I think Keith brings up some good points to consider about the waters and types of sailing one plans to do when considering putting together the system.
San Francisco Bay may have more rapidly changing conditions than the Long Island Sound waters I sail in. Since I tend to cruise and spend time at anchor I feel perfectly comfortable just having a wind generator, solar panels and a portable Honda 2000i for charging my 48 volt bank on my 30 foot 8 ton catboat when the need arises or to push the boat at three knots without draining anything from the battery. But, my Long Island Sound home waters also offer harbors or anchorages all over the area if I should ever want to duck into them to avoid bucking currents, winds etc... But, even when I had a diesel I would avoid plowing into head winds or bucking currents. 1) Because it was not fun and 2) It was fuelish. That does not change when going electric. We also need to remember boats were sailing in all our waters long before anyone ever heard the words prop diameter and pitch. The prudent mariner whether with electric or ICE on board also plans for
those times when nature is more a hindrance than help and/or the technology fails. I certainly am planning for such situations. I hope never to have to use them. Ultimately, I think it pays to have the luxury of time. My biggest screw ups where when I tried to push things to meet (often self imposed) deadlines. Those were costly learning curves. The tides and currents will eventually change and so will the wind. You just need to make yourself comfortable on board to wait for these changes or sail a more favorable, comfortable course until they do change. But, if one must absolutely, positively have get back to the home port ASAP well then there is a cost to be able to do that in both weight and dollars. It is all a trade off in the end. What works for me in Long Island Sound may not work in San Francisco Bay. Each of us has to consider how and where we sail and design systems that meet our needs and expectations. One size does not fit all.
Mike
http://biankablog.
--- On Tue, 6/2/09, aweekdaysailor <aweekdaysailor@
From: aweekdaysailor <aweekdaysailor@
Subject: [Electric Boats] Re: Boats over 30'
To: electricboats@
Date: Tuesday, June 2, 2009, 12:56 AM
Hmmm...I did the conversion based on those same assumptions - that I'd be able to catch the ebb out, slack back, and wouldn't get slammed in the nose - but real life intervenes (at least at my skill level).
I've found more often than I'd care to admit that on my boat, < 1/2 yours in displacement, that the rig you describe is inadequate when, for example, the tide is 2' higher than the book estimated and turns an hour earlier, or it gets hotter in Stockton than planned and the big Bay wind-machine turns on. Then you're cooked (unless you can anchor out without repercussions from the Admiral)
I believe you'll need at least twice as much motor and 4x the batteries you describe below. 4 hours at 3 kts (~50amps is my guess) is 200AH - you need 3X that at minimum to keep your batteries healthy. And yes these are sailboats, but you know how fickle wind on the Bay can be.
It isn't just speed...it's sufficient power to punch through a headwind, chop, or a contrary current. That's a combination of the horsepower AND the prop - and then how long the batteries will last.
I'll go back to my previous post - imagine all the trips you've taken in the bay - now imagine you started with 2g of fuel (and actually, ~50% of the horsepower) - that's what it's like on electric. Generator can help - but not as much as you think unless you turn it on way sooner than you need it. And most people only get a 1KW charger - 20amps won't push you very fast.
That is a very cool but stoutly built, heavy and I think full-keel boat. It's going to want some horsepower I think. You can start small and do some tests in the estuary to see what the real-world performance is like, but design nd budget it so you can easily add more battery and motor for best results.
-Keith
--- In electricboats@ yahoogroups. com, "sailingpm" <sailingpm@. ..> wrote:
>
> I've been reading this board for a few years now and have since gotten my own boat over 30' and have been waiting for the right time to jump in. I know nothing of the technical electrical stuff but from what I've read here and see what's available for sale. I am mechanically able to create my own set up, but I guess the question always comes back to power, and juice, which for me is still hard to determine will be enough. Below is my info, but I still need confirmation that this is suitable and/or reasonable. Thanks for the great posts. I'm still learning much.
>
> Union Polaris sailboat
> displacement type hull
> 36' on deck
> 32' waterline
> 22,000 lbs
> perkins 4-108 (taken out)
> 100 gal diesel tank (taken out)
>
> The challenge for me is to be able to mosey motor (3 knots?) out of the Alameda Estuary to the Gate and back on battery power in mild wind and at slack water. By then the batteries should be down to 80 - 70%? I will have a honda 2000 generator for anything further and to stop depleting the batteries. Speed is not so important. But I figure this is the range I'd like to make me feel comfortable on batteries only at a reasonable pace.
>
> I'm looking at one 48 volt Etek-RT
> 8 - 6 volt trojans for 48 volts
> mounted a la thoosa style with the pulleys and such at 2.3:1.
> My prop is 15", but I don't know pitch. It is in an aperture behind the rudder.
>
> Is this a reasonable starting point for a setup? I've seen a similar setup in the photos section in Vallejo.
>
> Thanks for sharing.
>
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