Bliss: 100hp diesel powers trawler, Seakeeper, and huge battery bank
The goal of the makeover certainly sounded like cruising bliss, but could a 100hp Yanmar diesel really propel a 39-foot trawler while also producing gobs of 12 volt DC to feed both Seakeeper gyrostabilization and a huge battery bank? I’m pleased to report that the dual MGDC 250 amp alternator setup seen above on the actual trawler Bliss has proven my skepticism unwarranted, and an already beloved cruiser became a “new boat” in the process.
Actually Bliss’s makeover sounds even more radical when you realize that the boat’s generator had to be removed to make room for the Seakeeper 5 though it requires 140 to 160 amps while underway (much of it via a Victron 3000 Watt inverter). But Luis Soltero — Panbo profiled in 2015 with mate Kim and Bliss — is as smart and focused about his vital boat systems as he is about marine communications, and they all enjoyed ample power and a smooth ride from the Chesapeake to Nova Scotia and back this summer. Except for one serious but quickly fixed glitch which I happened to witness in Camden.
While I’m told that the high and forward pilothouse on Bliss is a lot more comfortable in a seaway this year, the makeover didn’t change much else. Besides the new engine room camera that we’ve already seen on the starboard Simrad NSS16 evo2 screen, there are alternator controls on the dash along with two new small displays on-center overhead: the Seakeeper control head and a Simarine Pico power monitoring system.
Managing and monitoring the big current loads now flowing around Bliss is serious business, and I was impressed with how well it works.
Generating up to 500 amps — Luis reports that 400 is common underway — takes horsepower that is sometimes needed for propulsion. So if you click the upper left photo larger you’ll see an On/Off switch for the port MGDC J-180 alternator and a 100%/50% switch for starboard. (The Mark Grasser externally rectified alternators, along with a dual pulley kit, were sourced from OceanPlanet Energy).
The switches, along with the status and fault LEDs, wire to a Balmar CenterFielder which manages two Balmar MC-614 regulators. And the Simarine Pico screen above shows what happens when you shut down the port alternator and cut starboard generation in half. Just moments before the same screen showed 230 amps charging the almost-full 1,715 amp-hour house battery bank (seven EastPenn AGM 8Ds that also serve as ballast).
Incidentally, the Panbo entry discussing Pico’s outstanding, and still unusual, current monitoring abilities now has added screens from Bliss, and you’ll see the solar panel aspect below. But first let’s look at why the Solteros need to reduce alternator load sometimes, which is also why the new system is quite efficient, as mostly explained by Luis.
The hull power curve for Bliss shows that 25 hp is required to push the boat at 7 knots in light winds. This happens at 2100 rpm. The engine power curve for my J4H2-UTE Yanmar 100 hp engine shows that at 2100 rpm the engine puts out about 70hp. Finally the alternator power curve shows that at 6000 rpm (3x engine RPM due to the pulley ratio) the alternators want 18.4hp. So the engine load is 25+18.4 ==> 43.6hp, which is 60% and about perfect for keeping it happy.
However, if you’re maneuvering at low RPMs around docks, the extra horsepower load could be trouble, and hence the current limiting switches. But, wow, fuel consumption has hardly increased from the excellent 7nm per gallon Bliss typically achieved prior to the makeover:
We run from 2100 (7.0kn – 1.2 Speed/Length ratio) through 2400 rpm (7.3kn – 1.3 SL) and consume between 0.96-1.35 Gal per hour depending on speed and weather conditions. I notice that when its rough the fuel consumption goes up and I attribute that to the Seakeeper. The rougher it is the more electricity we need to generate to stabilize the boat and the higher the fuel consumption. But the SK does not use much fuel… and what it uses is worth it!
Moreover, the Solteros have only run the engine to charge the house bank a few times during a long cruising season largely away from docks, and it charges fast. But let’s note that the makeover also included a solar component.
Having tried and liked a four-panel 400 Watt array of Solbian flex panels, Luis added 380 Watts more on the pilothouse roof, plus now he can better see what they’re all up to thanks to Pico. (And I’ll add that without such monitoring it took me a long time to realize that fast-moving shadows from a big flag on a windy day reduce panel output on Gizmo much more than slow shadowing.)
