Why not electric engine powered boats

[Stumble]

Originally Posted by StuM

No, he didn't say 80% of hull speed with 50% of power. He said 80% of hull speed with 50% of throttle.

I suggest you learn a little about diesel engine power curves before opining on how to replace them.

Why learn anything when applying prejudice is so much easier? So far the number of fabrications, falsehoods, and mistakes far out weighs the amount of usable information. Add in a little bit of Luddite 'everyone used to sail around without engines' nonsense and it's barely comprehensible nonsense.

Electric power doesn't work because batteries can't provide a reasonable range, solar panels don't work because you can't put enough of them on a boat to drive a propulsion motor long, generators don't work because the size of the generator for 50% power is about the same as a direct drive at 100% power.

The short answer is that electric cruisers don't really work. Electric day sailers can so long as you accept their limitations. The rest of this conversation is just repetition of things covered here ad nausium.

[Lodesman]

Originally Posted by StuM

No, he didn't say 80% of hull speed with 50% of power. He said 80% of hull speed with 50% of throttle.

I suggest you learn a little about diesel engine power curves before opining on how to replace them.

It has nothing to do with diesel engine power curves - the power required to push a displacement hull through the water increases exponentially as the speed increases. Not sure if that was Valhalla's meaning, but that's the way I took it, as it's roughly correct.

Not sure why you need to be so insulting. Do try to be nice.

[Lodesman]

Originally Posted by Stumble

It still leaves you with a generator that is larger than the propulsion motor you took out, that is far too big for normal house loads.


50% power on my boat (38' sailboat) is 21hp or 16kw. Go take a look at the size of a 16kw continuious generator and compare that to a 32kw propulsion motor. What you will find is that the generator is actually larger, and heavier. So why would I want to install it again?

But it would be replacing both a propulsion motor and a generator for many. I can't be bothered to go searching engine specs - perhaps you have some figures at hand?

Perhaps the benefits can't fit neatly in the cost or weight savings categories. I think that having immediately available electric propulsion (off the batteries) would be useful in a sailboat if you need that extra bit of push to finish a tack, or the comfort of being immediately capable of motoring out of a colregs situation. This drain could easily be recouped via solar/wind/regen, and saves the need to run up the diesel and leave it idling "just in case." Since the diesel would be run only under full load, it will be happier.

[StuM]

Originally Posted by landlockedsquid

Thanks for answering.
So a 2400 watt generator is kinda small. Heck I have a 4000 watt peak 3000 watt continues sitting in my garage I used to use for powering the travel trailer.
And I had no solar or wind.
So how many watts do you think it would take to power a 25hp electric motor? What about a 50 hp electric motor?
I wonder if you could power that with a 9KW Onan Marine Genny?

The math is quite straightforward.

1HP = 745.7 Watts.

25HP = 18.6 kW
50 HP = 37.3 kW

9kW = 12HP

That is, of course, ignoring other factors such as efficiency. Is it more efficient to directly drive a prop from a diesel engine or is it more efficient to generate electricity with a diesel engine and use the electricity to drive a prop?

[StuM]

Originally Posted by Lodesman

It has nothing to do with diesel engine power curves - the power required to push a displacement hull through the water increases exponentially as the speed increases. Not sure if that was Valhalla's meaning, but that's the way I took it, as it's roughly correct.

It clearly was NOT Valhalla's meaning and I don't see how you can take this statement to refer to increasing boat speed. In fact is is quite the reverse and has everything to do with power curves.

"The propulsion engine is 25hp and about 50% throttle gets us 80% of hull speed in calm conditions. If there are adverse conditions (say a strong headwind) we need to use most of that 25hp to make headway."

[Paul Elliott]

Originally Posted by boat_alexandra

Why don't you take a plane and save a lot more time?

Cute.

Since you apparently have no interested in considering that other people may have different goals and priorities than yours, I will not waste my time, or yours, in further discussion with you here.

Fair winds,
Paul

[Cap Erict3]

http://www.rcgroups.com/forums/showthread.php?t=360425

[Lodesman]

Originally Posted by StuM

I don't see how you can take this statement to refer to increasing boat speed. "about 50% throttle gets us 80% of hull speed "

Gee, I have no idea

[seandepagnier]

Originally Posted by skipmac

In theory is correct but it is extremely rare that any boat will be motoring in completely dead calm, waveless, currentless conditions. With just a slight chop, wakes from other boats, etc a boat will constantly be accelerating and overcoming the inertia of the mass of that boat. In theory you say a larger boat would be as efficient. I don't necessarily concede that but in practice real world conditions will not work that way.

