What is the Cost to Own An All-Electric Boat, Anyway?

Our hybrid-powered Zogo is a perfect example of the comparative costs of internal combustion and electric-powered vessels.

It’s frustrating, but true: Nobody seems yet to know exactly what it costs to own an all-electric boat. So, if you’re considering purchasing something like Hinckley’s nifty new all-electric Dasheror joining our other clients and commissioning a custom boat from us — you will have to feel your own way to estimates on what that boat will cost to own.

Here is the bottom line on electrons: Electric propulsion is simply too early stage for meaningful wide ranging cost estimates.

Let’s start with Electric Cars.

It seems nutty, but the automotive world is the place to start for figuring out the costs to own an electric vessel. One of our favorite resources is the U.S. Department of Energy Alternative Fuels Data Center. This easy-to-use Website offers a mix of pull-down menus and usage assumptions that break out the interrelationships of the costs of all-electric and traditionally powered  vehicles. Click through and lets start by comparing a similarly-priced all-electric Chevy Volt to an internal combustion-powered Volkswagen Golf R. The chart shows how the estimated miles, number of trips and other factors — like which state you live in —  affect the costs for both over 15 years. And what you should see, is though fees can vary by how far and often you travel, and your local cost for electricity, electric drive does tend to save you money over the long haul.

We’re happy to figure out exactly how much you might save in your particular boat. It won’t take more than a few hours of our time. But for the basics, we can show you how to turn these automotive estimates into those that can work for boats.

The DIY All-Electric Boat Calculator.

Here is what you need to consider when thinking about electric propulsion in boats.

Basic efficiency:

  • Internal combustion motor is widely considered about 21% efficient
    • Roughly 80% of the energy produced is heat and is blown out in smoke
  • An electric motor can achieve nearly 95% efficiency
    • 95% of the energy in the battery is turned into usable motion energy
    • That’s usually about 5 times more efficient than an internal combustion engine.
  • Electrons are cheaper to distribute than atoms.
    • Extracting, processing and distributing fossil fuels is costly and elaborate
    • Storage and replenishing of electrons is relatively cheap and efficient
  • An internal combustion engine and transmission has roughly 2,000 moving parts:
    • Engine
    • Muffler and Exhaust
    • Fuel tank
    • Cooling water
    • Shaft, bearings, seals, strut, and prop
    • Starter battery
  • An electric system can have, at most, about 20 moving parts.
    • Motor
    • Cooling water
    • Shaft, bearings, seals, strut, and prop
    • Batteries

Annual costs

Let’s compare traditional power to All-Electric for the Hinckley’s lovely “Dasher.”

To analyze fuel costs let’s consider a simple comparison in 1,000 miles of range. And let’s use Hinckley’s Dasher, as an example. Let’s assume, we’re running the boat at 10 mph for those 1,000 miles and then lets feel our way to a dollar-per-mile cost for internal combustion vs. electric drive.

  • Diesel propulsion:
    • First, to assess how much horsepower is required to drive the boat at 10 mph, let us find the speed-to-length ratio for Dasher, at 10 mph, with the hull’s waterline length estimated at 28 ft. (SLR = 10 mph/  √28 ft.) . This yields a speed-to-length ratio of 1.89.
    • To achieve that speed, we’ll need the right weight-to-power balance. Using that 1.89 speed-to-length ratio, we know from calculations that for this SLR of 1.89 there must be 167 lbs of boat for every unit of horsepower.  Dasher weighs roughly 6,500 lbs and that 167 lbs per hp equals 39 hp to drive the boat at 10 mph.
    • Here is the quick formula for estimating fuel consumption: Gallons Per Hour  = (Specific fuel consumption x HP) / Fuel specific weight.
      • For Dasher GPH = (.4 lb/hp x 39 hp) / 7.12 lb/gallon = 2.19 gph.
    • So, at 10 mph, driving 1000 miles will take 100 hrs.  At that duration, we consume 100 hrs x 2.19 gph = 219 gallons.  Assuming diesel fuel costs $3.00  per gallon x 219 gallons.
    • Diesel’s bottom line: $657 for every 1000 miles.

 

  • All-Electric Propulsion.
    • We know from above that 39 hp is needed to drive Dasher at 10 mph.  From that, we convert power into kilowatts by dividing by a factor of 1.34.  So, 39 hp / 1.34 = 29.1 Kilowatts.  Ok, call it 30 Kw for ease.
    • Just like in diesel power, to run 1000 miles at 10 mph, we need 100 hrs. That means to deliver the electricity required, we need 30 Kw x 100 hrs or 3,000 Kilowatt hours, or Kwh.
    • The average cost of electric delivery nationally is $0.12  per Kwh. And ignoring many details in loss/gains in efficiency and other issues we’re evading for this illustration, we see that $0.12 / Kwh x 3,000 Kwh
    • All-Electric’s bottom line: $360 for every 1,000 miles.

See why are we so bullish on electric power? The properly designed all-electric vessel can offer enormous savings in the right setting. We have not understood why it has taken the industry so long to figure that out.

Let us know how you get on with your all-electric dreams. We are happy to help in any way we can.