STUDENTS IN KEVIN RITZ’S MARINE SYSTEMS CLASS at NWSWB are installing an e-propulsion system on Clean Bay, a 26-foot electric-solar workboat designed by naval architect Tim Nolan. Boat School alums Kere Kemp and Stanford Siver chose e-propulsion for their boats. We asked Kevin, Tim, Kere, and Stanford to share their perspectives on e-propulsion for different types of vessels and use cases.
CLEAN POWER FOR CLEAN BAY
An interview with Marine Systems Lead Instructor Kevin Ritz
How was the decision made to use e-propulsion on Clean Bay?
Clean Bay’s mission is to promote environmental stewardship by providing a free pump-out service to boats in the Port Ludlow Marina and by operating on clean energy. With an estimated range of 37 miles at 5 knots, Clean Bay can serve its intended mission with power to spare — going out to individual boats to collect wastewater then returning at the end of the day to empty its tank and recharge. Estimated recharging time is 7 hours using two 30-amp shore power outlets.
What are students installing on Clean Bay?
Students are installing a Torqeedo pod drive powered by four lithium ion 48V batteries — each weighing 80.5 pounds. In addition to the drive and battery system, they will be installing two monochrystaline solar panels and a range of onboard systems including bow thruster, pump, steering system, and VHF radio integrated with a chart plotter. Each student on the project team ran load calculations for propulsion and energy storage to come up with predictions on duty cycle.
We have two different battery systems on the boat. There’s a 48-volt system that operates the propulsion and pump and a 12-volt system that runs the bow thruster, VHF radio, lights, and a few other components. By putting a couple of the 12-volt batteries forward it helps with the weight distribution and the batteries are right where the bow thruster needs them. That’s a very high amperage DC circuit, so having the batteries right there is safer. It means that our conductor size and the amount of copper we’re putting in this boat is really limited; we’re not running all the way to the back of the boat.
Will e-propulsion be incorporated into the Marine Systems curriculum going forward?
Yes. We have been updating the Marine Systems curriculum with input from Charlie Johnson, president of JTB Marine, an ABYC Master Technician, and a member of the Boat School’s Program Advisory Committee. Charlie has installed many e-propulsion systems and helps write industry standards for e-propulsion. We are working with manufacturing companies to incorporate e-propulsion products into the hands-on part of the course, and students will have the opportunity to practice installing and operating both diesel and e-propulsion systems in a Poulsbo workboat built by students in the boatbuilding course. Learning to install and operate both types of system on the same boat will give them direct, real-world experience with both technologies.
A NAVAL ARCHITECT’S PERSPECTIVE ON E-PROPULSION
Tim Nolan, naval architect on Clean Bay, shares his experience with and perspective on e-propulsion.
What factors should boat owners take into account before choosing or converting to e-propulsion?
Be realistic about what e-propulsion can and can’t do. Do your homework. Energy density of diesel fuel is about .35 lb/hp-hr, gasoline is .42 lb/hp-hr, lithium ion is around 15 lb/hp-hr, and lead acid around 42 lb/hp hr. To replace 5 gallons (30.5 lbs) of gasoline would take around 1,100 lbs of lithium ion batteries or 3,000 lbs of lead-acid batteries. Electric propulsion is best suited for boats that are easily driven, make short trips between charges, or travel at economical (slow) speeds. It is a great choice for all of the above plus boats that loiter or need to be quiet and emission free.
How did e-propulsion influence the design of Clean Bay?
It led to an easily-driven hull (as long and narrow as practicable, pointy bow, transom above waterline) and a layout that provides access to the chargers and places the batteries low yet out of the way of the payload. The small size of the propulsion motor and batteries allowed me to optimize the location of the payload, placing it in the center of the boat where it is low and does not affect the trim of the boat when operating between the light and full load conditions. Note also that the “fuel” weight does not change; the batteries weigh the same discharged as charged, therefore they can be placed anywhere in the boat without affecting longitudinal trim.
Do you see increased interest/demand for e-propulsion among your clients?
Most of my clients want boats that require the energy density of diesel fuel. I would love it if that changed. I did a concept design for an autonomous solar powered cruising catamaran of traditional style that is very feasible. I would love to hook up with a client who wants to do more with less. I designed and built a 24ft electric marathon racer with David Janos and Pat Mahon that we successfully campaigned in the early 90s that went 10 mph for 60 miles with just 125 lbs of lead-acid batteries. I think we are ready for some smart solar electric cruisers.
The Thea Foss tender is a perfect application for electric propulsion because it makes short trips, goes slow, is easily driven, and can be charged every night. It uses a Torqeedo Cruise 10.0 Pod Motor with two 48 volt 48-5000 lithium ion batteries. The system is designed to be charged with 100V shore power originating either from shore or the mother ship via an isolation transformer. The launch is 23 feet long and will cruise with 10 passengers and 2 crew at 4 to 5 knots for 20 to 30 miles with a 33% battery reserve.
Anything else you want to add?
