.I'll likely never own a boat, but I'm curious about their energy consumption.
Hey Brian, think about this:
When you’re tooling down a level road on a calm day at a steady 2000 RPM with your 350 Chevy car or truck, you might be using 40 to 60 hp (tops) to push it through the wind and overcome rolling resistance. Nowhere near the HP that the engine is capable of producing at that RPM.
If you encounter a hill, you need to give it more gas, to produce more horsepower. Your speed and RPM are the same, but your HP and fuel consumption will increase.
if the hill gets steeper and steeper, at some point you will reach the HP limit for that engine at that RPM. A look at the RPM vs horsepower curve for a given engine will tell you what that the maximum horsepower is for that RPM. You will need to downshift, to increase your mechanical advantage, (through the transmission) along with increasing your RPM (and thus HP… higher on the curve.)
Think of a boat as going uphill ALL the time. At any given RPM/speed, the engine will be producing the maximum horsepower it can, and using the maximum amount of fuel, according to the engine HP curve. If it is cannot produce enough horsepower to maintain a given speed, the boat will slow down. If you want to increase speed, you will have to increase RPM, and thus increase HP. Up to its limit… the maximum HP it will produce, corresponding to the maximum boat speed.
So, grossly oversimplified, a given throttle setting will correspond in direct proportion to your RPM and HP and fuel consumption.
I say oversimplified, because your speed and HP demand will vary, according to the wind and sea state and current. And remember, water resistance increases exponentially with speed.
But you get the idea… In a boat, you are never tooling down the road at high speed, using just a fraction of the HP that the engine is capable of producing. It is always producing maximum HP for a given RPM. Always “going uphill.”
So Brian, if you are “curious about (boat) energy consumption,” Find out what engine(s) it has, and what RPM the owners cruise at. Then look at the fuel consumption curve for that engine at that RPM.
Or look for a boat review online for that or a similar boat… They often have RPM/speed/fuel consumption charts as part of the review.
Remember, that curve represents the maximum HP or fuel consumption that engine can produce at that RPM… In a different application, other than boats, it can always operate BELOW that curve.
So given the massive reduction in HP for the electric motor versus the gas engine, yes, the Silverton‘s boat speed will be significantly limited.
That’s why most electric boats are used for relatively short range, or slow speeds, or environmentally sensitive places; i.e. short bay cruises, trolling motors, or for research or eco-tourism in marshes and such, where the low noise level is significant to the boat’s working purpose.
Ever hear of a Duffy? Perfect example. Low speed bay cruises. Forever they have been driven by essentially a low-HP DC golf cart motor and lead acid batteries, though I’m sure newer models have better technology.
I don’t know what else is out there, but there were some boats called “Epic wake boats.” They could operate about nine hours at low speed, or one hour at high speed, pulling wakeborders and water skiers. Long gone now, a victim of economic realities. I think Ski Nautique made some electric ski boats too, but I don’t know anything about them.
Electric boats aren't exactly new. Sport fishing enthusiasts have long relied on electric trolling motors that are less likely to disturb the fish they're trying to catch and make it easy to maneuver in tight spaces. What EPIC has done with its 232se is taken the known benefits of electric power...
www.google.com
