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Old 17-08-2021, 04:10   #376
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Re: Replace Diesel with electric engine

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Originally Posted by s/v Jedi View Post
For us it is a really big thing that we need to visit a fuel dock; we would love to eliminate this dependency
Autonomy is one good reason for going all electric but again, if you are frugal with diesel, it won’t be diesel that forces you into harbour. Take my boat as an example. Between my heater, genset and engine, my average consumption is 15l a week. Only a third of that is for propulsion. I carry 350l of diesel in the tank and 20l in a can. My tanks aren’t huge but That is enough for 6 months at sea given my consumption. I carry propane stores that exceed this.

I can’t carry 6 months of food! At most we can carry 3 months of food. That means that our autonomy is mainly restricted by food not fuel. That is the case for most sailors who don’t just use their boats like displacement motorboats with big lightning rods. At some point we all get forced into harbour to provision properly and swinging by the fuel pontoon on the way in or out is not much of a hardship.

I can absolutely understand ditching propane for cooking if possible as getting ahold of that commodity is not always easy and induction cooking is safer and generates less waste heat and moisture. But most Water boats">blue water boats have sufficient tankage that fuel won’t be what forces the purist sailor into port.
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Old 17-08-2021, 04:15   #377
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Re: Replace Diesel with electric engine

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Just choose the tack with best VMG and go.

Yes, does not matter if you have 500 Miles to go. Wind will shift.
But if it is 2 p.m. and you want to go 12 Miles to the next marina.
Upwind with engine 6 knots 2 hrs.

On the tack 4 knots 12 NM x 4 = 48 NM / 4 = 12 hrs

Oh nice, you do not have to pay the marina as you will not reach it.
your nautical skills are impressive I recommend you to fly or ferry to the next marina. For tacking straight upwind, which is rare as normally you have a tack with a better angle, the distance is a third longer, so 12nm becomes 16nm which, at 4 kts boat speed would be 4 hours to get there, not your math outcome of 12hrs…

But there’s more. We will do 5 knots so just 3 hrs 15 mins for us.

But there’s more. We would leave earlier so that we would easily make it before happy hour

But there’s more. We don’t sail to marinas, we anchor in anchorages

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Old 17-08-2021, 04:28   #378
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Re: Replace Diesel with electric engine

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Autonomy is one good reason for going all electric but again, if you are frugal with diesel, it won’t be diesel that forces you into harbour. Take my boat as an example. Between my heater, genset and engine, my average consumption is 15l a week. Only a third of that is for propulsion. I carry 350l of diesel in the tank and 20l in a can. My tanks aren’t huge but That is enough for 6 months at sea given my consumption. I carry propane stores that exceed this.

I can’t carry 6 months of food! At most we can carry 3 months of food. That means that our autonomy is mainly restricted by food not fuel. That is the case for most sailors who don’t just use their boats like displacement motorboats with big lightning rods. At some point we all get forced into harbour to provision properly and swinging by the fuel pontoon on the way in or out is not much of a hardship.

I can absolutely understand ditching propane for cooking if possible as getting ahold of that commodity is not always easy and induction cooking is safer and generates less waste heat and moisture. But most blue water boats have sufficient tankage that fuel won’t be what forces the purist sailor into port.
Provisioning for long periods is complex… I know that well as we are two years into our 6-month expedition style trips. This means we leave with everything we need and return a minimum of 6 months later with all garbage we generated, leaving nothing in our wake.

The first trip we had some fails but our second trip we managed to extend it to 9 months and we still have provisions left. This includes baking bread twice a week, making yogurt once a week, making granola every two weeks etc. really everything and all made from scratch from healthy ingredients. This is not easy, we do a lot of pickling, pressure canning, vacuum packing using a vacuum chamber machine etc.

This was done without hunting/fishing, which can multiply how long provisions last. At the moment we are working on better methods for storing provisions, while fine tuning dishes, adding more variety etc.

Also, we will now start with more serious hydroponics aboard, which means bringing seedlings as well as seeds, nutrients etc.
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Old 17-08-2021, 04:58   #379
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Re: Replace Diesel with electric engine

That is hard core boat survivalist stuff. Definitely out of my league and experience.
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Old 17-08-2021, 06:01   #380
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Re: Replace Diesel with electric engine

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That is hard core boat survivalist stuff. Definitely out of my league and experience.
Hahaha you think? It’s combining old and proven food preservation methods with modern hi tech methods. It is becoming so popular that simple things like canning lids have been sold out for the past two years. Chest freezers, dehydrators, canners, even popular ovens have been sold out or very hard to get for years. The shortages go much further than toilet paper and hand gel
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Old 17-08-2021, 06:21   #381
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by moseriw View Post
Just choose the tack with best VMG and go.

