Swift Trawler Diesel-Hybrid

[devorenm]

Concept Craft: Get A First Look At Beneteau’s Hybrid Prototype | | PassageMaker

I was surprised by the results - the hybrid was markedly more thirsty under diesel power - so much so if you did any kind of serious cruising you would burn more tens/hundreds more gallons of fuel in a year than the straight diesel. Kind of cool concept with the very slow cruise in electric mode being extended by running of the small genset - but I felt a rather poor proof of concept.

I'm curious if a diesel electric pod type of set up might be more feasible - you would gain the efficiency of the pod drive set up but with a simple/cheaper drive line than a conventional engine driven pod set up.

What is the consensus on the efficiency advantage of pods at hull speeds?

 

[Phil Fill]

I view the eco option like a get home which many bigger single engines have. Old school is a gen set that is hydraulic drive on the single drive shaft or a separate drive shaft. Our bow thruster had a forward thrust powered be the gen set, which I took out, as there is still the hydraulic drive to the main shaft. So now dc electric drive is an option which been available for years.

 

[THD]

Devore-I don't find that surprising at all. I have posted this before, but starting about 8 years ago, we looked at designing and building a 57-65' diesel hybrid, designed from the bottom up as such. An investment group at the time was interested in producing and marketing it. We used Bill Crealock, along with a pretty knowledgeable marine engineer for the design. And Crealock did design a beautiful boat. The long and short of it was that we really found few if any real advantages to the system. And this was designed with off-the-shelf components, mostly Siemens (they have been doing diesel electric since about 1910 or so). We did find that a standard configuration in that size boat, twins with a large and a small generator, could conceivably be reduced to three, one large to drive both shafts, one large generator that could also drive the shafts if needed, ad a smaller generators. Calculated fuel savings were less than 5% closer to 3%. Complexity was not really reduced because of the addition of the electric motors. Although they are fairly small and fairly inexpensive (about $5k each), you could carry a spare or two. But we found only two substantial advantages, (1) the ER could be smaller (and more crowded!) so living space could be a bit larger because engines can be placed anywhere; and (2) all engines can be in sound shields so the boat can be amazingly quiet. Unfortunately, since this was back around 2008-2010, our research showed a substantial market just wasn't there.

 

[sdowney717]

Every 5 to 8 years have to spend $8000 on batteries is not a good idea.
This type application makes no sense.
Electric motors make sense if you don't use batteries to power them.
Batteries run down with usage, the heavier the usage the shorter the life. Having lots of batteries running down means high replacement costs sooner the more someone uses the electric motor, so their is a disincentive to actually use the electric motor.
What you just want putter around the marina silently?

Ask yourself why train locomotives do not use batteries to power traction motors..

 

[FF]

To be really "efficient" all one requires is a small diesel, that runs in the "buldeye"of its specific fuel consumption and a large slow turning prop.

Co Generation, coolant used for heating and exhaust for warm hanging locker would help.

Downside , no extra power for higher wave making speeds.

 

[sunchaser]

Good report THD. Nice to hear from somebody who has been there and done that from the dollars and (common) sense basis.

 

[Rustybarge]

Concept Craft: Get A First Look At Beneteau’s Hybrid Prototype | | PassageMaker

I was surprised by the results - the hybrid was markedly more thirsty under diesel power - so much so if you did any kind of serious cruising you would burn more tens/hundreds more gallons of fuel in a year than the straight diesel. Kind of cool concept with the very slow cruise in electric mode being extended by running of the small genset - but I felt a rather poor proof of concept.

I'm curious if a diesel electric pod type of set up might be more feasible - you would gain the efficiency of the pod drive set up but with a simple/cheaper drive line than a conventional engine driven pod set up.

What is the consensus's on the efficiency advantage of pods at hull speeds?

If I had to choose a hull to put hybrid power in it would be a catamaran; you'll need 40% less power for any given speed.

At15kts at cat needs 20hp/ton, a s-displ. hull 40hp/ton.

Of course it isn't that easy, as cats are ultra sensitive to weight and its hard to imagine how all those heavy batteries would affect the performance .

My son vapes with an electric cigarette , and he tells me that a good quality recargable lithium ion battery last only two years if you fully drain it and then recharge; that's only about 700 cycles.At that rate for the cost of new batteries you could buy a brand new engine Every two years.

 

[Baker]

You'd think Beneteau/Jeanneau would have learned their lesson with the Lagoon Powercat....they basically bankrupted that line of boats with that crap.

 

[Portage_Bay]

My $0.02 on using sophisticated power systems. Well, perhaps more that 2 cents, it's kinda long....

When considering diesel / battery hybrid or multi diesel gen set and electric final drive think about how the boat will be used.

For the diesel / battery hybrid a weak but usable analogy is the Toyota Prius. The Prius is most efficient in city driving. Stop and go, lots of time to capture waste gas power plant output and store it in the battery. It is least efficient at claiming a mountain pass because the power plant is asked to work continuously at a much higher load. A full displacement boat at hull speed is not unlike a vehicle climbing a mountain pass in terms of % power used. Yes, I'm ignoring the Prius's regen capability because it doesn't apply well to boat drive systems.

For a diesel / battery hybrid boat to work the power usage has to be Prius like. A cruising yacht doesn't fit that profile well. It's use profile is pretty much on at cruise speed or off.

Foss towing has been trying diesel / battery hybrids with their harbor assist tugs. A harbor assist tug's operational profile is lots of low power time with relatively short bursts of how power time. I haven't kept up with how well it has worked out for Foss.

For the multi diesel gen set and electric final drive system again it comes down to how the boat will be used. The fuel saving advantage comes into play when you have an operational profile that combines relatively short time spent at hull speed with lots of low speed work. Light off all the gen sets to cruise at hull speed. Drop to 1 gen set for low speed work. Once again a cruising yacht doesn't fit that profile very well.

I'm not a naval architect or engineer. I'm in the oceanographic research operations biz. We have just completed the design for a new near coastal vessel and are re-powering an ocean class vessel. For the new design we asked the designers to evaluate a diesel / battery hybrid power plant. We thought we might have the perfect use for a diesel / battery hybrid system. A research ship will cruise to a study site @ hull speed then drop to low or zero speed for the bulk of the mission. 80% plus of the mission time is at low speeds. We learned that even with that mission profile diesel / battery hybrid is not justified. The fuel, financial and environmental payback vs the additional cost and lost interior volume is just not there.

The near coastal vessel will be built with a multi gen set electric final drive system. The ocean class vessel has an aging such system installed which will be upgraded to newer more efficient gens and controls. Perfect fit or our operational profile. But not so much for a yacht. Yachts just don't spend enough time at low speed for the payback to work out.

That said, if you want it and can afford it go for it! Do keep in mind these are complex systems, the maintenance and operation costs are higher than a straight diesel mechanical drive system. Also we carry engineers who can keep the whole thing ticking along in fine order.