It depends on the wave period relative to the size of the boat. The smaller boat is better off in longer waves, the longer boat is better off in shorter waves.

The solar navigators I have seen that can achieve 11 knots in direct sunlight are a lot larger than my boat.

about where to install more panels on my boat and options are limited and laying panels on the deck and cabin top is not for me a safe option. I won't even get into the inconvenience of moving panels around every day plus finding a place below to store them when not in use.

What is wrong with the cabin top? I have had mine there for years without problem.

On the ICW lots of bridges have limits on when they open. Some only on the hour, some on the hour and half hour, many are closed 2-3 hours twice a day for morning and evening rush hour. Even under power I have been stuck between two bridges a few miles apart when I couldn't make it to the next bridge on the hour. Once I was ONE MINUTE late and the bridge would not open. Bridge tenders are generally very strict about following the rules and I imagine they will be pretty pissy about a boat trying to skull through the span. They are all in communication with each other so you slow down one bridges opening/closing due to low speed, low power or skulling and you will be marked and possibly blocked from further transit unless you can comply with their rules.

I didn't realize this, but perhaps it's an argument for the larger electric motor that can give you 3-4 knots in bursts of less than a mile. There is no technical reason this won't work even with an inefficient setup.

I will continue my be nice policy and just assume this was said in jest but I wouldn't see much humor if for example an ambulance was blocked and had to make a 20 mile detour to the hospital with a critically injured patient.

Maybe you also saved a lot of lives because there are less accidents in traffic jams.

If you allow all possible "what if" scenarios anything can be possible

Didn't say you do or would. I'm pointing out that it's a problem even in the US where many people are not as responsible about recycling and much, much worse in third world countries where they cannot. Lead is extremely toxic and is in no way green or environmentally friendly. Like it or not, lead batteries are not good for the environment.

Agreed, this is one reason I stopped using electric and built a more efficient sculling oar carved out deadwood from the forest that can really go well against 15 knots of wind.

Another issue of theory vs reality. In theory solar panels can be recycled. In practice from my reading on the issue, there is insufficient quantity of used panels yet to appear on the market (due greatly to their long lifespan) for anyone to be doing it on a commercial basis.

Yes, well having a long life is already a great thing, and my point is that eventually they will be recycled again and again shows that solar panels really are pretty amazing technology, and compared to alternatives much better for the environment.

Here I have to say you're getting a bit sanctimonious. By cruising on a boat, buying the electric motor that drives it, the batteries that power it, the solar panels that charge the batteries, the sails made of synthetic fibers, buy a computer, use the internet, buying a VHF radio, every thing you buy and use consumes energy to

I didn't buy my computer or my vhf radio or a lot of the sails I have... anyway this is also again a case of arguing that if I consume a small amount then it's ok for someone else to consume as much as possible.

produce and ship it to you and produces pollution to make the raw materials to make the goods. If you want to throw the first stone in this battle then you need to give up all consumer goods and anything produced from non renewable resources. For example, you have made the choice to use synthetic sails and synthetic fiber lines. If you want to criticize people for using diesel fuel then you need to switch to cotton sails and hemp and manila line.

Maybe I should use cotton sails and hemp line. But I can say the synthetic fibers can be recycled as well. Burning diesel fuel is not comparable to this in any sense.

Trees are renewable resources. As long as you aren't cutting redwoods or wasting the rain forest cutting a tree or two is not harming the environment.

I agree, if the correct tree is taken.

It is definitely cheaper to not have an engine. I cannot think of a sacrifice or compromise from not having one, it is the other way around.

Then you have ignored a lot of responses in this thread. Traveling at 2 kts for 99% of the boaters in teh world is a compromise. So is limiting where and when you can travel.

If we actually burn all the oil in the ground it's going to cook the world 3 times over. What kind of compromise is that?

There are exceptions. Study the Colregs. For example, larger boats constrained by draft you have to give them room. You are also not supposed to impeded navigation in a narrow channel

You need to be a "ship" typically 500 tons to be an exception.

If the channel is so narrow to impede your navigation on 12 meter boat, then it is also impeding my navigation on an 8 meter boat, so I don't see how sail power wouldn't still have right of way.

I am not claiming I will tack right in front of another boat, and I know the ICW is wide enough almost everywhere that any cruising boat under power can easily avoid me if I am tacking up the channel.

