Oceanvolt Hybrid Motor

[Dockhead]

Originally Posted by transmitterdan

Lots of variables there. Transmission ratio, prop dia and pitch are just a few.

It’s unlikely the mechanical drive and electric drive will be optimized with the same propeller.

The real test will be which system has the most hours on it after a couple years full time cruising.

Indeed. Propeller optimized for one system with not be as good for the other. A better test would be for each system to be driving a prop as close to optimized for that system as possible.



But good on Big Beakie for the interesting system design. I like it. I am quite sure that the hybrid drive will be significantly less efficient than direct diesel drive -- it's simple engineering, and we discussed the fuel curves and nuts and bolts of the question further up in the thread.



But he's got the direct drive diesel for extended motoring. The hybrid side saves him a generator -- saves him the weight and cost of one whole diesel engine, plus gives him the chance to burn stored shore or solar power.


I would definitely not put three diesel engines on a catamaran. I would do either something like this, or put large alternators on the main engines, maybe a mammoth one on a PTO on one of them, and with large LiFePo storage.

[a64pilot]

Originally Posted by BigBeakie

The test I was planning on doing is to keep it simple. To run the electric at 15kW from batteries which is the maximum continuous charge from the 16kW genset, so we are putting full genset output into propulsion only. Note boat speed in no wind no current conditions and run for set time, say an hour if possible, and note distance covered and fuel used.

Then find rpm on the Beta that replicates the same boat speed, and run same time at those RPM for same distance, and note fuel used.


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Others are disagreeing, but I think your proposed test will work very well indeed.
Partially because electric motors will operate efficiently over a very wide RPM range, so the prop will be driven efficiently by the electric motor, it’s easy to prop an electric motor, just get close to desired RPM, it’s a Diesel that is hard to prop to, and a Diesel is of course only correctly propped at wide open throttle, but that’s just the way it is.

Bottom line is how fast and how far will either system drive the boat X amount of distance. Everything else is sort of irrelevant. Yes one could argue the the electric system has an advantage because of the RPM / load flexibility of an electric motor or argue that a Diesel has the advantage due to less losses, but what does it matter?
What matters is fuel consumption with as many factors that you can control being equal.

Surely the electric drive system battery charging can be disabled? I Wallis assume so, so that if you ever got into a position that required max power you could?

[JC Reefer]

Andy Shell just did an episode about electric drive and sailboats. I don’t recall if it was On The Wind Sailing or How I think About Sailing but it was good stuff. The general consensus was that technology like oceanvolt is not really suitable for the majority of yachts out there.

[44'cruisingcat]

Originally Posted by BigBeakie

A64pilot - noted on the conditions for the fuel flow meter needing to account for the nett used diesel, good point, thanks.

Yvest- there were multiple reasons for our change from 2 x Servoprop Sd15's to 1 x AXC20's and 1 x diesel. The most important was that we revisited our thinking on adverse conditions and cruising grounds. We now intend to do some cruising in somewhat higher latitudes ( not really high latitudes) and upon review of pilot charts of those regions and our wind resistance analysis, and in conversation with experienced cruisers of those areas, we felt that for extended motoring, feeding two electrics from the 16kW DC genset, ie 7.5kW each continuous, was just a bit underpowered for conditions when sailing room was restricted and high winds could present lee shore risk. If we had purchased a 30kW DC genset, our decision would have been different, but we had the 16kW genset already.
We thought it prudent to feed one electric at least 75% power from the genset, ( instead of two at 50% power maximum) so that pointed us towards the AXC20. And it is shaft vs saildrive, which we also preferred if we were going with one diesel shaft drive. We also viewed the AXC as their most robust, industrial design/spec motor that is going into use for ferries and other commercial applications.
The lower regen numbers was the only downside of the decision, but the tradeoff was worth it, since we have alot of solar.

So now we expect to use the AXC20 almost all the time for most motoring situations, and have the 45HP diesel at the ready if things get hairy.


