Why the expense of a torqueedo? 4mph for a 21’ boat (especially a displacement hull like the redwing) would be easy work for just about any 24v trolling motor. You could even look at one of the engine mount models that Minn-kota makes, for about half the cost of the torqueedo. Also, it could be mounted on the bottom of the hull, use a standard rudder and it would be much like an inboard installation. 4 or even 6 group 27’s in a parallel/series arrangement should give you plenty of range, and be fairly affordable.
IMHO Rudders are WAY more effective for slow speed handling than using a motor for steering. My power friends are amazed how maneuverable my CP16 sailboat is with a trolling motor and rudder. It turns on the dime.
Kevin
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of luv2bsailin
Sent: Thursday, September 23, 2010 7:20 PM
To: electricboats@yahoogroups.com
Subject: [Electric Boats] Re: what are my electric options.......
That does sound like an almost ideal application for electric power. I've mostly worked with inboards, but have heard good things about the Torqueedo. I would look at the 48v models. Non-submerged-motor types like the Parsun tend to be noisier, and have the added complication of cooling water pumps and such.
For batteries, bank of T-105 6v golf car batteries and a 20a charger would probably do it. I doubt if you'd need over 20A to move a Redwing at 4 mph with a 48V system. My electric Albin25 does about 4.5 mph at 20 A in calm conditions. Is there any current on the canal? That could change the equasion of course.
Speaking of golf, It has been rumored that Scotland has a few courses. You might find a good source of battery and charger info at one of those.
Good luck, that sounds like a fun project!
Jim McMillan
--- In electricboatyahoogroups.com, "runnerie42" <geoffgamsby@...> wrote:
>
> Good morning tom,
>
> You are correct electric is the great for this application. There isn't much to break on an electric motor so I doubt you will have to Swap the motor out.
>
> If the motor is using 30 amp to travel 4 knots. it would take you just under 4 hours to get halfway up the canal which would be 120 amp-hours (15 nm / 4 knot =3.75 hrs round to 4 hrs, 4hrs X 30 amps = 120 amp) This is the usable amp-hour you should have in your battery bank. 50% discharge (suggested lead acid discharge) you will want a 240 ah bank. 80% discharge (some AGM & lithium) ~150 ah
>
> There are several options out there, torqeedo, & parson are two major MFR.
>
> geoff gamsby
> www.straightturn.net
>
>
> --- In electricboats@yahoogroups.com, "incunabulaonline" <tomfindlay@> wrote:
> >
> > Hello Electric Group,
> >
> > I'm building a Redwing 21 as a two berth charter boat exclusively for a small 30 mile canal situated here in Edinburgh Scotland. Hirers would charter for a two day, one way cruise including one overnight stop halfway along.
> >
> > The batteries could be charged if required, at a marina halfway along the 30 mile route.
> >
> > I dont want an inboard electric engine and would prefer outboard(s) for practical reasons if a breakdown occured. (easy to swop engines)
> >
> > What are my options, remembering it's only for a 30 mile journey with an overnight break halfway along. The speed limit on the canal is 4mph
> >
> > I think electric is an ideal solution in this instance, but what kind of outboard(s) and what kind of batteries and all the gubbins that goes with it, like an onboard charger that can simply be plugged in on the marina?
> >
> > Tom
> > Edinburgh
> >
>
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