A bit more on fuel

Sans Souci is still working its way up the Pacific Coast of Baja. The weather report for the next few days looks good. Although, Jeff mentioned this morning that they had one of their most uncomfortable nights yet. The wind was coming off the beach (on their starboard side), and combining with the swell from their port side, to create a washing machine effect, with Sans Souci trapped in the middle.

The current plan is for Sans Souci to stop in Ensenada on Friday, take on some fuel, then cross the border into the US and arrive at Nordhavn’s facility, in Newport Beach California, on Saturday. I’m not sure how long the boat will be at Nordhavn. There is some work to be done, but other than a couple of small projects, all of the work can be performed in Seattle when the boat gets north. It may be a two day stop, or a two week stop. I sent an email earlier this morning to Nordhavn to get their thoughts.

And, returning to yesterday’s discussion on fuel….

I forgot to mention that all of the numbers presented included a 25kw generator running at all times (approx. 1.5 gallons an hour). On a major passage, I might be able to run without the generator most of the time, so the numbers presented could potentially be improved upon significantly. The alternators on my main engines each put out 100 amps, at 24v, for a total of 4.8kw. Without the air conditioning, this might be adequate to keep the boat going. I’m not sure.

There was a question posted yesterday about whether the second N68 had different engines than my boat. The answer is: yes. I have twin Luggers (a marinized version of a John Deere engine), and the second N68 has twin Detroit 60s. Thus, there is a chance that my boat’s performance will be slightly different. My guess though is that any difference in fuel efficiency is negligable. The horsepower requirement to move his boat, and my boat, through the water at any given speed is the same. Diesel engines are what I would call a “mature industry.” I haven’t directly compared the two spec sheets, but my guess is that if I match them at a given horsepower the fuel consumption will be within a percent or two of each other.

Also, someone asked about the website for the second N68 – the website address is: http://www.graceoftides.com/. However, there’s no need to click the link, because there is nothing there. David started the site, then decided to start it over, to make it better. I’m not sure if he’ll work on it again or not. I’ve been lazy about updating my own site. Other than the blog, I haven’t updated it in months. Oh well….

And, lastly…

We had dinner last night with the owners of an N62 that is crossing to Japan with us next summer; Steven and Carol Argosy from the N62, Seabird. Whereas I have refused to think beyond Japan, Roberta and Carol had no such hestitation. While Steve and I were talking boats, the ladies were plotting all the interesting places we can go once we cross the Pacific; Papua New Guinea, Indonesia, China, India, Thailand, etc. Roberta reminded me once again as we were leaving the restaurant, that whereas I spend a lot of time whining about crossing the Bering Sea, that it is really only 20 days, that will be an adventure, and that once on the “other side” we may never see cold water again.

Steven mentioned that he had just added a “hydraulic generator” to his boat. I have heard of hydraulic alternators, but have never heard of a hydraulic generator, and still don’t know that I completely understand the distinction, if any. He said it is the generator-side of a normal generator, but powered by a hydraulic line coming from a hydraulic pump, powered by the main engine, or his wing engine. It is giving him 20kw of power. I mentioned that I had hydraulic alternators on my boat that I haven’t been using because they seem no more efficient than the generator, and he pointed out that there is no oil to change, or impeller to change on his hydraulic generator. A great point. I change the oil on my generator every 200 hours, and it gets annoying after a while. My generator tends to run 24 hours a day when away from the dock, so this means weekly oil changes. We have a oil change system that makes the oil changes very simple, but its still not fun. I may give my hydraulic alternators another chance… (I have approx 12kw from two hydraulic alternators). 

One fun piece of triva we discovered last night was that twelve years ago, when Roberta and I were thinking about buying a Nordhavn 62, we visited a Nordhavn 62 named Atlas, that had just arrived in Seattle from Australia. When I mentioned Atlas, Steven said “That’s our boat! We renamed it!” Steven has cruised Seabird to Seattle from the east coast. It’s amazing how these boats get around, and it seemed kind of cool that we would be crossing the Pacific in the company of the first Nordhavn 62 we ever saw.

