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  #1  
Old 02-24-2010
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Announcing the Lean Green Machine Challenge

Here's the throw-down on this hoe-down:

Build an electric propulsion system that works as well as, if not better, than my diesel engine.

Here's the low-down:

I have an aging Yanmar 1GM-10 engine powering my Georgian 23. I have a 10 gallon fuel tank. My engine puts out a raging 9 hp and 13 ft/lbs of torque. It burns 1/3 gallon/hour at cruise (3000 rpm) At that engine speed, it pushes my boat comfortably at hull speed (5.5 knots, roughly). Based on the numbers, under power I have a 30 hour range. Total weight of the propulsion package including full fuel tank is under 320 lbs. it also has an alternator which handles charging my starting battery and house battery. My slip is on an unserviced dock which means that shorepower charging is not an option so we are already running pretty lean and mean with our electrical usage. I don't have much room for a big solar array, although I am installing 30 watts worth of panels on my new davits. because this is a small cruiser, there is not a lot of spare space aboard, so it's nice to have a compact propulsion system that hides under the cockpit sole.



Sadly, I need to freshen my engine this year. Compression is getting lowish, so I see new rings and a freshened head in my future. Likely gonna cost me about $1000 and a weekend of my time (I do my own wrenching.) I am contemplating whether it makes more sense to pull the engine out and install a new one, which would be in the $5k range.

So, the discussion about electric propulsion got me thinking...


If a new engine would set me back $5k, then:

**I will offer $1000 to anyone who can build and demonstrate a reliable system that will do what my Yanmar does for the same money, weight and space. Furthermore I will BUY the system that meets the parameters outlined below:**

30 hour range at hull speed*. (*New! Revised! Proof that I really really want somebody to succeeed! The range requirement is now 50% LOWER!!!!!!!! 15, FIFTEEN, ONE FIVE hours!!)
Charging onboard electrical systems.
Total weight under 320 lbs.
Must fit under cockpit. 74" long x 24" wide x 20" high.
Total cost under $5000.


This is a small cruiser, 20' at waterline, displacing 4350 lbs.


So all of you inventors, dreamers, clean/green propulsion proponents, this is your change to convert me, and earn some cold hard cash at the same time.

Last edited by bljones; 02-24-2010 at 10:04 AM.
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Old 02-24-2010
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BL,

The 30-hour criteria is a bust. It's not going to happen, not even if you dropped the extra coin for Li4Pho batteries.

At the very least, it would take more space and more weight than your old system did by a considerable margin.

All other criteria are do-able.
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Old 02-24-2010
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I'd point out that the charging onboard electrical systems is also a bust... unless the system is a hybrid electric with some sort of fossil-fuel burning component... it will need a separate source to charge the system itself...

BTW, there's no way you'd get enough stored electricity to power the boat for 30 hours at cruising speed with a weight limit of 320 lbs. Just ain't gonna happen. Four T105 golf cart batteries are almost 300 lbs... and they only supply 450 amp-hours at 12 VDC.... or 225 @ 24 VDC, at a 20 hour discharge rate.
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Last edited by sailingdog; 02-24-2010 at 10:06 AM.
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Old 02-24-2010
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Ohhh, alright, I guess I have to sacrifice SOMETHING.

Let's cut the range requirement by 1/2.
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Old 02-24-2010
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SD, notice that I dropped a hint in the description of my current charging system? A replacement of my Yanmar has to do all of the things my Yanmar does, but that doesn't mean it has to be a single system.
Think outside the box, man!

Come on, I am not unreasonable. How would you overcome my charging needs??
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Quote:
Originally Posted by bljones View Post

30 hour range at hull speed*. (*New! Revised! Proof that I really really want somebody to succeeed! The range requirement is now 50% LOWER!!!!!!!! 15, FIFTEEN, ONE FIVE hours!!)
Charging onboard electrical systems.
Total weight under 320 lbs.
Must fit under cockpit. 74" long x 24" wide x 20" high.
Total cost under $5000.


I'll build your system for $1G (maybe per day).


Remove two numbers, like the $!G total labour, and $5G total cost and you could have your drive train and a better boat in the process.

But clearly that was your point. An old POS gas engine is always going to be cheaper, hence the reason I use them.
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Old 02-24-2010
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i will trade you a 45 watt panel for your motor tommarrow
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Old 02-24-2010
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EASY!!!

2 beautiful paddles or oars; cost less than $100, weigh much less than 300 lbs. As a bonus, you get to stay in shape with a great cardio workout and save space too.

Perfect!!!
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Old 02-24-2010
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Quote:
Originally Posted by Architeuthis View Post
I'll build your system for $1G (maybe per day).


Remove two numbers, like the $!G total labour, and $5G total cost and you could have your drive train and a better boat in the process.

But clearly that was your point. An old POS gas engine is always going to be cheaper, hence the reason I use them.
Well sure, if we remove the total cost, then OF COURSE I could have a better boat, because money would be no object... but it is. I do not have an unlimited budget. Most sailors i know don't have an unlimited budget. Even Larry starts to hesitate writing cheques after the first 10 mill.

Where are you getting "POS gas engine" from? let's compare apples to apples- I wouldn't put a gas engine in, or take the hack approach of simply strapping a 9.9 hp longshaft outboard on the transom- THAT would be significantly cheaper and easier, but unsuitable.
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To get us in the ballpark, I will assume that 5hp will push you to hull speed(this might be low depending on the boat) which is 3.7KW. To run 30 hours, you need to store 111kWhrs of electricity. The storage required for this would not come even close to your weight or space requirements. It is also way too big of a system to charge without an enormous solar array which is not possible in this case.

To recharge this, if you do it over 10 hours (this is quite a while if you can't charge at your own slip), you would be charging at 50A @ 220V not accounting for any inefficiencies. This is impractical so you would probably have to double the charge time.

If there is a solution to this, it is going to have to be out of the box. I am not a fan at all of hybrid electric propulsion systems for boats unless they are used to extend range in rare circumstances on a truly electric system. These systems are less efficient, have more stuff to go wrong, etc. The reason why hydrogen was hyped for so long is that it is a reasonable media in which to transfer energy quickly. Too bad it is not in the realm of practical for a project like this.
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