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Are we closer to an electric tow boat?


Horton
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I have been reading about new electric cars and trucks plus old cars converted to electric. Correct Craft did a one-off 10+ years ago. Seems like batteries and motors required must be getting closer to being commodities. Anyone know anything?

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@oldjeep looks like that one-off Nautique. Any idea if they have done more?

 

@Orlando76 the ski world is going to ever bigger and more expensive combustion engines. The auto industry is moving electric. At some point maybe electric boats are practical. Really just asking the question.

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For a ski lake, electric boats make A LOT of sense. Always getting back to the dock after 15 mins, so fast charging is easy to do. No more fuel carrying (with the related risks).

 

Powerwise, an electric motor is far superior to a combustion engine, giving full HP at all RPMs.

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There really hasn't been any news about the CC/PCM electric acquisition since July- http://www.correctcraft.com/?s=p220

 

For slalom skiing pick your poison - HP/RPM is readily available their stinking SUV out accelerates lambos over short distances - what I think is going to be a handicap is that you basically have two different realities even with electric cars - There is Tesla which is trying to "in house" its manufacturing and control all aspects of their manufacturing costs and therefore has the best margin - but then again has finally just showed a profit (but is massively in the hole), and you have other companies like Daimler who claim electric cars to be about half as profitable as the models they replace. Daimler for instance thinks that it will take about 10 years for the market to adjust for their vehicles to reach the same margins as the IC cars have. Daimler for reference ~80 billion equity... Tesla -4 billion.

 

What that tells me in re: tow boats - I'm really not sure... If you evaluate how we use energy, the best option for three event ski boats is probably just to exempt them. We're such a small niche field I'd wager we contribute more pollution designing a change than is recouped by the improvement....

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I imagine wake or surf boats will go electric first. They push so much water and need so much power. A 6.2 is not a big engine in surf. What I wonder is when we're talking about the cost of supercharged 6.2 if that doesn't get us in the realm of electric being economical.

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Something I previously posted in another electric boat thread:

 

An electric ski boat has a number of advantages and challeges.

 

Pro

- very quite, can talk (well, shout) to the skier

- clean (may open up lakes with gas engine restrictions)

- high torque motor means it only needs about 150 hp

- instantaneous power control: no more ABC,123 for Zero Off

- operating cost: way fewer moving parts, way less maintenance. Electricity is 1/10th cost of gas (in Canada)

 

Cons

-expensive. This is still the case with cars, but improving. It will take a long time for the cost to come down for ski boats. However, with the new 2019 Nautique's price, this may not be a problem. ;-) Last I heard, Tesla thinks it's close to $100 per kWh. That may changes things.

-battery capacity: it takes about 10 kWH for an 8 pass slalom set. That's no more than 10 sets per full charge fora 100 kWH battery

-charge time: industrial power could likely charge the battery in less than an hour, but it's no so easy to get this kind of power to the dock. 240V, 80amp could probably recharge a set's worth of power in 30 minutes. (I didn't do the math)

-battery tech: Tesla has the best batteries in the business but they may not be good for a ski boat which needs to maintain high output for a 30 second pass. Cars generally accelerate for a much shorter time. Different chemistry may be needed.

 

When an affordable electric Nautique is available, I will be first in line. Kudos for Correct Craft for getting the ball rolling.

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Weight is a major factor I'd imagine, but it'd be really cool to be able to place the battery weight wherever you want it as a manufacturer. Also wouldn't need the doghouse to be nearly as large or as long, freeing up tons of interior space.

 

For slalom tug on a private lake, I think it'd definitely make sense. For wake sports, not so much. Those guys ride forever, never get tired, and burn WAAAAY more gas doing their stuff (much higher energy consumption).

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Just my .02 cents, there will need to be much higher electric automotive powered market penetration or market share for the transition on the water sports boats application to be economically realistic. The personal boat market uses automotive developed powertrains after all the R&D has been spent to keep costs viable. Realize that the marinizers actually more than double the cost of the base engine just to convert it to marine use, which must means the base IC engine is very affordable. Consider how much feedback is on this site simply on the cost of new towboats and the availability of cheap fuel in the US (largest market) are significant challenges.

 

Are we closer, certainly and there will be more offerings coming although I think there will be several one offs before one really gets mass produced. Makes way more sense to happen in Europe first given the disparity in fuel costs.