But maybe you’re wondering how I got all the way down here without discussing the Seakeeper? The system demo in Camden Harbor did not end well when Luis tried to spin it up repeatedly only to get shutdown error messages after a few gyro RPMs. He was remarkably calm as he tried multiple reboots, but I stopped taking pictures and asking questions.
I’d been getting exultant emails about Bliss’s improved motion during the trip up and I knew that the next planned legs included Nova Scotia’s exposed west coast. In his shoes I might have felt the need to swear loudly.
Then again, Camden was about the perfect spot for the manufacturing defect — quite rare, I’m pretty sure — to show its ugly head. The install was first discussed last summer with Seakeeper dealer and local phenomenon Yachting Solutions, and a YS tech was back on Bliss just hours after the sad demise of my demo visit.
The diagnosis and repair involved a shipped-in gigaohm meter, a courtesy stay at the Rockland Boat Basin, a Seakeeper specialist driving up from Pennsylvania, and finally the haulout and 600-pound gyro replacement… but Bliss was stabilized and underway Downeast just about a week later. And the Solteros are very grateful to Yachting Solutions and Seakeeper for excellent warranty service.
Which reminds me of some excellent engine care I saw on Bliss. Note in the upper left photo how a premium Keenan Filters system is protecting the Yanmar from dirty diesel (and also the Keenan remote filter switch partially seen in the dash photo). Moreover, Luis has been monitoring the diesel’s ultra fine Jackmaster bypass oil filter with frequent Blackstone Lab oil analysis and likes what he’s seeing.
So I never photographed the Seakeeper on Bliss in operation, let alone experienced the effect in a seaway. But fortunately Luis provided these shots, which start with some pleasing anti-roll performance in famously nasty Chesapeake “chop” early in their summer cruise and end with the SK run time statistics collected by the time they hid out from Hurricane Dorian last week in Stamford Harbor.
This Marine Traffic track of Bliss is incomplete both because there are not enough volunteer AIS receiving stations and because the MT membership I earn by maintaining a station only includes 90 days of tracking — and both are good reasons why you should consider setting up a station at your home, business, or boat.
But despite the dotted line, Bliss did indeed motor a long leg from Cape Breton to Nantucket during which “the SK performed brilliantly.” And just yesterday while doubling back to Newport and experiencing the SK5’s “weakest point of sail” — “6-foot seas with 20 knots of wind abaft the beam at 120° from bow and against a 1 knot of current” — Luis shot some videos showing the gyrostabilization working to the max with still comfortable results.
I hope to add an edit of that video to this post soon, though it strikes me as already clear that modern electric power electronics have made Bliss a much more blissful cruising boat. And, incidentally, the results of this well monitored and controlled dual high power alternator system are similar to what the Integrel system highly automates in one package.
In fact, Integrel told Luis that their system would handle the high continuous SK loads no problem, though it wasn’t available for install in the U.S. last winter. That situation might change soon, and we will soon be covering another exciting new advancement in boat power technology, the Wakespeed WS500 Advanced Regulator.
PS 9/16: What’s it like when the SK5 is working hard on Bliss? Big thanks to Luis for sharing his video and observations:
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!
Thanks, Luis, and I forgot to mention Ben Stein’s thorough entry about installing and putting 7,000 miles on a SeaKeeper9 (now probably pushing 9,000 miles):
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.
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.
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.
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.
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.
amazing write up and back up. thank you all. the alternators, monitoring, and inverter seem to work as will as an integrated unit.
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.
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)
11.5, 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.
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.
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
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.
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.
following up after 800 hours of use… SK continues to work great. Very happy with the performance.
Since this article was written we have moved away from the MGDC alternators with remote rectifiers and replaced them with 2x APS 250 Amp alternators.