I have some ideas for small human/solar/electric cruisers. You can collect electrical energy with solar panels and impellers (air and water) and even pedals, then store it in batteries for propulsion. It opens up a whole new way of cruising that treads lightly on the environment and poses some really fun and interesting design challenges that can take advantage of the strides made in storage batteries, electric propulsion drives, and solar panels. On a small scale, the new technology is affordable and accessible.
USING E-PROPULSION FOR RECREATIONAL SAILING
New Zealand yachtsman Kere Kemp has been using e-propulsion for three years on his Dark Harbor, Kotimana, a 26-foot daysailor built by students in the Traditional Boatbuilding program at NWSWB. We asked him to weigh in on his experience with e-propulsion.
It’s the best thing since sliced bread, mate. Clean, green, and on tap when you need it. (Plus, it has extra benefits in light wind races. Oops, I’ll deny that I ever said that!!) Dark Harbors were never originally designed for or fitted with engines, so finding a system that would provide the flexibility necessary for today’s marina berths etc. was important for us. Sean Koomen, Chief Instructor at NWSWB, discovered the Torqeedo system during the planning stages for our girl and as we delved into the company’s systems it became pretty obvious that it was ideal for a boat like a Dark Harbor. Another option would have been a stern mounted outboard. But as we say down here, “yeah nah!”
How are you using e-propulsion?
Mainly used for getting in and out of our marina mooring and, depending on the wind, running down the estuary, about a 15-20 minute run time. Also, around the marina, in and out of the Trav Lift, and very occasionally if we ever need to stay head to wind while we reef down. All of the boat’s electronics are run off the system / batteries including a GPS that provides a speed over ground read out on the system’s computer screen. Only thing not connected, could be if we wanted, is the battery-charged Raymarine Micro-Net 100-2 for dual displays via bluetooth that we use for true boat speed and water depth via a transponder and separate impeller.
What system are you using? Are you satisfied with it?
Torqeedo. Extremely satisfied, have never run out of battery but if it ever does run down, we can recharge a 2000W gas-powered portable generator with adapted charge cord that plugs into the shore charge port. The latter is very
handy for overnight trips. I’ve never actually tried it, but the Torqeedo system also allows for regenerative charging
while sailing — if you have (as we do), a folding prop.
What would you say to someone considering e-propulsion for a boat of your type?
It’s a no brainer. Yes, it’s a bit expensive up front, but reliable, powerful, and it’s just there when you need it via a flick of
the morse key.
What’s your connection to the Boat School?
Alum, class of 2016. Post retirement and one of the best years of my life!
NEVER TOO OLD FOR E-PROPULSION
Port Townsend sailor and Boat School alum Stanford Siver is adding e-propulsion to Ziska, a 118-year-old sailboat with a colorful history — most recently becoming the heaviest boat to complete the Race to Alaska (R2AK).
Ziska was built in 1903 in England as a yacht to the lines of the working Morecambe Bay Prawners of the day. Originally, she was engineless but an off-center two cylinder horizontally opposed petrol engine was added in 1909 and taken out sometime before 1974 when she broke a mooring line in a blow and was all but wrecked. She’s been heavily reframed and replanked and there is no indication of her original tanks or engine mounts left. Modern harbors aren’t set up for engineless boats of Ziska’s size to easily sail into or out of. And they aren’t even set up to row in. Ziska has two 12′ oars but only rows at half a knot and there often isn’t room for oars in a tight marina and getting her in and out often requires support. And yes, Ashley Butler did solo sail her 25,000nm in six years engineless but the thought of adding a diesel engine to her with the added tanks, filters, water lift, through hulls, noise, and fumes…not going to happen. E-propulsion is clean, quiet, doesn’t take up much space below,
no fumes, and it’s where we should all be heading.
What system are you putting in?
Torqeedo Cruise10 20HP Pod Drive with 15KWH of Torqeedo
lithium ion batteries with an aesthetically modified Torqeedo
throttle that doesn’t smack of baked on enamel over aluminum
but of bronze and teak although there’s still a question of where
to put the throttle.
What is the anticipated range and what are the operating parameters?
A prop bank of 15KWH should carry Ziska (11 tons) 50nm at 3kts but only 15nm at 5kts. Enough to get in and out of marinas and anchorages with a little left over for getting out of the way of things.
What is your connection to the Boat School?
I went to Boat School in 1992 and have been a part-time sailor since. Alum shipwright J Galloway was part of Ziska’s core restoration team and jumped onboard for the R2AK. Alum rigger Matt Fahey (class of 2000) built her new rig and Pat Mahon, a former boat school instructor, built her spars and consulted throughout the project. Her sails, made by the Chimenti family’s Force10 sail loft, included a Boat School sailmaking class. Jo Abeli, an NWSWB boatbuilding and marine systems intensive grad, installed Ziska’s systems. Dana Pope, currently in the marine systems course and already signed up for the boatbuilding program, volunteered to help on Ziska’s systems as an apprentice.