Magnum 53 Hybrid

Discussion in 'Boat Design' started by John Kane, Jun 8, 2013.

  1. John Kane
    Joined: Jun 2013
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    John Kane Junior Member

    I posted this on the hybrid section but haven't had any response so I am trying boat design as it fits also.

    I would appreciate any thoughts.

    I have just started a new project in Fort Lauderdale on a magnum 53. This may be of interest to your readers as I am converting a Magnum hull into a sport fish with Hybrid propulsion.

    This will consist of twin diesel MAN V10 820hp with two 24kw electric motors coupled to the existing zf transmission and drive shaft with a 35kwh-72v lithium battery bank.

    It will also have a jet thruster for bow and stern all coupled to a joystick control system.

    We will also be installing 6-345w solar panels on the t-top to produce up to 10kw every day.

    The end goal of the project is to be able to propel the yacht up to 8 knots for trolling as well being able to travel and maneuver at slow speeds for a few hours at a time. The other advantages will be to create a great number of redundancies within the power and propulsion system.

    Financial and environmental benefits will long term be a big factor.

    I will give you one real world application so you can appreciate the benefits.

    Leave River bend marina(the boats current location)use joystick control to maneuver out of tight spot under only electric power,travel down the river wait for bridge using GPS holding system (to stay in one spot without drifting)continue on down the river to bar cut at the exit from the new river(so far all under electric propulsion stored from the solar panel production at 5 to 8 knots for around 45 mins to 1h)exit bar cut to enter the ocean start the diesel main engines then switch electric to boost mode and accelerate using electric and diesel power for around 10 seconds until the boat gets up on plane then pull the electric motors back to neutral. At this point we are doing around 30 knots heading to Bimini in the Bahamas under diesel power,(the electric motors now become powerful battery chargers up to 25kwh being returned to the 35kwh-72v battery bank)arrive in Bimini after around 90 mins,(45 nm)come down to 5 knots and move the electric motor controls to forward position and turn Diesel engines off and commence fishing under electric only continue pulling in fish for 2h at 5-8knots,(main battery bank will be low) start Diesel engines and continue fishing for 2h.(this rotation could continue as long as you would like switching seamlessly between electric and diesel propulsion) travel under electric across the shifting sands and down the channel to End of the World Bar and dock using the joystick control.(have enthusiastic conversations discussing the fish caught and all the bigger ones that got away!) No need for shore power,retire to your air-conditioned yacht and enjoy the silence(the 72v bank through an inverter will be supporting all the systems as well as backing up the 24v and 12v Batteries) Wake up after a very rested sleep and travel back out to start the fishing using the electric and diesel rotation every couple of hours. After another long day fishing head back under the Diesel engines back to Fort Lauderdale, come back down to 5knots and re-engage the electric motors and shut the diesels off, travel back down the river to the marina and dock once again using the joystick control. Switch the electric motors off and your epic, environmentally friendly,economical,stress free fishing trip has come to an end. The boat will continue to sustain itself using the 2kwh solar system and the banks will be full again in 3 to 4 days with no additional power source.

    During the 2 day trip we have been under electric power for an estimated 10h saving around $370

    In conclusion our intention is to push the boundaries of what is possible currently using ideas from a number of marine and automotive products while improving our enjoyment while reducing our cost and the impact on our environment.

    I hope you managed to get through my story and find it compelling enough to contact me.

    Regards John Kane
     
    Last edited: Jun 12, 2013
  2. kerosene
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    kerosene Senior Member

    You are mixing kW kWh and A. Makes it impossible to figure out what kind of setup and specs you are using.

    10kWh of energy per day from solar array wil equal running you diesels for about a minute full blast. Yay!!! And to be honest 10kWh might be optimistic daily result from that array.
     
  3. John Kane
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    John Kane Junior Member

    Kerosene the intention is only for the solar to gradually build up the batteries when the boat is sat idle not to run the propulsion. If you actually read the post then you would see how the electric motors are powered.
     
  4. FMS
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    FMS Senior Member

    You are one of the very few who have requirements that solar and electric augmentations can satisfy.

    Silent, exhaust-free trolling I can understand as a benefit.

    Does your calculation factor in the additional cost of hauling the weight of the batteries at planing speeds?
     
  5. kerosene
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    kerosene Senior Member

    You are still mixing the units - and I did get that the solar is just supplementing.
    Like Jeremy in the other thread I too am interested in how you calculated saving 300 gal of fuel. And like FMS I am curious to how do you compare to not having the weight and complexity of the electric systems on board.
     
