I agree a lot depends on what the client wants .and what proportion of sailing he requires . 3KW of panels is going to leave little room for sails . and perhaps 1 ton is the limit to the battery size .Say 40KWH. 3KW in good weather gives about 9KWH in UK upto 12 KWH in south west US or Australia.
Chris S
--- In electricboats@
>
> Hi there,
>
> I rarely run at full throttle and the Torqeedo will soon show an over
> temperature warning at full throttle and automatically reduces power
> down to about 4kw. But even at that your estimate of range is about
> right for full speed operation.
>
> But my usual power setting is around 1000 watts, which gives me say 3
> to 4 knots. And at three knots for 8 hours, I'd have 24 miles range
> (thats 80% discharge). Most of the time I only use it for say 10 to
> 20 minutes before getting the sails up and no longer need the motor.
>
> When the wind is contrary and the channel narrow, requiring lots of
> short tacks, it is useful to have the motor running at a low throttle
> setting, even just a few hundred watts, to help her to tack easily and
> to maintain way when the wind knocks. I find this to be a nice
> compromise - it doesn't use much power but makes the sailing much
> easier, and gets me to the destination much quicker than sail power
> alone.
>
> Oh man, I envy your budget! 100 kwh would suit me just nicely. But
> alas, I couldn't afford the weight penalty of such a pack. (1200kg).
>
> In my limited experience I find that getting out into the ocean means
> that I use little or no power for the motor. My recent trip from
> Brisbane to Sydney took a couple of days and the motor was only used
> while still landlocked. The motor was needed for getting out of the
> Caboolture river, and then navigating some channels in Moreton Bay and
> then crossing the bar at Gold Coast Seaway. I think that used maybe 6
> or 7 kwh. And getting into port at Broken Bay required running the
> motor only for a few minutes to pick up a mooring.
>
> The advantage that I have is that my boat is an ex racer and sails
> really well, and so doesn't taunt me to run the motor even in light
> conditions. My last couple of small adventures from Broken Bay to
> Sydney Harbour were sailed all the way in light winds (5 to 10 knots)
> and the handful of other sailboats at sea at that time were all
> motoring or motor-sailing. From what I've seen those Bavaria's sail
> really nicely and I'd expect the lure of motoring would also be limited.
>
> It could be that the success of your conversion may hang on the
> mindset of your client and the kind of sailing he/she does. Is he
> inclined to want to motor at the least opportunity? Or does he love to
> sail, and will not even be wishing to run the motor except when nosing
> up to the dock? Will it be only used at weekends, or sailed around
> the world?
>
> Another source of power you'll want to consider is the power of the
> boat through the water when sailing. Regen from the motor when under
> sail has been discussed here quite a lot and there's not a clear
> consensus on it. For some it has proved successful and others have
> rarely seen it. A search of the archives will turn up some
> interesting reading. A towing generator or a wind generator that
> converts to water turbine is another option as a power source
> especially if ocean passages under sail are likely.
>
> It will be a challenge finding a way to fit the panels and wind
> generators on board. Could it be that you could approach it from the
> opposite direction? That is, figure out what solar and wind power you
> can reasonably fit on the boat, and from that estimate speed and range
> capability and whether that would that satisfy your client.
>
> I hope you have fun with your designing...
>
> Cheers
>
> Chris
>
> On 06/05/2010, at 4:38 PM, r1ck_r0ck_4_
>
> > Thanks everyone for your expertise. I still have a lot of research
> > to do.
> >
> > Chris, How long does your 10kwh lithium propulsion pack last? The
> > graph of your energy consumption shows that you need 5kw to go 5kt,
> > so you can only go about 8miles max motoring?
> >
> > I was looking at putting in 100kwh of lithium for the main drive
> > pack into the bavaria, but I feel this is still useless unless I can
> > top it off with solar and wind if the owner decides to take it out
> > for a long cruise out in the ocean for a few days.
> >
> > My thinking is the only way for the boat to match the same 210L of
> > diesel's capability is to have a lot of solar and wind energy
> > generation. I estimated about 3000W of solar panels and 2000W of
> > wind will be needed, but it'll be very difficult to install
> > everything in a nice package.
> >
> > Only if he could trade his boat for a 50' Catamaran... Then I'll
> > have plenty of room for solar panels.
> >
> > .
> >
> >
> >
>
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