SUGGESTIONS SOLICITED. Bob suggested I read his "Hindsight" post and ask my questions about electric boat propulsion on this list, so I have joined it, and would like nothing better than to be informed of a practical solution to the propulsion needs of my 8000 lb, 26' x 7.5' x 1' draft sailing barge. The original gas outboard mounted inboard as a quick and dirty "saildrive" will not work because of the shallow draft and pointy underwater stern shape. Inboard propulsion of any kind will not work. The prop will suck air. The boat will be used in very shallow water and the propulsion will have to be protected as in kick up outboard or other. My rudder is much deeper than the hull and kicks up. A rudder mounted motor with feathering prop or prop turning just enough to prevent drag (sometimes generating electricity would be ideal) would be the best solution if it is practical and affordable. The boat weight is already near the maximum regarding trailerability, so weight is a consideration. Being unfamiliar with this forum I invite suggestions and links. I have considered the Torqeedo because I believe electric will be the way of the future upon the advent of practical fuel cells and because the Torqeedo outboard motor could mount on the rudder and a gas outboard cannot. The relevant part of my post from the Bolger Boats forum concerning the Torqeedo is pasted below.
Bob,
An Atomic Four is rated at 30 HP. What hp and voltage motor did you replace it with? Did you increase the size of the prop and turn it slower? 48v I assume based upon 8 Trogans which I assume are 6v golf cart batteries of what amperage? Does the boat perform as well under electric power as it did with the Atomic Four? How long at what speeds do your batteries propel your boat? Does your Honda generator allow for continuous operation for as long as you keep gas in the Honda?
Are my cost estimates out of line?
Prior post to Bolger group:
Cost of Torqeedo:$3300 for the 24v cruise 2.0 remote plus two 12v 210 amp AGM batteries at $400 each, or $3800 for the Torqeedo recommended 48v cruise 4.0 remote plus four 12v batteries at $400 each. Run time at hull speed would be approx 2 hours, approximately 12 nautical miles for the 4.0. ROGUE is not a marina boat so a generator is needed: $1000 - $1200 for quiet Yamaha or Honda. It is also needed for extended run time. Solar chargers are about the same cost but do not allow extended run time. $150 or more for charger ($850 to $1000 for 48v). So going with what Torqeedo recommended for ROGUE: $3800 + 1600 + $1000 + $1000 for charger/inverter (need inverter anyway so $500 for choice of electric outboard and getting a more expensive inverter/charger). Total: $6900 Nearly half the material cost for building ROGUE.
vs
Tohatsu 9.8 hp Four-Stroke with gas tank, remote control, electric start and 12v alternator: less than $3000.
Eric
--- In electricboats@yahoogroups.com, loosemoosefilmworks <no_reply@...> wrote:
>
> Electric propulsion with six years of hindsight...
>
> I'm just about to get around to taking out my Home brew Mark 2
> Electric drive in preparation to installing a new one and it has made
> me think a lot about various electric propulsion subjects. Hindsight
> is great that way.
>
> Of course you can't really talk about the Mark 2 without touching on
> the Mark 1 system which was your basic Etek motor and a golf cart
> controller a beast that was prone to serious over heating as none of
> us seemed to get the big difference between electric propulsion for
> boats and electric propulsion for land vehicles and the different
> usage they entail. Throw in the fact that sailboat needs are quite
> different than power boat needs as well...Not really surprising that
> the mark one system was something of a steep learning curve and a
> sometimes pain in the butt.
>
> That said it worked out pretty well...
>
> The Mark 2 system was not too different but I did switch to an
> Advanced Electric motor which made all the difference...Over heating
> was a thing of the past and while I did do a lot of tinkering with
> props and gear ratio it pretty much worked all the time and other than
> my own "tweaking" was a no maintenance no repair kind of thing...It
> worked from day one and is still working.
>
> So why am I ripping it out and replacing it with an Electric yacht
> drop in?
>
> Part of the reason is that I am going to be doing a lot more long
> distance cruising in the near future and a regen capable system
> seemed like a good thing. Electric yacht makes a good unit and their
> controller is first rate. Plus it is a simple solution and of all the
> electric drive systems I have come across it is the one that seems to
> have both feet on the ground and gets just what a Auxiliary propulsion
> system for a sailboat needs to be. Throw in the fact that they also
> have some very clever things in the pipe line... Bottom line is that
> any system I'd design for myself would just be a clone of sorts so
> why reinvent the wheel?
>
> So what have I learned having had electric propulsion for going on six
> years?
>
> One...It is seriously cheaper to upkeep than a internal combustion
> system. when I pulled my Atomic Four a friend also pulled his and
> replace it with a Diesel so we have something of a control group as he
> is a seriously anal retentive guy and keeps track of every cent he
> spends and the two systems work out like this...
>
> I spent $890 for the initial electric drive a year later I replaced
> the Etek with an Advanced Electric which was about $500 but was able
> to use the old controller. I switched to chain drive and bought a
> bunch of sprockets allowing me to experiment with different gear
> ratios which cost an astounding $30 from Surplus center. Other than
> grease for bearing that was it...Not a whole lot out of pocket.
>
> My friend who installed a new Yanmar on the other hand spent around
> $4000 ( he got a great deal) on his engine plus another $2000 give or
> take on installation.in the five years since he has racked up a total
> of $6000 ( just over in fact) in parts,oil changes,filters and
> suchlike. Like me he does all his work himself so this is simply parts
> and does not include labor or personal work time. His diesel usage
> averaged thirty gallons a year.
>
> In the six year I just recently replaced my battery bank..My first
> bank cost $400 ( Trojan clones I bought in Puerto Rico) which were
> still holding up but I decided to replace them as six years was
> pushing it a bit and I got a deal on real Trojans for $100 a
> piece...So the new bank cost $800. Throw in gas for my Honda 2000
> generator based on time spent charging the propulsion bank which adds
> eighty hours of generator time over the last five years which comes to
> 257 hours which equaled $342 for gas or $5.70 a month.
>
> My friend with the Yanmar and I both sail and do not do long passages
> under power. Propulsion systems are just used for auxiliary use of
> getting in and out of tight places the odd bit of powering in no wind
> situations and suchlike. In the six years I have logged about 9000
> miles of sailing while my friend has logged right around 7000 miles.
> As it happens the Yanmar is in need of a complete rebuild but will
> most likely be replaced with another Yanmar as the rebuild costs come
> pretty close to simply replacing the engine. The engine was well
> maintained.
>
> I'm sure conclusions can be drawn from all this...Though I'm not going to.
>
> What I am going to mention though is that I hear a lot from armchair
> experts about how electric does not work...I hear a lot about how
> batteries don't hold enough power to make it work and suchlike. I hear
> a lot about how we all have to wait for some techie advance that will
> all make it possible. I hear even more from people who are convinced
> about electric propulsion but still spend far too much time arguing
> battery technology and perfect hull forms instead of just doing it (
> to steal a phrase from Nike) and getting on the water. The perfect
> test bed is putting an electric motor in a boat and using it!
>
> All the best
>
> Bob
> http://boatbits.blogspot.com/
>
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