Project engine

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never-outbored
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Project engine

Post by never-outbored »

Hello,
As we all know, the government want us to believe hydrocarbon powered outboard engines are soon to be dead. Because of this, I am determined to bring a Seagull into the 21st century, with a fully electric drive unit. I am looking for a 40-/+ which i can use as the base engine. I will keep all the original components of the engine intact, so from the outside it looks like a stock seagull. Also if anyone can put me in contact with anyone they know of that have tried this before so i can soak up their genius, I would be quite grateful.
Cheers, N-O,
(a 2 stroke enthusiast who wants to part of the electric revolution)
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cookie1
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Re: Project engine

Post by cookie1 »

Interesting project ! If you went for model with the larger gearbox you might have space to house a motor , especially if you extended the casing . If this is possible it might be relatively straight forward . Good luck 👍
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Oyster 49
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Re: Project engine

Post by Oyster 49 »

If you removed the flywheel would a small motor fit under the recoil starter housing? Petrol tank could hold electrics?
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Charles uk
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Re: Project engine

Post by Charles uk »

I'm sure you could get a 24Volt cordless drill motor into what's left of an empty crankcase & flywheel cover & the battery inside a 3D printed cylinder with the head, tank & plug making it look normal.
Make it idiot proof and someone will make a better idiot.
Chris B
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Re: Project engine

Post by Chris B »

Decide what you're going to use the outboard for and how much power you'll need. You've got to start somewhere - but don't be surprised if you later discover that the space available for your propulsion motor and ancillary components forces a horsepower reduction.

Now convert your anticipated horsepower requirement to watts. That's the easiest bit of your project. In round figures 1hp = 746 watts.

Expect around 15% of the motor's rated wattage to vanish in internal losses within the motor, and there'll be further losses in the drive train between motor and propeller. Work out the total losses as best you can, then convert to watts and add that figure to the required motor wattage.

Having allowed for internal losses and sorted out the motor you require, hunt for a DC motor of the correct rating, and of a physical size which will fit comfortably inside the enclosure which you wish to accommodate it. When sizing up the available space, don't forget that your motor will need room for air to circulate around and through it.

When running on load, your electric motor will require cooling, so within your design you'll need to allocate space for a cooling fan. You'll also need to create a route for fresh air to reach the fan, and another for it to leave.

Best of luck...

C
Chris B
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Re: Project engine

Post by Chris B »

One more point to be aware of...

I'm assuming - possibly incorrectly - that you'll want to run your electric outboard for more than a minute or two at a time.

If that's the case, then when you're choosing your electric motor it's very important to check the motor's designed duty cycle. Any motor that's suitable for driving an outboard will need to have a continuous duty cycle rating, commonly marked as CONT on the motor's identification plate. A motor with a continuous rating will run at, or close to, its designed maximum load for long periods without overheating.

A battery powered electric drill motor might be small enough to fit your project (albeit probably seriously lacking in power) but please be aware that the electric drill motors I've encountered have an intermittent rating. Those motors are designed to run under varying loads in relatively short bursts. They are not designed to run under load for more than a short period of time. If you place one of those motors on a continuous load for more than a few minutes, it will either shut down via its thermal protection device, or it will barbecue itself.

C
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Charles uk
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Re: Project engine

Post by Charles uk »

Chris I saw a feather weight with a cordless drill powerhead in NZ several years ago, I think the Mad Professor built it, all the Kiwis will know who that is.

Problem was that the battery only lasted 10 minutes, & as this was a couple of days before the race, my attention was taken by other things so I didn't study it.
Make it idiot proof and someone will make a better idiot.
Chris B
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Re: Project engine

Post by Chris B »

Hi Charles -

It's quite possible that the self-limiting factor of his battery capacity saved the motor from overheating. If space in the powerhead means using a smaller motor than optimum (a scenario which is definitely on the cards) then one could consider giving the drive motor an easier time by reducing the propeller diameter, or by fitting a prop with a shorter pitch.

As Charles has observed, if this electric Seagull is to be of practical use, then battery capacity is likely to emerge as a problem. I avoided mentioning battery capacity earlier because the guy wants to have a go at at an interesting project and he's been humble enough to ask for help. So I didn't want to chuck too many obstacles in the way in one go. But now we're on the topic, battery size / capacity might be an issue - it really depends what the OP is hoping to use his converted motor for.

Some time ago I did a calculation for somebody else who wanted to build a small electric outboard. The numbers revealed that a pair of 12V 75AH lead / acid batteries in parallel would have provided somewhat less than 20 minutes of thrust at full throttle. That said, the same electric rig would've run for around 8 hours at tickover speed - but who's going to do that?

Even with recent advances in battery technology, an ongoing problem with battery power is the low energy density compared to petrol. For instance - and depending on the engine - if you could pick up in one hand enough petrol to take you 100 miles, you'd probably need a beefy pallet truck to move a battery that was required to power an electric motor doing the same job.

On the subject of DC motors for this project, Bosch produce a range of excellent and compact general purpose motors, one of which might fit the bill. They're expensive to buy new, but I'd be inclined to trawl the world's favourite online auction site and pick up a used one.

If that sounds like a good route to take, I'd suggest a visit to the Bosch website, which has detailed spec sheets and dimensioned drawings for their motors. Find a motor that looks promising, make a note of the product code, and then try to locate a used one online.

And while I'm here - Happy New Year!

C
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Charles uk
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Re: Project engine

Post by Charles uk »

There are a lot of electric boats cruising up & down the Thames on a sunny Sunday.

I watched a chap on you tube in a flying bathtub landing outside a shop, buy some bread & fly off, times are a changing!
Make it idiot proof and someone will make a better idiot.
Chris B
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Joined: Tue Jan 29, 2019 2:37 pm
Location: England

Re: Project engine

Post by Chris B »

"There are a lot of electric boats cruising up & down the Thames on a sunny Sunday."

There certainly are. Probably because the Thames upstream of Teddington on a sunny day is the perfect place for an electric boat. (I lived in Cookham for a while and got to know your stretch of the river quite well).

As I suggested in my earlier post, the viability of the project depends on how the OP intends to use his electric Seagull. Pottering around on the sheltered water of a slow flowing river is one thing. But an exposed tidal area on a breezy day is something else. The first scenario could be quite economical on power consumption, whereas the second one will be power hungry.

When you're driving a propeller in water, the power demand increases exponentially as you increase the propeller rpm. So your energy demand at the power head produces a logarithmic curve as rpm is increased. This is directly reflected in the amps drawn from the battery and has serious consequences for battery endurance. That's why the power calculation I did for a previous electric outboard project indicated nearly 8 hours battery duration if the motor was running slowly but less than 20 minutes at full speed.

The times are indeed a changing. And if we're going to go all electric they need to change some more - because at the moment the energy density of even state-of-the-art batteries falls way way short of petrol and diesel. Battery technology's certainly improving but it ain't there yet.

C
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