[Attachment(s) from Julian Webb included below]hi- i apologise for the poor quality of the attached info, i had to photograph someones copy in limited time.- attached file is from Lynch (the early motor man) who spent half his life actually doing it while others waffled, postulated and argued theory.- empirical beats theoretical every time, no contest.- he beautifully, practically and sensibly explains why you can use an electric motor of 1/3 the h.p of the old i.c. engine and get the same results, unless you have high top speed as your goal.- i contacted Fischer Panda, Aquawatt, Mastervolt and others and all i got were increasing prices and decreasing feedback! when i sent them all the figures and asked them to suggest a system, i kept getting things like "the biggest prop you can use is 480mm". and when i asked isn't it better to have a larger prop at slower rpm, they too ran away, "experts" leaning on theory without practice, and all those nice software fields to fill in, much more scientific!- i've gone it alone and if it had not been for the engineer/welders health would have been finished by now.- be VERY careful using off the shelf a.c. 3 phase industrial gear. the net has a few examples of how this usually leads to disaster. it shouldn't, and thanks to 6 months hunting down those disasters and finding a great motor/drive supplier who has stuck with me i'm sure i'm ok. we set out the whole system in a friends factory and ran it under every situation we could think of, so it should work fine.- remember most of "the" electric drive package suppliers use 3 phase a.c. motors and slap a low voltage inverter on it.- have a look a most of their torque curves and you'lll see they're no better than the average 3 phase a.c. motors........ at 10 times the price!!!- if weight is an issue then p.m. motors can't be beat.- super important to remember is that prop choice can make or break your conversion. i CANNOT find a prop designer who will design me a prop. the minute they hear "electric drive" they back away, which is bloody stupid as i can give them motor torque, rpm etc figures and i have drawn up a hull plot. all they want to know is what the old engines were and what the speed figures were at what revs. to me this proves they know sod all and have software that they have fields that have to be filled in or it/they can't produce a result.- i would still be VERY grateful to anyone who can suggest a prop maker (anywhere in the world) who can design a prop using the existing boat and equipment, not just use the old drive specs and tweak it a bit.- anyway enough of my burblings, i hope this answers a few questions, and remember while this isn't a glossy brochure with gorgeous boats and tits in bikinis, it is proven information AND it is adaptable by anyone to any situation.good luck, julianOn 22 December 2012 15:07, oldgoat1968@att.net <dcsteere@dcsteere.com> wrote:
I dropped them a line. Don't know if they're willing to chat informally on a hobby level or whether they prefer to run a money-making business. I'll let you know how the conversation goes.
--- In electricboats@yahoogroups.com, matt elder <mattelderca@...> wrote:
>
> I still say you should talk with the New Electric guys over in Amsterdam.
> The setup they have should work fine in your application. You could go further if you want to spend the cash, maybe dual motors?
> The links are in my post below in this thread.
> Do it!
>
>
> Â
> mattelderca
>
>
> >________________________________
> > From: "oldgoat1968@..." <dcsteere@...>
> >To: electricboats@yahoogroups.com
> >Sent: Saturday, December 15, 2012 1:45:38 PM
> >Subject: [Electric Boats] Re: Conversion of stern drive
> >
> >
> >Â
> >Actually, I'm more interested at this point in doing preliminary design planning. Does it make any sense at all? My 5.7L V-8 has max torque around 300 ft lbs at around 3,000 RPM. HP peaks at around 4,000 RPM at around 215 HP. It has a 99 gal fuel tank that would provide plenty of room for a battery bank. Based on my positive experience with an EV, I think I can get by with far less torque (and horsepower, too) from an electric motor, but I lack the skills to do a simple, back of the envelope calculation of how much power and torque I'll need. It would be nice to occasionally achieve a plane for short periods of time and to have a total endurance of maybe 3 or 4 hours, most of it at hull speed. Does this make any sense at all using a typical LIFEPO4 battery pack, and motor/controller similar to those the EV enthusiasts are using? The boat is pretty big (26 foot Sea Ray Sundancer) and it may just be totally in-feasible.
> >
> >--- In electricboats@yahoogroups.com, "Reid" <axius@> wrote:
> >>
> >> Dave,
> >> There is a stock Mercruiser drive which mounts the gas engine midships and uses an automobile type drive shaft to the rear. This system is shown in most Mercruiser manuals. This may be easier than trying to support an electric motor off the 2 spring mounts on the transom plate, plus a support from the front motor mounts?
> >>
> >> --- In electricboats@yahoogroups.com, "oldgoat1968@" <dcsteere@> wrote:
> >> >
> >> > Brent, I'm very interested in this conversation. I, too, have a 1985 26' Sundancer with a 5.7L V-8 Mercruiser inboard-outboard. Mine is a B-2 outdrive, a conversion from the original B-1 model. I have completed an EV project on a 95 Acura Integra. I used a 3 phase AC motor (AC-50) which is conservatively rated at 59 HP and it has plenty of torque and power to push my car along quite nicely. Economy is excellent, too -- a measured 2.6 cents per mile over about a six month -period (a little over 3,000 miles). My thought is that a similar sized motor might be sufficient to drive my big boat. Not trying to win races here, but occasionally getting it up on plane would be a goal. Seems to me it would be relatively easy to configure a motor mount for a 9 inch motor and an adaptor plate/hub arrangement that would mate to the splined shaft coming out of the Mercruiser. Anybody every try such an arrangement?
> >> > Dave
> >> >
> >> > --- In electricboats@yahoogroups.com, "mattelderca" <mattelderca@> wrote:
> >> > >
> >> > > There are some brilliant guys in the Netherlands that frequent this group.
> >> > > http://www.newelectric.nl/
> >> > > Although not as big a project as yours, their install would scale up a bit and fit well depending on your expectations. Not sure if you could run around at planning speed for any real length of time, but low cruising speeds should prove very doable. Be sure to watch their Youtube videos, as they say a picture is worth a thousand words.
> >> > >
> >> > > http://www.youtube.com/user/NewElectricPowerboat/videos
> >> > >
> >> > >
> >> > >
> >> > > --- In electricboats@yahoogroups.com, "brent.jaybush" <brent.jaybush@> wrote:
> >> > > >
> >> > > > Has anyone attempted or been successful converting a fairly large stern drive to electric drive?
> >> > > >
> >> > > > I have a 1979 26 ft. SeaRay powered by a Mercruiser/Chevy 260 HP 350 CU V8 gas hog with a 100 gallon tank for the black gold.
> >> > > >
> >> > > > Just beginning to research the possibilities. Certainly no shortage of space for batteries.
> >> > > >
> >> > > > Edison Marine has created a large 17' runabout with enough powering for hull speed, so it seems it should be feasible, perhaps with limitations.
> >> > > >
> >> > > > I already run it around MDR at a sea snail's pace using a surplus trolling motor on the swim step, so a proper EV design should do far better, but achieving plane speed is probably out of the question.
> >> > > >
> >> > >
> >> >
> >>
> >
> >
> >
> >
> >
>
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