Yes, does not matter if you have 500 Miles to go. Wind will shift.
But if it is 2 p.m. and you want to go 12 Miles to the next marina.
Upwind with engine 6 knots 2 hrs.

On the tack 4 knots 12 NM x 4 = 48 NM / 4 = 12 hrs

Oh nice, you do not have to pay the marina as you will not reach it.


It’s not 12nm x 4kt = 12hr

It’s 12nm / 4kt = 3hr.
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Old 17-08-2021, 06:58   #382
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Re: Replace Diesel with electric engine

It really looks like most guys have never been on the tack. Oh I confess, x4 is a bit much but I never did it below 2,5. Average was around 3

So what?

Oh I forgot you all own racers beeing able to do constant 5° to the wind.

With drift and waves I am happy to make 40° to the wind and most of the guys who says other things simply lie and did not try it more then an hour.

Wind shifts +/- 15° are quite normal. waves that hammer you out of your course, currents and the way leeward too.

And my calculation under sails was always the same 1 hr straight but minimum 3 mostly 4 hrs on the tack.

Boats: you name it Salona, Bavaria, Jeanneau between 36 and 52 and a Vagabond 47
Stats over 15 years.

SO WHAT DO YOU WANT TO TELL ME?

What you did ist looking at the meter and reading that you are within green or red.
OH yes yes this is the ultimate truth if you want to lie on yourself.

Navigate it on a paper chart and write in your proposals and the look at the truth.

Sure you never did it.
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Old 17-08-2021, 07:20   #383
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by moseriw View Post
Just choose the tack with best VMG and go.

Yes, does not matter if you have 500 Miles to go. Wind will shift.
But if it is 2 p.m. and you want to go 12 Miles to the next marina.
Upwind with engine 6 knots 2 hrs.

On the tack 4 knots 12 NM x 4 = 48 NM / 4 = 12 hrs

Oh nice, you do not have to pay the marina as you will not reach it.
Oh, that's silly. Jedi and many other boats will make about 75% VMG while tacking upwind. So if he can go 6 knots under sail he can go 4.5 knots VMG sailing upwind. The 12 miles will take 2.66 hours, and if the wind is not directly in the nose, probably less.
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Old 17-08-2021, 07:30   #384
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by moseriw View Post
It really looks like most guys have never been on the tack. Oh I confess, x4 is a bit much but I never did it below 2,5. Average was around 3

So what?

Oh I forgot you all own racers beeing able to do constant 5° to the wind.

With drift and waves I am happy to make 40° to the wind and most of the guys who says other things simply lie and did not try it more then an hour.

Wind shifts +/- 15° are quite normal. waves that hammer you out of your course, currents and the way leeward too.

And my calculation under sails was always the same 1 hr straight but minimum 3 mostly 4 hrs on the tack.

Boats: you name it Salona, Bavaria, Jeanneau between 36 and 52 and a Vagabond 47
Stats over 15 years.

SO WHAT DO YOU WANT TO TELL ME?

What you did ist looking at the meter and reading that you are within green or red.
OH yes yes this is the ultimate truth if you want to lie on yourself.

Navigate it on a paper chart and write in your proposals and the look at the truth.

Sure you never did it.
Moseriw, We sail upwind more than we sail downwind (and enjoy it more; less rolling and more speed in light wind). We've sailed many thousands of miles, much of it upwind. We know what we are doing.

I absolutely tell you you are wrong about what people can do upwind and I am happy to present to you actual courses traveled as evidence.
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Old 17-08-2021, 08:15   #385
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Re: Replace Diesel with electric engine

My rule of thumb on distance x 1.33 for upwind tacking is based on a 40 degree true wind angle. If you do 45 degrees it becomes 1.4 but it never becomes 4.0 or even 2.5
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Old 17-08-2021, 08:18   #386
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Re: Replace Diesel with electric engine

Dirk1, I said that regen is a fraud because it is sold as a way to recharge batteries by sailing, mostly by people trying to convince others that the EV proposal is better than it actually is.

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Regen of 35kW @12V??? What are you talking about?I used 34kw as an example of how impossible it was.
1st 35kW EP needs 96V (probably 48V with a really fat cable).
2nd (and most important) - props are usually optimized for one direction - forward.
yes, so that means that you get less power out of regen at a given speed than it takes to drive your boat at that speed under power

3rd The prop-slip has to be compensated too. Means you need a lot more speed under sail.

