Although I've made a few comments on this yahoo group I've never posted anything before but I just got the boat running on electricity for the first time and feel like sharing the moment with as many people as possible since I've been working on this thing for two years now.
But first I would like to thank all the posters on this forum for the gold mine of information about electric propulsion that travels thru here. Following the banter for the last 4 months has been very helpful.
Next I'd like to introduce the 'Arc'himedes, a 31 year old, 45', bilge keel,(formally ketch rigged), solar electric cruiser that is just about ready for it's extended maiden voyage around the great loop.
-Construction material- Steel reinforced ceramic/fiberglass composite
(That's a nice way of saying ferrocement covered in Fiberglass epoxy)
-Water line length-41'
-Length on deck-45'
-Length overall-48'
-Beam-13.5'
-Displacement-Approx. 20 tons fully loaded
-Draft- 3'
-Diesel motor- 50 yo, 38hp British Standard from a double decker bus
-Electric motor-brand new 9 hp, D&D shunt with Altrax DCX500 control
-Solar array- Currently 3 kW at 48V, (16%eff.) to be expanded to 5 kW
soon for 100amps at 48V total with limited tracking ability.
We had our first little shakedown cruise on Friday and so far so good. Here is a youtube link to a short video.
http://youtu.be/t188REMgnvA
Despite the rule of thumb of 1kW/ton displacement I cheated a lot for economic reasons and spec'ed out a 9 hp shunt (golf cart type)motor on steroids that delivers 29ft*lbs of torque at 2300rpm continuous. So I have about .35 kW/ton but I believed it would work OK because of the high torque rating on the motor and a uniquely hydrodynamic hull design with an autoprop that optimizes the propulsion from the shaft. (Turns out I was right and what a relief that was!)
Total cost so far for Electric motor and accessories, (excluding batteries and solar)was less than $2500. I'll have about $7000 in the solar and another $1000 in electrical accessories when I'm done. So for about ten $large$ I've got a system with a never ending fuel supply that will push my boat on inland waterways at 5 mph whenever the sun is shining. Considering the old diesel burns about 1 gph at 5 mph and fuel is up to nearly $5/gal I figure I'll break even in about 10,000 miles which should be about the time I have to change out my firt set of brushes on the motor.
After two short test cruises I'm happy to report that the helm responded very well and the boat was quite responsive at slow speed with plenty of thrust to control it in close quarters. It was a little sluggish after 3 mph working it's way up to 5 mph but not that bad. It took about 2 minutes to go from dead stop to a full 5 mph into a moderate headwind on still water and we made over 5 kts when we turned around and put the wind to our stern. We'll see how it does in 8' seas but all I have to do is remove the #40 chain from the electric motor and the system defaults back to the ancient 38 hp diesel that runs like a top.
So once again, thanks to everyone that has asked or answered a question on this forum. You were a big help.
If you'd like to see more about this work in process you can also go to my first mates blog at archemedesproject.blogspot.com.
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