Electric vs. "Conventional" outboard comparison - from a different angle?

[FabioC]

I am considering to buy an outboard for my dinghy and looking at electric ones as well. Going electric has some clear advantages (for me, the most important ones are weight and low noise) and disadvantages (especially cost, obviously).

In comparing them, I am wondering about two aspects that are rarely mentioned:

1. My dinghy usage is sporadic. I can easily go four weeks without using the dinghy (then maybe I use it a lot for a week, then go other four weeks without using it). Aren't all "conventional" outboards a pain to maintain when they are not regularly used? Electric ones seem to have a strong advantage in this respect. Am I correct thinking this way?

2. Electric outboards can be stored flat, while "conventional" ones have to (or at least it would be preferable to) be stored vertically. Is this statement correct? If so, electric outboards seem to have a very significant advantage in terms of ease of storage (of course, assuming that you would not store the outboard on the stern rail, then there is no difference)

My last question is this: when they state something like: "this electric outboard is equivalent to a 4HP conventional outboard", how accurate is that comparison? are they really equivalent from a power perspective or is there a catch? In other words, if I know I need a 4HP "conventional", can I get an "equivalent" electric or should I go with slightly higher power?

Thank you!

[SailingPNW]

So currently most of the electric outboards are a bit of a good/bad option, I have a Torqeedoo 1003.

For the good, it's amazing for quick trips to the dock and short hops. I can easily charge it with my solar, though it does charge someway slowly, and essentially is zero maintenance. It's also easy to put on the dinghy without having to use a lift. It's also quiet comparatively, though I think newer ones are even better.

For the bad, it's slow even under full power, even pushing my dinghy (takecat 260). The range is also somewhat limited, with the cost of adding additional range prohibitively expensive.

Would I do it again? Yes, it serves 95% of my needs. That said I am considering to supplement it with a 5 HP propane motor for times I want to go further and explore.

[ranger58sb]

Originally Posted by FabioC

1. My dinghy usage is sporadic. I can easily go four weeks without using the dinghy (then maybe I use it a lot for a week, then go other four weeks without using it). Aren't all "conventional" outboards a pain to maintain when they are not regularly used? Electric ones seem to have a strong advantage in this respect. Am I correct thinking this way?

2. Electric outboards can be stored flat, while "conventional" ones have to (or at least it would be preferable to) be stored vertically. Is this statement correct? If so, electric outboards seem to have a very significant advantage in terms of ease of storage (of course, assuming that you would not store the outboard on the stern rail, then there is no difference)

My last question is this: when they state something like: "this electric outboard is equivalent to a 4HP conventional outboard", how accurate is that comparison? are they really equivalent from a power perspective or is there a catch? In other words, if I know I need a 4HP "conventional", can I get an "equivalent" electric or should I go with slightly higher power?

1. That's been our experience with gas outboards and similar usage. We're also considering electric as a more useful option for our case.

2. Most 4-stroke gas outboards can be laid down, too -- but only in one specific orientation.

As far as I know, the thrust/HP comparison figures being offered are generally accurate.

You might check out Elco electric outboards as a possibly viable alternative to Torqeedo, Minn Kota, etc. Elco also has some battery/charger info on their website, so you could compare conventional and lithium features, especially battery weight.

-Chris

[rwidman]

I replaced my Honda 2 HP 4 stroke with an ePropulsion Spirit Plus electric. It is much better for my use. It's guaranteed to start, has no centrifugal clutch and revers is just turning the handle, not the entire motor.

I charge the battery by plugging the charger into my boat's 120 volt outlet.
.

[valhalla360]

Originally Posted by FabioC

I am considering to buy an outboard for my dinghy and looking at electric ones as well. Going electric has some clear advantages (for me, the most important ones are weight and low noise) and disadvantages (especially cost, obviously).

In comparing them, I am wondering about two aspects that are rarely mentioned:

1. My dinghy usage is sporadic. I can easily go four weeks without using the dinghy (then maybe I use it a lot for a week, then go other four weeks without using it). Aren't all "conventional" outboards a pain to maintain when they are not regularly used? Electric ones seem to have a strong advantage in this respect. Am I correct thinking this way?

