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post #41 of 62 Old 05-21-2019
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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Originally Posted by Cassidy View Post
Actually my boat can also do the first two of those and thatís why I know how hopelessly inefficient it would be to replace diesel.

My watermaker has a 1.5hp electric motor and the only way I can run that for an hour or more is to run the diesel at the same time. The current draw from my house bank is about 160A when itís running at 850psi.

And thatís a baby electric motor compared to a primary drive motor.
Your house bank is also probably a) tiny relative to a propulsion bank and b) lead-acid. Because of Peukert, the bigger the draw the less power you get.

The house bank on my boat prior to conversion was a pair of 105AH (20hr rate) AGMs. That's 210 AH @ 12V or 2.5KWH at the absolute slowest rate of discharge. You want to discharge to less than 50% to make the batteries last, though, so now you're down to 1.25KWH of usable capacity. To add insult to injury, the lead-acid charging rate is limited, so if you do dip down to 50%, it's going to take hours to get back up to 100%.

In comparison, my lithium drive bank is just over 9KWH with a cutoff of 20% SOC, or roughly 6x my usable house bank. They're much more energy dense, don't have differentiated charge curves, absorb charge at a rate that would fry a lead acid battery, and have at least 10x the cycle life. As long as I take care of the batteries, I doubt I'll ever wear them out. Assuming it takes a full cycle to get out of the marina and back again, that's 5.4 years of going out every single day.
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post #42 of 62 Old 05-21-2019
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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IMHO the really scary thing about nuclear power is the time it takes to build a power station. Sure the current time is around 10 years that is 6 months to a year of work and 9 years futzing around with politics and health and safety.

But if the lights start going out and people are facing rolling power cuts and industry has to shut down I bet there will be some fast tracking and the risks will go up, way up especially as there will be less training time.

BTW The French have 68 working nuclear power stations.
It takes a lot more than 6 months just for the construction. But like any project, it's subject to staged inspections, and that does add time. Well worth it, considering the consequences of a catastrophic failure.

There are plenty of ways to mitigate demand other than building new plants. Here in MD the utilities do things like offer rebates for buying high efficiency appliances, educate people on why they should dump incandescent bulbs, offering incentives to charge electric cars at night, etc.

France has a mostly-nuclear grid for a very good reason. After the oil shock of 1973 (France as mostly oil-based electric at the time), they decided to make themselves fossil fuel independent, and went mostly nuclear. As of about 2008, they've started replacing their nuclear with renewables, with the goal to drop to 50% nuclear by 2035. They also export electricity to the tune of about 3B Euro a year, so there's a big financial incentive to keep electricity cheap enough to export. Hence they were a bit late to the game with solar and wind. They don't have the same pollution issues most other countries have.
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post #43 of 62 Old 05-21-2019
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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You're a frontiersman for sure and I'm glad you like your EP. Just to understand, you're hoping to add enough solar to make 2.5kts, without need to recharge? If so, this essentially makes the point about it being a tough cruisers choice. That speed would be a dead stop in the face of some conditions. As I'm sure you know, in order to get a continuous reliable 480 watts of solar PV production, you'll need substantially more capability. Of course, it will do no good at night or in a storm.

I'm not arguing against your path, just pointing out the shortcomings for long distance cruising. The hybrid approach, I know you also employ, does make it a bit more feasible, but the OP was about a "one fuel" cruising system. Curious what solar tech improvements you're waiting for. I see it getting less expensive, but I'm not reading about any imminent significant efficiency per PV sqft or other such improvements.
I certainly understand the hesitation about EP conversions for some. I certainly had to make a leap of faith when I did the conversion in 2008. But, having had over ten years experience there is no place I would not take my boat now that I did with my diesel. Indeed I feel it is a much better experience than when I had the diesel. It is MUCH quieter and much less vibration when doing extended motoring. Even when Electro Sailing with the generator running. Which does not happen that often. As for long distance cruising I'm sure you know their are people cruising with no engine at all. Kevin Boothbay comes to mind.

As for aiming for a pure solar operation at 2.5 knots. It is just a goal to aim for and shows how one can take advantage of new technologies as they come along. Once you install a diesel, well there you are. EP is adaptable. While 2.5 knots may not seem like much under solar. if you were stuck in the doldrums it's better than flopping around and worrying about the limited amount of diesel you still have on board. Don't forget you still have additional power from the battery bank or generator you can draw on as needed. For example at night.

With EP I have a multi-legged stool for making fuel (energy). This includes solar, wind, prop regen and a small generator as needed for charging and Electro sailing. In fact I'm adding a new generator into the mix this season. It will provide more power than my current Honda 2000 for faster charging and Electro Sailing. It's bigger than that workhorse Honda but, has other features like electric and remote start. It's another example of EP upgrade adaptability and also gives me another backup for charging at minimal cost.

If the original OP is planning on doing day trips in and out of a marina dock then a pure EP system would work fine. For my cruising needs I wanted to make sure I had the range when I needed it and the ability to charge batteries fast without going to land. Though it is primarily a sailboat and that's how I like to use it. But, I never hesitate to add a little EP power when needed. Unlike when I was loath to fire up the diesel when the winds started to lighten. EP compliments the sailing experience beautifully. Personally I really don't see any limitations for long distance cruising with an EP system like mine.
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post #44 of 62 Old 05-21-2019
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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If so, this essentially makes the point about it being a tough cruisers choice. That speed would be a dead stop in the face of some conditions.
Geez, why did I find it so tough to say this?
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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Your house bank is also probably a) tiny relative to a propulsion bank and b) lead-acid.
My house bank is 700AH so not that tiny at 8.4kw but yes, it is lead acid.

