Sail boat engine choice - electric or diesel

[JulienPete]

Originally Posted by roverhi

A restriction in fuel flow will also limit engine output. Is your fuel filter possibly mucked up or the fuel probe in the tank obstructed??

Anyway, would see if I could find a reason for the engine not reaching max operating rpm before I chucked it overboard whether it's replaced with electrons or a new diesel. Both are way more expensive than possibly fixing what you already have.

Also check the fuel on/off tap. We had problems with our boat for a couple of years in that it would run for 20-30 sometimes a lot longer. And the engine would lose power and after a few minutes stop. We changed everything on the fuel side all lines and the type of fuel filter to no avail. Eventually found that the gate on the fuel tap (the last thing we changed) would slowly shut until the engine starved of fuel would stop. Depending on the state of the sea 20 -30 mins later the engine would start again. The boat bouncing about would open the fuel tap gate which could last the journey or stop randomly.



It could be your fuel tap gate is stuck part way down/no opening fully, therefore not allowing enough fuel to get to full power.

[carstendenmark]

Thanks for the back-on-track posting, DeValency !

When waves, wind and current are against me when motoring, my old 10HP diesel can't get me out of the place (SOG=0). Most Maxi 87's has 13HP, some up to 24HP.
I think I will be happy with my 12KW electric, with a suitable prop.
For longer passages in no-wind conditions (sailing impossible), my "2 hour at 5.5 knots" battery amps will bring me 60 NM, when cruising steadily at 3 knots. In that range, I'm sure I can find a marina to refill her, before all amps are gone.

The more I read of it in the local sailor magazines, the electric "new age" IS coming for sailors who wants to sail and not motoring. Means that, with a new electric engine, I will have buyers for my boat, should I be forced to sell it (hope not).
The aspect of an almost maintenance-free, start-every-time, smell-free, non-dirty, no-filter changes-and-diesel-pest and low-noise motor must appeal to many sailors, I think. At least it does to me !

For VERY bad conditions I have my VHF radio with a mast antenna = might save my a.. when in distress. Lots of rescue choppers in my "confined" waters :-)

Thanks to all. I'll go for it !

PS :
Anyone who knows, or know someone, about converting an existing saildrive to fit an electric motor ?

[newhaul]

Originally Posted by carstendenmark

Thanks for the back-on-track posting, DeValency !

When waves, wind and current are against me when motoring, my old 10HP diesel can't get me out of the place (SOG=0). Most Maxi 87's has 13HP, some up to 24HP.
I think I will be happy with my 12KW electric, with a suitable prop.
For longer passages in no-wind conditions (sailing impossible), my "2 hour at 5.5 knots" battery amps will bring me 60 NM, when cruising steadily at 3 knots. In that range, I'm sure I can find a marina to refill her, before all amps are gone.

The more I read of it in the local sailor magazines, the electric "new age" IS coming for sailors who wants to sail and not motoring. Means that, with a new electric engine, I will have buyers for my boat, should I be forced to sell it (hope not).
The aspect of an almost maintenance-free, start-every-time, smell-free, non-dirty, no-filter changes-and-diesel-pest and low-noise motor must appeal to many sailors, I think. At least it does to me !

For VERY bad conditions I have my VHF radio with a mast antenna = might save my a.. when in distress. Lots of rescue choppers in my "confined" waters :-)

Thanks to all. I'll go for it !

PS :
Anyone who knows, or know someone, about converting an existing saildrive to fit an electric motor ?

Explain your 60nm range that is about 10 to 12 hours powered running on boats our size

[newhaul]

[QUOTE=carstendenmark;3226867]

For VERY bad conditions I have my VHF radio with a mast antenna = might save my a.. when in distress. Lots of rescue choppers in my "confined" waters :-)
/QUOTE]

Another one of those eh? That is not good planning for a sailor .
Take responsibility for your actions ! Don't make my insurance go up .

[carstendenmark]

Newhaul : 5.5 knots @ 60 amps (40% left), 3.0 knots @ 10 amps (0% left). 200 AH bank of LiFePO4.

[carstendenmark]

A VHF is not for planning, it is for EMERGENCY

[Adelie]

Originally Posted by valhalla360

No HP is HP. There is no such thing as magic electric HP.



