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Old 25-05-2010, 07:53   #1
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Considering Electric Outboard - Advice ?

I have an Ericson 25. It displaces 4000lbs with 2000lbs of ballast. I sail it on the Chesapeake Bay where there is wind and current. I'm looking to replace our 9.9HP inboard diesel with an electric outboard. Considering either the Torqueedo Cruise 2.0 (121 lbs. static thrust, comparable to 5-6 HP) or the Cruise R. 4.0 (214 lbs static thrust, comparable to 8 - 9.9HP).

Does anyone have any thoughts as to whether either will provide enough power?
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Old 25-05-2010, 07:59   #2
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First I'd say add an inboard genny to drive the outboard(s). Second I'd say consider two outboards off the one genny with lower horsepowers. That will save the cost of batteries and charging, give you extended running times, and provide a lot of quiet electric power with the right genny but still have the grunt to push against wind and tide. And lighter units to handle.
I think electric outboards are the way to go when it's necessary to replace the engine.
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Old 25-05-2010, 08:48   #3
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innie or outie

why not consider an electric inboard, the running gear is all there, no holes to drill... it is more expensive (same price if your getting two ob's) but seems worth it since it wont look like an abortion... check out the electric yacht systems, Electric Yacht - Electric sailboat propulsion systems that are cost-effective, yet CLEAN, GREEN and QUIET!, im doing an electric conversion this summer as well and have been talking to scott of electric yacht, i had been planning to build my own system but they make it so easy, that if time is of the essence, its worth it...

p.s. the other idea im kicking around is a 48v water maker (home built) that will operate off the motor bank when the motor is regenerating on long passages....
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Old 25-05-2010, 08:57   #4
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Do not follow the ´comparable´ hype. Make sure you have enough battery size to store your new fuel. And see if the shaft / case of the electric motor are strong enough and up to the job you will ask of them.

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Old 25-05-2010, 10:28   #5
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Yes, the power will be there. Range, that is another story. As a diesel comparison, would you be comfortable carrying only about 2 gallons of diesel for your inboard? That would have about the same range, roughly, as a decent sized battery bank for your outboard.

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Old 26-05-2010, 06:30   #6
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Thanks

Thank you all for your replies, your thoughts have given me new ideas.

Chris- Do you think I can improve my range by increasing the number of batteries?

Pressure Drop- Thank you for the suggestion of considering inboard electric, I'll do some research

Eleven- When you say a genny to drive the outboards, do you mean I can use the generator to charge the batteries while not in port (thus increasing my range)? Or could I also run the generator to power the outboard (thus having technically infinite range)?
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Old 26-05-2010, 07:30   #7
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Sure, you can increase the range with larger batteries. Once you know what drive unit you have, and how much it might draw at different points on the throttle, you can calculate how long your batteries will take you. Doing rough calculations is easy, as these always assume a clean body, efficient prop, and calm water without any current. Once you change any of the variables, then the calculations change. If you Visit the website SolidNav :: Alternative to Diesel Engine - Electric Sail Boat, they have some examples of using their product at different speeds, and show the ranges based on a given power output.

You should join the electric boats Yahoo group, lots of people there much more knowledgeable about this stuff then I am.


Arby Brent on that group has an interesting direct drive motor that might suit your needs.
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Old 26-05-2010, 16:12   #8
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I've always wondered why people don't use aircooled gas horizontal shaft motors to run inboard shafts. It seems totally doable!

Diesel, money not being an issue, is the way to go.
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Old 26-05-2010, 16:57   #9
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witzgall - thanks for the link, i had not seen that company before, really appreciate it
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Old 26-05-2010, 20:05   #10
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Inboard electric - Vetus one of them.

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Old 10-07-2010, 17:57   #11
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Torqeedo electric outboard

When I designed my boat I thought I could place an outboard in the stern of the boat mounted as a "saildrive". Well into the building project I learned that the propeller would not work in that position. ROGUE's 1' draft and the pointy underwater shape at stern would not keep the prop covered with water. It would suck air at the least provocation as a similar design did. I also decided that ROGUE had enough wetted surface in the form of leeboards and I don't want to drag a propeller through the water. I've spent more than ten years trying to decide on a permanent solution for auxiliary power. I have considered a Yulo (Chinese sculling or of unusual efficiency), water pump as a jet drive, hydraulic motor and folding prop mounted on my rudder (elegant but expensive and inefficient even if I could find someone to design and build the thing), various ways of mounting a four stroke, and electric outboards. I'd be a lot wealthier if I had been paid for all the time I have spent investigating these various options. I've been using a dinghy with outboard as a tug and that may well turn out to be my best permanent option if I create a more elegant solution than the one I have been using. I have some ideas about that.

