"Turbineguy: Nom de Zoom" (will-alib)
10/09/2018 at 13:41 • Filed to: None
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"Turbineguy: Nom de Zoom" (will-alib)
10/09/2018 at 13:41 • Filed to: None | 0
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Mid-day stream of consciousness/fuck off mode: On .
How suitable for a boat would a Model S powertrain be? Figure a 27-30ft single screw inboard boat, which the 250ish hp electric motor should motivate fairly well. (I’d think the high torque would be very useful in a boat)
The battery pack weighs 1,200lb which is a lot, but the combined weight of a Mercruiser 5.7 with the drive unit and the fuel tank (80gal capacity) is almost 1,300lb. Include the Tesla’s motor and it’s mostly a wash. Naturally the motor would run at a higher power setting in a boat than in a car, and I’ve no idea how much that would reduce running time on full charge but my guess is it should still last a few hours at moderate cruise speed. T
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iggest danger I can think of would be getting salt water on the battery, so it’d have to be well sealed off from the environment. There’s gotta be some crazy Colin Furze type out there that’s thought of/attempted this already, right?
PatBateman
> Turbineguy: Nom de Zoom
10/09/2018 at 14:17 |
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Airboat
Michael
> Turbineguy: Nom de Zoom
10/09/2018 at 14:20 |
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Gasoline carries about 33.4 kWh per gallon. At 30% thermal efficiency, you’re looking at 80 gallons * 33.4 kWh/gallon*0.30 for energy available to motivate the boat, or 801 usable kWh
P 85 d batteries carry 85 kWh.
So you’d have about a tenth the range.
BigBlock440
> Turbineguy: Nom de Zoom
10/09/2018 at 14:32 |
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Assuming a normal car’s gas tank is 15 gallons getting you that 300 miles, the gas powered boat would have over 5 times the range. Google’s telling me that a 300 hp gas engine will burn 24.5 gallons per hour in a boat, so about 3-4 hours depending on your throttle. So a Tesla drivetrain and battery pack will get you less than an hour out there.
HammerheadFistpunch
> Turbineguy: Nom de Zoom
10/09/2018 at 14:35 |
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Electric Marine solutions exist ( check out torqueedo) and the power is fine but the range stinks. Most electric it hybrid Marine installations are for house power and no wake zones
Future next gen S2000 owner
> Turbineguy: Nom de Zoom
10/09/2018 at 14:39 |
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https://www.torqeedo.com/us/en-us
I don’t think it would work well. Consider this. The water drastically drops mpg and translates it into gals/hr as the more usable figure. Now to get the P85 levels of range in a car, using a 5.7, you would need a roughly 13 gal fuel tank. Figure 20 mpg and 13 gallons to get 26 0 miles in range. Now for the same weight associated with an 80 gal fuel tank you get 1600 mile range.
Also, a couple companies out there use batteries to power boats. They work okay but the power/density of gasoline makes it a much better option on the water. The weight penalty of batteries don’t matter as much in a car because rolling & air resistance is so much lower than hydrodynamic drag.
functionoverfashion
> Turbineguy: Nom de Zoom
10/09/2018 at 14:43 |
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There have been some electric-drive Nautiques, although they didn’t exactly take over the market. It’s pretty ideal for a slalom boat, where you’re doing a very short run through a course, let’s say, then stopping. Most people with inboard direct-drive boats aren’t running them at high loads for many hours at a time. This video is from 2011 (!!) so for sure, the project didn’t really take off. But things are very different now...
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Turbineguy: Nom de Zoom
> Michael
10/09/2018 at 15:09 |
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Turbineguy: Nom de Zoom
> Future next gen S2000 owner
10/09/2018 at 15:14 |
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Ash78, voting early and often
> Michael
10/09/2018 at 15:15 |
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Thermal efficiency question: I’ve heard 30% used for cars, but isn’t it much lower for boats due to their much higher drag? Or are you talking about efficiency just within the engine (ignoring the tranny/wheels/tires or boat prop)?
That could shrink the gap a bit, but your point stands.
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Future next gen S2000 owner
> Turbineguy: Nom de Zoom
10/09/2018 at 15:25 |
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I don’t think the next level is enough. When ever batteries energy density reaches gasoline. I think that is a couple levels between now and then.
Manwich - now Keto-Friendly
> Turbineguy: Nom de Zoom
10/09/2018 at 15:55 |
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The powertrain won’t be an issue.
It comes down to how much range you need. I would expect that it would only get 1/3 to 1/4 of the range in a boating application.
And I don’t think there’s any fast charging infrastructure for electric boats.
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Michael
> Ash78, voting early and often
10/09/2018 at 15:58 |
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The engine is still about 30% efficient, it’s the extra drag that makes fuel consumption go up
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Manwich - now Keto-Friendly
> Michael
10/09/2018 at 15:59 |
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The efficiency of the electric motor is in the 90% range. So instead of 1/10 of the range, it’s probably more like 1/4 to 1/3 the range.
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Turbineguy: Nom de Zoom
> Manwich - now Keto-Friendly
10/09/2018 at 16:01 |
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N
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Manwich - now Keto-Friendly
> Turbineguy: Nom de Zoom
10/09/2018 at 16:06 |
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Getting to planing speed won’t be a problem. That electric motor I think is capable of spinning at 10,000rpm.
And I think if you run it at just over the minimum speed to be planing, then range should be okay... but still, maybe only 1/3 of the range you’d have in a car.
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Turbineguy: Nom de Zoom
> Manwich - now Keto-Friendly
10/09/2018 at 16:12 |
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Manwich - now Keto-Friendly
> Turbineguy: Nom de Zoom
10/09/2018 at 16:22 |
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If it’s a case where you’re just using the boat to go from the marina to the cottage on an island and it’s not too far, it could make sense.
There would definitely be huge fuel savings.
For the last couple of summers, I’ve rented a cottage on an island that is a 10 min boat ride from the marina. Over a 1 week period, I’ve spent $100-$150 on fuel plus another $60 on 2 stroke oil (small speedboat with a Mercury 60hp 2 stroke outboard 3cyl) going to and from the marina as well as using the boat to pull a tube or someone water-skiing .
For recreational cottage use, I could see an electric boat working just fine.
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Turbineguy: Nom de Zoom
> Manwich - now Keto-Friendly
10/09/2018 at 16:30 |
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Michael
> Manwich - now Keto-Friendly
10/09/2018 at 17:41 |
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85kWh * 0.90=76.5 kWh available, vs 801 kWh of available gas engine energy. Both after efficiency losses.
9.5% of the range of gasoline
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Manwich - now Keto-Friendly
> Michael
10/09/2018 at 18:04 |
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DAMN YOU AND YOUR MATHS!!!
pip bip - choose Corrour
> Turbineguy: Nom de Zoom
10/10/2018 at 06:18 |
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be the guinea pig and find out
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Michael
> Manwich - now Keto-Friendly
10/10/2018 at 07:34 |
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The best compliment you could pay an engineer :)
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Turbineguy: Nom de Zoom
> pip bip - choose Corrour
10/10/2018 at 08:38 |
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If I had the $$ right now I’d do it.