ePropulsion Pod Drive

weightless

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little bit of delay when moving from neutral to either forward or reverse.
Electronically controlled throttles for diesels sometimes add delay in, too. I suspect that's intended to protect the gearing and shafts. It may be a useful thing even on an all electric setup. Sheering the prop off the shaft would not be helpful.

 

Bull City

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@Beanie 101  @DDW  @ChrisJD  I'm getting pretty far along with the ePropulsion Pod Drive 3.0. The company rates it at 6 HP, which would be an improvement over the Torqeedo 1003, which I now use. As has been discussed on other threads, Torqeedo probably over rates the HP. The 1003 at wide open moved my boat at about the same speed as my old Honda 2 HP, also wide open. 

So, my question is how accurate do you think ePropulsion is at rating the HP of their products? Is 6 HP really 6 HP?

Thanks.

 
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Crash

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Indeed. I've hidden the my post on that 'cause I committed multiple stupidities in it. I do suspect that putting the pod near the trailing edge would give it less moment to steer the boat with prop-wash and would put it's drag further from the pivot point of the boat. Those might give the rudder a better chance of controlling the boat in reverse.
Here's the J/109 saildrive location.  I'd guess the distance to the rudder from the saildrive is almost the same as it is on the J/100.  The J/109 is one of the easiest boats to drive and maneuver around the docks, forward or reverse.  There is plenty of flow from the prop over the engine in forward to kick the stern one way of the other if needed.  There is very little prop walk in reverse.  Several times while backing down a narrow fairway into my slip, I had other "dock watchers" tell me it must be nice to have a bow thruster...

I think Bull will be shocked at how easy his boat becomes to drive and maneuver should he put a pod drive (or saildrive) in the location he is showing.

j-boats-j-109-layout-1.webp


 

andykane

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At 3kW it's actually only 4hp, although I would expect it to have much better performance in reverse since you don't have exhaust gas getting sucked into the prop. I guess running this at 100% is comparable to running a 6hp gas outboard at "cruising rpm"?

For comparison the Torqeedo 1003 appears to be 1.1kW, so the pod is certainly a decent step up.

 

DDW

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Yeah, input power is 3000 watts and as a matter of settled physics that is at most 4 hp, electric motors are ~90% efficient so less than that output. A 6 hp outboard probably doesn't produce 6 hp at the prop though. If a boat is getting pushed at close to hull speed, then the difference is small. I didn't think gas outboards had a "cruising rpm", you just run them wide open all the time. A somewhat esoteric real world example, I've had the eProp Spirit and a British Seagull Silver Century on my (rather heavy) Bullfrog dinghy. 1KW vs. 5 hp claimed. It goes maybe 0.3 knots faster with the BS engine. You are used to the Torqeedo, and it is probably very real that this will be 3 times as powerful. 

 

weightless

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A 6 hp outboard probably doesn't produce 6 hp at the prop though
Aren't outboards usually rated at the prop?

I wonder what "maximum overall efficiency 51%" means in the specs? Maybe the input charge -> motor output?

IIRC, the 1003 is rated 800 ish watts at the prop.

 

El Borracho

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Aren't outboards usually rated at the prop?

I wonder what "maximum overall efficiency 51%" means in the specs? Maybe the input charge -> motor output?

IIRC, the 1003 is rated 800 ish watts at the prop.
An “at the prop” rating must be shaft hp at the prop. Prop losses not included. Easy to measure with a dynomometer.

A “max overall” spec of a system that includes a prop implies they are measuring thrust at some particular speed. Hard to measure. Sounds dubious.

A 51% efficiency is reasonable for control losses, wiring, motor at max power, bearings, cooling losses, etc. DC motor efficiency is only high (80-90%) at relatively low speeds and low power, quickly deteriorating (to 50%) as speed and power increase.

It is what it is...good or great if the goofy thing satisfies ones needs.

 

Bull City

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I tried to compare the HP, Watt, and thrust Tech Specs for the Torqeedo Travel 1003, since I have one, with the ePropulsion 3.0 Pod (6 HP) and the Torqeedo Cruise 2.0 Pod (5 HP). Of course they use different measures/terms. Here's what I came up with. I would be grateful for your observations.

