Seakeeper install…. 7,000 miles later

Ben Stein

Ben Stein

Publisher of, passionate marine electronics enthusiast, 100-ton USCG master.

27 Responses

  1. William says:

    Great article! Thank you for sharing. Looking forward to doing the trip someday!

  2. Ben Ellison Ben Ellison says:

    I have somehow never managed to get aboard a SeaKeeper demo, but I have many boating writer friends tell me that it is truly amazing. I particularly heard that when we gave the Seakeeper3 12v smaller boat system an award at IBEX. (Great install video here: )
    But what I didn’t realize until now is how gyro stabilization can not only help with sickening rolls but also give fast boats a wider range of usable speeds. The cost and complexity probably makes some “salty sailors” wince, but I say COOL, and thank you, Ben S.

  3. Charlie McVey says:

    Great article Ben. Look forward to other articles

  4. Barry S says:

    Great article. Can you speak a little to the electrical needs as well as the start-up and shut-down procedures.
    I am under the impression that it takes quite a while to start-up and get rotating at the needed RPMs consuming a lot of power and that shut-down has a similair reguirement.
    Thank You

  5. Andy says:

    Would be really interesting to hear a bit more on the maintenance side of SeaKeepers and other gyro stabilizers. How much work is needed, how often and how much can be be done by yourself. And what is the period between major overhauls?

  6. Ben Stein Ben Stein says:

    Barry S, the rated power requirement is a maximum of 3kw or 3,000 watts. I typically see the stabilizer consume just under 12.5 amps (at 240v) during startup which is right at rated max. The startup or spin-up time is while the stabilizer gains RPM. When it is set to 9,000 RPM (it can also be set to spin at 7,200 RPM) it takes about 45 minutes to reach 7,650 RPM, the speed at which the ECU will let you unlock the brake and gain stabilization. Once the stabilizer is up to speed power consumption typically drops and varies between 3.5 and 12 amps depending on sea state.
    Shut down consumes nearly no power. The first few minutes after turning off the electric motor the cooling pumps still run to cool the bearings. I can’t remember the exact amount of time, but it’s relatively short. The main coolant circulating pump on the stabilizer is 24v so it doesn’t require the generator be running. The spin-down can take up to 8 hours but during this time there’s no power drawn.

  7. Ben Stein Ben Stein says:

    I don’t have any data on major overhauls. The factory reps mentioned some of their higher hour units when I asked about longevity and those numbers were impressive.
    The brake system and cooling system fluids call for annual maintenance. The sacrificial anode depends on the water the boat is operated in. Other items are mostly inspect and replace as needed.
    Here’s what Seakeeper provides:

  8. Gary G says:

    Thank you for the great article. Last summer we installed a Seakeeper 6 in a Defever 45 trawler. Since we only installed it in Sept. and have only a short time with it, we were glad to see you’re experience in large seas. As for the electrical requirements, it takes both 12/24 vdc and 120/240vac. Start up time for the stabilizer to reach effective rpm is 30-40 minutes. We start it up while under shore power and then switch to gen-set just before departing the dock. Power draw is app. 2300 watts at start-up and 1050-2300 watts while underway (depending on amount of stabilization required. While it takes about 45 min. To spool down, there is no power requirement for this. The expenses is large, but in our case not much more than fin stabilizers, plus there are no hull protrusions to snag on lobster pots.

  9. Sdpaddler50 says:

    Thanks for posting. Great article.
    We have a new build 45 ft. Trawler being constructed now with one. It’s a large investment but I am glad we did it.
    How long does the DC coolant pump run after you shut down? IE, if the gyro requires up to 8 hours to completely stop, I assume no pumps are needed for cooling during that duration and you can leave the boat while it’s still spinning?
    Are the zincs easily accessible?
    Can you do the basic annual PMs on your own during the Warranty period, or is a Seakeeper trained tech required?

  10. Dan Corcoran (b393capt) says:

    On the water experiences with products are exciting to read about, thank you for sharing this with us.
    Ben, do you still provide hats for first time writers?

  11. Ben Stein Ben Stein says:

    Hats? There are hats?

  12. Ben Stein Ben Stein says:

    I haven’t checked too carefully. I believe the pump will run for an extended period of time, maybe as long as a few hours. I have been told by Seakeeper that within about five minutes of shutting off the bearings are safe even if all power is removed. I wouldn’t hesitate to leave the boat during the spin-down period regardless of pump running or not. The zinc is pretty easy to access, on the top of the heat exchanger to the left of the ball. I know the Seakeeper literature says maintenance should be performed by a Seakeeper trained tech, I don’t know if this is a requirement or not. The brake service I believe requires some specialized tooling to properly re-pressurize the brake circuit.
    Ben S.