Until the Torqeedo, there were no adequate electric drive options. Because of electric storage problems electric propulsion must be very efficient. Inboard mountings are unlikely to meet this criteria because of bearing losses and the likelihood of inefficient propeller compromises, and that assumes not having to gear the motor down to prop speeds. (Using an electric motor in place of a transmission so as to be able to move the weight and accessibility of the engine to another location may be viable; trading mechanical transmission inefficiencies for electric inefficiencies. When fuel cells become reliable, and long lasting in the marine environment, electric drives will be the way to go.)

Torqeedo outboards are elegant and efficient designs, far superior to anything else on the market (I've been looking for years and considering various options.) The lighter weight and small visual impact of the Torqeedo may make mounting it on ROGUE's tiller practical, though it would still affect the steering when heeled. ROGUE is so well balanced I can leave the tiller to go do other things while sailing to windward. The convenience of flicking a switch to motor back to port when the wind dies may be worth it to avoid the inflate the dinghy, launch and secure it as ROGUE's tug, mount the outboard and gas tank, start the engine scenario.
There are other mounting options as well, all of which are more elegant with the Torqeedo than a four stroke mounted the same way. Solar cells and a nice quiet honda generator could be used to top off the battery and extend range for the few times I would want to motor any distance.

The biggest question is, what size Torqeedo would provide adequate propulsion for my boat??? Or yours Ericsn25Chespk

I have not been able to find any reliable information about what the actual usable thrust of various gas outboards would be on my boat. A six HP two stroke has been adequate. However, matching outboard horse power figures with electric horse power figures provides no comparable information about performance in the real world. Even thrust figures are not relevant because they are measured in various ways, and what is relevant is the ability to move a displacement hull along at less than 6 mph, so even real measures of static thrust is not terribly relevant except when it is not enough thrust to exceed the efficient speed of my hull. Even Torqeedo's technical information stating in the same chart, propulsive equivalents and thrust equivalents to gas outboard HP and the horse power are different from two terms I would interpret as synonyms, but they quite apparently are not, so I have no ideal what it all means in terms of my needs. (My boat is a sailboat. Auxiliary propulsion is for bridges, canals, and when there isn't any wind.)

If anyone has any information about real world performance of Torqeedo outboards in comparison with the gas outboard that had been propelling a particular sailboat, I sure would like to hear it. I talked to a dealer who used (I believe) an 801 mounted on a 19' full keel sailboat along the coast of Maine. It handled waves and current "like a six hp gas outboard". That motor was a beautiful design. LONG shaft. Can be tilted up. Can also slide up the length of the shaft.
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Old 13-07-2010, 06:46   #12
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There is a guy who put one of the Torqeedos on a PDQ 36 catamaran as one of his "emgines" the boat came from the factory with one diesel as the original owner wanted( that is another discussion). I know it help him in handling the boat have twin screws but I am not sure of his final opinion of it. You may look on the PDQ owners forum and find a thread about his install.
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Old 17-02-2011, 12:26   #13
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Torqueedo vs Four Stroke

What was the outcome of your situation.

I have an Allegra 24. Total rebuild in progress. Propulsion decisions to be made. Money down on Yamaha outboard with big thrust.

On comes suggestion of Torqueedo. Lighter unit, simpler bracket, have space for batteries.

Allegra weighs approximately 6500 pounds.

It is a pocket cruiser that gets little cruising, mostly afternoon adventuring. This is not likely to change in the near future

Appreciate input. Annualized costs of gas vs electric. One, five, ten year costs. Would rather make decision on a number than a feeling.
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Old 17-02-2011, 12:43   #14
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You might want to check out Mastervolt aquapod drives. They do look elegant, won't be cheap and as always fuel (amps) storage is the real problem. Anyone know a small effecient DC generator? Also I think it is Stillete that makes a nice saildrive that can be powered by electric moter.
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Old 17-02-2011, 13:42   #15
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The aquapod blgklr suggested is for an inboard installation. Mastervolts podmaster might work but requires 24v and will draw something like 100amps at full throttle for the 2kw unit.

Wollschlager might consider installing an electric trolling motor or 2 that run off 12v provided there is enough installed battery capacity on the boat.

For getting in and out of a marina in a sheltered location, 100 ah should be fine. If you moor in heavy current areas or on a river more battery capacity and the second motor will be needed. A small backup generator on board might be wise too if distances or currents become large.

The trolling motor has the advatage of being lots cheaper up front, having redundancy if you have 2 motors, and using the installed battery capacity rather than bringing another battery onboard. If you need to install more battery capacity to be comfortable, the batteries have greater capacity for hotel use when you aren't using them as much for propulsion.

Even though the whole system of 2 motors and an extra battery is going to be heavier than the Torquedo, the bulk of the weight will be in the battery which will not be located at the end of the boat.

And when you upgrade to the Yamaha, you can more easily keep the trolling motors which are a lot smaller than the Torquedo. Also the Torquedo is going to depreciate a lot more in total $ if not percentage-wise.

The downside is you would need an extra battery for a dink if you wanted transfer a motor to that. That's where the torquedo has the advantage, everything is in one unit and overall weight is less.
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