                                                                                                 Torq 1003    eProp 3.0    Torq Cruise 2.0    
Input power in watts                                                             1000             3000            2000
Propulsive power in watts                                                    480                ?                  1120
Comparable petrol outboards (propulsive power)            3 HP             6 HP            5 HP
Comparable petrol outboards (thrust)                                4 HP             ?                   6 HP
Maximum overall efficiency in %                                          48                 51                 56
Static thrust in lbs*                                                                 68                 ?                    115

 

TwoLegged

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I tried to compare the HP, Watt, and thrust Tech Specs for the Torqeedo Travel 1003, since I have one, with the ePropulsion 3.0 Pod (6 HP) and the Torqeedo Cruise 2.0 Pod (5 HP). Of course they use different measures/terms. Here's what I came up with. I would be grateful for your observations.
Each of the possible new engines delivers at least twice as much power as the current outboard.  So why does the compariosson matter?

 

weightless

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I guess you can fill in the eProp's "propulsive" power as 3,000 x 0.51 = 1,530. There are about 746 watts in a hp ("in 1492 Columbus sailed the ocean blue and if you divide that number in two...").

I'm very skeptical of the "comparable" with outboards of some power numbers. And I'm not sure what they mean by "propulsive power". I think they don't mean power at the prop shaft and suspect they're including the complications of propeller choices. That seems not helpful and potentially misleading to me.

The top line for the electric looks like apples to apples. WAG: all else being equal, the eProp should deliver around three times the power of the 1003. All the numbers below the top line seem a bit fishy to me.

 
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Bull City

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I did some crawling around with a tape measure today. There is really only one place for the E80 Battery and pod drive, and it's probably the best place: under the forward end of the cockpit. In the plan below, the pod is still in blue, and the battery is in red. It will mean loosing the storage bin, but there's just a few lines in there. The place where I keep the spare Torqeedo batteries will be freed up, and that will easily house the lines.

H-Boat Pod Plan 1.png

 
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weightless

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Just wondering:

Can you get a folding or feathering prop? What are the options for prop selection and sizing?

Will it harm anything in the system to let the prop freewheel? 

Can the prop be locked?

Is there someone with one of these installed on a sailboat who can share their experiences? 

Has anyone ever kept one of these in the water full time? What about anti-fouling?

 

Bull City

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Just wondering:

Can you get a folding or feathering prop? What are the options for prop selection and sizing? ePropulsion does not offer one, but Torqeedo does, for $900. Also, another company, Aquamot, makes a pod, They offer a folding prop too. I've requested pricing from them. 

Will it harm anything in the system to let the prop freewheel? I am guessing not, otherwise, they would have a locking mechanism. 40+ years ago, I raced with a friend on a Tartan 27. He had a 2-bladed prop, and would go below and line it up with the keel to reduce drag.

Can the prop be locked? Don't know, but will ask.

Is there someone with one of these installed on a sailboat who can share their experiences? I've corresponded with a fellow in Switzerland who has an Aquamot on an H-Boat. He's had it for 3 years and is happy. It replaced a Yanmar, when the lake banned 2-cycle engines.

Has anyone ever kept one of these in the water full time? What about anti-fouling? I asked the fellow in Switzerland, but haven't heard back. He hauls at the end of summer.
These are excellent questions. Answers above.

 

TwoLegged

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Why you want to lock the prop? Even if you aren't using regen, surely locking it just increases drag?

 

TwoLegged

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If it's 2-bladed, and you could lock it so it's vertical and parallel to the keel, it might be good for drag.
I'm no expert, but I would have thought that free-spinning would be less drag than locked in any position.  It's going to be about 2feet behind a foil, in fast-flowing water, not tucked into a fat cutout on a long keel.

 

Ishmael

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I'm no expert, but I would have thought that free-spinning would be less drag than locked in any position.  It's going to be about 2feet behind a foil, in fast-flowing water, not tucked into a fat cutout on a long keel.
Marginally less drag, and a lot of wear on the components. I'd go fixed vertical.

 

weightless

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Why you want to lock the prop? Even if you aren't using regen, surely locking it just increases drag?
I was wondering if letting it freewheel might cause harm -- stresses diodes, burns bearings, wears seals, makes a horrible racket,  to force a folding prop to fold, whatever. If so, then locking it might be a useful thing. Drag may not be the only consideration.

The drag argument can take over a conversation. My guess, similar to yours, I think, is locked would be more drag. Still, locking the blades, particularly if you could keep them in the wake of the keel, might be desirable all things considered.

 
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