-Ken W

8 Responses

  1. In response to the person who asked what the others are doing after Japan…

    There are four boats making the trip: Starr, Grey Pearl, Seabird and Sans Souci. Only Starr has a firm plan. Her owners, Don and Sharry Stabbert were planning their third trip to Polynesia when we “interrupted” them. All of our talking about the Aleutians, Siberia and places they hadn’t thought about changed their route, but not their destination. They love the south pacific cruising, and I suspect that is where they will go. As to the rest of us, I don’t think any of us have more than a vague idea. We don’t know if we’ll stay together as a group, or scatter to the wind. Personally, I don’t know if we’ll head north, west, east or south. I don’t think any of us knows for certain where we’ll go next, much less after that. My best guess is that after we’ve cruised Japan a bit we’ll head south to Taiwan. All of us have talked about wanting to visit Ta Shing, where our boats were built. But, who knows?

    Roberta and I say this is a first step in a circumnavigation, but I’m using that term VERY loosely. I know that we start and stop in Seattle, but beyond that I know essentially nothing. Will we take 3 years to go around? 10 years? I don’t know. It really all depends on how much fun we’re having, and who has a clever idea for someplace that sounds good to go. And, of course, the inevitable intrusions of reality (such as having to go home for personal or business reasons).

    I’m purposely forcing myself to not think beyond this next summers cruising. I’m not sure why, but it seems like wasted effort, and bad luck. I know there are lots of interesting places to see, and that my boat can get me to any of them. So… I’ll figure it out when the time comes.

    -Ken W

  2. Dan and all: Thank you for the great feedback and clarifications. As Dan refers to, there is another piece to this story. Steven mentioned that there is some new innovation, a new “brain box” that makes the hydraulics generators now much more practical than they were in the past. I actually understated the output of his hydraulic generator. He has a 25kw hydraulic generator, which is plenty of power to do anything he wants to do.

    None of this is a free lunch. There is a math formula that can be used to convert gallons of diesel fuel to kilowatts. If you are generating power you are consuming fuel. Whether it be a generator, a hydraulic alternator, a hydraulic generator, or even the main engine alternators, you are consuming incremental fuel to generate the electricity. A key issue here is efficiency. Anytime that fuel is converted to energy, there is some lost energy. A perfect device would exactly match the formula, but it never works that way. And, it can vary by utilization. For instance, a 25kw generator might be 90% efficient when producing 20kw of electricity, but only 20% efficient if asked for only 3kw. These devices are designed to generate electricity most efficiently at certain rpms and loads. Varying from these design-points can result in wasted fuel.

    One of the interesting things about someone’s (I forget whose) comment on this topic is that the hydraulic generators are less picky about load than normal generators. There have been times on my boat when we have deliberately “loaded up” the generator, just to keep it happy. For instance, it is not recommended to run a 25kw generator for days with a 10kw load on it. This is one reason I have a large and a small generator (25kw and 16kw). However, we discovered while cruising in warm weather climates that the 16kw isn’t a true “backup” for the larger generator if it can’t keep the a/c flowing, and are upgrading to a 20kw. This means we’ll sometimes need to find extra load, or risk under-loading the generator.

    Lastly, I thought briefly about if I could simply get rid of one of my two generators, and rely on a hydraulic generator as my “backup power source.” This isn’t totally inpractical. There is a 43 now circumnavigating (Kosmos – http://kosmos.liveflux.net/ (http://kosmos.liveflux.net/blog/)) making the entire passage with a single 8kw generator, and doing very well. Diesel engines very rarely fail if you keep them properly maintained. Give them oil and clean fuel and they are happy. I’ve thought about if there are ways to free up some space in my lazarette by getting rid of some equipment. I added a passarelle, which is essential in Europe, but a pain in the tail throughout much of the rest of the world, because it takes up a large and awkward amount of space inside my lazarette. Dumping one of my two generators overboard, and just using my hydraulic alternators, powered by my main engine as my emergency backup power source, would work. I won’t do it though.. the crowding in my lazarette caused by the Atlas international power system, two water makers, a generator, two glendinning cord retrieval systems, four a/c chillers, four large inverters, the passarelle, a huge battery bank, and more is bad .. but not that bad. Compared to the engine room in most sportfishers, it’s a luxury of space. I grumble a lot, and think about ways to reduce equipment, but its unlikely I’d ever actually slim to a single generator. I like redundancy, and am unlikely to ever do anything which reduces the number of backups of anything on my boat.