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Good move.

[44'cruisingcat]

Originally Posted by BigBeakie

The test I was planning on doing is to keep it simple. To run the electric at 15kW from batteries which is the maximum continuous charge from the 16kW genset, so we are putting full genset output into propulsion only. Note boat speed in no wind no current conditions and run for set time, say an hour if possible, and note distance covered and fuel used.

Then find rpm on the Beta that replicates the same boat speed, and run same time at those RPM for same distance, and note fuel used.


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That might mean running the hybrid at it's optimal speed vs the diesel at a sub optimal speed.

Or vice versa.

Still the result should be somewhat indicative.

I'd bet the hybrid isn't going to use 1/3 the fuel.

[Montanan]

Of primary comparative issue with eMarine versus eVehicle is that for battery powered machines, eMarine has the added difficulty of having to place comparatively heavy and bulky energy storage as batteries instead of as fuel. This results in space being taken up inside the hull and also increased displacement, i.e., a large hole formed in the water, which added displacement of water needs to be accomplished every inch the vessel travels, thereby inducing lots of work and drag and inefficiency. Whereas a vehicle is displacing air which does not require as much effort to move out of the way every inch the vehicle travels.

Hybrid drive schemes require an alternate charging system, solar is great for modest power demand, hence one is in need of carrying a fuel based prime mover to power a generator to recharge the batteries for extended range of travel. The prime mover can be operated at optimal efficiency when operating a generator so there is the prospect of marginally enhanced fuel efficiency overall and supplemented with solar or wind power, or shore power. eMarine is excellent for short distance operating vessels, such as tug boats and ferries which have ready access to docks for rapid recharging.

The torque available from a motor can be immense, typically when an eMarine application is specified for a displacement boat, [slow / non-planning] a much wider diameter and steeper pitch propeller is utilized then with an ICE powered craft. When the eBoat is put into gear and operated at slow rotational speed, you often need to hold on as it lurches abruptly forward due to the much larger torque and propulsion capacity.

The other major issue involves safet. If there is a problem with the propulsion system, a vehicle just pulls off the roadway and gets towed in and the issue resolved, or in the worse case, a battery fire occurs the driver just exits the vehicle and walks away. But battery fires on a vessel or an airplane do not have the same easy exit possibility which is why when we package our lithium powered lawn, garden and forestry power tools the packages are labelled Forbidden for transport on vessel or airplane. The batteries are categorized as Class 9 Hazardous Goods for transport purposes. Our company pays a hefty premium to transport lithium batteries by cargo air or by sea transport and there have been fires onboard cargo airplanes due to lithium battery failures leading to loss of plane and of flight crew.

[a64pilot]

Originally Posted by 44'cruisingcat

I'd bet the hybrid isn't going to use 1/3 the fuel.

Numbers like that come from things like the Diesel fuel consumption was computed at hull speed, Diesel full throttle.

The hybrid consumption was computed at hybrid system at full throttle, but they failed to mention that was at 1/2 hull speed or some other much lower speed.

So they can truthfully advertise that at full tilt the hybrid system only uses 1/3 the fuel of the Diesel.

Of course even at first glance their claim is absurd, think of how many Commercial boats would line up to buy something that reduced their fuel consumption to 1/3 or what it is now, think of how much that would pad profits.

It has its place, just don’t count on Solar at all, for most of us we have to be super efficient to get by on Solar, and for those rare ones that have excess, they happily use all of it heating water or cooking and still lust for that as yet unobtainable air conditioning.
Propulsion by example uses many times more power than air conditioning. So don’t even think about Solar propulsion unless your capable of running the AC 24/7.