  6. Jeremy Harris
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    Jeremy Harris Senior Member

    Confusing having two threads the same.

    The bottom line is that the numbers are off, massively so. Either there's a couple of orders of magnitude error crept in to the original calculations or the suppliers of the sub-systems have made a balls up in their specs.

    As I mentioned in the other thread, at the very best 6 off 345 Wp PV panels are going to give you around 10 to 15 kWh per day. Over 3 to 4 days this is equivalent to at best 5 US gallons of diesel used in a fairly poor efficiency diesel engine.

    To save 300 US gallons of diesel (about 3622 MJ of energy when burnt in a 30% efficient diesel engine) over 4 days of collecting solar energy would require an array capable of collecting around 251 kWh per day, around 15 to 20 times bigger than the 6 panel array proposed.
     
  7. John Kane
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    John Kane Junior Member

    Sorry my diesel gallons saved is off. The benefits will come from the redundant power from the motors at less than optimal rpm's as the electric motors will be regenerating that power back to the battery bank the fuel savings are unknown as I know their are losses within the electric battery electric conversion. The other benefits financial or otherwise are the engine hours saved therefore considerably less running costs on the Diesel engines this hour savings could be up to 50%. Then the solar storage as mentioned and the ability to store large amounts of power while the boat is at rest, the last being the environmental which I will include noise pollution when traveling in waterways and in marinas. One of the big advantages is the ability to run your Ac and dc loads overnight without a generator running.

    Thank you for your comments
     
  8. daiquiri
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    daiquiri Engineering and Design

    How does this thing work? What do you intend by "less than optimal rpm"? :confused:

    That's what you take away from the bill, ok. Now about what you add up - did you consider the cost of substitution of the Lithium batteries each time they arrive to the end of their life time? That is quite an additional cost!

    Cheers
     
  9. John Kane
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    John Kane Junior Member

    One more thing I am trying to get my head around. This boat has two very large Diesel engines which will not be very efficient at cruise I will be burning 2 gallons per mile which in a monitory sense would be $8 in my case maybe more as in the Bahamas diesel is at $6.50 so it would be $13 but I will use the $8. At just above idle to travel at let's say 5 knots we still may be burning 1 gallon per mile so I will use this as comparison to the electric. For the electric motors to power the boat to 5 knots it will probably only take around 15kw total which means I can run the 30kw out the lithiums for 2 hours and travel 10 miles. This a would equate to 10 gallons in my case which would be $80 . This is free if it has been stored over a few days from solar and if plugged in it would be around $10. I have to run I will come back later.
     
  10. daiquiri
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    daiquiri Engineering and Design

    Again, don't forget to calculate the payoff time of the additional power system... ;)
     
  11. Jeremy Harris
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    Jeremy Harris Senior Member

    The trouble is, you're not "saving large amounts of power" at all, plus you're paying a heck of a lot of money, and adding a lot of weight and bulk to the boat, for what will probably end up being poorer overall economy.

    It's true that big diesels run at low power have a poorer SFC than they do when run at high power, but not by enough to make a difference. A typical good marine diesel will have an SFC at cruise power of around 0.20 to 0.22 kg/kWh. Running at light load that drops to around 0.23 to 0.28 kg/kWh.

    Do some energy budget calculations to see what the true energy requirements are. For example, let's say you had a typical one day "mission profile" that consisted of:

    1 hour at 20 kW slow cruise out of harbour
    1.5 hours at 850 kW fast planing cruise to destination
    4 hours at 20 kW slow cruise fishing
    1.5 hours at 850 kW fast cruise back to shore
    1 hours at 20 kW slow cruise manoeuvring to harbour

    The energy budget for this trip, irrespective of type of motor used, would be:

    20 kWh + 1,275 kWh + 80 kWh + 1,275 kWh + 20 kWh = 2,670 kWh

    Out of that total energy budget, the "low speed" energy part = 120 kWh and the "high speed" energy part = 2,550 kWh.

    Let's assume your diesels have an SFC of 0.21 kg/kWh at fast cruise. They'll burn around 170 US gallons of diesel if they are running at 70% of max power in the fast cruise.

    Let's assume that your diesels are pretty poor at low power, and the SFC increases to 0.28 kg/kWh for the low power part of the day. 120 kWh at 0.28kg/kWh gives a fuel usage of 10.6 US gallons.

