK no OEM offers them as an option, I seriously doubt they have already shipped hundreds of them.

Whilst the cost, simplicity of installation and no cooling requirement are compelling traits,

I'd find it hard to spec one given the lack of installations and hence reviews on the product.
Suspect in a year or so one would have a better informed decision to to make - however, if successful it's also likely that the SK continues to migrate lower in price. (gbp aside !)

 

[jrudge]

thanks, all very interesting indeed !

we run electric fin stabs from 2 x 5KW invertors (70ft - 50Ton boat)
2 x 5Kw is peak power, but average consumption is a fraction of that.
during navigation the battery's are permanently recharged from the 2 x 140Amp/24V standard engine alternators
we run the stabs at anker aprox 1 to 2 hours from the battery's,
while swimming or lunch on the cockpit, no genny running !
stabs are ALWAY'S on.

I assume that consumption from gyro's is much more stable compared to fin stabs, any details on peak / average power consumption available?
looking at the power figures, would be perfectly doable with a invertor imo
the price of invertors is neglecteable in the total sheme of a stabiliser installation, and are a nice feature to have onboard anyway.

also in my case, CMC, the fin stab manufacturer didn't consider the use of invertors, but their typical installations are much bigger than mine
so conslusion: I probably have the only invertor driven pleasureboat stabilizers on the globe

No idea on peak consumption etc. My total guess would be a higher draw under acceleration and then a lower one to maintain it, but how much lower is anyones guess!

 

[Deleted User YDKXO]

I think the precession mechanism on the MC2 is also quite neat. Instead of using hydraulic rams, they have a circular gear track and servo motor operating in the horizontal plane (because the flywheel rotates around a horizontal axis). I think this is part of the reason the unit is quite a lot smaller, as the gear track is mostly accommodated in the footprint of the flywheel housing above it.. You can see it clearly in the 3D view on the bottom right of this drawing.

Thanks for that NickH. I was wondering how precession was controlled given that the flywheel rotates about a horizontal axis. It does seem like a simple device which is no bad thing. Any idea how the precession is controlled compared to Seakeeper? Any feeling for how noisy it will be?

 

[jimmy_the_builder]

No idea how many they have shipped and i did not hear that part of the conversation.

You were too busy eating crisps

 

[jrudge]

Guilty!

 

[Nick_H]

Any idea how the precession is controlled compared to Seakeeper? Any feeling for how noisy it will be?

If you mean how is it controlled mechanically, then as I say, Seakeeper uses hydraulic rams vs. the gear track on the MC2. I think you mean the relative algorithms though, and I don't know the answer to that.

Noise is a good question, as there's no vacuum. I assume the one at LIBS wasn't running? Maybe MB&Y can get onto a boat with one fitted?

 

[WhiskeyTownRacer]

Size I think is really relevant as on a S65 ( only quote that as i know it) the install cost was mostly taking the boat to bits so anything that can mitigate this is worthwile.

I would like to know that in for example a 23 tonne boat would a 20 tonne unit be fine, or is there some logarithmic type rule that says that this would be wholly inadequate to stabilise the boat.

.

You may find this interesting reading: http://veemgyro.com/wp-content/uploads/2015/11/Whitepaper-1401-What-is-the-GMT-20140711.pdf

It delves into some of the factors when sizing requirements are being considered and is a decent read for those with limited knowledge of the area, like me.

Intuitively the content seems sensible but some engineering type might be along to contradict it : )

 

[Deleted User YDKXO]

If you mean how is it controlled mechanically, then as I say, Seakeeper uses hydraulic rams vs. the gear track on the MC2. I think you mean the relative algorithms though, and I don't know the answer to that.

Noise is a good question, as there's no vacuum. I assume the one at LIBS wasn't running? Maybe MB&Y can get onto a boat with one fitted?

Thanks. I understand how the precession is driven mechanically in both cases, it was more about how the precession was controlled. I know that is done by a bunch of complicated algorithms on the Seakeeper but I was just wondering how it was done on the MC. And yes my question on noise was prompted by the fact that the MC flywheel doesn't operate in a vacuum. How noisy is your Seakeeper btw?

 

[Nick_H]

Thanks. I understand how the precession is driven mechanically in both cases, it was more about how the precession was controlled. I know that is done by a bunch of complicated algorithms on the Seakeeper but I was just wondering how it was done on the MC. And yes my question on noise was prompted by the fact that the MC flywheel doesn't operate in a vacuum. How noisy is your Seakeeper btw?

Well right now it's very noisy, because the bearings are shot!

In normal operation it's very quiet, and you don't hear it over the background noise of the genny, unless it's working hard in choppy sea at anchor when you hear the operation of the hydraulic cylinders and a slight whine from the gyro.

 

[MapisM]

unless it's working hard in choppy sea at anchor when you hear the operation of the hydraulic cylinders and a slight whine from the gyro.

