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.
Richard

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?

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.

WesK said:

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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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.

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.

Richard, Do you carry propane for cooking? That's another fuel source. Lehr is making propane outboards up to 15 hp.

HopCar said:

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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Throw five on the swim platform and he'll be the midnight express of trawlers!

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.

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.

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).

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.

"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?

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.

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.

manyboats said:

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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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.

Ski in NC said:

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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If your "get home" motor can't overcome the currents (and wind) in your boating area, it's pretty pointless.

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.

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.

WesK said:

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. 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.

WesK said:

If your "get home" motor can't overcome the currents (and wind) in your boating area, it's pretty pointless.

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manyboats said:

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.

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My thought as well. Most of the boats on this forum couldn't overcome the currents in BC or Alaska.

A 10 HP DC motor night be the size of a garbage can and weigh a few hundred pounds.

Small light ones need an electronic controller , not just an off on switch. which might cost what a wing diesel would cost.

WesK said:

If your "get home" motor can't overcome the currents (and wind) in your boating area, it's pretty pointless.

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Unless it's not really a come home engine but a second means of propulsion to get you out of harms way whether other traffic or environments issues. Most single engine boats thinking of secondary propulsion usually lose the engine...not the drive train...not to say it doesn't happen but I would say singles stopping are because of engine issues by a large margin.

It may take a lot of HP to buck wind and current but it doesn't take nearly as much to go perpendicular or even with it to safer water.

Assuming I could still stay afloat after a catastrophic powertrain failure, the farthest away from land I'll be would be in the Gulf Stream (to or from the Islands), or perhaps crossing the Gulf of Mexico on the loop, so I'd likely call for a tow anyway. I'm just thinking of those moments when your engine goes down and enough directional stability could be had to stay out of trouble. The worst zero power situation I've been in was waiting for a bridge while with and current were taking me toward the supports as other go-fast boats were coming off plane at the last moment, throwing huge wakes abeam. Maybe I had 30 seconds. Taught me a great lesson in staging my boat too close to the bridge. High pucker factor.

As expensive as a diesel outboard would be, it would be a bracket and a fuel line job. With my rudder, I think one knot or so is all I need for acceptable directional control. The unit would be out of the water, fairly easy to service or remove, and you could take it with you or sell it separately when you moved to another boat. If one needed to dock or maneuver under 1 knot, a handle while standing in the veranda or swim platform would probably work in a pinch. Of course, a remote throttle and/or shut off would be convenient while single handling. Two aboard would be better.

I find it hard to deny that in this case, twins with separate fuel filters and day tanks take some of the worry out of this, but they gotta have decent rudders. This was one of the criteria that kept me looking at Great Harbour's and a few Catamarans right up to the end.

10 hp electric power is going to need a bit more then a belt or two to connect to the main shaft I would think.

I would rather see the elect running a hydro. pump then send it to a hydro. motor. But if you do that then just run the hydro's off the gen-set and forget the elect.

My get home motor is cheep and requires no maintenance, I call it Sea Tow.

Here is a 30 or 55hp outboard that runs on all fuels, gas, diesel, jet fuel even. Only weighs 10-20 pounds more then a standard motor, Cost I have no idea?




http://www.evinrude.com/en-US/engines/MULTI_FUEL_ENGINES

SCOTTEDAVIS said:

10 hp electric power is going to need a bit more then a belt or two to connect to the main shaft I would think.

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I think you're right Scotty....I wouldn't do it anyway. Even if you could manage a decent ratio, lateral Loading of the shaft couldn't help the log and seals much.

What about Hydraulics? After coming back to the US from living and cruising in Germany, I imagined that I'd take my boat all hydraulic. The Euro 400 river trawlers we were renting had Nanny-Peachment (Kabota) diesel/hydraulic drives with a hydraulic bow thruster. You could pull the throttle right through the gate from full ahead to full reverse without hesitation, no issues. When I saw that the drive shaft was nothing but a simple hydraulic motor bolted to the transom with maybe a 8-10 inch shaft and a prop on the other side, I figured hooking-up a get-home system would be nothing more than another smaller hydraulic motor bolted elsewhere on the transom, perhaps with a folding prop....so simple. Problem is that you do loose efficiency through the hydraulics. I got to know the owner of LeBoat Charter of Europe as he only lived a few blocks away in Berlin. The Nanny/Peachment system stopped all his rental transmission and shaft issues immediately, but the 85 HP Kabota behaved more like a 40 HP, no kidding. Maybe 5.5 to 6 knots WOT with a 40 ft. WL.

If I began with an 11 HP diesel Genset and PTO, it's not hard to imagine that I wouldn't have much left after the Hydraulic Motor and stuff like line friction and simple mechanical loss through a few bearings and PTO, not to mention less efficiency at the prop location, less efficient prop, and on and on. I could probably do better with a paddle.

Larry, I was not aware of the lose experienced with hydro's, wow! I can see why it's not done. I guess the best set-up is a wing with a smaller diesel for power.

Reinventing the wheel, while not very likely, does bring some interesting conversation to the table, and you do learn things.

Thanks

SCOTTEDAVIS said:

............. My get home motor is cheep and requires no maintenance, I call it Sea Tow.

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I was going to suggest that but I didn't want to start an argument. Mine is TowBoatUS, but they cost about the same and provide the same service.

It pays to read the fine print on the towing assistance insurance policies...while similar...they aren't exactly the same and one or the other may be better for your needs or where you primarily boat.

Especially if you boat in a relatively small geographic area...the best thing is to look over the fleet and equipment that may assist you and talk to the owners and captains that will assist you. Every franchise owner has some flexibility in what they will and won't do for you and often the equipment and competency levels between the 2 companies in a given area can be quite different.

So while the $$$ may be only a little different...the quality of service can vary quite a bit.

Just asking: what about towing with the dink vs pushing? Assuming a 10 to 20-hp outboard, it would seem an easier way to maneuver to safety except into current or wind. The only additional equipment would be a rope.