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Honestly just the simple packaging benefit alone would be enormous. Not having an engine box sitting in the middle of boat would be huge! This is the one thing that blows me away every time I look at a Tesla. How efficient it is with space from interior space to the storage in the "frunk" etc. Also the noise reduction would be a big benefit in my opinion.

 

It's not about being green and/or saving money. It's about building something better.

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@Horton asked if we are closer - I think the answer to that is easily yes. :) However, I think there is a different answer if the question were, "Are we close?"

 

I did a little bit a looking - 1 gallon of gasoline stores approximately 33.7kWh of energy. When skiing a standard slalom set of six passes I believe that the commonly accepted number is that the boat uses 1.25 gallons of gas. Some of that gas is "wasted" while the boat idles at the end of each pass. That would not happen with electricity, so lets just assume that an electric slalom set would use 33kWh of energy. A Tesla Model S can be purchased with a 100kWh battery, so...

 

100 / 33 = (roughly) 3 or (precisely) 3.03030303....

 

Therefore, if the data I found is true that means a Tesla Model S battery pack would power 3 slalom sets before it would need to be recharged.

 

The other issue for skiing is weight - the 85 kWh battery pack for the Tesla weighs 1,200 lbs. I could not find more data, but let's assume the 100 kWh weighs 1,400 lbs. Do the math, I am being slightly generous. A gallon of gasoline weighs 6.3 lbs / gallon. An American V8 weighs roughly 575 lbs. More math (sorry):

 

25 gallons of gas x 6.3 lbs = 157 lbs

V8 engine = 575 lbs

Total = 732 lbs.

 

So, the weight of your energy storage and power plant in a typical ski boat is around 750 lbs. Just the batteries in a Tesla are double that. What would the electric motor weigh, maybe 100 - 200 lbs? How many of us would like to slalom behind a machine with an additional 850 - 1,000 lbs in the boat? I know my hand is not going up.

 

My belief is that there needs to be a step-change in energy / battery storage capability before we can put batteries in as the primary power supply in a boat. Cars are a completely different energy equation, as others have pointed out here: they coast; they can regeneratively put energy back into the batteries; and they don't sit in water (which decidedly does not get along well with electricity).

 

I hope that we can get there. A quiet, powerful and all-day electric ski machine would be awesome.

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@KRoundy that's some solid math, but you're forgetting one important factor. While it's true that fuel packs about 33.7 kWh into a gallon, an internal combustion engine only operates at around 20-25% thermal efficiency. That means 75-80% of that energy is being lost by just turning it into heat.

 

Given that, your 3 slalom sets on a 100 kWh battery turns into closer to the range of 10-12 sets due to the much better thermal efficiency of electric propulsion.

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@UWSkier That is a very good point that I neglected to factor into my calculations. So we could get perhaps a dozen sets out of a Tesla-battery setup. I still stand by my weight calculations, however...

 

So, let’s see what we could do for the same amount of weight. If we put in a 200 lbs electric motor that would leave 550 lbs left for battery. My battery weight to kWh math shows that each kWh costs 14.12 lbs of battery. That allows us to drop in a 39 kWh battery. Let’s round that up to 40...

 

UWSkier and I have determined a slalom set costs 6.74 kWh (20% of 33.7). We could get almost six sets before the batteries are drained. That is pretty good and could definitely work for a private lake / personal setup where you and a few friends get in some skiing before going to work or at the end of the day. Pretty cool! It would not work for tournaments, ski schools or clubs where six sets is just getting started.

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Graphene polymer batteries are real close; speculation has Tesla pursuing their use relatively soon.

1kWh/kg density (6x lighter than Li for equivalent energy), 5x faster charge.

So with @KRoundy calc; that's 36 sets with the same weight and a quick recharge to boot!

 

Graphenano Co reputedly has developed those capable of charging and discharging approximately 33 times faster than a Li battery; we’ll see.

 

Cool stuff happening.

 

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So what I'm hearing is that for the .00001% of boaters who live on a private ski ditch this would be an awesome idea. (That would be if they were not still mostly driving old nautiques)

 

So, just for grins at what price would an electric boat still be desirable? You're looking at 100K for a regular gas powered boat based on readily available parts. Figure an electric boat in the ultra low volume that they would be produced in would be double?

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@oldjeep no smart buyer pays near 100k

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Not much additional R&D required at all. They would be lifting technology from elsewhere just like they did with gas engines.

 

Sure there would be some experimentation with engine and battery placement, have to try a few different props, but that's about it.

