Sail boat engine choice - electric or diesel

[TrentePieds]

The stress on "efficiency" has been absolutely wonderful. But there are those among us who, for our sins, no doubt, are compelled to focus on something as prosaic as efficacy :-)

TP

[chrisr]

i'd like to...again...raise the side benefits of the diesel

after an hour or so running a diesel you have a) hot water b) fully charged house batteries

after an hour or so running an electric motor you have neither

seandepagnier : pls explain how you propose to deal with these issues and how this affects the comparative efficiency ?

cheers,

[TrentePieds]

Quote: "seandepagnier : pls explain how you propose to deal with these issues and how this affects the comparative efficiency ?"

Yes, I'd like to lend my voice to that request. I would also like to hear from Sean how efficiency can be achieved in a variable pitch propeller.

Perhaps also a little something about foil design, Betz limits and Reynolds numbers

TP

[wingssail]

Originally Posted by chrisr

i'd like to...again...raise the side benefits of the diesel
after an hour or so running a diesel you have a) hot water b) fully charged house batteries...

chrisr, I am definitely in the Diesel camp, but you are making big assumptions here.

Some boats have engine heated water, not all. Mine does not. I heat water with a propane instant water heater, which could also be used on a boat with electric propulsion.

Few boats can fully charge their batteries with an hour of running the diesel.

The main, and only real problem, in my opinion, with electric propulsion is the energy density of batteries. You cannot store enough power in current batteries to go any distance under power, and replenishing what batteries you can carry is slow.

Boats that can do it are no longer boats, they are solar farms which float.

When electric solves the storage and replenishment issue all the other issues will disappear.

[carstendenmark]

I am so stupid !

Why bother of "diesel vs. electric" ?

Should have bought that real DeLorean from Back To The Future, when it was on auction !!!

Transfer that engine to my boat. No more problems with long range propulsion, cooking, hot water, A/C, home cinema, etc. etc.

Before doing so, I would use the flux capacitor to take just a sneak peek into the 2050 future, to see how far the powering of boats with such engines has come

Ohh, while I am there anyway, I'll watch the stocks on Wall Street too...

[TrentePieds]

Uf da. Ka' du nu dy dig :-)!

TP

[newhaul]

Originally Posted by seandepagnier

@newhaul and @skipmac

You seem to just want to justify diesel power because it's what you are doing already. This is basic human behavior: typical for people without much imagination. It's also clear you are not really very good sailors or engineers, not knowing the first thing about electric motors insisting that you need to motor 500 miles which everyone knows is a nonsense requirement, despite this, electric boats have a longer range as they generate power underway. I have nothing more to reply to your statements, I will ignore your biased perspective from here on.

I really think you need to actually answer my questions concerning your battery bank .
Read a couple pages back you will find them . I am a retired Navy engineer . I'm the guy that had to make the idiot ideas coming out of Norfolk work.
Sorry but your ideas while intreguing are lacking some serious technical backup.
In other words I doubt your word as to the numbers .

[newhaul]

Originally Posted by newhaul

More information needed .

320 watt hour at what voltage? Are you saying at 13.6 volts or 25ah
Or are you at the cell level 3.6 volt at 320 or 88 ah?

I would love to see what happens when you hit lvd or hvd with that 12 dollar bms.

Now what is the final voltage of your proposed bank?

Are the cells plastic or alluminum cased?

These are the battery bank specs that I would really like to see

[Adelie]

Originally Posted by chrisr

i'd like to...again...raise the side benefits of the diesel

after an hour or so running a diesel you have a) hot water b) fully charged house batteries

after an hour or so running an electric motor you have neither

seandepagnier : pls explain how you propose to deal with these issues and how this affects the comparative efficiency ?

cheers,

By definition, running an electric motor for propulsion isn't going to generate power for the house batteries and the boat will have secondary systems for that. So complaining about that is sort of like bemoaning that apples aren't oranges because all fruit should be apples. Battery charging is a tradeoff you have to make if you chose electric drive. Also, running the engine for an hour would probably not fully charge your batteries unless you were only drawn down to about 90% or they were lithium and you had a honking big alternator.

A lot of electric motors are water cooled these days. No reason that couldn't be used to provide hot water service. Just nobody is pursuing it much or posting about it when they do.

