Gyro stabilization

[menta]

Dear all
I am considering buying a Princess 62 that is fitted with a Seakeeper Gyro model NG9
As this is a rather tall and quite heavy boat at over 30 ton, I would appreciate your feedback on effectiveness of gyro stabilization for such or similar planning boat
In particular I am interest in your experience regarding performancee while in motion and up to what boat speed it is effective
Thanks
Menta

 

[Boatbore]

I put a seakeeper 3 on my sunseeker Superhawk 50. Technically the SK3 is aimed for boats up to 40 ft but mine is very narrow with a deep vee so the concencus was that it would work, and it does. At rest it is an absolute miracle machine and I tend to leave it on also when underway as there is some benefit even if it considerably less than at rest.

Your questions are very precise and I would suggest a long chat with someone from SK. The point is not to eliminate 100% of movement but to gain a benefit from whatever you would have been suffering without it. Speak to Osmotech and they will tell you there is a simple test that you can do using an iPhone app that records the amount of roll with and without the seakeeeper on.......the aim is to get the resulting % as high as possible. Your post is asking for very specific answers but I think you should assume that under all conditions and all circumstances the Boat will rock less with the SK on than with it off....... the bigger win is then how much ? I can tell you that my own set up eliminates between 85% and 90% of roll at rest.... that is a simply transformational experience if you keep a boat, as I do, in a place where swells tend to be beam on to wind direction. My SK will pay for itself in rose that isn’t spilled and glasses not smashed in no time !

In terms of the weight of the boat and it’s top heaviness, then yes of course that must make a difference, but assuming the gyro is correctly specc’d for the size of Boat then it will perform flawlessly. If it was a factory fit, then I would imagine there will be data to demonstrate how effective it is. Go on to the SK website and watch some of the demo videos until you find a similar or identical boat and it will show you first hand.

Good luck with your purchase...... don’t agonise over whether you should buy the one with the SK or the one without......definitely buy the one with. In a few years I would seriously think that the majority of new boats will come with one fitted as standard and it will be hard for anyone who has had one to go back to not having one so you will be repaid in cost terms in the future.

I hope that’s all helpful.

 

[rubberduck]

We have had it fitted on an Absolute 47, seakeeper 5, my wife now has a different view of the boat, much happier whereas she used to put up with it. At rest we got 87% reduction in roll on test, anything under planing speed is also notable, above that the boat is stable anyway, although we keep it on & have auto trim tabs as well. Its like a different game now.

 

[jimmy_the_builder]

Dear allI am considering buying a Princess 62 that is fitted with a Seakeeper Gyro model NG9As this is a rather tall and quite heavy boat at over 30 ton, I would appreciate your feedback on effectiveness of gyro stabilization for such or similar planning boat In particular I am interest in your experience regarding performancee while in motion and up to what boat speed it is effectiveThanksMenta

Try a pm to nick_h, he has a Princess 57 with a seakeeper fitted. He will give you first hand experience about performance at rest (very good), up to hull speed (noticeable) and planing speeds (marginal).

 

[NGM]

Try a pm to nick_h, he has a Princess 57 with a seakeeper fitted. He will give you first hand experience about performance at rest (very good), up to hull speed (noticeable) and planing speeds (marginal).

I have a smaller but equally 'top heavy' Princess with a SK5 fitted. I'd agree with the above summary although I'd replace the 'very good at rest' with fantastic.
It made a meaningful difference to our boating experience, I can't remember a day or night at anchor when we didn't have it on.

 

[Nick_H]

Do you mean the "old" P62 flybridge, circa 2006-2010? If so, there is a test report for one fitted with an early model 7 gyro, you may find it on SK website, or you could ask them to send it to you. An SK9 has 30% more anti-rolling force, so you should get excellent performance.

I have model 8 fitted to a Princess 57 which is 26T dry. The difference at rest is night and day, and I rarely run it at full speed as the lower setting does the job. It's also excellent at displacement speed, we have long lunches whilst underway with no hesitation to put wine bottles and glasses on the fly table. It still works at planing speeds, you just don't notice the effect so much.

The SK9 is the right size for a 62 footer imho, you wouldn't need a bigger one.

 

[menta]

Dear Nick,
thanks for your response.
I presently have a P62 bought new in 2008 and now I am thinking of exchanging it for the new F62.
The boat recently tested by MBY where they were talking about having to throttle down to displacement speeds for the gyro to work in order to cope with some of the seas they met.
As I am doing most of my boating in the Aegean sea where the waves are typically very steep and of short period, beeing able when needed, actually quite often, to slow down without breaking everything or having half the people on board seasick is a great advantage.
Assuming that over ca. 14 knots the boat gets on planning mode, at least this is what my 62 does, how would you rate the performance of the stabilizers below that threshold and above.
If they were still offered I would probably go for the fins as then all these considerations would be irellevant but unfortunately fins are an option only for the 70 and above which is significantly more expensive!
Looking forward to some first hand input!
Thanks
Menelaos

 

[menta]

Dear all thank you very much for all your input. Will let you know how things develop

 

[MapisM]

For the usage you are describing, I would rather consider retrofitting fin stabs on your current boat, unless you have any specific reasons to change her.
Btw, she's quite likely better built and powered by more solid engines, compared to current production.
Of course, I'm not expecting your Princess dealer to agree...

