Reducing pollution from boats by switching to electric motors • Hacker News Board

Re: Reducing pollution from boats by switching to electric motors

#81

Post by jmpman » Thu, Aug 08, 2019, 5:23 AM UTC

jmpman wrote: post #76

sokoloff wrote: post #67

Earlier quoted context omitted.

Here's a pretty decent, graspable explanation: https://physics.stackexchange.com/questions/142463/does-a-ti... Tires that are not slipping are not creating any force against the road surface (so they don't have to slip when coasting, but will slip while accelerating longitudinally [braking or accelerating fore/aft] or laterally [cornering]).

Would you say that a rubber belt on a pulley is slipping? I’m sure at a microscopic level there are some places where the belt isn’t making perfect contact and the rubber is slipping across the pulley, but at a macro level, the belt remains in contact with the pulley in the same place from when it initially contacts until it disconnects.

https://youtu.be/ZVW9uMeFXK8

Yet another video about static coefficient of friction on tires that aren’t slipping. Electric cars are more easily able to keep their tires in this maximum static coefficient of friction range, maximizing acceleration.

Re: Reducing pollution from boats by switching to electric motors

#82

Post by andyrebele » Thu, Aug 08, 2019, 5:36 AM UTC

Accujack wrote: post #22

tyingq wrote: post #10

Earlier quoted context omitted.

They seem to be selling an outboard engine and battery pack that goes on your outboard boat, so I'm confused by your comment. https://www.purewatercraft.com/pure-outboard/

They're selling a 25-40 hp equivalent. My boat needs something like two 75 HP motors to run safely at displacement speeds, and much more to get on plane. In case you're curious, it's about 10M long. You have to have a larger boat to travel away from shore with any safety... small boats have to stick to the coast. My boat isn't actually very big, and doesn't have the range or stability to travel between continents awa…

There are 3 answers to the "higher power" topic: 1) higher power motors are easy, bigger batteries are expensive and heavy. 2) frequency and regularity of usage are the best determinants of whether electric makes economic sense, not size/power, but the bigger power boats tend to go infrequently and highly variable distances. 3) longer-term the low utilization rate high capex problem is solved by shared usage models (as it has been in every other field).

Re: Reducing pollution from boats by switching to electric motors

#83

Post by andyrebele » Thu, Aug 08, 2019, 5:39 AM UTC

semi-extrinsic wrote: post #66

liability wrote: post #47

Earlier quoted context omitted.

I've seen tiny outriggers used for fishing,etc that are two-stroke. Maybe some jet skis too? I'm not sure. Certainly anything substantial won't be two-stroke.

Evinrude's E-Tec line is two-stroke and goes up to 150 horsepower in the G1 series, and to 300 horsepower in the recent G2. That's pretty substantial. OTOH, they have done a lot of engineering to meet emissions requirements, so they are a far cry from grandpa's old outboard that left trails of blue smoke.

The E-Tecs have done exactly what you said - a lot of engineering to meet emissions requirements. Unfortunately, the requirements for outboards include CO, NOx, and HC, but not P2.5 or P10 (particulate) emissions, because they are much simpler and less scrutinized than the regulations on cars (which DO have particulate limits). The E-Tecs put out 30X as much particulate emissions as the 4-strokes.

Re: Reducing pollution from boats by switching to electric motors

#84

Post by ajross » Thu, Aug 08, 2019, 5:41 AM UTC

andyrebele wrote: post #72

ajross wrote: post #25

What this article is really saying is "Two stroke engines are outrageously nasty". Which we knew. They really are dozens of times worse for immediate pollutants (soot/particulates, hydrocarbons, NOx) than a routine car engine and catalytic converter. And they're significantly less efficient, so even their CO2 output is quite a bit higher than a gas engine of the same power. But they're a tiny market and no one has bo…

This is not 2-stroke. This is 4-stroke engines. There are no catalytic converters on marine outboard motors, so the 4-strokes are allowed to be > 100X as polluting as cars.

It's a 25-40HP outboard. I don't have numbers, but the bulk of completing conventional engines in that range are going to be two strokes. They aren't selling big motors yet.

Re: Reducing pollution from boats by switching to electric motors

#85

Post by andyrebele » Thu, Aug 08, 2019, 5:42 AM UTC

analog31 wrote: post #50

liability wrote: post #47

Earlier quoted context omitted.

I've seen tiny outriggers used for fishing,etc that are two-stroke. Maybe some jet skis too? I'm not sure. Certainly anything substantial won't be two-stroke.

