i guess this electric propulsion has been debated before on sailnet and i didnt want to redundantly revisit it, but more wanted to think about what is up and coming in the next few years and how it will affect industry (and how someone might make a buck off of it).
in as much as it is relevant, however, i will add a couple of comments about why i think electrical propulsion does have a more positive immediate future:
1. It IS here. i use an electric outboard on my dinghy. casioqv uses an electric trolling motor on his C22. numerous others do similarly. also the lagoon hybrid 420 cat. 5 years ago there was nothing. it is here now, albeit in its infancy, but undeniably, and 5 years from now will be only further along.
2. I would quibble with equating one horsepower of a diesel engine with 750 W of an electric motor. while one horsepower of mechanical power at the driveshaft of a yanmar and 750 W of electrical power into an electric motor will ultimately produce the same amount of heat, this does not take into account the application being considered - diesel drivetrain and alternator losses or very very very different torque curves not to mention ideling with a diesel compared to simply "off" with an electric. however, lets be pessimistic and accept the 750 W/HP. consider the 56 kWh lithium ion battery pack that is used on the Tesla Roadster, the only all electric street car currently in prodction. at 7.5 kW (what we are equating to "10 HP" but in reality would be more akin, ballpark, to 15-20 hp) this would give 7.5 hours of motor cruising. more than adequate for most day trips. this is today's technology, available now. more advanced battery and ultracapacitor technology is already in the pipeline. add more batteries or small generator or cruise at lower power and we quickly get into the 20s and 30s of hours of motoring time.
would i get rid of my diesel inboard if i could motor 30 hours with an electric drive? sure.
3. i dont expect an electric drive without an absurd and impractical amount of solar would [I]ever[I] exceed the range/energy density of diesel (11 kWh/L compared with, ballpark for current lithium ion technology only 1 mJ/L = 0.3 kWh/L) but hey, its also about convenience. the energy density of my sails is pretty much infinite, but i still have an inboard. would some people trade no trips to the fuel dock, no maintenance, no noise, no oil, no diesel for less range. sure they would. especially if they mostly sail.
4. The market has spoken. its happening. electric propulsion is on its way (for cars). all lage manufacturers are developing plug in hybrids or all electric vehicles to be released between now and 2012. ALL of them use lithium ion (not that a new, better lighter cheaper and higher energy density technology might not replace it). my outboard uses lithium ion. i can charge it from solar. lithium mining, exploration and battery stocks are taking off. China is trying to acquire strategic lithium claims. the market is sometimes wrong, but i wouldnt bet against it.
Last edited by ArgleBargle; 09-06-2009 at 10:33 PM.