    -Ken W

  3. Ken, what other boats are planning on going to Japan with you? Starr, a Northern Marine 75, Seabird, a Nordhavn 62, and one other 62? Is the other 62 Grey Pearl?

  4. Hi Ken,

    In actuality, what Steven installed was a new controller on an existing hydraulic generator. The hydraulic generator was installed as original equipment on that boat and is powered by a hydraulic pump mounted on a “C pad” PTO on the gearbox which spins at engine RPM.

    Five or six early N62s and hull #2 (no longer with us) of the N57 series had these generators installed. They were pretty nifty but were temperamental and subject to RPM oscillation. It was essential to maintain a steady generator RPM (and thus frequency), with changing engine RPM, oil temperature and the biggy; sudden heavy shock loads such as air conditioning. The generator RPM was kept under control by an electric “step valve” which got its signals from a rather primitive brain box (think dip switches, wires and soldering) which monitored the frequency. In practice, we could never really get the generator to settle down on a consistent basis. Oscillations would occur, inverters would drop out, AC pilot house electronics such as monitors would flash off and tempers would flair. In the end, we felt that we shouldn’t build the Nordhavn systems around the concept and gave up.

    Now Steven has brought the old beast back to life with the new controller. Excellent! I will be very interested to follow the progress.

    Looking forward to Sans Souci arriving on Saturday!



  5. I don’t believe that a hydraulic generator/alternator would be any different to a diesel powered one regarding overload. The electrical side would be the same and with a properly sized hydraulic motor it could probably handle overloads longer.

    I am not familiar with USA products and it would be interesting to know what Steven has fitted. Doing Web searches it seems that their are several suppliers for vehicle mounted units though I doubt they would have the long term reliability. Units with 1800rpm generators would be a better choice.

    I think you would still need your two diesel units to give you backup when anchored out. The hydraulic generator would be best placed where the existing alternators are to keep the piping short and compact.

  6. Ted – Great comments! I missed, or more likely, didn’t understand your comment last year. I wish I had paid closer attention. I have already purchased a new 20kw generator which is sitting in Seattle ready to replace my 16kw as soon as the boat arrives. With 20/20 hindsight, I could have saved space by swapping to a 25kw hydraulic generator. I’ll look this winter into what would be required to swap my two 6kw hydraulic alternators for one 25kw hydraulic generator.

    Your point about light loading is an important one, and something I had never focused on. Do you happen to know how the hydraulic generators do with overload? Conventional generators accept short overloads without problem (eg: a 25kw generator, can put out 30 or 35 kw for a 1/2 second when needed to bring an electric motor on line.)

    -Ken W

  7. Strictly speaking a generator produces DC (Direct Current) voltages and an alternator produces AC (Alternating Current) voltages. However the terms are loosely used. Steven has probably fitted a hydraulically driven alternator if it produces 240/110 volts AC.

    Your alternators actually produce 24/28 volts DC, but this is a hang over from automobile usage to differentiate that the car had the more modern alternator based charging system rather than a DC generator/Dynamo. Your alternators produce an AC voltage which is rectified to DC within the casing of the alternator using semiconductor diodes.

    As I mentioned last year in the bulletin board, your boat has substantial hydraulics so you could probably replace your existing alternators with a single 25kw 240/110 AC alternator. This would be used on passage making rather than running your diesel generators/alternators. You could have full air conditioning as necessary and less problems with power management. Overall I think efficiency would be about the same as it simply makes your main engines work slightly harder. You don’t have to worry about your diesel alternators running with light loads.

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