2. Electric outboards can be stored flat, while "conventional" ones have to (or at least it would be preferable to) be stored vertically. Is this statement correct? If so, electric outboards seem to have a very significant advantage in terms of ease of storage (of course, assuming that you would not store the outboard on the stern rail, then there is no difference)

My last question is this: when they state something like: "this electric outboard is equivalent to a 4HP conventional outboard", how accurate is that comparison? are they really equivalent from a power perspective or is there a catch? In other words, if I know I need a 4HP "conventional", can I get an "equivalent" electric or should I go with slightly higher power?

Thank you!

1) If you have a way to keep it charged during periods of heavy use and you don't need long distance/high speed...yes, electric is a good option. If you are just tooling in at low speed from a couple hundred yards out at 3-4kts, a trolling motor is a great option. If you are 3 miles from the dock and expect to do it at 20kts, not so much.

2) The bigger advantage is you can put an electric inside a hatch and not worry about fumes.

The catch with "equivalent" HP depends on how you are using it.
- If you cruise at displacement speed speed, it's absolutely false. Horsepower is Horsepower. There is nothing different.
- Where it can have a grain of truth is if you are trying to get the dingy up on plane. HP = torque * RPM. Since an electric motor can generate peak torque from zero RPM, it is capable of generating more HP at low RPM. This allows you to increase the HP applied more quickly. This is somewhat canceled out since the prop slips in the water and can't absorb all that low end power and the gas motor quickly gains torque as the RPM comes up...so you might get away with a slightly lower HP motor and still get on plane but it's not going to be half.
- This idea comes from cars, where they benefit from this significantly. Generally, the wheels don't slip in normal use, so the car can take full advantage of the max torque from zero RPM. It's not uncommon for an electric vehicle to have 70-100hp when the gas version is 150-200hp because the car doesn't need 150-200hp to maintain freeway speeds and the low end torque gives peppy performance.

[UYA]

Originally Posted by valhalla360

- If you cruise at displacement speed speed, it's absolutely false. Horsepower is Horsepower. There is nothing different.

Here is an explanation from Torqeedo what they mean by "equivalent":
https://www.torqeedo.com/us/en-us/te...fficiency.html

[StuM]

So basically, Torqeedo state:
"Propeller efficiencies in the lower horsepower class can vary by a factor of 3 between petrol outboards and Torqeedo electric outboards."

They then extrapolate that unproven statement to claim:

Our propellors are 3 times more efficient than anyone else's at pushing a boat through the water in all conditions

[donradcliffe]

I used a torquedo the other week in Hanalei Bay. Three 200 yard trips to the beach and back and it was down to 50% charge.

[valhalla360]

Originally Posted by UYA

Here is an explanation from Torqeedo what they mean by "equivalent":
https://www.torqeedo.com/us/en-us/te...fficiency.html

Lots of magic HP talk.

Outboards measure at the prop shaft. So explain why gas outboards, simply don't use a magic prop and triple the propulsive power output?

[fourlyons]

Originally Posted by valhalla360

Lots of magic HP talk.



Outboards measure at the prop shaft. So explain why gas outboards, simply don't use a magic prop and triple the propulsive power output?

I thought the link explained it quite well; the electric motor has a very flat torque curve compared to an ICE. No magic needed.

[valhalla360]

Originally Posted by fourlyons

I thought the link explained it quite well; the electric motor has a very flat torque curve compared to an ICE. No magic needed.

Props can slip in the water, so torque curve doesn't explain it.

If the props were that much better, one of the big outboard companies would have bought up the rights.

[rwidman]

Originally Posted by donradcliffe

I used a torquedo the other week in Hanalei Bay. Three 200 yard trips to the beach and back and it was down to 50% charge.

I suspect you were travelling at near the maximum speed. Or, that the battery wasn't fully charged to begin with.

My ePropulsion will run for ten hours at a relatively slow speed, less the faster I run it.

That said, the choice of gas vs. electric depends on a lot of things including your intended use. For many folks, electric makes a lot of sense. For others, it may not.


BTW: The OP mentioned storage. An electric outboard can be stored virtually anywhere, including an enclosed compartment or even the engine compartment (or room). Not so a gasoline powered outboard. This needs to be stored outside where gasoline or vapors cannot enter the boat.