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  #11  
Old 09-08-2012
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Re: Optimal propulsion system

I had been thinking about an electric option for my Pearson 30 for if/when the A4 dies. Electric motors are very efficient. With a timing belt reduction you have almost limitless combination for matching the ideal motor rpm to the ideal prop rpm. You will find numerous posts and articles expounding on the benefits of electric propulsion so I will not go into detail here. I will say that most of the claims are reasonable accurate. The one drawback (and it is a major one) is energy storage. Batteries are just not up to the task of replacing fossil fuels... yet.

The serial hybrid approach is one way to bridge the gap at this time. While not ideal it is, in my opinion, a good stop measure. As battery technology improves the only change you will have to make is replacing the batteries and possibly the charging system.

You will have to determine if electric propulsion will work for your mission in the first place based on your distance and speed requirements. For me as a lake sailor it is a good fit. When I was on the Chesapeake Bay; not so much.

The reduction in complexity and the very small size of an electric motor required to power my boat to hull speed was remarkable. The largest expense was batteries. Both financial and physical space/weight.

As I look at daysailer to replace my keelboat (new mission requirements) I am 90% set on electric for aux propulsion.
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  #12  
Old 09-08-2012
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Re: Optimal propulsion system

The lighter the boat the better electric gets. You can cruise the flats fishing with a trolling motor for a long time.Keep us informed on how the project goes. Interesting subject.
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Old 09-10-2012
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Re: Optimal propulsion system

Quote:
Originally Posted by davidpm View Post
She would rather sail at 2 to 3 knots than motor at 5 knots.
Me too. So you adjust your expectations, don't set a schedule that has you going near hull-speed all the time, and enjoy life at a slower pace. Easy-peasy, and doesn't cost a penny.
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Old 09-10-2012
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Re: Optimal propulsion system

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Originally Posted by denverd0n View Post
Me too. So you adjust your expectations, don't set a schedule that has you going near hull-speed all the time, and enjoy life at a slower pace. Easy-peasy, and doesn't cost a penny.
Actually for this investigation I'm expecting the following:
It will not be cheap
It will not be simple
I want to be able to go hull speed whenever and for as long as I want as long as long as I'm willing to run the diesel.
I want to go quietly for as long as the batteries hold up when the diesel is not on.

I'm pretty sure it is doable the real question is if I'm willing to pay for it in both time, money and complexity.
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Old 09-10-2012
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Re: Optimal propulsion system

Just an observation about battery capacity. I have a lot of interest in electric for cars and motorcycles, and the batteries are not where they need to be yet, true.

I am assuming a 30 ft sailboat:

For the space that you save by putting in an electric motor, and weight reduction, say 200lbs (based on an atomic 4 is about 350 w/fluids). How many 6v golf cart batteries could you wire in that space. I know with the size dimensions of my engine compartment I could probably rack 6 - 6v golf cart batteries @ 72lbs each 423lbs. So you gain about 200-250 lbs, of course now you don't have to carry fuel so subtract that weight and you aren't too much heavier.
Now with that much power - 1560 amp hours @12v based on
http://www.trojanbattery.com/Products/T-1456V.aspx
and looking at the speed to distance assumptions of the Vetus mentioned earlier in this post, you could get quite a good distance for minimal weight addition. I have 150-200lb friends so I will bring one less and it is a wash haha.

Then it really all goes back to charging, and if you are not a long distance cruiser you can most likely do it right at the dock. With shore power and that setup you could even use a golf cart charger/charging system.

Additionally I am currently setting up 4 of those batteries as my house bank which has 2 huge 12v monsters of the same relative size, but only 200 AH total. so there is an additional reserve 520AH, optimally of course, but engine starting battery becomes obsolete and there is space for 2 more.
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Old 09-10-2012
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Re: Optimal propulsion system

Is the objection that fossil fuel is being burned or noise and vibration that is upsetting the peace and tranquility? IF it is the latter wouldn’t it also be prudent to look into ways to dampen the noise and vibration to a reasonable level? Some of the modern small diesel cars are very smooth and quiet. Case in point the VW TDI.
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Old 09-10-2012
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Re: Optimal propulsion system

"The hunter e33 has this as an option"
Only one problem, Hunter's parent company are now out of business, so you'd have to try finding a leftover or a used one.

I don't see generator noise as being as issue since one of David's criteria was "not missing a slip assignment" which means he can just plug in and recharge at the end of the day.

Find a Chevy volt, gut the drivetrain and the very economical generator from it, and voila, the rest is just wrenching. Especially if you can plug in most nights to recharge.

Short of that, I'd wonder if new engine mounts (after 5 years they've stiffened up and make for a noisier shakier boat) a shaft isolator, balancing, and some engine bay insulation might not be the best ways to tackle this.
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Re: Optimal propulsion system

Silly idea perhaps, but what about an outboard motor on a bracket? Ugly perhaps, but not overly expensive in comparison. The 4 stroke ones are pretty amazingly quiet. Could use that most of the time, then fire up the big diesel if you really needed the power. That would probably be the most economical and simplest solution.


FWIW I think electric is a great idea overall, the power generation potential while under sail would seem to me to be a nice bonus too. The costs certainly aren't insignificant though, especially if you want to be able to move at hull speed for as long as you have fuel. If my Yanmar dies I may got that route.

It's the last idea that I don't really understand perhaps. What is your current fuel range at hull speed? If you could have enough batteries for even 50% of that range, and a generator that could charge your batteries at 50% of the consumption rate(5kw for example) you could get the same range as your current setup if needed, much easier than trying to have a generator that will produce 100% of the electric motor's requirements. Or 75% of the range on batteries at hull speed, with a generator that could produce 25% of your requirements... Which would get you almost to the Honda 2000 territory.
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Old 09-10-2012
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Re: Optimal propulsion system

Quote:
Originally Posted by RNDROB View Post
Is the objection that fossil fuel is being burned or noise and vibration that is upsetting the peace and tranquility? IF it is the latter wouldn’t it also be prudent to look into ways to dampen the noise and vibration to a reasonable level? Some of the modern small diesel cars are very smooth and quiet. Case in point the VW TDI.
That looks interesting but I saw only 300hp engines. Need a bigger boat.
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Old 09-10-2012
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Re: Optimal propulsion system

Quote:
Originally Posted by hellosailor View Post
"
Short of that, I'd wonder if new engine mounts (after 5 years they've stiffened up and make for a noisier shakier boat) a shaft isolator, balancing, and some engine bay insulation might not be the best ways to tackle this.
Has anyone done this? What was the result?
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