Althiough in theory the remote rectifiers on the Mark Grasser are good idea.. in practice we had both of our alternators fail this winder while cruising in the Bahamas. So… no alternators == no seakeaper, no toilet, no lights… in essence a real crisis. We had to have a replacement alternator flown in at $$$ get us home. As it turns out the MGC alternators are quite sensitive to vibration. They required two mounting points on the large 3 phase wires that come out of the alternator. If these wires are not secured correctly and securely engine vibration causes the solder joints to fail. And when they fail they shoot tremendous amount of current down the field wire which can damage the voltage regulator and other sensitive electronics upstream. Fortunately our wakespeed took it all in stride and just blew a fuse that was easy enough to replace.
Additionally the long 3x by 2Ga wire runs to the rectifiers were difficult to remove since they were installed while the engine was out of the boat and they have no attachment points on the alternators. We had to pull out the old wires and then run the new news. So… replacing the alternators was not easy.
Bottom line we have moved away from the remote rectifiers and MGDC alternators because they are fragile and difficult to remove for service. We got a total of about 600 hours of use out of the alternators. MGDC did offer to repair the alternators under warranty but we decided, given our reliance of this critical system, to move to American Power Systems alternators.
The APS alternators with built in rectifiers are terrific. They generate considerable power at low engine RPM, run cool, and are easy to remove should they need service.
we continue to be very happy with the wakespeed regulator.
Very interested in so much of what you’ve done here. I have a 1985 Kadey Krogen 42 that I’m looking to put a Seakeeper into. They recommended the 9 but that’s $40,000 more than the 6. Bliss looks similar in specifications to my 42. Can you share her specifications? I am also very interested in converting to lithium batteries for power in order to replace/limit my generator. Would you be willing to consult with me or direct me to someone who might? Thanks!
Sorry for the tardy response. I am just seeing your inquiry now. Bliss displaces 31,000 lbs. She has a SK5 which is rated to about 40,000 lbs. Bigger is usually better as far as SK stabilizers go BUT they also require much more infrastructure to run. Looking at the specs I see that SK6 is rated for 24tons or 48,000 lbs of displacement. According to https://www.boats.com/reviews/go-anywhere/ the KK42 displaces 39,500 lbs… But that is probably the dry weight… So… probably 44,000 lbs is my guess after she is loaded up. The SK6 is rated for 48,000 lbs so although a 6 will work in moderate seas it probably will not be able to stabilize the boat in following seas with wind > 15kts. Note that Bliss is able to handle following seas with 20kts of wind with the SK5 but with greater wind and larger seas the unit is unable to keep up. Check out the video above. the conditions in the video are about as much as SK5 can handle. If we were ever to replace the SK we probably would go to a 6 which would allow stabilization in bigger seas.
Anyway…. on Bliss 31000/40000 –> 77% of SK5 capacity where as for a KK42 (assuming 44,000 lbs) –> 92% SK6 capacity and 73% SK9. Bottom line… I think the recommendation for a SK9 is probably correct. an SK6 will give you stabilization in moderate seas but the performance will be less than that of the SK5 on Bliss.
In retrospect, although SK recommended a 5 for Bliss I think a 6 would have been better for the kind of traveling we do. the SK5 works 95% of the time, but when it gets rough Bliss still rolls.
Since this article was originally written we have added Blige keels to Bliss. Properly designed and installed Blige keels (note the emphasis of PROPERLY) do the following.
1. Reduce the Max amplitude of Roll
2. Increases the Roll period making the roll more “comfortable” and tolerable.
3. Cause the vessel to return to back to upright position much more quickly (the return to upright is exponential vs linear)
The Bilge keels reduce the energy required by the SK bring stabilize the boat making it more efficient. AND the Bilge keels offer stabilization were the SK5 to fail.
Note to properly install Bilge keels you need to know the following.
1. water flow stream lines around the hull
2. roll meta center for vessel
both of which can be difficult to obtain unless you work with a Naval architect. Once you know those two figures the manufacturing and installation is fairly inexpensive and straight forward.
One suggestion… You might look at refurbished units. They are usually a lot less expensive. Many SK customers swap out their units for a variety of reasons and SK remanufactures the units and sells them at a reduced price with a 1 year warranty vs 3. The SK5 installed on Bliss was a refurb.