[chrisr]

Originally Posted by wingssail

chrisr, I am definitely in the Diesel camp, but you are making big assumptions here.

Some boats have engine heated water, not all. Mine does not. I heat water with a propane instant water heater, which could also be used on a boat with electric propulsion.

Few boats can fully charge their batteries with an hour of running the diesel.

The main, and only real problem, in my opinion, with electric propulsion is the energy density of batteries. You cannot store enough power in current batteries to go any distance under power, and replenishing what batteries you can carry is slow.

Boats that can do it are no longer boats, they are solar farms which float.

When electric solves the storage and replenishment issue all the other issues will disappear.

thanks, and i agree with you : there are other ways to produce hw. if you have sufficient solar, you can make it electrically. our previous boat had gas hw (as well as engine hw)

my point was that there are efficiencies associated with a diesel that are not being considered, and that changes the equation

as regards charging : true, not many can fully charge in an hour (depends how low you start with i suppose) but again my point was that a diesel is putting juice into the batteries - not taking it out.

these things need to be considered when comparing efficiency

finally : agree completely that the # 1 problem with electric is the inability to store enough energy. our boat carries 750L of diesel which is enough for 1500nm or so. electric will be an option for us when we can get the same range for similar weight / space / cost.

cheers,

[newhaul]

Originally Posted by Adelie

, running the engine for an hour would probably not fully charge your batteries unless you were only drawn down to about 90% or they were lithium and you had a honking big alternator.

.

Not really . now for my 29 full keeler I would need at least 600ah in my lfp bank 400 for the propulsion and 200 for the house loads. As is I have an md2 with a 130amp alternator and a 240ah lfp bank ( + plenty of solar and wind generation) with a 100 amp b2b I can fully charge my bank from just over half to 80% in that hours time . For about a liter of diesel.
And yes it can run on biodiesel but why pay double .

[Adelie]

Originally Posted by wingssail

...
The main, and only real problem, in my opinion, with electric propulsion is the energy density of batteries. You cannot store enough power in current batteries to go any distance under power, and replenishing what batteries you can carry is slow.

Boats that can do it are no longer boats, they are solar farms which float.
....

I think that you can do it these days without becoming a floating solar farm, but the cost in speed and convenience is such that most folks are unwilling to accept it.

For most boats near 30' 500W will get you about 2.5-3.0kt. If you can live with 63-75nm/d that's doable on a moderate sized boat, and you need to accept that if the sun is overcast and the winds dead you can't even do that.

To do this you need 1000W or so of solar panels and about 650Ahr at 12v (carbon foam or lithium) dedicated to propulsion. 1000Ahr if using flooded, gel or AGM.

[chrisr]

Originally Posted by Adelie

I think that you can do it these days without becoming a floating solar farm, but the cost in speed and convenience is such that most folks are unwilling to accept it.

For most boats near 30' 500W will get you about 2.5-3.0kt. If you can live with 63-75nm/d that's doable on a moderate sized boat, and you need to accept that if the sun is overcast and the winds dead you can't even do that.

To do this you need 1000W or so of solar panels and about 650Ahr at 12v (carbon foam or lithium) dedicated to propulsion. 1000Ahr if using flooded, gel or AGM.

there are many boats i know that have 1000w of solar just for the house load. this is nothing special

what you are proposing is ANOTHER 1000w (for only 2.5-3.0k propulsion) ie 2000w total. hence wingsails reference to a solar farm...

cheers,

[waterman46]

Originally Posted by newhaul

If you spilled any fuel into the water the best option is a small squirt of Dawn dish soap.
.

Just had to point out that it is illegal in many places I've been, to disperse a hydrocarbon spill using any detergent. I don't know the science, but that's the law.

Originally Posted by newhaul

The price of electric means nothing if you are using solar or wind to recharge .

If you know of a place where I can get those FREE solar panels, please let me know .

[newhaul]

Originally Posted by waterman46

Just had to point out that it is illegal in many places I've been, to disperse a hydrocarbon spill using any detergent. I don't know the science, but that's the law.




If you know of a place where I can get those FREE solar panels, please let me know .

You really want all my secrets don't ya

I actually have about 300 in my 400 Watts solar and 400 wind including controller. ( Just took 4 years to get it all together from canceled projects of others.