Bliss: 100hp diesel powers trawler, Seakeeper, and huge battery bank

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now pleased to have Ben Stein as a very able publisher, webmaster, and editing colleague. Please don't regard him as an "expert"; he's getting quite old and thinks that "fadiddling fumble-putz" is a more accurate description.

9 Responses

  1. Luis Soltero Luis Soltero says:

    Hi Ben,

    I think it might be good to follow up with some performance notes on the Seakeeper 5 since there is not much mention on how the unit performs under different sea conditions.

    The SK is really good at dampening/eliminating any motion caused by an abrupt event. The motion sensors on the unit are very sensitive and as soon as motion is detected the SK wields massive momentum (600 lbs at 11,000 RPM) to counter the motion. So… wave patterns that have high frequency/short wavelength (or period) are stopped in their tracks. So… wakes caused by monster power boats overtaking you at 15 knots and passing 10 feet away from you whereas in the past would cause the boat to almost capsize (just kidding here but certainly cause lots of stress with wild rolling) are just not an issue any more. Now we smile and wave at the idiots as if on a sunday drive and continue on our happy merry way… Its a remarkable thing to experience.

    so basically short choppy seas at the beam and forward are pretty much nullified.

    as the seas build and move aft of the beam the effective (or observed) wave length lengthens. (i.e. waves have longer observed frequency) the SK struggles more to dampen the roll. This is not to say that the SK fails… The roll that is observed is
    1. Much smaller in amplitude than it would be otherwise
    2. The roll is immediately dampened and the boat recovers back to its upright position right away. The “ring” effect is immediately dampened. End result… the watermelon stays on the counter since the forces acting on it are gentle.

    I keep talking about the “ring” effect. This is when successive waves in a wave train cause the vessel to augment its roll with each successive wave that hits it. Usually this has a magnifying effect. the first roll might be 5 degrees. the next wave builds on the first causing the next roll to be 10deg, etc… with the SK you see the first roll (which is dampened) and then the boat goes upright… subsequent rolls (if any) are much smaller than the first. This is very important since this “ring” effect in our experience can cause a lot of heartache.

    Bottom line… while surfing downwind the boat does roll… but it’s a roll that is much gentler of smaller amplitude that corrects itself very quickly.

    The worst point of sail for the SK5 on Bliss is from 120 deg off the bow. Dead downwind is better than quartering seas. As mentioned above and demonstrated in the video the SK5 will work fine under these conditions with 6′ seas and 20-25 knots of wind. Under these conditions the SK hits its stops at +- 60 degrees and once there can’t provide further righting motion. Under these conditions we see < 5 degrees of roll with moderate roll period (as demonstrated in the video). With larger seas the SK5 reaches its stop and the boat continues to roll with larger amplitude. However, as soon as it starts rolling back the SK is back in action opposing the motion deducing the roll amplitude and period. So good but not as good as in "choppy" seas or sea forward of the beam.

    The SK5 acts in wind like it does with waves… Sudden gusts like what you might experience on the front end of a big squall is countered… but sustained winds can be thought of as waves with infinitely long wave length. The SK5 can't address that. So the boat heels. Unlike fins that can be used to correct heel angle the SK5 is totally ineffective at this. So… for big sustained winds alternative corrective action must taken. On Bliss we have installed pumps that allow us to move water and fuel from tanks on one side of the boat to the other. The 150 gal water tanks (one on each side) are quite effective as ballast. The fuel tanks are lower in the boat and more centered but they can also be used as trim ballast. Otherwise changing course to decrease the effective wind strength is all that can be done.

    The highest wind we have seen since we have had the SK5 is 35 knots sustained… Bliss did fine in this and we did not feel unsafe. Higher winds are things we would want to avoid….

    Case in point.. on our 4 day passage from St. Peter Cape Breton Island to Nantucket across the Gulf of Maine we never saw more than 20 knots of wind with moderate swell. However, given the large tidal currents flowing into/out of the bay of fundy there were many times (especially during tide change) where we saw sloppy/choppy seas with standing waves and eddies. The SK5 performed perfectly under these conditions. It’s like the thing was invented for this kind of perturbed seas. We never saw more than 5 deg of roll the entire trip and most of the time it was near 0.

