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Old 14-03-2008, 09:47   #16
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KHK007
"@gosstyla: On which data/experience do you base your saying that: 18 hp should be more than enough ?"

From data I collected on my 47 ft cat which I recently sailed from Valdivia, Chile to Ft. Lauderdale, FL - it has 2 x 33 hp Glacier Bay electric motors. Also from data available on other boats which I have recently been researching for another project.

This site might be of interest to you:
HANDS-ON APPROACH TO PREDICTING PRELIMINARY POWER REQUIREMENT OF SMALL BOATS

By the way I said 18 hp in answer to your question - not that I think 18 hp is adequate for what you are planning. I think my boat was slightly under powered with 66 hp.
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Old 14-03-2008, 10:00   #17
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I gather there are some new capacitors now that store efficently. DC drive motors give a wide power range and good efficiency. Are you using wind genny too? A frame across the stern can raise the blades above head height and mount all your gismo's too. De-masting and de-deiseling an old prout is easy as the mast 'sits' on the rear bulkhead. You've shed alot of weight and drag. Mahe (36?') or nesxt one up is the 'new' option and maybe they'd like to get in on the 'Green' publicity? Would they do bare or basic fit hulls for you? Would you want to keep tankage to increase you water capacity, expensive on electric to drive a water maker or skim it and allow for running the w/m. Maybe 18hp will give you cruise speed equal to a cruisers trip times but what when it gets cloudy, whats plan 'B'?
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Old 14-03-2008, 10:08   #18
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Oh yeah... I know where you can get an older Prout Snowgoose for $36K or so. It's not in perfect shape, but if you are looking for a hull to experiment on... it's a good candidate.
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Old 14-03-2008, 10:34   #19
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I don't understand how this is supposed to work...

Mid lattitude total solar radiation is about 5000 kW hours/sq m/day. +/- depending on exactly where you are.

Lets assume you need a 20 HP motor and everything in your power train runs at 100% efficiency (In our dreams!), that means you need to generate about 15 kW-h for every hour of engine operation.

Solar panal efficiency is ~15%, so I figure you will need about 20 sq meters!!! of panals to generate enough power to run the engine for one hour a day.

Forget about the batteeries you need to store 15kW-h of power.

I think I have been generous with my assumptions. Am I missing something or did I slip a decimal point?

Seems to me you'd be better off just building a sailboat that didn't need an engine at all... People DO sail without engines...
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Old 14-03-2008, 10:48   #20
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Hi,

I know that in the end I can only try to figure it out with the whole system. The most difficult decision is to decide on a cat (hull). All the other parts can be changed quite easily. I have a masters in experimental physics and crossed 3x the atlantic and would really like to try it testing different system components like a case study. But if some people who own cats with electric engines like the Lagoon 420, Fastcat 435 can give me an advice on how much power they need with which configuration (brand of batteries, genset, electric motors, propellers) it would be easier for me...

@gosstyla: On which data/experience do you base your saying that: 18 hp should be more than enough ?


Thanks,

Kai
Hallo Kai

to power the Fastcat 435 at 5 knots no wind conditions we need 3 kw per side of shaft power or a total of only 6 kw
with 2 x 4.5 kw we get 6.5 knots
with dual 9 Kw motor we get 9 knots of speed

Greetings

FastCat 435
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Old 14-03-2008, 11:37   #21
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Hallo Kai

to power the Fastcat 435 at 5 knots no wind conditions we need 3 kw per side of shaft power or a total of only 6 kw
with 2 x 4.5 kw we get 6.5 knots
with dual 9 Kw motor we get 9 knots of speed

Greetings

FastCat 435

I think you need a masters in experimental physics to generate that much solar power on the deck of a boat. This engineer can't figure out how to do it!
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Old 14-03-2008, 14:29   #22
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I think you need a masters in experimental physics to generate that much solar power on the deck of a boat. This engineer can't figure out how to do it!
Check this out:

transatlantic21: transatlantic21

They built a 2nd deck, basically to lay out solar panels which I assume well exceeded the cost of the hull. They did make it across the Atlantic, but I'd hate to see what happens when you're in a storm (dark skies) and caught trying to get off a lee shore or some other kind of situation.

It's an interesting and fun project... but not so practical.