Prop slip occurs while powering too

In real life regen is about 10-15% of the nominal forward power.

OK, so if your boat can be driven at 6 knots with 7.5 kw, you are expecting 10-15% back by regen? That's 1/12 the power it took you to drive the boat (and this is best case). So you would need to sail 12 hours to replace the power you used in one hour. Actually, it is much worse than that.

But that is totally o.k. @5-6 kts sailing speed. Sailing 24hrs and regen with 3 kW produce over 80 kWh per day. That is probably more than the battery capacity - even with a wash day or a 4 course menu with induction cook top and convection oven...

Totally fictitious. If you use 7.5 KW 10-15% (your numbers) is regen of 750w to 1000w, less than 1 kw, not 3kw.

(BTW - 80kWh battery capacity weighs about 700kg!)
As Jedi said - 1/2 hour of nominal output would be o.k. That leads to about 20 kWh capacity) and needs less than 1kW regen power.
It is also wrong to only compare HP or kW numbers. 20kW on the shaft of an electric motor are (almost) 40HP ICE performance designation.

No way does an ICE waste 50% of it's shaft hp, this is argued elsewhere in the thread.

It makes no sense to throw half-truths around.

Regen is not a fraud!
But the bottom line is irrefutable: If it takes 7.5kw (10HP) at the propeller to drive a boat forward, turning that propeller while sailing to extract power will take at least 10hp also (more with the prop losses).

And that 10HP is in addition to the 10HP it needs to get out of the sails to move the boat at 5-6 knots. Few boats have that much excess power available from the sails.

Another way of looking at it is: If it takes 10 hp to move your boat, where is the extra 10HP to spin the prop in regen mode coming from?

The obvious answer is two fold:
  1. The drag of extracting power by spinning the propeller slows the boat.
  2. Even the most modern hydro generators, such as Watt&Sea, produce very modest outputs. The company claims that "the cruising model will recharge a 200-amp, 12-volt battery to 50 percent of its capacity after 10 hours with a 5-knot boat speed" This is about 120watts. and it still knocks up to 1/2 knot off of the boat speed (point 1). https://www.google.com/search?q=how+...hrome&ie=UTF-8

Buyers want to believe the electric boat motor story, and they willingly believe that regen is going to do something for them, generally it is a lot of optimism which I doubt actually pans out and the sellers know that.

That's why I call it a fraud.
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Old 17-08-2021, 09:02   #387
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Re: Replace Diesel with electric engine

Quote:
BTW - 80kWh battery capacity weighs about 700kg!
nope, LiFePO4 80 kWh battery weight ~425 kg.
LiNMC weight in 1/4 less than LiFePO4 ~340 kg.
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Old 17-08-2021, 09:29   #388
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Re: Replace Diesel with electric engine

"...Your bowthruster analogy has merit though. 6kW to move the boat sideways at 2kt vs 7.5kw to move it forward at 6kt sounds about right. Good comparison....."
VERY doubtful the bt will "move the boat sideways" at 2kts! It will TURN the boat & in doing this might move the tip of the boat at 2kn...
I find this insistence on the feasybility of EP absolutely hilarious. Go to any crossroad of circumnavigators & count the boats with EP! Jimmy Cornell failed - but youall surely will outdo him! He's been out there (where few of you have gone) & back, multiple times & had sizeable funds to let the pros do it-& it didn't work. But surely youall...will (nice turn of Kraut-phrase "show him where Bartl fetches the cider!" I am thrilled waiting for it to happen!
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Old 17-08-2021, 09:50   #389
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Re: Replace Diesel with electric engine

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Originally Posted by s/v Jedi View Post
but it never becomes 4.0
Well it could - if you can't get closer to the wind than about 75º
Maybe he sails a square-rigger
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Old 17-08-2021, 14:23   #390
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Re: Replace Diesel with electric engine

Not sure I agree with you about hydrogeneration wingsail. It has its issues, but from what I have heard from those who have this on their boat, they easily get 300W out of them when powered up to hull speed (where any speed loss from the unit is neglible). 300W day in day out on ocean passages is 7.5 kWh a day. Most boats fitted with these make more power than they can use when they are working.

Assuming an average usage of 3.5kW under sail, you would be able to top up the bank at a rate of 2-3 kW a day. It would need to be a long passage - 10 days or so - to fill a bank big enough for an all electric boat, but it’s doable.

The main issue with such units is that they are notoriously unreliable, high maintenance and finicky in use. Also 90% of the time it’s an idle asset..
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