[44'cruisingcat]

Originally Posted by Montanan

The other major issue involves safet. If there is a problem with the propulsion system, a vehicle just pulls off the roadway and gets towed in and the issue resolved, or in the worse case, a battery fire occurs the driver just exits the vehicle and walks away. But battery fires on a vessel or an airplane do not have the same easy exit possibility which is why when we package our lithium powered lawn, garden and forestry power tools the packages are labelled Forbidden for transport on vessel or airplane. The batteries are categorized as Class 9 Hazardous Goods for transport purposes. Our company pays a hefty premium to transport lithium batteries by cargo air or by sea transport and there have been fires onboard cargo airplanes due to lithium battery failures leading to loss of plane and of flight crew.

Different lithium chemistry. Power tools, phones etc are frequently lithium polymer batteries.

On boats they're usually lithium ferrophosphate. Slightly less energy density, but safer.

[cj88]

Originally Posted by a64pilot

It has its place, just don’t count on Solar at all, for most of us we have to be super efficient to get by on Solar, and for those rare ones that have excess, they happily use all of it heating water or cooking and still lust for that as yet unobtainable air conditioning.
Propulsion by example uses many times more power than air conditioning. So don’t even think about Solar propulsion unless your capable of running the AC 24/7.

The videos of the electric catamaran I posted the links to further up this thread also runs AC, but not 24/7. But it was interesting to see what is possible or not possible depending upon your needs.

[SDChristian]

Originally Posted by BigBeakie

The test I was planning on doing is to keep it simple. To run the electric at 15kW from batteries which is the maximum continuous charge from the 16kW genset, so we are putting full genset output into propulsion only. Note boat speed in no wind no current conditions and run for set time, say an hour if possible, and note distance covered and fuel used.

Then find rpm on the Beta that replicates the same boat speed, and run same time at those RPM for same distance, and note fuel used.


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Once you’re done with this test you can then move on to mount Nigel Calder’s Integrel alternator and possibly remove the generator (or just save dearie use).

[john61ct]

Originally Posted by 44'cruisingcat

Different lithium chemistry. Power tools, phones etc are frequently lithium polymer batteries.



On boats they're usually lithium ferrophosphate. Slightly less energy density, but safer.

Not necessarily, once EP is involved

[a64pilot]

Originally Posted by SDChristian

Once you’re done with this test you can then move on to mount Nigel Calder’s Integrel alternator and possibly remove the generator (or just save dearie use).

How would this work?
You either use the engine to drive the prop or use it to drive an alternator? If you try to do both you overload the engine assuming this is rather large alternator.
Are you suggesting one engine to both drive one prop electrically and the other mechanically?

[john61ct]

Called Triskel, 48V DC gen, here's a past thread on it http://www.cruisersforum.com/forums/...ii-207549.html

Unique control system keeps engine load within optimum load / fuel efficiency range, by decreasing alt loading when more energy called for by the propulsion.

Clawing off a lee shore, power production stops.

Stop moving and 100% goes to power generation.

Have yet to hear from customers, may still be in prototype / testing.

Not cheap.

[valhalla360]

Originally Posted by Dockhead

Indeed. Propeller optimized for one system with not be as good for the other. A better test would be for each system to be driving a prop as close to optimized for that system as possible.

Even bigger than optimizing they system is defining the use case.

I can manipulate the use case to show 3 times as "diesel" efficient. Just do short runs followed by long stays at a dock charging thru the shore power cord...then not bother to describe the use case. The result is most miles will be under shore power and you won't use much diesel, so technically, it won't use a lot of diesel.

Likewise, assume half the speed for the EV vs 80-90% of hull speed for the diesel.

[schoonerdog]

just as another price point, OceanVolt did a quote for our boat, replacing two 40hp yanmar engines, price for the sail drives $33,000(approximately price of two new diesel engines); Price for batteries, $16000 (vs $2000 current setup); price for generator, cables, control, propellers, $35k. So looking at around $84k, before labor. I imagine labor for removing the old engines, redoing the engine compartments, etc probably at least $11k. Maybe 95k in total. Range under batteries alone would be about 40 miles at 4 knots, generator would be obviously much much greater.