    One final take away about this last year… Small boats like bliss and Gizmo are hard to stabilize using traditional methods. Roll tanks, Active fins, Paravanes require real estate that we just don't have. Initially I felt the same way about the SK.. there just was no room in Bliss for the thing. That is until we discovered that we could remove the generator and replace it with the SK. The SK fits perfectly in the footprint of the old generator. The ah-ha moment (with the help of Bruce Schwab, Nigel Calder, and friends at OceanPlanetEnergy.com) came when realizing that generators are hugely inefficient and that there are much better ways to do manage your electrical systems using alternative technology. So there was nothing to loose and much to gain by dumping the generator!

    –luis

  2. Ben Stein Ben Stein says:

    This gets me thinking a little (and that can be dangerous and expensive) about the possibilities of running my SK9 off an inverter. The 230v 9 requires a maximum of 3,000 watts at startup and steady state closer to 1,600. Louis has done some impressive calculations to figure insure there’s adequate propulsive power available but I suspect that Have Another Day’s two 675hp engines are throwing away large multiples of what would be required to make the power. The biggest issue I see is that I don’t think I’d be able to run the SK for long without the engines running and I think I’d need a separate battery bank for whatever time that might happen. Real estate in the engine room is at a premium and my boat is already stern heavy so I’d need to find a way to add any weight to the bow.

    But man, the ability to run the Seakeeper without firing up the 23kw generator sure would be nice.

    -Ben S.

    • Colin A says:

      Ben,
      I’m sure your diesels have plenty to give for the stabilizer. ( I assume your boat is 24V that makes it a bit easier). If you have the inverter power, you could go with a large battery charger and use your Gen for shorter run times to keep the stabilizer running when the main propulsion is off which would give some efficiency gain if you were running unloaded to just keep the stabilizer at speed. At 1,600 watts (not sure how long start up is to put in the calc) a Pair of 8D (230AH) batteries (wired as 24V) would give you a couple hours runtime to 50% discharge, Now given the weight concerns Lithium is worth a look. If your not going DIY (I’m cheap personally) lithionics has a good rep a pair of their 8D (300AH) replacement 24V (slightly bigger then an actual 8D but slightly less weight) would get you close to 7 hours run time at 20% DOD. Lithium really does have some advantages for systems like this.

  3. Luis Soltero Luis Soltero says:

    Hi Ben,

    My guess is that you should have no problem running the SK9 off of the engines. The thing to keep in mind is that 2x 250 alternators == 20 hp (worst case)… so if you look at the engine hp output at your cruising speed (the graphs should be readily available from the engine manufacturer) subtract 20 from that figure to find out how much power you actually have at your disposal. Getting power curves for your boat from the carver might be more difficult but again my guess is that at displacement speeds you are way over powered. You have much more horsepower than say a Nordhavan 63 and that is a MUCH larger boat!

    So… 2x 250 amp (at 12v) alternators per engine is ==> 12Kwatts way more than what you need. You would need 2x victron inverters to get your 3000 watts continuous. Your alternators would be loafing and running at 1/4 of their capacity which is good. 1 inverter might do it but i would hate to run the inverter full out for extended periods of time. But if all you really need is 1600watts to run then it could be that one inverter would do it. The inverter would be peaking at 3kw a lot lot while spinning up but once up then you would be set since it would only be running at 1/2 capacity… However.. it is nice to run the house off of inverters without having to start the genset. So 2x is probably the right number.

    There is no reason why you could not keep your current generator setup in addition to having an engine driven setup. Given that you could easily have 12Kw at your disposal form your engines really the only time you would need to run the genset is when at anchor. Underway all of your power requirements can be met by the DC generation system.

    As far as batteries go.. Although we have a large bank we often spend long periods of time at anchor and when foggy or rainy the batteries do go low. Sometimes as low as 40% of total charge. Under these conditions we don’t run the SK off of the batteries. We start the engine 30-50 minutes before lift anchor and let the engines warm up and the SK5 spin up. Keep in mind that at 800 RPM you will have more than enough power to run the SK9. So.. just idle for a while before you go and you are all set. And.. you could also switch to lithium batteries which are much lighter if you wanted to spin up the SK9 without having to start the engines.

    I would give Bruce at OPE a call to discuss high output alternators and inverter options. From what I see you are in much better position to this than Bliss given the size of your engines.

    –luis

  4. Luis Soltero Luis Soltero says:

    Hello All,

    Many have asked what cause the SK5 to fail after 170 hours.