 

[jfm]

Ng9 is the right size for that boat.
Gyros are excellent at zero speed stabilisation. Slightly ( 1.1x) better than fins.
Underway gyros are highly limited at stabilisation due to the laws of physics. Ignore any salesman who says otherwise. Fins are awesome underway and have almost no limits on their ability to remove roll underway. 5x if not 50x better than gyros.
That’s the choice you have to make, if you have a choice.
If you don’t have a choice then gyro is a lot better than nothing underway, and awesome at anchor. Sk9 is the top choice among gyros, at this size

 

[Deleted User YDKXO]

I retrofitted a Seakeeper 9 into my Ferretti 630 last year which weighs 39t dry. It works well at anchor and at slow displacement speeds but at any speed above 8kts, the gyro cannot overcome the hydrodynamic forces acting on the hull and it becomes increasingly less effective. At planing speeds there is no effect. I am not unhappy with that because I bought the SK9 mainly for stabilisation at anchor but all the same time I am a bit disappointed that it has no effect at speed. IMHO Seakeeper oversell their product in this respect. The fact is that if you want stabilisation at speed then a gyro is far less effective than fins. Seakeeper recommended the SK9 model for my boat but in retrospect maybe the SK16 would have been the better choice but then the cost and space requirements would probably have been prohibitive and I wouldnt have bought one at all so maybe they knew what they were doing

Another negative about the SK9 is that it takes about 45mins to spool up to speed so you cannot just switch it on when you need it like fins so we find ourselves running it all the time when we go to sea or drop the anchor, whether we need it or not, and that means that the generator is running all the time as well. Luckily our generator is pretty quiet so it is not too much of an issue but on a boat where the generator is more intrusive it could be an issue. On the positive side, the SK9 itself is very quiet even when it is in operation

Overall, I would say that a gyro is worth having if you spend a lot of time at anchor like we do but if you are looking for stabilisation under way, then look at fins

 

[menta]

And since we are talking about fins, does anyone in the forum have personal experience with the Humphree active fin systems? Given the progress with servo motors - after all today for an industrial machine to be considered state of the art it must be electric instead of hydraulic - do not see why it should not work very well.

 

[BartW]

And since we are talking about fins, does anyone in the forum have personal experience with the Humphree active fin systems? Given the progress with servo motors - after all today for an industrial machine to be considered state of the art it must be electric instead of hydraulic - do not see why it should not work very well.

5 seasons ago, I have retrofitted CMC electric fins on our 70ft planing boat. (cruising speed 20kn)
we are still very exited about the results, at anker aswell as during navigation,
can't imagine using the boat without them anymore

no experience with Humphree, but a few years ago their mechanical technology demo'ed at a show, was years behind on CMC,

my system is compact, light weight and very efficient on power consumption,
the system in my boat can run at ankor on battery's for 2hrs or more... (the only fin stab system in the world afaik ;-) )
I believe that CMC has now also a new even more compact model for boats up from 50(?)...60ft

detailed info on our rebuild project here:
http://www.ybw.com/forums/showthrea...el-engineering-question&highlight=engineering
and here:
http://www.ybw.com/forums/showthread.php?295561-Blue-Angel-(Canados-70s)-Rebuild-thread

 

[jfm]

And since we are talking about fins, does anyone in the forum have personal experience with the Humphree active fin systems? Given the progress with servo motors - after all today for an industrial machine to be considered state of the art it must be electric instead of hydraulic - do not see why it should not work very well.

Servo motors have many advantages over hydraulics and are indeed state of the art in industrial machines. The problem however is that you need big ratio reduction gearboxes for fins, and those gearboxes are noisy (in an annoying way). That doesn't matter in industry but it does on a boat. So the bottom line is to decide whether you can live with the noise of electric fins. Hydraulics, despite some other disadvantages, as well as some advantages, are near silent if well designed.

These are early humphrees. I believe they have improved since but only by a degree and not in a big way. See what I mean about noise?
https://m.youtube.com/watch?v=EjFEoynDPwI&t=0s&list=UUrJBIkc-lHKQ0IHJ-U2PCmw&index=17

By the way, last year I was contacted repeatedly and heavily by humphree's senior management in Sweden demanding that I take that youtube down. Poster "yavbay" on here. Properly nasty bunch of losers. I refused, and they got heavier but then they discovered that empty litigation threats spook me. Ultimately I offered to take the video down just on their request, but on condition that I would put up another much worse video that they had no copyright claims on and which they couldn't stop me from putting on YouTube. I showed them the second video. After that, they never contacted me ever again- they just went silent. So please don't think that dealing with Humphree means you would be dealing with nice guys.