As I understand it, there are increasing restrictions and calls to ban 2-stroke marine engines for smaller lakes, because the exhaust contains a fair amount of oil mist that settles on the water.

Besides the oil, the carbureted 2-strokes emit 25%+ of their fuel unburned.

Re: Reducing pollution from boats by switching to electric motors

#86

Post by andyrebele » Thu, Aug 08, 2019, 5:50 AM UTC

ajross wrote: post #84

andyrebele wrote: post #72

Earlier quoted context omitted.

This is not 2-stroke. This is 4-stroke engines. There are no catalytic converters on marine outboard motors, so the 4-strokes are allowed to be > 100X as polluting as cars.

It's a 25-40HP outboard. I don't have numbers, but the bulk of completing conventional engines in that range are going to be two strokes. They aren't selling big motors yet.

Most 25-40 HP outboards sold today are 4-stroke. The only significant brand that's still 2-stroke in the US is Evinrude, and it has < 10% market share.

Re: Reducing pollution from boats by switching to electric motors

#87

Post by andyrebele » Thu, Aug 08, 2019, 5:51 AM UTC

dglass wrote: post #49

jimmaswell wrote: post #38

Earlier quoted context omitted.

Is 2 stroke really that common for personal-use boats? I've only heard of them running on 93 gas, which is all I see sold at marinas, no oil to mix in.

With 2 stroke you need to mix the oil with the fuel before injecting it into the engine in order to lubricate all the moving parts. With 4 stroke the oil and gas are kept separate and you just feed the fuel in. 4 stroke is more commonly sold today but with boating, the lifespan of the equipment is so long that there are a non-trivial amount of 2 stroke engines still in use today.

True, and they're so bad that CARB published a report saying one long day in a 2-stroke jetski pollutes as much as 10 years in a typical car.

Re: Reducing pollution from boats by switching to electric motors

#88

Post by andyrebele » Thu, Aug 08, 2019, 6:00 AM UTC

andyrebele wrote: post #77

ajross wrote: post #25

What this article is really saying is "Two stroke engines are outrageously nasty". Which we knew. They really are dozens of times worse for immediate pollutants (soot/particulates, hydrocarbons, NOx) than a routine car engine and catalytic converter. And they're significantly less efficient, so even their CO2 output is quite a bit higher than a gas engine of the same power. But they're a tiny market and no one has bo…

There are 15.7 million recreational power boats in the US alone (1 for every 10 households), 70% of those in the installed base are powered by outboard motors. This is not the car market, but it is not tiny.

While it's not a small market, it's in the Bay Area's blind spot. Fishing is the 2nd most popular outdoor activity in the US, behind running. In the US, there are 20 million people who fish for freshwater bass alone (1 in 16 Americans). Bass Pro Shops is the Missouri unicorn that grew from nothing to be big enough to buy Cabela's for $5 billion, based largely on their boat sales.

Re: Reducing pollution from boats by switching to electric motors

#89

Post by jbergens » Thu, Aug 08, 2019, 6:57 AM UTC

ajross wrote: post #84

andyrebele wrote: post #72

Earlier quoted context omitted.

This is not 2-stroke. This is 4-stroke engines. There are no catalytic converters on marine outboard motors, so the 4-strokes are allowed to be > 100X as polluting as cars.

It's a 25-40HP outboard. I don't have numbers, but the bulk of completing conventional engines in that range are going to be two strokes. They aren't selling big motors yet.

I think it is illegal to sell >= 25HP two stroke boat engines in Europe. When we last bought one they only had four strokes.

Re: Reducing pollution from boats by switching to electric motors

#90

Post by matt-attack » Thu, Aug 08, 2019, 7:03 AM UTC

jimmaswell wrote: post #38

ajross wrote: post #25

What this article is really saying is "Two stroke engines are outrageously nasty". Which we knew. They really are dozens of times worse for immediate pollutants (soot/particulates, hydrocarbons, NOx) than a routine car engine and catalytic converter. And they're significantly less efficient, so even their CO2 output is quite a bit higher than a gas engine of the same power. But they're a tiny market and no one has bo…

Is 2 stroke really that common for personal-use boats? I've only heard of them running on 93 gas, which is all I see sold at marinas, no oil to mix in.

I grew up in the 80s & 90s running a 150HP 2-stroke Mercury outboard. Fed it oil on each fill-up. Amazing sounding engine, but in hindsight, horribly polluting.