Solar Catamaran

* Wilbur Hubbard wrote, On 3/28/2007 6:22 PM:
....
>
> The weight is a bit obscene. The battery bank alone must weigh at least
> two tons.

That seems a bit high. Plus, the motors are quite light and there's
no fuel tank. And how much does the rig and sails, plus other gear
for a sailboat weigh?

>
> Then there's the array. 100, 100 watt panels at 20lb each is a ton.
> That's a ton on the roof so to speak. And it looks like the roof is made
> out of 2X4s - more weight up high. Must do wonders for the stability
> curve. Oh, excuse me, catamarans don't have a stability curve. It's more
> like a stability square. Very good stability till it gets to 90 degrees
> then it's over she goes to stay over forever.

You keep saying that, but you seem to have trouble finding cases of
them going over.

>
>>
>> One more item: although they talk about doing 5 knots, the log is
>> filled with entries showing speeds as low as 3.5 knots, and very few
>> days over 100 miles, even though they had a tailwind much of the time,
>> plus a quarter knot current in their favor. Thus, they may have only
>> been getting 3-3.5 knots worth of power from the system.
>
> You must remember photovoltaics make almost no electricity if it's a
> cloudy day. Certainly not enough to power electric motors strong enough
> to power a vessel.

Actually, the new ones do better on cloudy days, but total output
seems to be the liming factor on this boat. I think its really
designed as a water taxi that would get a shore power charge every night.

> The could improve that thing about 50% quite easily
> by being able to tilt the roof so the array was always facing the sun.

They are at a low enough latitude so that that's not much of a factor
towards the side, and tipping fore and aft could be a problem.

> If they were really smart they could shape it like a wing sail and get
> solar and sail power at the same time. Just a thought.

If you could invent a sailcloth that functions as a solar panel, you'd
really have something!

In article <vUBOh.736$EJ6.384@newsfe24.lga>,
wilburhubbard@thefarm.invallid says...

>If they were really smart they could shape it like a wing sail and get
>solar and sail power at the same time. Just a thought.
>
An excellent thought. Be awfully heavy sails, though.

In article <RaadneSdL870bpfbnZ2dnUVZ_o-knZ2d@>, jeffmo@foo.net
says...
>
>You keep saying that, but you seem to have trouble finding cases of
>them going over.

There are many, some of them of very famous people in very famous round the
world races. It's why competition cats have an escape hatch in the bottom.
They trip on big waves when broaching and go all the way over --
permanently.
>
>If you could invent a sailcloth that functions as a solar panel, you'd
>really have something!

I have no doubt that it will be done. One type of solar cell is an amorphous
crystal, meaning it is essentially glass. Modern high-tech sails are not
made from woven fabrics but laminated sheets. Could not one of those
laminates be amorphous solar cells?

"Jeff" <jeffmo@foo.net> wrote in message
news:RaadneSdL870bpfbnZ2dnUVZ_o-knZ2d@...
over forever.
>
> You keep saying that, but you seem to have trouble finding cases of
> them going over.

I guess you have a short memory. I recall one washing up on the beach in
California upside down will all hands missing and most likely dead. It
washed up on the beach upside down. About a month or two ago.

Wilbur Hubbard

* Wilbur Hubbard wrote, On 3/29/2007 1:59 PM:
>
> "Jeff" <jeffmo@foo.net> wrote in message
> news:RaadneSdL870bpfbnZ2dnUVZ_o-knZ2d@...
> over forever.
>>
>> You keep saying that, but you seem to have trouble finding cases of
>> them going over.
>
> I guess you have a short memory. I recall one washing up on the beach in
> California upside down will all hands missing and most likely dead. It
> washed up on the beach upside down. About a month or two ago.

Yup, that's certainly one case. Although, there were a number of
interesting issues with that one, such as what were they doing out
there, and how many other people died in the same storm. One key
point is that had they stayed below they would have survived, and
anyone who might have been on deck on a monohull in the same
conditions could easily have been lost. If the EPIRB had been rigged,
they may have been rescued, since there was evidence that at least one
person was on the overturned vessel for some time.

And as I said, there have been a few such cases, but not very many.
Showing that cats have a capsize rate roughly the same as the monohull
sinking rate does not mark them as unsafe.