Is also the whine affected by the precession movements? I'd have expected it to be constant.

That aside, it's really weird that a sudden lack of AC supply can create such damage.
I mean, I understand that AC is more efficient, but why on earth didn't they use DC at least for cooling, if it's that critical?!?

 

[Nick_H]

Is also the whine affected by the precession movements? I'd have expected it to be constant.

That aside, it's really weird that a sudden lack of AC supply can create such damage.
I mean, I understand that AC is more efficient, but why on earth didn't they use DC at least for cooling, if it's that critical?!?

It's not supposed to be that critical, the official advice is to run the cooling pump for 10 mins after shutdown if possible, to improve long term durability, rather than you must run it to avoid immediate damage. I think it must be the cause of the bearing failure though as it occurred immediately after the generator problems.

On the noise q, I take your point, perhaps when the gyro is precessing the distance from noise to ear, and the angle of attack varies, which makes the whine more noticeable. It's not at all intrusive, so I've never given it much thought.

 

[jfm]

Nick, it's interesting to hear that your bearings have failed. Beautiful though gyros are, the one big unknown in the seakeeper fleet is the bearing change issue. You will be fine because yours was installed by lowering into a lazzerette from above without chopping up the boat, but most are installed during build before the boat is topped and i have never seen an installation where the builder has provided for lifting equipment to disassemble the thing. Think of our neighbouring s58 installation for example. I'd expect seakeeper use the best bearings they can buy but when the current installed fleet start wanting new bearings there might be some big shipyard bills. It would be really interesting to know whether yours failed due to cooling deprivation or normal wear. You could easily install back up cooling from say the boat's pressurised potable water supply, or a 24v standby pump using the same seacock and some y valves

 

[jfm]

On the noise q, I take your point, perhaps when the gyro is precessing the distance from noise to ear, and the angle of attack varies, which makes the whine more noticeable. It's not at all intrusive, so I've never given it much thought.

Also the bearing loads change between thrust bearing loads and rotational bearing loads, due to gravity, as it prescesses. That could impact the whine, (even if both bearing loads are handled by a single -tapered- bearing)

 

[henryf]

I'm sorry to hear of your bearing failure Nick. Better then losing your marbles I suppose

When I was at the Singapore boat show last year I spoke for some time with the US team from Seakeeper. One of the things they mentioned which surprised me was the need to change annodes regularly, think weeks rather than months. I think they were talking 2-3 month intervals. How often have yours been changed?

The service guys on the ground seemed to be saying that the low voltage cooling pumps were made of cheese and lasted no time at all compared to 240 volt pumps. Obviously out there you have generators running all the time you are on the boat for air conditioning. It does sound worthwhile to fit low voltage cooling in parallel to the 240V pump just as a back up for what it would cost.

I really like the idea of gyro stabilisation particularly in Asia where the seas might not get quite as rough to necessitate fins.

I hope you get the bearing issue sorted - just look into annode recommendations from Seakeeper.

Henry

 

[Nick_H]

Nick, it's interesting to hear that your bearings have failed. Beautiful though gyros are, the one big unknown in the seakeeper fleet is the bearing change issue. You will be fine because yours was installed by lowering into a lazzerette from above without chopping up the boat, but most are installed during build before the boat is topped and i have never seen an installation where the builder has provided for lifting equipment to disassemble the thing. Think of our neighbouring s58 installation for example. I'd expect seakeeper use the best bearings they can buy but when the current installed fleet start wanting new bearings there might be some big shipyard bills. It would be really interesting to know whether yours failed due to cooling deprivation or normal wear. You could easily install back up cooling from say the boat's pressurised potable water supply, or a 24v standby pump using the same seacock and some y valves

Agree all that, although the 24v backup pump option would also need some smart switching (or at least i'd need a generator shut down alarm) as it sometimes takes a while to realise the genny/gyro have stopped if we're anchored in a calm bay and just using the gyro to deal with intermittent boat wakes.

I agree it would be interesting to know for sure if the bearings failed due to overheat or wear and tear, or a mixture of both. On one hand Seakeeper's advice is that it's OK to stop the cooling immediately when you switch off the gyro, and the 10 minute cooling overrun is only a "good practice" recommendation, but on the other hand the gyro ran faultlessly for 5 years/2,000 hours until I suffered the genny problems, and the bearings failed straight after that.

Henryf, thanks for the info, and the misplaced assumption that I've retained all my marbles . We change the anodes twice a year, but even if that's not enough I don't think it can be related to the bearing failure, as it would be the heat exchanger, raw water pump or something else in the seawater cooling circuit that would fail, and that would cause a waterflow or overheat alarm and controlled shutdown of the gyro.

I still think gyros are wonderful things, and would still recommend them and spec one on any new/used boat, but I will make sure in future that the cooling stays on even if the genny shuts down.