    So first of all let me state for the record that it was Ben’s fault! The unit had been working perfectly all the way to Camden Maine. We used it as we sailed into the inner harbor and tied up to one of the town floats. It was only when Ben came aboard to have the unit demoed that it failed to start. Ben broke it!

    The error condition message was “Over current”. There was too much AC current being drawn on start up.

    The cause…

    If you look watch the video above you can’t help but notice that the SK moves often and fast. The hydraulic arms are pumping away and the 600 lbs sphere swings from up to +60 degrees to -60 degrees frequently. Its pumping away when in stabilization mode. It is absolutely essential that all wires and hoses that are attached or near the sphere have clearance. As it turns out the AC motor wire that feeds the bottom of the sphere would just happen to brush (and I mean just slightly brush) up against one of the hydraulic hoses when the unit approached one of the stops. So… at the end of the swing. After 170 hours the wires fatigued and some of the strands broke causing resistance and hence requiring higher amperage. This must have happened while under passage to Camden but since the unit was running it required much less current than on startup. So the problem did not manifest while under way. Only on start up the next morning the we realize we had an issue.

    SK5 support was great. At first it was not obvious what the problem was. So… they sent a tech out with a MegaOhm meeter to test the motor windings. They were all fine.. there was enough conductor there to allow the 1000V test to pass…. Then they overnighted an electronics package which the YS tech installed. That did not resolve the issue. SK then had their head tech drive up from Pennsylvania in a custom van with a replacement sphere. The boat was hauled and the sphere replaced.

    After the installation of the new sphere we made darn sure that there was ample clearance between all the leads, wires, and hoses on the unit. All this was covered under warranty. Its obvious that the company stands by its product and customer satisfaction is a high priority for them.

    The unit has performed flawlessly since then. Now before we make any lengthy passages I do a visual inspection to make sure that all hoses and wire leads are secured in their place and that nothing is hanging loose or that there is no chafing between components. I am pretty certain that this was a one off freak accident. The tech who had been working for SK for over 8 years assured me that he had never seen a failure like this one before. So…after 400 hours now I am confident that the replacement unit will work fine moving forward and have total confidence in the system.

    –luis

  5. Rick Gard says:

    amazing write up and back up. thank you all. the alternators, monitoring, and inverter seem to work as will as an integrated unit.

  6. Luis Soltero Luis Soltero says:

    Those of you who are considering running a seakeeper directly from your DC system might be interested in the following email sent to SK support.

    Hello SeaKeeper support,

    I would like to share the following observations with you about running an SK5 through an inverter connected to a 12V battery/charging system.

    when you first apply power to the unit before the on button on the display is pressed the unit consumes between 1-2 amps at 120V AC. When you turn on the unit it slowly starts to draw current until the RPMs hit about 6000. The ramp up is slow and linear with it peaking out at 17-17.5 Amps @ 1200. From this point on the unit keeps a constant 17-17.5 Amp draw until the target RPM speed is reached (either 8400 or 11000 RPM). Amperage draw drops to 6-7 Amps @ 120V AC when the unit reaches the target RPM. With 17-17.5 Amps AC (2100 watts) the current draw on the DC side is 204-210 AMPS at 12V. It is imperative that the cabling between the 12V battery/charging system be able to support the current draw with little drop in the voltage.

    The victron phoenix inverter is rated at 2400 watts continuous at 25deg C. It drops from that as the temperature increases. The unit will also go into a volt/current fault state if the feed voltage drops below the programmed threshold. When this happens the SK5 will start loosing RPM without any errors or warnings. The SK5 tries every minute or so to ramp up but the inverter then cuts out. Stabilization is lost.

    In our installation at 210 Amp DC draw we see a .2 V drop between the main battery bank and the inverter at exactly 12V. so the current draw when the SK5 > 6000 RPM is 2520 watts. The inverter is rated at 3000 VA on the input so it is being pushed hard. It is imperative that the inverter be kept in a cool place with good air circulation or the rated output will drop below that which is required to spin up the SK5!

    on Bliss we ran the SK5 in this configuration for about 450 hours without issue. Then we started having SK5 start up issues. As it turns out one of the DC leads between the battery and the inverter had a corroded terminal causing resistance. The cable would carry up to about 15Amps on the AC side then heat up causing resistance to go up, voltage to drop, and the inverter to fault. So at about 5000-6000 RPM the SK5 would start loosing RPM on the ramp up. On powering off the SK and letting it sit for 15 minutes before staring back up the ramp up sequence would start a fresh and the unit would hit the 8400 RPM mark low speed mark without hitting the 15Amp AC threshold for the feed cable. The amperage would then drop and the unit would perform fine for the rest of the trip.