 

[MapisM]

And since we are talking about fins, does anyone in the forum have personal experience with the Humphree active fin systems? Given the progress with servo motors - after all today for an industrial machine to be considered state of the art it must be electric instead of hydraulic - do not see why it should not work very well.

Menta, why are you interested, if you don't mind me asking?
I mean, if you are sticking to your plan of replacing your P62 with the F62, it's either a gyro or nothing, as I understand?

Otoh, if you are considering my suggestion in post #9, then the choice for retrofitting fin stabs is a total no brainer, and it's the one that BartW mentioned in his post #13.
First of all, at CMC they invented electric fin stabs, and their products are the reference in the industry - all the way up to megayacht installations, which aren't exactly vessels targeted to penny pinchers.
Besides (consistently with the previous point), they are nowhere near as noisy as the Humphree toys - though I partially disagree with jfm on the noise issue, because if you really like to sleep in total silence, the only solution known to mankind is to pick an anchorage where you don't need stabs at all, shutting them (regardless of whether hydraulic or electric) and the genset down.

Btw, stabs aside, you might be interested to have a look at a brief debate on the choice of a new vs. an old(ish) Princess, after I mentioned incidentally in another thread what I suggested to you here.
Just look at this post and the following replies...

 

[menta]

Dear Mapis,
I am still investigating as I am not sure I am doing the right thing
After all my main goal is to be able to reduce speed, not necessarily down to displacement, when the going gets rough, something quite common during summer months in the Aegean sea
Stabilization at rest and especially during night is not an issue. With all the islands and coves in Greece, during 25 years of boating I have maybe faced problems with swell only 4 - 5 times
And gensets during the night are off

Now why change from my current 62, which by the way I thorougly enjoyed all these years, to the new:
Even though my current boat, bought new in 2008, is in excellent shape and meticulously maintained, after 11 seasons and about 1.400 engine hours has already started giving some hints that going forward it will be needing some extra maintenace apart from the regular service work...
And I am sure you must agree, if these unforseen problems happen during the summer season it can be very frustrating.

In closing I also agree with you that in newer boats the yard is trying to save as much as possible.
In fact as I am essentially talking about the same boat, the P62 ordered this time 2006 and the F62 negotiated with the yard now, the number of items where they are cutting corners is unbeleivable!
For example old boat came standard with a 40 kg Delta - new is 32 kg, old boat had a 100 A Mastervolt charger - new 60 A, old had stndard electric macerator with back up - new is extra, same with stern winches, etc. etc.

But after finishing the fights with the yard and specifying it the way I want, I hope I will have again a new boat that God permit I will enjoy for several years and then who knows.

 

[MapisM]

Dear Mapis,
I am still investigating as I am not sure I am doing the right thing
After all my main goal is to be able to reduce speed, not necessarily down to displacement, when the going gets rough, something quite common during summer months in the Aegean sea
Stabilization at rest and especially during night is not an issue
...

If that's what you are aiming at, nothing can beat fin stabilizers - which can give you also a more than decent stabilization at rest anyway.
'Fiuaskme, considering what you are saying of your current P62, I would retrofit her without wasting one minute looking at new boats.

I do understand your concern about boats needing some extraordinary maintenance as they get older, but I don't think that the chances of having some major issues out of the blue that can spoil your holiday are so much lower with a new boat, compared to an older but properly maintained one.
Not to mention that your current boat is powered by Cat C18, as I recall? If so, there's only one way someone could convince me to replace a couple of well maintained 1400 hours C18 with brand new VP D13: by giving TO ME a substantial amount of money on top!

 

[menta]

Indeed, C18s are excellent engines! Also never considered the VPs. As a matter of principle would never go for the most extreme product of any manufacturer. Going for the MAN 1200.
In any case there is a chance the retrofitting facility of Princess MY Sales will be fitting the fins on the F62
If this is the case problems probably solved.
Anybody have any experience doing work with them? At least they have access to all technical drawings regarding hulls, etc.

Otherwise agonizing will continue for some more time...

 

[jfm]

though I partially disagree with jfm on the noise issue, because if you really like to sleep in total silence, the only solution known to mankind is to pick an anchorage where you don't need stabs at all, shutting them (regardless of whether hydraulic or electric) and the genset down.

Not arguing or anything but I hand in mind the quality of the noise rather than a search for "total silence". A jerky (even dubstep) noise at frequent but irregular intervals is more annoying to a lot of people than the gentle (not silent) constant hum of a nicely installed 1500rpm genset back in the e/room.

(BTW this last super hot 2018 summer I ran genset all night every night just to give guests airco - nothing to do with stabilisation. Calm anchorages made it worse because the absence of wind meant that leaving windows open did not help! #firstworldproblems)

As regards a retrofit of fins, I would want very full details of what the installer is going to do before handing them my boat. A retrofit is possible to do well, but also possible to get wrong