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@Jordan : Lifting technology and validating it for an alternate use are very different, the manufacturers should validate the system for viability and reliability rather than letting the customer do that. In addition, for this market, AWSA testing, speed control integration and basic functional testing will all be part of bringing an electric boat to market. Those tasks won't be insignificant in either time or $ particularly for a manufacturer that has an excellent reputation as do the big three.
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My boat house is wired for 220 but I currently just use 110 down there by not wiring the second line in. 200 amp would require even thicker gauge than I currently have so that's a show stopper unless I want to rewire. I'm hopeful that in the future as batteries get better, charging stations can draw significantly less power. Honestly, I could live with a system that would only give me 6 sets back to back and then need a recharge but who knows what will be possible. A 220 charging station with batteries, solar and a 110 line in might be all I need.
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I think that at the moment, the technology won't work for most people. The DC rapid chargers available here in Europe are 50kW and I think that the non-Tesla ones are the same in the US. The Tesla superchargers are 120kW and I don't know how much they cost to install but a 50kW rapid charger costs anywhere between £50,000 and £100,000 to install here in the UK depending on location but we are talking about areas like motorway service stations, not a lakeside - I suspect it would be way over £100,000 at many lakes because of the amount of cabling required.

 

A 50kW rapid charger takes over 2 hours to fully charge a 100kW/hr Tesla battery, so if you have to stop skiing every 8 - 10 sets and then have a 2 hour delay to recharge, I don't see anyone paying an extra 100k on top of the boat for that privilege.

 

I think there will need to be a pretty dramatic upgrade in this technology for electric boats to be a practical proposition for the majority of users. Electric cars have ranges of 80 - 300 miles when fully charged. This is more than the average daily mileage for the vast majority of people so an overnight, slow charge approach is ideal. Tow boats have a completely different usage pattern.

 

If, however, you had a boat which got used one day a week for a limited number of tows (less than 10), then the idea of solar panels would come in to play - you could slow charge for "free" over several days. There is, however, a limit on how much energy the sun delivers per square foot of planet earth so no matter what improvements come along in solar or battery tech, it would not be possible to charge quickly without huge solar arrays. You will never see cars being run from photo cells on their roof - it isn't possible.

 

I'm not down on electric vehicles - I drive one every day and think electric cars are absolutely the future. I just think it will be a long time before this tech makes sense for the majority of water skiers

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An element not available to the marine aspect is the ability for recharging on the fly via brake energy, coasting regen systems, flywheels etc. That technology will be a key to integrate electric for extended automobile range. The Porsche 919 is a pretty cool example of multiple technologies integrated to provide a 1,500 HP vehicle that starts with a 1.4L V4. The bigger issue may simply be getting recharging power to the boat itself.
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@oldjeep, I am sure this varies by state and country. In Ontario, Canada many cottages including my own run deep well submersible pumps in the lake to provide household water. All that is required to run 220v right into the water is dedicated circuit with a GFCI breaker(5ma trip threshold)

.

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Interesting thread - my wife and I are already contemplating building a house on our local "ski ditch" next year, so while we're doing it...I'll run 220 to the boat house. I'm sure it will happen sooner or later. If I win the lottery I'll cover the boat house in Tesla solar roofing :)
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Charging of any battery basically comes down to:

How quickly the technology can be charged with out damaging the cells/chemistry.

How many amps at how many volts can you supply.

 

Tesla has batteries that can charge 170 miles of range in 30 minutes - that's charging 480V at 300 Amps. Something no residential home has and certainly not at the boat house.

 

When you talk about running service its not the voltage that adds costs it is the amperage.

 

Pretty cheap to toss a 60 amp subpanel in a boat house with a direct bury rated wire for a few hundred feet to be able to power lights, pumps, that margarita blender, a fridge or what have you. Costs go up quite a lot if you need to have enough amperage to rapid charge the old boat between sets.

 

@Jordan example is pretty basic - the amperage requirement of a small 220V pump is tiny - 7 amps/HP full draw - so a 10 amp breaker, 14 gauge wire and voila. not so for a high speed charger.

 

 

 

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#1. What the heck is 220? Pet peeve.

#2. Yes amperage is expensive but to say voltage isn’t is incorrect. Voltage can get expensive and quick.

#3. 480v is possible in any home.

#4. To get 208 or 240 to a boat house via a permit requires basically GFCI protection and a lot more education and testing and expense than the average person will acknowledge. But in short, no different than 120v.

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