Hybrid boat discussion

[Jerry Farnham]

I just read a great article about Hybrid boats in the most recent Professional Boat Builder magazine. Amongst some this is a touchy subject. That same group of people may even think that we should go back to steam… or sail. I believe technology is a train, you either jump on board… or get ran over by it.

 

There are two different types of Marine Diesel Electric Hybrid set up’s. Serial and Parallel. On a Serial type set up you have a generator that feeds a battery bank. Then the battery feeds the electric motors turning the shaft. The advantage of this is your generator is always proper loaded due to charging batteries. The fault, in my opinion, is no solid mechanical link between diesel engine and propeller. That brings us to the Parallel set-up. The diesel and the electric motor are in some way coupled to the same prop shaft via a clutch, jack shaft, or transmission of some sort. Styer actual has an electric motor between the engine and transmission in an all inclusive package with less mechanical parts. I like this set up due to the mechanical link from engine to propeller. Disadvantages being engineering and space in some cases.

I think most members here on this forum would be interested in the Parallel set up, why? Let’s take my dream 38 Young Brothers which would be built for cruising the Maine coast spectating and participating in the Lobsterboat races held up and down the coast of Maine. Here I am casting lines from the dock batteries fully charged. It’s early in the morning and the family and guests are asleep. I leave the dock under electric power. All electronics, lights, and other accessories are on feeding from the massive lithium ion battery bank converted down to 24 or 12 VDC. I make my way out of the harbor, river, or channel and it’s time to get cruising. I fire off the diesel engine and start cruising. I arrive at the racing venue batteries fully charged because the electric motor also acts as a generator. Ah ha, it’s my turn to race. When the flag drops the diesel engine and the electric motor work together to push me down the track in a fast and efficient manner. After the day of racing is over with we set anchor knowing we have enough battery power to keep a few courtesy lights on and run other small electrical loads like the f/w pump or VacuFlush toilet.

Another more common scenario is your out trolling. Why idle that diesel around on a trolling valve? Prolonged idling is a sin in the diesel world. Why not shut your engine off and troll via electric motor. You will have better speed control with the electric motor, and less noise in the water and out.

I know what you’re thinking. If this is so great why are not more people doing it? One reason is the technology is still in its infancy, even though it has been around since WWII (remember German U-boats) it’s not perfected. Lithium Ion battery technology is getting more trustworthy and there are several companies working on drivetrain solutions. Another reason is cost. I was told by someone that was thing of repowering that the Styer diesel hybrid @ 200 horse power was a $50,000, and that was just the engine. Now through in lithium ion batteries that are around $5000 for one 8D, and in my opinion lithium ion is the only way to go on a hybrid boat of any kind. The last reason is some people are scared of change, and those are the people still floating around in wooden boats with a bed sheet in the air.

Now I on purpose didn’t fill this post with a bunch of numbers and technical jargon. That is for you and your boatyard to look at. There is a lot of info out there and this is by no means a new technology, it is an evolving one.  Here are some sites to feed your brains on.

http://www.steyr-motors.com/marine-diesel-engines/marine/the-steyr-hds-hybrid-drive-system/

http://www.hybrid-marine.co.uk/

Electric or Hybrid

http://www.mastervolt.com/

http://www.lithiumion-batteries.com/lithium-marine-batteries.php

http://www.torqeedo.com/us/en-us/products/inboards

And as always I am here to answer questions.

Topic

[Woo]

Space constraints, cost, weight, complexity, low hull speeds, the list goes on as to why hybrids aren’t really suitable for smaller (and especially planing) vessels.

Reality is that the power that a gallon of fuel contains far exceeds what can be garnered from a battery based hybrid setup. My boat can do 1,000NM on a full tank of fuel that’s housed under the aft deck alone. To obtain that range from a battery, even the best lithium, in a similar package, would be an ask. And then, where would the fuel for the IC engine go? The IC is still needed to charge the batteries. There’s no shore-power out there.

There is no coasting in a boat, no down hills, no braking regen…. it’s always steep up-hill. So, no matter the time you spend on electric-only motor in quiet mode, the IC engine will need to re-fill those battery packs. Sure solar can pop a bit back in, but it’s a very small bit.

I see the discussion often, see many ask when we’ll see hybrid outboards….. to me the answers are obvious.

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