Thank you so much for the detailed response. We have decided to go with the SK6 for both financial and infrastructure concerns. I was hoping we would get about the same response you were getting with your SK5. Time will tell! We will try to limit our cruising in following seas and >15 knots, but we all know how that goes! So….. when we figure out we should have gone with the SK9, I’ll give you call about a used SK6! I’ll keep the blog posted….
Congratulations on taking the SK plunge. You will be thrilled with your unit. The SK6 should work just fine for you. It will totally stop the roll in moderate conditions. In rough conditions it still work work greatly deducing the maximum amplitude of the roll and lengthening the roll period. So although in 20-25 kts the boat might roll, the roll will be dramatically less than without the SK. So its all good. The 9 would have kept the boat totally up right in rougher conditions but no matter what your Sk6 will make your boat 10000 more comfortable than it is now.
The good thing about the SK6 is that it requires less energy to run. A 350amp APS alternator + a AIMS inverter should allow you to run the SK from your main engine without having to run the generator. Once the SK comes to speed you will have power to burn. Li batteries would be nice but if you plan to run the SK while the engine is running then you won’t need to add any additional battery capacity.
Note that my SK at low speed (8400 rpm vs 10700) draws 80 amps DC once its at speed vs over 200 when spinning up. So… with our 1800 AmpHr gel battery bank we can run overnight without taking the bank below 50%. A nice onion if you are unlucky enough to have to spend the night in a rolly anchorage!
The Seakeeper has been operating without issue for 3 years since this article was written until last week where we got a low hydraulic pressure warning. So.. that is 3 years with basically the only maintenance being the periodic replacement of the zinc. Not bad for a very hight tech machine that weights almost 1000 lbs and spends at 11000 RPM! Actually, in truth we have had issues with the stabilizer not coming up up in every instance the problem has been related to some supporting infrastructure element such as alternators, inverters, and raw water pumps none of them sold or installed by SK. With the electrical system debugged, the SK has been working without issue until last week.
As a transient vessel on the move its been difficult for us to schedule regular SK maintenance. I have called the SK dealer in Annapolis over the last few years for preventative maintenance checks and always get… “I can’t see you for… 4 weeks (or some long time in the future)”. So we have been checking for hydraulic leaks, changing the zincs, and hoping for the best. that has worked now for over 1000 hours…
So… we are on our way to Canada was very distressed to get an SK error right at the beginning of our voyage. I called the dealer in Annapolis to beg for service.. Nope.. 4 weeks or more before they would even consider looking at the vessel. Sigh… so I asked if there was anyone else that could look at the unit… That is when we discovered Dynamic Marine in Ocean City, NJ (609-517-1300). We called up Chris (the owner) and he said no problem, come on over and we will take care of you ASAP. And… in discussing the issue with Chris discovered that Greg Oreily, the long time SK tech that did our warranty service in Maine 3 years ago, now works for Dynamic Marine!! So that sealed the deal.. up the Chesapeake, down the dreaded Delaware, through Cape May, and up to Ocean City… And fortunately for us, the SK had decided to cooperate and operated flawlessly for the 20 hours of the trip.
We arrived on a wed afternoon and Greg was on the boat Thursday morning at 8am! 3 hours later he was done and gave the SK a clean bill of health. As it turns out the hydraulic fluid accumulators on the unit have a rubber diagram that flexes with every move of the brake pistons. And they wear out after a few years of use. So… as part of the periodic maintenance they need to be replaced. Not a big deal if you have equipment required to flush and pressurize the hydraulics once the accumulators are replaced. Voila.. good for another X years an other 1000 hours of operation.
Now that we know of Dynamic Marine we will stop in Ocean City on our yearly Migration North/South and be a bit more conscious about scheduling maintenance on the SK.
Kudos to Dynamic Marine and Greg and Chris for outstanding support.
Thanks for the update, Luis, and nice to see Bliss tootling up the New Jersey coast — https://shipfinder.co/ship/367645410 — with your DataHub AIS sharing and PredictWind tracking at work:
But no hurry. Air and sea temps are both about 52 here in midcoast Maine today 😉