What I am claiming is that you don't have the right to just motor down the middle of the channel at 5 knots when I am tacking up it from the other direction, you should move all the way to one side so I can tack up the other side, and this can be done 100% of the time without issues. If someone were to cause a collision because they refused to do this because they think it's wrong to sail in the channel or some other nonsense, then I will be sure they regret their mistake.

[Cap Erict3]

As these threads pop up regularly, I occasionally scan commercial products for economically viable engine generator, inverter, motor equipment with cruising boats in mind.

The portable Inverter style are great for what they do and a diesel version (Not wild about gas in enclosed areas) has the potential to drive a small boat.

Haven't seen one yet nor do I have more than curiosity on the subject. I have met folks with a passion for the electric conversion but none with electrical engineering backgrounds.

In the recreational boat world anyway.

[StuM]

Originally Posted by Lodesman

Gee, I have no idea

True!

[skipmac]

Originally Posted by boat_alexandra

[/COLOR]
It depends on the wave period relative to the size of the boat. The smaller boat is better off in longer waves, the longer boat is better off in shorter waves.

The solar navigators I have seen that can achieve 11 knots in direct sunlight are a lot larger than my boat.


What is wrong with the cabin top? I have had mine there for years without problem.


I didn't realize this, but perhaps it's an argument for the larger electric motor that can give you 3-4 knots in bursts of less than a mile. There is no technical reason this won't work even with an inefficient setup.

Maybe you also saved a lot of lives because there are less accidents in traffic jams.

If you allow all possible "what if" scenarios anything can be possible

Agreed, this is one reason I stopped using electric and built a more efficient sculling oar carved out deadwood from the forest that can really go well against 15 knots of wind.

Yes, well having a long life is already a great thing, and my point is that eventually they will be recycled again and again shows that solar panels really are pretty amazing technology, and compared to alternatives much better for the environment.

I didn't buy my computer or my vhf radio or a lot of the sails I have... anyway this is also again a case of arguing that if I consume a small amount then it's ok for someone else to consume as much as possible.

Maybe I should use cotton sails and hemp line. But I can say the synthetic fibers can be recycled as well. Burning diesel fuel is not comparable to this in any sense.


I agree, if the correct tree is taken.

If we actually burn all the oil in the ground it's going to cook the world 3 times over. What kind of compromise is that?
[/COLOR][/COLOR]

You need to be a "ship" typically 500 tons to be an exception.

If the channel is so narrow to impede your navigation on 12 meter boat, then it is also impeding my navigation on an 8 meter boat, so I don't see how sail power wouldn't still have right of way.

I am not claiming I will tack right in front of another boat, and I know the ICW is wide enough almost everywhere that any cruising boat under power can easily avoid me if I am tacking up the channel.

What I am claiming is that you don't have the right to just motor down the middle of the channel at 5 knots when I am tacking up it from the other direction, you should move all the way to one side so I can tack up the other side, and this can be done 100% of the time without issues. If someone were to cause a collision because they refused to do this because they think it's wrong to sail in the channel or some other nonsense, then I will be sure they regret their mistake.

OK, this has reached point of tedious and silly. Are you really seriously suggesting blocking a major road would be a good thing and might save lives? An the Colregs do not specify a minimum size vessel where constrained by draft applies. It is constrained by "draft" not length or size.

I've answered every single question and addressed every single issue you've raised and you continue to ignore half of what I say and talk in circles around the rest. It appears to me that you only want to prolong and provoke with no wish to actually learn. It is obvious that you have formed your opinion and no logic or discussion is of any real interest.

Obviously getting nowhere and I've got some family matters to deal with so enjoy the thread.

[Tx J]

boat_alexandra,
I respect you a lot, watching your worldwide travels and port calls is amazing. I've seen you get unfairly beat up here by those unaware of your work on Opencpn.
But you have to realize you're a bit of an anomaly, even for the sometimes eccentric world of sailors. A good anomaly, IMO.

Purely in the spirit of jesting with you, I think you might rename your boat, or ID, from "boat_alexandra" to "boat_amish". Apropro for one of a somewhat Luddite outlook, no?

[Lodesman]

Originally Posted by StuM

True!

Someone needs to explain sarcasm to you. Let me google that for you

[StuM]

Originally Posted by Lodesman

Someone needs to explain sarcasm to you. Let me google that for you

Thank you for your educational post.