Actually, the regeneration benefits are pretty substantial, but only
useful if you're willing to put up with the drag (that could be a big
caveat).
In one review of an electric Lagoon 440, they quoted about four hours
sailing required for every hour motoring. For a boat like the lagoon,
that's great. Since you're never even going to come close to
approaching wind speed, the extra drag won't be that noticeable; this
is one area where sailing a condomaran has its benefits.
Anyway, the Lagoon is driven by a 15kw generator. If we
conservatively assume a 5:1 sailing/motoring ratio instead of a 4:1
ratio, that's 3kw being generated by the motors in sailing mode.
That's a lot of solar panel area for a boat. Even 1kw of solar panels
might be difficult to mount in a fashion that keeps the panels out of
the way of crew and sheets, and also keeps the windage down.
I'm not saying it's worth the drag. That's a personal question. For
me, most of the time, it would be worth the drag. Motoring for a half
hour on each end of a day would mean I could never bother with using
fuel on a daysail, and also keep . Or, for that matter, in most
cruising situations. If I were to be cruising offshore, though, you
can bet I'd have a genset large enough to give me full power, and
plenty of diesel to back it up.
A Visionarry could probably get away with an 10kw generator as
opposed to the Lagoon's 15kw. Using OSSA Powerlite equipment, that
should be roughly a 100kg weight penalty for the generator, plus at
least another 100kg for the batteries. Using lithium-ion batteries,
you could get up to 3200 Ah storage for 100 kg, which would be roughly
3 hours motoring a 10kw motor at full throttle (assuming you're only
going to use 80% of the battery capacity), and up to ten hours at a
more gentle pace. As with most motors, distance/time provided by an
electric motor goes way up as the throttle use goes down, and full
throttle is rarely required.
Gasoline-powered outboards would be lighter, but they definitely
require burning fuel in order to move, their fuel is explosive, and
they will never work once the fuel runs out. The hybrid electric
system is 150kg heavier, but it does cut down on both noise and fuel
use, and it has the unique benefit of providing at least some motoring
ability (4:1? 5:1?) once the fuel runs out. That's a neat feature.
The ideal setup for me would be a pivoting longtail drive or a
retractable drive at the bottom of the hull. Either way would give you
the option of disabling the regeneration and grabbing a few extra knots
when needed. I'd also put up as much solar panel area as I could in
order to keep the batteries topped off while moored.
I agree with Col about using reverse for dealing with motoring
"backwards". Since there's no need to shunt while motoring, you should
be able to use the forward gear in a fixed motor 90% of the time.
Reverse would be fine for the other 10%, especially since the electric
drive won't depend upon a manual transmission with different gears for
forward and reverse.
- Mike
colcampey wrote:
I'm planning electric drive but will use the reversability of the
electric motor for reverse. I think your idea would work better with
an outboard electric motor.
My impression re regeneration is that the benefits are too marginal
to make it worth relying on. A small increase in solar panel size
would be just as effective with no extra drag.
Cheers,
Col Campey
--- In harryproa@yahoogroups.com.au , "oceanplodder2003" <dana-
tenacity@...> wrote:
>
> I was cruising the Solomon Technologies site. I like the idea of
> electric drive. I don't like internal combustion engines, I don't
> motor very much. I don't like the idea of dragging those bloody
great
> props around.
>
> So I thought about recharging with the props till the batteries are
> nearly full, then getting them out of the water and using solar/wind
> to top them off.
>
> Would this work. A Single (or double) Solomon drive mounted on the
> centreline of the boat with a shaft that drops down to the water
when
> in use. The drive unit is hinged. The hinge allows it to rotate 180
so
> it can pass through vertical (don't do this in shallow water) and
> "shunt" so you can motor/recharge on either tack.
>
> Hope I described that adequately.
> Am I nuts?
>
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