  13. Ben Stein Ben Stein says:

    Gary G, I would like to hear about your experiences as well. Gyro technology isn’t as proven as fins and I know many people building displacement trawlers are still spec’ing fins because they’re tried and true. I’ve seen a few passage making trawlers equipped with Seakeeper and have been curious to hear from someone who’s operated one over long distances. The one area I’ve often wondered about is that underway fins never run out of stabilizing force since they can leave a fin out catching water indefinitely, the same isn’t true for a Gyro. It’s rarely been a problem on our boat but the reality of our boat is its overall seakeeping abilities aren’t as strong so we don’t find ourselves out in some of the conditions others might.

  14. Anonymous says:

    Ben S, email me and we can discuss our SK experiences without hijacking Ben E’s great blog. Ben E, would you pls send Ben S my email.
    Further, the SK 6, which is 2/3 the size of the SK 9, uses 110 vac, plus 12vdc. The water pump is a 110 vac pump, but is controlled by the 12v controller. When one shuts off the power, the water pump shuts off, but Seakeeper says this is okay. When the SK is spinning down, it is not generating heat that requires external cooling. On our SK6, it only takes 4-5 hours to spin down (my first Post said 45 min, but autocorrect took over!)
    User maintenance involves periodic checking for leaves and corrosion. The big items involve changing cooling fluid (user can do) and changing the hydraulic fluid in the braking pistons. This requires a very expensive tool one can purchase from Seakeeper. You need to have Seakeeper do this task to keep in warranty, but later I see no reason a mechanically inclined user couldn’t, if you had the tool. We’re in fresh water (Great Lakes) so zincs are not too much of a concern, but they are easily reachable.
    All in all, it is an easily maintained system, far easier than fins.

  15. Ben Stein Ben Stein says:

    Not to worry about hijaking Ben’s thread. This ones actually mine, I wrote the article :-). I can provide my email off line but I think others would be interested in hearing your results.
    Ben S.

  16. Gary G says:

    Last post by Gary G, sorry

  17. Xavier Itzmann says:

    Great, well-written article.
    NVH? Noise, vibration, harshness?
    I suppose it could be zero, as you don’t mention it, or maybe it is all moot as a 23kw generator is running anyway? Still, it’d be interesting to hear if there is any in the wind-down process, in case the genset has been turned off.
    Thanks in advance,

  18. Ben Ellison Ben Ellison says:

    Yes indeedy, Dan, first-time Panbo writers still get the highly-sought-after but not-available-in-any-store Panbo long-billed cap 😉

  19. Ben Stein Ben Stein says:

    You hit the nail on the head with mention of NVH potentially being moot due to the other mechanical sources of NVH. Underway or with the generator running, or really even the air conditioning, you can’t hear or feel the gyro at all. If you’re at the dock during spin-up you can hear a slight whine which is the main noise the stabilizer makes. During spin down that same slight whine can be heard during the high RPM portion of the spin down, I’d say down to about 4,000 RPM you can still hear a little bit of a whine.
    I should clarify the whine isn’t disruptive in any way. The engine room is sound-shielded against two 12 liter diesels and a 23kw generator so the sounds of the stabilizer that make it through are quite minimal. We have a set of chairs directly on top of the engine room hatch. The stabilizer is directly under that hatch and the stabilizer spinning up, running or spinning down doesn’t affect conversation or being able to sit and enjoy the scenery at all.
    Ben S.

  20. Gary G says:

    Second Ben S’ comments about NVH. Our SK is in the engine room, directly under the main salon. With the generator running (8kW)(and its not too loud either) you do not hear any sounds from the gyro. When the genie is turned off at shut down, you do hear a quiet whine, but not obtrusive. The whine goes down as the spinning goes down. Actually, it is more noticeable off the boat on the dock, than inside the boat. There is no vibration whatsoever from the gyro.

  21. Xavier Itzmann says:

    Gary and Ben S, Thanks.

  22. Nigel ha says:

    Another alternative is MC 2 quick gyro.
    These are vertical , require no external cooling, are way cheaper. Their marketing must be crap as they get no press, but to me are a better alternative from my limited reading and talk to a rep at the Sydney boat show.

  23. Ben Stein Ben Stein says:

    I’ve been a little intrigued about what Quick has up their sleeve as well. I haven’t seen pricing data on them but I do know that a large part of the expense of ours was the installation expense. That’s more a function of the amount of force placed on the hull than anything else so I don’t expect that to change much. The cost of a thru-hull for cooling and an AC pump is pretty small.
    It’s concerning to me to note the Quick -MC2X30, which is rated for roughly the same size boats as a Seakeeper 9 is very heavy. A MC2X30 is 965 kg while a Seakeeper 9 is 550kg. That’s not too surprising. Seakeeper is spinning the counterweight at 9,000 RPM while Quick is at 4,000RPM. To get the same angular momentum it’s going to require a much heavier flywheel.
    Ben S.

