Elco electric outboard props?

[Jdege]

Elco advertises their electric outboards as having a "traditional design with standard aluminum casting so replacement parts are readily available".

And certainly looking at them they look much more like Yamahas or Evinrudes than ePropulsion or Torqeedo.

But does that extend to their props?

The Torqeedo Cruise 6.0 has two alternative props, a three-blade and a five-blade optimized for displacement hulls. The three-blade is standard on their outboard and the five-blade on their pod drive, but either will work on either.

Elco advertises their props are "designed to harness the power of your vessel and enhance its acceleration, top-end speed, and handling". Which sounds like exactly what you'd want on a dinghy or jon boat. But for a displacement hull you'd care more about efficiency at low speed - which is why Torqeedo offers alternative props.

I'm seriously considering mounting an Elco Ep-9.9 outboard on a displacement hull.

What I'm wondering is whether the Elco's "traditional design" extends to their props? Torqeedo and ePropulsion seem to use custom props, available only from them. Does Elco use a standard prop shaft for which alternative props are available?

[ranger58sb]

Ask Elco?

I've read that their outboards use Yamaha drives. No clue if true or not.

-Chris

[Jdege]

Originally Posted by ranger58sb

Ask Elco?

I've read that their outboards use Yamaha drives. No clue if true or not.

-Chris

What I've read online is that Tohatsu makes the aluminum chassis for most of the small outboards, including both Yamaha and Elco. And you can always trust some random guy on the internet.

I signed up for something on Elco's website that resulted in one of their support/sales guys phone me, the other day. I sent him an email this morning.

[Adelie]

My guess is that Elco’s props are off the shelf from another maker.

If you can confirm this and determine which one then you want the largest diameter prop you can get if you are pushing at displacement speeds. Probably you want a flatter pitch too but the need is less apparent for electric than it is for ICE.

The electric prime mover being at the top of the motor has 3 effects, 2 good, one bad.
A. Motor is out of the water so not subject to shorting when the shaft seals fail, not if but when. One of the big two (Torqeedo & ePropulsion) requires factory/dealer maintenance every 12-24mo that includes shaft seal replacement. The other doesn’t mention seals but the manual is fuzzy on the issue.
B. Motor at tip means the only bulge in front of the prop is the bevel gear which is much smaller than the podded motors the big two use. Less drag.
C. Because the motor is at the top of the outboard that means there is a shaft bearing and a bevel gear which are drag items which drop efficiency several percent.

B.&C. May balance out somewhat, not sure to what extent.

There may also be cooling differences since the big two have immersed motors which may have an advantage depending on how Elco cools their motors.

[Jdege]

There may also be cooling differences since the big two have immersed motors which may have an advantage depending on how Elco cools their motors.

Elco outboards have an impeller below the waterline that pushes cooling water through the motor. When the system is running right there's a stream of water flowing from a tube at the rear of the motor housing. If you don't see it either the cooling line is blocked or the motor isn't deep enough in the water, or both.

https://youtu.be/-8K6OrLON4U

The impeller, of course, needs periodic maintenance. But that's a minor thing.

[mcarthur]

Originally Posted by Adelie

If you can confirm this and determine which one then you want the largest diameter prop you can get if you are pushing at displacement speeds. Probably you want a flatter pitch too but the need is less apparent for electric than it is for ICE.

Apart from playing with Gerr, is there any other way to calculate diam and pitch that suits electric for a given speed (electric = slowish) and drag (vessel type + shape/FD/SD)?

I've played online a little but I suspect I need to go back to the formulas since it's a pretty different case to the original needs.

[Adelie]

If you can figure out what the source of the lower unit it, looks like Yamaha to me, you can see what prop you have and what the largest on available is.

I don’t think anybody makes custom outboard props that aren’t wildly expensive. Live with off the shelf.

[jwc1926]

I have been in contact with Elco. I can confirm that Yamaha 9-spline is what you want for the Elco 9.9. Elco's engineers specifically recommended 7.5" x 9 pitch (RH) aluminum prop if you, like me, are looking to increase the pitch from the factory pitch of 7, which could be useful if you're looking to increase top speed:

https://www.crowleymarine.com/yamaha...5x9rh-aluminum

I wanted stainless steel, so I opted to go with this from Amazon:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Right now I'm having trouble getting the stern of my 1444 welded Jon boat from getting up--in part because I've got an 84 pound battery, 65 pounds of motor, and me in the back. There's a lot of churning going on right behind the stern, and I can't get a good plane. Part of the issue is that I'm also using an adjustable jack plate with a 5-inch setback because my transom is too thick for the motor clamps. So, I'm going to add a small hydrofoil too: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Between the hydrofoil and the stainless steel 8-pitch prop, I'm hoping to get my stern up, achieve a smooth plane, and get my speed up to around 8-9 mph. Right now I'm topping out at about 6 mph with maxed out RPMs. We'll see how it goes.

