Lessons Learned - August 2018

The Future Of Marine Propulsion Is History

Most of today’s motoryachts have a propulsion system based on an internal combustion engine of either diesel or gasoline fueled design, a reduction gear such as a transmission, V-drive, Pod drive, or stern drive and a propeller of some variety. Is the future of propulsion just continued improvement on these existing systems or is there something new on the horizon?

New ideas are generally adopted at either the low end of the market where the costs are low enough for small companies to enter the market with innovative products or at the high end where the end user is not cost sensitive and wants leading technology products. Then once the technology has been proven and moves into higher volume products, costs come down and the mainstream users adopt the “new” technology. Marine propulsion systems seem to be following this same rule.

At the smaller boat end of the spectrum we find the Duffy Electric Boat that is built in a factory in Southern California and have been in production since 1970. They build an all electric battery powered in house designed boat that seats eight and can run for up to eight hours on a single charge. Their designs have been in production for more than 40 years and have sold more than 10,000 of these high quality port and cigar cruisers. There are six models available with prices starting around $27,000, or about the same price as a good dinghy. Duffy uses a proven battery technology; the old tech lead acid golf cart batteries are perfectly adequate for the purpose. At five knots the Duffy’s have a run time of six hours and can be recharged overnight. Perfect for an evening cruise around the delta.

Looking for something a little faster than the Duffy, point your compass north to Canada. The Canadian Electric Boat Company has been in business since 1995 designing and producing several different models of electric launches using old tech lead acid batteries. In 2016 they went into production of their latest design, a high performance 22-foot electric boat that has a top speed of 35 knots and cruises at 17. Using Tesla Lithium Ion batteries, she has a run time at cruise of two hours with the 104 kW/h battery option. Can you imagine pulling a water skier and have six passengers on board with a zero noise and zero emission boat? Of course, that speed does get a bit pricy with a fully optioned day boat north of $300K.


Big Boats

At the far other end of the spectrum we find modern cruise ships using either a gas turbine or diesel engine with the output shafts directly connected to electric generators producing electric power to the electric traction motors inside the azipods. Even though many ships are still being built with conventional diesel engines almost all new cruise ships have some form of diesel electric propulsion. On these ships the electric propulsion engines inside the Azimuth Thrusters are connected to the electric generators. Azimuth thrusters are pods housing electric motors, coupled to propellers, that can rotate 360-degrees and provide excellent maneuverability. If you have operated a vessel with the Volvo IPS drive you will immediately understand the ease of maneuverability that independently rotating Azimuth thrusters provide.

What works well for the 50-foot yacht works even better on the 1200-foot cruise ship. They not only provide better fuel efficiency, they also reduce stopping distances as the pod can be rotated 180-degrees and provide maximum thrust astern. The azipod propeller faces forward because in the pulling, or tractor configuration the propeller is more efficient as it is operating in undisturbed water. Because the pod can rotate 360-degrees around the axis, the thrust can be applied in any direction. Early pod drive fitted ships demonstrated around 9% improvement in fuel efficiency over conventional propulsion system when they were first being used in the early 1990’s. With modern computer dynamic optimization, the overall fuel efficiency improvements are now double that at around 18%.

The primary advantage of these diesel electric propulsion systems is that they allow the generator to operate at the most efficient speed regardless of whether the ship is moving at 5 knots or 25 knots. Think this is new? No way! Electric motors using electric battery storage have been used on submarines and electric boats for nearly a hundred years. Just like the early days of the pure electric vehicles that had a range of 50 miles before needing to be recharged, the first pure electric ship was launched in late 2017. Guangzhou Shipyard International launched a 2,000 dead weight ton coal carrier on November 12, 2017. She is an all electric Lithium Ion battery powered ship with a range of 40 nautical miles. This is just the start of the technology curve just like Tesla came in ten years later and now offers larger and better vehicles with a range of 300 miles.


Commercial Passenger Boats

San Francisco has more than a dozen passenger only ferries in operation operated by the Golden Gate Bridge Highway and Transportation District, GGBHT, and the Water Emergency Transportation Authority, WETA, all with traditional diesel engines. The bay is also served by another two dozen dinner and tour boats operated by Red & White Fleet, Blue & Gold Fleet, Hornblower Cruises and Events, Commodore Cruises and Events and several others companies operating vessels with mostly traditional diesel propulsion.

The first generation of hybrid ferries entered San Francisco service in 2009. The Alcatraz Cruises Hybrid fleet was retrofitted to use power generated by ten-foot-tall wind turbines and photovoltaic solar arrays covering the awning on the top decks. That power is converted and stored in battery banks that then power the navigation tools, lighting and other electronics on board the vessels. Excess power is stored in the main propulsion battery banks.

That was a good start, but the next generation of true diesel/electric hybrid ferries is on its way. Red and White Fleet ordered a new build 600 passenger vessel from Bellingham, Washington based All American Marine that will be a Lithium-Ion battery electric hybrid and expected to be in operation in San Francisco before the end of 2018.

Now that the diesel electric ferry is reality and there are more on the way, the question is what is next? California is currently the only state where Hydrogen Fuel Cell cars are available, and it may be the first state with a hydrogen fuel ferry. Just a few years ago Sandia National Labs and the Red and White Fleet began designing a high speed hydrogen fuel cell vessel for operation in San Francisco Bay. The plan not only includes development of the ferry propulsion system but also what will probably be the largest hydrogen fueling station in the world. The United States Maritime Administration, MARAD, agrees that the plan is feasible, but expensive. The MARAD study found that fuel costs would be three to six times more expensive than diesel but the design has many advantages including the elimination of carbon emissions and zero risk of environmental damage from diesel spills.

As an early adopter of technology, I have been driving a hydrogen fuel cell car for the last two years. I can confirm the zero emissions and the more expensive to operate fuel costs, but it is different, quiet and it pees water out the back on command.


Lessons Learned

Do not count out old technologies. Just as the early electric automobiles were displaced by those powered by the internal combustion engine, that 100-year dominance is threatened by new battery technologies. The current generation of pure electric automobiles has a range exceeding 300 miles and can be recharged in 20 minutes. With further advances in battery technology range, recharge time will continue improve. Consider that some European countries have announced their intention to halt the sales of new automobiles with internal combustion engines as early as 2022 in favor of pure electric vehicles. The automobile manufacturers are racing to bring out electric vehicles with better range and shorter recharge times. Rivaling the pure electrics is the hydrogen fuel cell hybrids. With tens of thousands of these cars on the road today and the refueling infrastructure continually growing, expect to see more of this technology in the future. Get ready for the propulsion system in our mid size motoryachts to change dramatically. Your next yacht may be powered with new, yet old, diesel electric or hydrogen hybrid propulsion.

Time for me to sit back, enjoy a good glass of port, and light up a fine cigar. Until next month please keep those letters coming. Have a good story to tell, send me an email. patcarson@yachtsmanmagazine.com. I love a good story. H

© 2010 Yachtsman, All Rights Reserved.   |   Home   |   Contact Us                     Bookmark and Share