I went through some figures to see if I could build steam propulsion a few months back. When compared with diesel, nothing works better. It's just got more engergy per unit volume and unit weight than any other fuel used for this purpose. I suppose nuclear would be best, but I hear it's hard to buy that stuff!
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Old 14-03-2008, 14:29   #23
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1 + 2) The Lagoon cats are to heavy and not aero- and hydrodynaic enough. They had to increase the power of their genset from 11 to 17 kW. 11 KW would be feasable with a cat of 15 * 8 m but not 17 under real conditions.
Kai,

I'm not advocating buying a Lagoon. I'm saying to look at the components they use.

While you're at it, look at Island Pilot. They just built the boat you describe, except it has diesel backup.

Brett
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Old 14-03-2008, 15:15   #24
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Hi,

@fastcat435:

Thank you for your figures!

I send you a mail asking if it would be possible to use your Fastcat for this purpose. But I got an answer that the project is interesting but you are not able to deliver a cat before end of 2011...

Otherwise after having seen a lot of cats in the meantime your Fastcat 435 looks like beeing the most appropriate cat I can find on the market apart from ordering a very special one...

@GreatKetch:

With 5000 kW hours/sq m/day I wouldn't even ask here but do it!!!!

@ssullivan:

The Prout Snowgoose 37' are not large enough to have enough surface except for doing first tests... If I wanted to do my circumnavigation under sail with a good and not too expensive cat...

I want to use an ocean going cat which the sun21 cat isn't really...

@LtBrett:

I checked the components and with Lagoon guys at the Cannes boat show last year.

If the guys frominfo@dsehybrid.com could build a cat 6 to 8' larger to be able to put more solar panels on with the same weight by alightening the cat from american style luxury to make the interor look like a normal sailing cat it would almost be the vessel I need...

Kai
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Old 14-03-2008, 15:25   #25
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@ssullivan:

The Prout Snowgoose 37' are not large enough to have enough surface except for doing first tests... If I wanted to do my circumnavigation under sail with a good and not too expensive cat...

I want to use an ocean going cat which the sun21 cat isn't really...

Understood. I meant to say that the Snowgoose would be a good hull to experiment on at such a dirt cheap price. The hull is in good shape on it... I was looking at buying it. The deck, however, wasn't in great shape, so I did not buy it for my purposes. Perfect experimental boat @$35K or so.
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Old 14-03-2008, 17:41   #26
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Check this out:

transatlantic21: transatlantic21

They built a 2nd deck, basically to lay out solar panels which I assume well exceeded the cost of the hull. They did make it across the Atlantic, but I'd hate to see what happens when you're in a storm (dark skies) and caught trying to get off a lee shore or some other kind of situation.

It's an interesting and fun project... but not so practical.
Not so practical? A bit of an understatement! Did you look at how long it took them to get across? Going with the wind and current the whole way? They were nothing hardley more than a drifting log who made steerage way! I know their website CLAIMS they can do 5-6 knots 24 hours a day, but just look at their actual progress... how many 120 mile days did they do????

Don't get me wrong, solar energy has potential, but powering a boat isn't even theoretically possible for the foreseeable future. The power numbers just don't add up.

As a stunt? Sure, go ahead. But it's right up there with rowing across the Atlantic.
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Old 14-03-2008, 17:49   #27
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I've always thought it would be interesting to make an entire set of sails from amorphous solar cells or a main sail from a patchwork of high quality efficient crystaline cells.

"but powering a boat isn't even theoretically possible for the foreseeable future. The power numbers just don't add up."

Very true
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Old 14-03-2008, 17:53   #28
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Not so practical? A bit of an understatement! Did you look at how long it took them to get across? Going with the wind and current the whole way? They were nothing hardley more than a drifting log who made steerage way! I know their website CLAIMS they can do 5-6 knots 24 hours a day, but just look at their actual progress... how many 120 mile days did they do????

Don't get me wrong, solar energy has potential, but powering a boat isn't even theoretically possible for the foreseeable future. The power numbers just don't add up.

As a stunt? Sure, go ahead. But it's right up there with rowing across the Atlantic.
I agree 100%. I figured I'd show you the link since your post had asked how someone could get a lot of power from solar mounted on deck... answer? Build another deck! ha ha
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Old 14-03-2008, 21:54   #29
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"but powering a boat isn't even theoretically possible for the foreseeable future. The power numbers just don't add up."

Very true
ummm...

Island Pilot DSe Home Page

Brett
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Old 15-03-2008, 06:15   #30
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Hallo Kai

our delivery time is now the end of 2009 because of our new factory that we are moving into , it triples our production capability,s .
Standard the green motion is delivered without a diesel generator and it is my feeling if you are in no hurry you do not need one with 1800 watt of solar panels on board and a masthead mounted wind generator with 300 watt capacity.

Greetings
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