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Old 01-26-2014, 04:46 PM   #1
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electric outboard as a get home engine

I was reading the reviews of two electric outboards in the BoatUS mag and I wondered if an electric outboard could be hooked directly to the generator as an EMERGENCY get home engine.

Probably worth the effort to ask the manufacturer.
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Old 01-26-2014, 08:20 PM   #2
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I assume your generator puts out 110 / 220 volts AC and the electric outboard runs on some voltage of DC power so you couldn't just plug it into the generator.

I'm sure there are probably ways around that but why electric?
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Old 01-26-2014, 08:24 PM   #3
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I don't think you will get far with any sort of 5 HP outboard motor pushing a full sized trawler. And as above, you need a way to convert 120 volts AC to 12 volts DC. If your main engine quits because of a fuel problem, the genset may not run either.

I think it's back to the drawing board on that one.
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Old 01-26-2014, 08:28 PM   #4
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I don't think you will get far with any sort of 5 HP outboard motor pushing a full sized trawler. And as above, you need a way to convert 120 volts AC to 12 volts DC. If your main engine quits because of a fuel problem, the genset may not run either.

I think it's back to the drawing board on that one.
Actually, that had been my rationale for not having a get home engine in the first place, the high probability they it is a fuel problem.

Ok.
Thanks all.

I'll keep on thinking.
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Old 01-26-2014, 08:37 PM   #5
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Wes, Torqueedo is now making a 40 hp electric outboard. They even mention using a generator as a range extender for the batteries. Richards idea is not impossible but I suspect it would be pretty expensive.
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Old 01-26-2014, 08:39 PM   #6
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Richard, Do you carry propane for cooking? That's another fuel source. Lehr is making propane outboards up to 15 hp.
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Old 01-26-2014, 09:15 PM   #7
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Richard, Do you carry propane for cooking? That's another fuel source. Lehr is making propane outboards up to 15 hp.
Throw five on the swim platform and he'll be the midnight express of trawlers!
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Old 01-26-2014, 09:25 PM   #8
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ah...diesel electric has been around a long time...just have to find the right combo of generator and electric motor to do what you want it to...I doubt electric outboards are the way to go but there are other options out there.

and yes...my philosophy on major distance traveling is to have separate fuel tanks filled from different sources where possible so at least part of your fuel is hopefully as good as or better than the other half.
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Old 01-26-2014, 09:49 PM   #9
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I've always thought that a decent sized outboard on a stern bracket would make a good emergency get-home, or at least lend enough directional stability to work on the main while quartering waves. Trouble is, whatever outboard you get over 15 HP is going to be a darned heavy dinghy engine, so you might need an additional OB for that, OR, get a bigger dinghy to handle the bigger engine. Then there's the extra gas aboard, or maybe propane. An electric 40 HP must be really expensive, probably heavy too.

If I've got to dedicate a bracketed OB for a get home, it'll probably be a Yanmar 27 HP Diesel with the idea that it'll just hang there, BUT, will use my same tanks. A fuel polishing system and maybe a day tank would be the wise thing, regardless. Of course, I'd have to buy it somewhere in the Caribbean as these engines aren't EPA approved for sale in the US. Second choice would be a bigger dinghy and the 15 Lehr from Hopcar. My 9.5 Caribe already squats with the 9.9 Merc.

I've moved my old reconditioned 4.5 Northern Lights/Lugger into a new hatch under the veranda. Another Manatee owner has supposed that I could run a direct shaft off a pto to a foldable prop very easily, but I believe the Lugger 3 cyl. is only 11.5 HP, maybe less. It might be enough for a couple of knots.
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Old 01-26-2014, 10:04 PM   #10
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I would think a much more efficient and convenient way of getting a get home system is to have a DC motor alongside the propeller shaft with a belt drive including a disconnect and connect system with appropriate speed reduction (big pulley onPS and small pulley on elect mtr). An HTD belt probably won't even slip in bilge water either.

Just run off the batteries and/or recharge as you go w an aux gen.