    Does this give a better idea as to how the potential fuel saving is going to be very small?

    Next, let's look at the endurance on electric only power. Your 35 kWh battery pack will have, as already mentioned on the other thread, a usable capacity of around 25 kWh at best. This will give you just over 1 hour of cruising at low speed, maybe around 1/6th of your requirement. The solar panels will only add another 10 to 15 kWh, so you might, with luck, get two hours from the pack. If you use the main engines to charge the battery pack then that hits your main engine fuel usage, so putting 25 kWh in to the battery during the fast cruise out will cost you about another 2 US gallons of fuel, the same on the way back. You can't make the 4 hours fishing time at low power on the battery, so will need to run the main engines at least every hour or so to charge the pack back up.

    I've ignored all the house loads in this example, but AC will, for example, eat up a big whack of the energy from the battery pack, too.
     
  12. John Kane
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    John Kane Junior Member

    I have to talk in laymans terms as I am not an engineer or mechanic but in my post above I showed a $70 saving minimum on a 10 mile trip. The extra weight is minimal as my house bank with agm would be 4 8d which would way close to 1,000 pounds my propulsion and house bank which is 6-450amp will weigh 840 pounds then add the electric motors and inverter this we come out around 1,350 pounds so only a 350 pound gain, or 45 gallons of fuel. I will also have considerable weight savings on the generator side as I am planning on using a 6kw dc to dc generator which only weighs 250 pounds and is extremely efficient as opposed to a 15kw ac generator which weighs close to 750 pounds

    So between the reduced fuel that will need to be carried and the generator downsize as the remaining ac peak loads on the ac side will be boosted by the battery bank the boat will in fact be lighter.
     
  13. Jeremy Harris
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    Jeremy Harris Senior Member

    But, how are you calculating that fuel saving? Where are your numbers coming from?

    The raw facts are that, although the main engines won't be running efficiently at lower power they aren't actually costing you much in terms of fuel.

    There are some other good reasons why running them at low power for long periods isn't a great idea, and there is certainly merit in having a lower power propulsion system for operation when fishing, but frankly a complex hybrid is not a sensible, economical or viable way to do this.

    The bottom line is that you can't meet your expected mission profile with the system you've outlined. In fact I don't think you can even meet 30% of it by the time house loads, AC etc are taken in to account. The cost will be high, a properly managed 35 kWh lithium battery will set you back around $15,000 as a bare minimum. If you want a reasonable level of reliability (say, around that achieved with electric vehicles) then you're looking at over $20,000. It will last around 8 years, maybe 10, if looked after. A 35 kWh lithium pack will weigh around 250kg, or around 550lbs not including the casing, battery management system, etc.

    To get the sort of endurance you're looking for in low power mode, allowing for the charge from the main engines during high speed cruise and a small amount of charge from the solar power system, you need a battery pack with an installed capacity of around 100 to 120 kWh. This would cost a minimum of around £50,000, would weigh around 715kg, or 1,576lbs and would be a fairly big challenge in terms of engineering. The safety issues alone in making such a battery pack viable for this application are non-trivial. Even Boeing struggled with battery safety when they designed a significantly smaller (just 0.3 kWh) lithium battery pack for the 787.
     
  14. daiquiri
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    daiquiri Engineering and Design

    Jeremy, I seriously doubt they will last more than 4-5 years. Li-Ion batteries are very sensible to many things - principal ones being charge/discharge procedure, storage procedure and ambient conditions, temperature. It would all have to be really perfect, imo, to make them last 10 yrs. And we are talking about marine use here, which is all but forgiving for any man-made device or object.
     

  15. Jeremy Harris
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    Jeremy Harris Senior Member

    I agree wholeheartedly. I've tried to give the most optimistic estimates here, really just to illustrate why, even being optimistic, this idea as it stands isn't really viable.

    If it were me, then I think I would explore the option of using a quiet and efficient gen set to run the low power electric auxiliary motor. It'd be more efficient than the main engines, could run the house loads, AC, beer cooler etc at the same time as running the low power propulsion. It'd save running the main engines at low power, which would save a bit of fuel, but more importantly would save them getting fouled up internally from long periods of low power operation. Best of all it'd be a fairly straightforward engineering job, using off-the-shelf parts and be more likely to be understood by repair yards in the future.
     
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