I stand in awe of your battery bank but no matter how fast your bank can absorb charge and all those other good things, the current solar capability is somewhat limited especially on cloudy days, so is wind and water generation and the power that your bank so gleefully gives up to the propulsion cause has to be put back from somewhere. Genset or shorepower yes, passive sources maybe not.

Reading the last sentence of your post re getting in and out of the Marina taking one full cycle, what do you do if youíre 10 miles from home and a strong headwind develops and the bad weather looks like deepening and nightfall approaches?

Look Iím sure it works for you and probably many others - my opinion is itís not for me.
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

So bad weather is approaching. It's a headwind. It's getting dark. What's a sailor to do? Why turn on the motor of course.
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post #47 of 62 Old 05-21-2019
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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BTW The French have 68 working nuclear power stations.
And they are breeders with fuel recycling which the US started, but walked away from in the 1970s due to political pressures. Even with no new nucs having come on line in decades and all the wind and solar farms that have been put in in recent years, nucs still generate over twice the kWhrs of solar and wind combined. And natural gas and coal produce close to 10 times that of solar and nuclear combined.

So most of the power used by those Tesla autos is coming from burning hydrocarbon fuels, just someplace other than under the hood.

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post #48 of 62 Old 05-22-2019
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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Originally Posted by mbianka View Post
......As for long distance cruising I'm sure you know their are people cruising with no engine at all. Kevin Boothbay comes to mind.
I'm not trying to talk anyone out of EP. If an engineless boat is the comparison, I won't argue that EP, even at 2.5kts, isn't a vast improvement. EP is also quieter, cleaner and has less maintenance. No beef there.

However, if one wants the utility to make hull speed in the doldrums, or needs to run out of the way of a storm for 48 hrs, EP with only renewables just won't get the job done. This is done with diesel, without breaking a sweat. Add a fuel burning generator to EP and that changes the calculus. One now has two motors, instead of one, and redundancy is always pretty good. Although, one is right back to why carbon fuel has an energy density and portability advantage.

EP and solar/wind regen only, won't get one cruising too far. Unless, ironically, the engineless comparison is made.

I think we'll see EP on more boats in the near future, because most boats do not go very far and having a small generator as a safety net will get the job done. I don't see it for serious blue water boats anytime soon. Unless, again, one would be willing to make those trips engineless. Ironically, I'd say more than half the sailors I know, typically stay pretty close and could get away with EP, but outfit and keep their boat in the condition needed for an offshore cruise they may make once a year. Has something to do with the bug, I guess.


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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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My house bank is 700AH so not that tiny at 8.4kw but yes, it is lead acid.

I stand in awe of your battery bank but no matter how fast your bank can absorb charge and all those other good things, the current solar capability is somewhat limited especially on cloudy days, so is wind and water generation and the power that your bank so gleefully gives up to the propulsion cause has to be put back from somewhere. Genset or shorepower yes, passive sources maybe not.

Reading the last sentence of your post re getting in and out of the Marina taking one full cycle, what do you do if youíre 10 miles from home and a strong headwind develops and the bad weather looks like deepening and nightfall approaches?

Look Iím sure it works for you and probably many others - my opinion is itís not for me.
That's a pretty massive, as house banks go. That must be around 600lbs of lead acid.

One of the big question marks for my build is regeneration. I won't have any hard data on that until she's back in the water and I can do some testing. I'll be posting all of that once I have it. How much regen I get is going to go a long way towards determining a doable power budget for longer trips. This will also go a long way towards me estimating the power budget for an eventual catamaran conversion.

I would never be in the situation as you stated it. However, if I was that far from the marina, I'd probably have a full propulsion bank, so 10 miles even into a headwind should be no problem. I it was, I'd just powersail as close to the wind as I could and tack. Failing that, there are plenty of sheltered areas ~10 miles from my marina where I could drop anchor. This is the Chesapeake bay we're talking about, not the open ocean. Khaleesea is a coastal boat or bay cruiser, not a blue water boat, even with a diesel.
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Re: Crazy Propulsion idea for next cruiser... Thoughts...

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So most of the power used by those Tesla autos is coming from burning hydrocarbon fuels, just someplace other than under the hood.
While cars do run at least partially on carbon based fuels burned at power plants, how much it pollutes depends greatly on where you live. But don't think for a moment that they are somehow "just as bad" as gas powered cars. In most states, EVs are *considerably* greener than any gas powered car, even the latest hybrids.

Kentucky and WV have the most carbon-based electricity production. Even then, an average EV gets the equivalent of a 45 MPG car, meaning it's better than anything short of a Prius.

In MD, where I live, it's the equivalent of a 70 MPG car.

In the best state, WA, it's the equivalent of an 85 MPG car.

In Quebec, which is 99% renewables, it's effectively carbon-free. It's also the cheapest electricity in North America at 7.7c/kwh.

Then there's the cost of electricity vs gas. In no state is it cheaper to run a car on gas than electricity. Even in HI, where electricity is the most expensive, it's still cheaper to run on electricity. Going the other way, in ND, where electricity is the cheapest in the country, it's ~1/3 the cost of gas per mile.
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