    We recently replaced the feed line to the Inverter with a single larger gauge wire. Now the unit operates without issue again.

    We have purchased a second spare inverter given that we are running the unit at 90% of its rated capacity during spin up and worry that the inverter might be the weak link in the whole operation.

    Our engine driven DC generating system is capable of 5KW of output at 12V so no problem running the SK5 in this configuration for days while motoring. The inverter is only really stressed during the spin up cycle.

    Please feel free to share this with any other customer wishing to run AC driven SK from their DC system.

    Take care.

    –luis

  7. Luis Soltero Luis Soltero says:

    Hello All,

    those of you wishing to run a SeaKeeper using a 12V source and an inverter will find the following useful. Note that the specs are for a SeaKeeper5. Larger units will require more power.

    Specs from SeaKeeper.

    Line Voltage(VAC or Vrms), Input Current(Amps), Power (watts)
    90, 25.5, 2300
    100, 23.0, 2300
    110, 20.9, 2300
    120, 19.2, 2300

    Battery Voltage(VDC), Battery Current (Amps), Power req’d. for 2300 w @ 93% eff. (watts)
    11.0, 225,2473
    11.5, 215, 2473
    12.0, 206, 2473
    12.5, 198, 2473
    13.0, 190, 2473

    bottom line… the unit requires 200 amps DC, 2300 watts AC to spin up. Note that once the SK reaches its target RPM the consumption goes down considerably. The more it has to work the more watts it needs but on average that ranges between 1200-1500 watts.

    Starting the summer of 2020 we started having startup issues with the unit… Here is the email sent to SeaKeeper on the resolution of that problem.

    I believe we finally got to the bottom of our SK5 start up issues and I wanted to share our experience with you with the idea that it might help other users wanting to run your products off of 12V DC systems.

    Short story

    Bottom line… the Victron 3000 VA phoenix inverters are not up to the job. Replacing this with an AIMS Power 3000 watt inverter solved the problem.

    Long Story

    In our original design we selected the Victron 3000 VA (i.e. input watts) inverter with the idea that it would be able to provide the 2000 watts required to start up the SK5. We ran with this inverter for 1.5 years without issue. All of our cruising to that point was in cold water in the north east and canidan maritimes where the water runs between 45-60 degrees. F We had no start up issues during this period.

    Once covid we started cruising in warmer waters. We started experiencing issues in early summer in the Chesapeake Bay. After observing that we had no startup issues when connected to shore power and only running on the inverter we purchased a second brand new Victron Phoenix inverter to discovered that we continued to have the same intermittent start up issue. The original inverter was sent back to victron where they concluded that the unit was in perfect order.

    We then installed a digital thermometer next to the Inverter and noted that we were having issues starting when the temperature in the compartment was greater than 80 degrees F. Careful inspection of the Victron inverter specs shows that the unit is rated at a maximum of 2400 watts below 80 degF and at 2100 watts above 80 degF. As stated above the SK5 needs 2300 watts to spin up. So… in warm temperatures and/or after a long run where the temp in the compartment raises above 80 degF you stop and then start the SK the victron does not provide sufficient power to start the unit!

    Once we discovered the temperature/failure relationship (which took about 2-3 weeks) we purchased an AIMS Power 3000 watt inverter from amazon
    https://www.amazon.com/gp/product/B00O2GJXYC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

    The unit is rated as follows
    3000 watts continuous through 104 degF
    9000 watts for 20 seconds
    6000 watts for 90 seconds
    2600 watts continuous above 104degF

    This new inverter can provide the required 2300 watts at all times. Since then (knock on wood) we have not had issues starting the unit.

    Moral…

    when running off of a DC power inverter its important to understand how the inverter performance is affected with temperature. Additional cooling/venting should be installed if possible to keep the unit cool. The inverter should NOT be installed in the engine compartment (ours is not). The inverters generate quite a bit of heat when running and can warm up a large space reducing its output capacity.

    Thanks for all your help. This one was a difficult one to diagnose and resolve.

    –luis

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