  24. Sdpaddler50 says:

    That is a large RPM and weight delta for the other brand, but I don’t know anything about them so I can’t comment further.
    Our SK5 is going in now on a new Trawler build.

  25. Luis Soltero Luis Soltero says:

    Hello All,

    Finally took the plunge and purchased a seakeeper for Bliss our 40′ Bendford custom pilot house trawler.

    Unlike “Have Another Day” Bliss is quite small for a 40′ trawler having been built on the hull of a cascade 39 cutter sailboat. At 15 tons she has little room to accommodate both a generator and the seakeeper… So.. after thinking long and hard about how we would run the power hungry seakeeper without a generator we finally took the plunge and dumped the generator!

    So… the seakeeper now sits where the generator was. The next issue that had to be solved was how to power the seakeeper with our 100HP yanmar while underway. This challenge was addressed by the installation of 2x 250 AMP alternators with external rectifiers which drive a 3kw victron inverter connected to the ouse bank. The alternators generate 400+ amps continuously (warm) although the seakeeper 5 needs only about 120amps to run once it has reached its 10,000 RPM state. Starup consumes about 180 Amps DC at 12 V… again something that the dual alternator setup can manage. We have a 2000AMP/HR AGM house battery bank that allows us run the seakeeper for 8-10 hours (50% discharge of battery bank) while at anchor. Again the dual alternator setup produces enough current to run the seakeeper while charging the house battery bank.

    One problem that had to be overcome was running the engine at low RPM. at 4Hp per 100Amps the alternators can consume 16Hp which the engine will support at low RPM but not while motoring. Although designed for a dual engine setup we used a balmar centerfielder II to control the output from the alternators. We have 2 switches running to the pilot house which allow us to control the output current from the alternators. One switch disables the port alternator altogether while other switch puts the starboard alternator in small engine mode reducing the output to 50%. this allows us 4 output settings. 100/75/50/25%. While idling or motoring slowly we can reduce the alternator output to direct the engines HP to the prop.

    At 2400 RPM the engine produces about 75Hp 25 of which is used to drive the boat at 7.2Knots. this leaves plenty of power (50Hp) to drive the alternators which require 16HP at max output.

    This is basically a poor man’s implementation of nigel calders integrel system
    sold by Bruce Schwab Energy but not available in the USA yet.

    Finally to monitor all the current that is being shipped around the boat we used a Pico system with shunts on both alternators allowing us to see the exact amount of current generated by each and to monitor the state of our large battery bank as well as the current draw by the seakeeper.

    And… the seakeeper is amazing… our rollyboat is not so rolly anymore!

    Take care.


    • Ben Stein Ben Stein says:


      Wow, yours is a much more interesting install than my boring old generator based system. I love that you can run the Seakeepr at anchor on battery alone and avoid the noise, smell and fuel burn of a generator. As I was reading your description I was thinking how similar it sounded to Integrel and then you mentioned your poor man’s implementation of the same concept. The one thing I was left wondering was if you considered going to a lithium battery chemistry for the charge acceptance characteristics of those batteries. That strikes me as the only pain point in what you have built.

  26. Luis Soltero Luis Soltero says:

    hi Ben,

    Lithiums would be nice… I have looked into them but the cost is high. 2000Amp/Hr of Li batteries is about $25K or greater. And… Bliss uses the lead for ballast so swapping out the batteries will required adding lead to the the boat.

    Having said that… Li is in my future… just not quite yet.

    For now the AGMs do the job. My 7x8D + 1x4D house bank has no problem generating the amps required to run the SK5.

    The integral is a fantastic concept… In doing my due diligence on the install and looking at the power curve for Bliss (provided by the designer Benford) and the power curve for the engine it is pretty obvious that a ** LOT ** of diesel HP is lost when motoring. this loss can easily be converted to DC current which is much more efficient running a genset. I did contact Niegel about installing an integral system on bliss since that is really the perfect solution. However, the system was still quite new at the time and he was not ready to sell systems in the USA. So… we went with the manual approach.

    We did look long at hard at other stabilization technologies (fins, paravanes, bilge keels) but in the end Bliss with her 34′ water line is just too small for most. The bilge keeps might have worked OK but who wants all that wetted surface in the under body.

    All in all a great learning experience.

    we are headed up to the Canadian Maritimes (PEI) this summer and the seakeeper will be much appreciated after rolling gunnel to gunnel in the Bay of Fundi last year.

    Take care.


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