Originally Posted by Jdege

Elco advertises their electric outboards as having a "traditional design with standard aluminum casting so replacement parts are readily available".

And certainly looking at them they look much more like Yamahas or Evinrudes than ePropulsion or Torqeedo.

But does that extend to their props?

The Torqeedo Cruise 6.0 has two alternative props, a three-blade and a five-blade optimized for displacement hulls. The three-blade is standard on their outboard and the five-blade on their pod drive, but either will work on either.

Elco advertises their props are "designed to harness the power of your vessel and enhance its acceleration, top-end speed, and handling". Which sounds like exactly what you'd want on a dinghy or jon boat. But for a displacement hull you'd care more about efficiency at low speed - which is why Torqeedo offers alternative props.

I'm seriously considering mounting an Elco Ep-9.9 outboard on a displacement hull.

What I'm wondering is whether the Elco's "traditional design" extends to their props? Torqeedo and ePropulsion seem to use custom props, available only from them. Does Elco use a standard prop shaft for which alternative props are available?

[Jdege]

Actually, in my use case I'm more interested in increasing thrust at low speed, than in achieving higher speeds.

[Adelie]

JWC
I would suggest moving the battery as far forward as the leads will allow and get a tiller/throttle extension so you can move forward yourself. Hydrofoils would be my last remedial action as they cause drag.

Jdege: JWC’s link looks like a good remedy for you.

[jwc1926]

Originally Posted by Jdege

Actually, in my use case I'm more interested in increasing thrust at low speed, than in achieving higher speeds.

In that case you’d want to lower the pitch, but I’m not sure if they make anything less than a 6.5 for a 7-1/2 inch prop. If you can find a 9-spline Yamaha that is 7-1/2 x 6.5 or so, maybe that would work, but watch your RPMs.

This is the only one I could find that appears to fit 9 spline motors:
https://www.bottomlinemarine.com/pro...00_10929.shtml

[jwc1926]

Originally Posted by Adelie

JWC
I would suggest moving the battery as far forward as the leads will allow and get a tiller/throttle extension so you can move forward yourself. Hydrofoils would be my last remedial action as they cause drag.

Jdege: JWC’s link looks like a good remedy for you.

I experimented with that. I am going to hollow out the rear seat and put in a hatch so I can move the battery forward next to me (inside the seat, which is pretty huge) instead of all the way back next to the transom. Moving it any further forward with a passenger buries the bow and reverses the problem. The optimal position for the battery with a passenger up front is next to me, but that doesn’t bring my stern up enough. The new 8 pitch stainless prop and small Attwood hydrofoil will be here tomorrow. The hydrofoil is only 8.5 inches from front to back and has the shape of fighter jet wings. It’s not big and bulky, so it shouldn’t create a ton of drag. (I ended up going with this smaller one, rather than the one I linked to earlier, to help reduce drag.) Between the relatively low profile hydrofoil and a higher pitch prop, the speed should balance out, and theoretically I should be able to get the smoothest ride possible for my setup, which ain’t changing anytime soon. It’s a matter of money, which for me means getting what I have currently to work. It’s a fun challenge. If I hit 8 mph on a plane I’ll be tickled. We’ll see.

[Nicholson58]

Hollow out the seat? I hope you do not plan to compromise floatation. I had a small boat disappear under me once. Long swim.

Michigan Wheel is a good prop source as is Solas. I found changing to SS improved performance and is not too expensive in small props.

Unless your motor is powerful enough to plane the boat a longer pitch will only stall in its own turbulence. Both named sources have calculators and good tech support to help match prop to hull type and weight. Use them.

[jwc1926]

Originally Posted by Nicholson58

Hollow out the seat? I hope you do not plan to compromise floatation. I had a small boat disappear under me once. Long swim.

Michigan Wheel is a good prop source as is Solas. I found changing to SS improved performance and is not too expensive in small props.

Unless your motor is powerful enough to plane the boat a longer pitch will only stall in its own turbulence. Both named sources have calculators and good tech support to help match prop to hull type and weight. Use them.

I always carry a spare plug, I have a bilge pump, and I'm not sure I could flip the thing even if I wanted to on any of the small, inland, electric-only lakes I frequent. That said, I'll start by seeing what switching to stainless steel with a small hydrofoil achieves. Elco recommended a 9 pitch to me, which seems too high. I'm hoping the 8 stainless will be optimal in combination with the hydrofoil.

[Jdege]

Originally Posted by jwc1926

In that case you’d want to lower the pitch, but I’m not sure if they make anything less than a 6.5 for a 7-1/2 inch prop. If you can find a 9-spline Yamaha that is 7-1/2 x 6.5 or so, maybe that would work, but watch your RPMs.

With a gas engine, exceeding max RPM with a flatter prop is a real concern. With an electric it is not. The motor controller will not exceed safe RPMs.