Electric Propulsion?

Part of the allure of a sailboat, is the freedom of the wind (well, when there is wind). The low impact on the environment, and enjoying nature without an engine running in the background.   Well in my many travels through the internet (it really is a big place), I've come across a couple references to green sailing, and electric propulsion.  It sounds too good to be true - and probably is.  The engine when running is quiet, but for long cruising you can't really recover enough power without a genset.   But maybe battery technology will improve - I mean seriously, at the rate I'm progressing on my journey we'll probably have transporters before I sail! So below are comments from one of the companies that produces the engines.  Just something to think about.

Just push the throttle and go.

No more grinding the starter,
Or praying the engine will catch,
Or waiting for it to warm up,
Or clunking the gears into forward,
Or ear-shattering noise,
Or obnoxious fumes.

You slide away from the pier in silence - as quietly as under sail. The only sound is water slapping the hull. The only smell is the salt sea air.

It's clean, green, electric sailing. And with oil near $100 a barrel, and environmental regulations increasing, it's the sailing wave of the future.

Energy from batteries:
Batteries deep in the hull provide the energy to move. They've been charged from dockside AC or from onboard solar panels.           

Electrons flow from the batteries through a controller that chops them into pulses. The pulses surge through the motor windings and create fluctuating magnetic fields that silently spin the shaft.      

If headwinds or high seas start to slow the boat down, more electrons automatically flow through the motor. Boat speed stays steady, without operator control.

Regeneration:
Regenerative sailing converts renewable energy from the wind to electricity that recharges the battery pack. A rough guide is that three hours of sailing regenerate the electricity from one hour of motoring. But the ratio varies greatly depending on sailing speed, prop size, rate of electrical consumption while motoring, etc.

When the sails go up in open water, you throttle the motor back so it's just ticking over. The motor turns the prop slowly while you sail. It corkscrews through the water and cancels most of the drag. When boat speed increases - from sliding down a wave or the wind picking up - the prop is forced to turn faster as the water rushes by. The motor then becomes a generator and sends electricity back to the batteries.

As you rise up the back of a wave, the ammeter reads negative. The motor is consuming more electricity to maintain speed on the upslope. Heading back down, the ammeter turns positive as the boat speeds up. The motor is regenerating electricity and recharging the batteries. On a windy day, the boat can return to the dock with more power than when it left.

If the wind dies, you push the throttle forward to maintain speed. Apparent wind picks up and keeps the sails pulling. Now you're motorsailing, but still with no noise or diesel smell, and you haven't burned a drop of fuel.
   

Generator backup:
Eventually the batteries discharge to their preset minimum level. A cocooned diesel generator starts up automatically. From the cockpit, it's barely audible over the wind through the rigging.

The generator runs with maximum efficiency at a constant, optimum speed. It recharges the batteries as the boat continues motoring, and shuts down automatically when they're fully charged.

Quiet nighttimes:
On the hook at night, the air conditioner starts up and runs quietly off the batteries. Depending on their state of charge, the batteries may power the AC through the entire night. If they run down, the cocooned generator automatically starts running quietly to bring them back up. No more getting up in the middle of the night to start a noisy diesel engine to recharge the house batteries.

Maximum control:
Heading back to the dock, the boat is easy to control. The motor can be slowed to single digit rpms, stopped and started repeatedly, and reversed in an instant.

No more wrestling the shift lever from forward to neutral to reverse to forward again. No more heading into a slip too fast with no way to go slower. Collisions with the dock are a thing of the past.

Its all part of clean, green, electric sailing - the sailing wave of the future.


It sounds good, but until the battery technology improves, I don't know if it will appeal to cruisers or not.  This all probably goes against the simpler is better statement that I've been told to follow, but it sure sounds like a neat idea!