The boats propeller is probably 5 times as efficient as a small OB and the usual aux gen is many times as powerful as small OB (gas, electric or propane).
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Old 01-26-2014, 10:44 PM   #11
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Hmmm. The crank pulley of my genset is now aligned with the main shaft. A belt could easily run from the crank pulley to a pulley on the shaft, but I'd have to do use a slave shaft for enough reduction. Using a DC motor, yes, but how much HP could one get from say 4KW going into it. Thanks for the alternative thinking.
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Old 01-26-2014, 11:08 PM   #12
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"I would think a much more efficient and convenient way of getting a get home system is to have a DC motor alongside the propeller shaft with a belt drive..."

I was thinking along the same lines. Several companies are making very powerful electric motors for powering boats. In fact Torqueedo sells a 40 hp inboard motor as well as their outboard. No idea how much power it would take.

If your generator has a 10 hp motor, no matter how you connect it to a propeller, electric motor, belt, hydraulics, you can't apply more than 10 hp to the prop.

I guess then it's a question of how much horse power does it take to move your boat at a decent speed? What is a decent get home speed?
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Old 01-26-2014, 11:34 PM   #13
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I towed/pushed a bud's dead 35' sportfish with my dink. 2hp Evinrude from 1976. Moved it maybe a knot, but it did move. Got him to his slip. Light and slight conditions.

You could probably move a trawler somewhat with electric bass boat trolling motors. Hopeless against wind and seas, but in good conditions it will work.
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Old 01-27-2014, 06:55 AM   #14
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The choice would be to locate a high thrust , large prop outboard , as used on sailboats.

About 10HP , so the weight would not be extreme , and it would work to get the dink around the harbor .

Might even work as a push boat , so the OB would not have to be moved.
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Old 01-27-2014, 10:28 AM   #15
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I would think a much more efficient and convenient way of getting a get home system is to have a DC motor alongside the propeller shaft with a belt drive including a disconnect and connect system with appropriate speed reduction (big pulley onPS and small pulley on elect mtr). An HTD belt probably won't even slip in bilge water either.

Just run off the batteries and/or recharge as you go w an aux gen.

The boats propeller is probably 5 times as efficient as a small OB and the usual aux gen is many times as powerful as small OB (gas, electric or propane).
That's great as long as the reason you need a "get home" engine isn't that you've damaged or lost your prop. Of course you still have the possible fuel contamination issue for the genset.
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Old 01-27-2014, 10:31 AM   #16
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I towed/pushed a bud's dead 35' sportfish with my dink. 2hp Evinrude from 1976. Moved it maybe a knot, but it did move. Got him to his slip. Light and slight conditions.

You could probably move a trawler somewhat with electric bass boat trolling motors. Hopeless against wind and seas, but in good conditions it will work.
If your "get home" motor can't overcome the currents (and wind) in your boating area, it's pretty pointless.
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Old 01-27-2014, 10:44 AM   #17
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I've been looking at modifying my swim platform to allow mounting the 3 hp dink outboard. I've been caught once on a dead calm day when the sails were of no use, and the starter motor failed. Under those conditions it would move my little boat sufficiently.

Another bonus is that it could be used as a stern thruster if in tight quarters on a windy day.
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Old 01-27-2014, 10:48 AM   #18
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AusCan, One of the guys on this forum did just that. He made a very nice mount for his swim platform and put a 5HP Lehr propane engine on it. If I remember right it was Murray who did that.
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Old 01-27-2014, 10:58 AM   #19
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If your "get home" motor can't overcome the currents (and wind) in your boating area, it's pretty pointless.
I'm trying to say in a nice way "no it's not"

The expression "get home" is not really not "the point". It's getting to any safe place. And the closest safe place quite likely may be in the opposite direction from where you were going when the engine quit. So then the current may very likely be going in a desirable direction. Perhaps all you'd need is enough way to cross over to the other side of the channel.

That said this is another time when the full displacement hull is your friend since at very low speeds it's drag is so low. That's why it's so rare to see a sailboat that's not FD. But as the speed gets down in the two knot range even most SD boats can easily be pushed along to safety w very little power.

But for those that need to live in a near perfect world and actually "get home" .... better look for a twin engined boat.
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Old 01-27-2014, 11:05 AM   #20
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If your "get home" motor can't overcome the currents (and wind) in your boating area, it's pretty pointless.
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I'm trying to say in a nice way "no it's not"

The expression "get home" is not really not "the point". It's getting to any safe place.
My thought as well. Most of the boats on this forum couldn't overcome the currents in BC or Alaska.
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