Where electric has an advantage is it can generate more HP from lower RPM since it can generate max torque from zero RPM.



So if you are doing 0 to 6kt drag races, yes, the electric powered boat has an advantage.



But cruising monohulls get up to speed and run at constant speed from then on...HP = HP.

The Uma folks have posted that 1.2kW with their old motor got them 3kt boat speed in flat conditions. That 1.6hp.

Would a 1.6hp gas motor get that boat to 3kt?

[seandepagnier]

I made a new test today. Drawing 9.4 amps from 13 volt LiFePo4 battery I achieve 2 knots boat speed on 120 watts. This is more than twice the efficiency of an electric trolling motor with typical sized propeller.

https://youtu.be/XgMlcdPjUc4

This is 0.16 HP. It seems like sail drive setup is not very efficient because of limited propeller size.


I am also using 16 gauge lamp cord wire twisted together in 6 places to power this.

[seandepagnier]

Originally Posted by Dockhead

Recharging by regeneration works pretty well on larger faster boats, but doesn't work well on smaller slower ones. You should get an exact factual estimate before you count on getting any usable power from regeneration. I doubt that you would on a boat that size.

again and again this is repeated but it's wrong. It's because everyone is doing regen wrong. You can regen on any boat and even at slow speeds, but you _cannot_ use a propeller to do it efficient. You must have a purpose built repeller which is not a propeller flipped around (unless you can reach through the 4th dimension and convert left shoes into right ones) So once you have a repeller, it must be sufficient size for the speed, and then you will produce that much power, and it can be hundreds of watts at 2 knots if your repeller is 6ft diameter.

If you try to regen using a tiny undersized inboard propeller it won't do much below 5 knots and even then the efficiency (power/drag) is terrible.

Power can also be needed to get off a lee shore in bad weather, or similar situations in bad weather.

In bad weather the sails are very powerful, and I clawed off many lee shores using storm jib beating in 40 knots. Counting on an engine to do this is poor seamanship and often boats are lost and talked about at length on this forum doing just this, rather than using sails!!


You simply do not need to power against weather and this way of thinking needs a shift.

Anyone who knows, or know someone, about converting an existing saildrive to fit an electric motor ?

don't bother. saildrive will never be efficient propulsion because the propeller diameter is limited too small. Your efficiency will never be very good and you will use more than twice the power (see my previous post and video)

[seandepagnier]

Originally Posted by valhalla360

Large ships are drastically different animals and not comparable to a small cruising boat.

only because they don't use stupidly undersized propellers like 99.9% of cruising boats do.



Your prop diameter must be more than half the beam of the vessel. If this is not true, you are doing propulsion wrong.

https://www.youtube.com/watch?v=XgMlcdPjUc4

[wingssail]

Originally Posted by seandepagnier

...In bad weather the sails are very powerful, and I clawed of many lee shores using storm jib beating in 40 knots. Counting on an engine to do this is poor seamanship and often boats are lost and talked about at length on this forum doing just this, rather than using sails!!

You simply do not need to power against weather and this way of thinking needs a shift...

Yes, this is correct. For getting off a lee shore, "Counting on an engine to do this is poor seamanship."

Absolutely, and this is another reason for upwind performance.

I will also say that people with electric motors tend to become good sailors.

[seandepagnier]

Current yacht propellers are around 20-25% efficient at best speed.

Originally Posted by Dave_S

My understanding is that there is not too much more we can improve on what we have. That solar panels and electric motors are within a couple of percent of maxed out for efficiency which leaves batteries to make gains but they are only the storage in the middle. If the amount of energy you make and the amount you use are going to be fairly constant where do you see the improvements ?

So where are the improvements?

1) much larger propellers needed
2) contra-rotating propellers
3) kort nozzles.
4) variable pitch, variable camber propellers

All of these can give potentially huge gains in efficiency. Try dividing the power requirement of an electric drive by 4, and it becomes much more interesting.

Originally Posted by carstendenmark

Newhaul : 5.5 knots @ 60 amps (40% left), 3.0 knots @ 10 amps (0% left). 200 AH bank of LiFePO4.

You seem to have an overall efficiency of around 25% which is a great start but huge improvements are possible. My motor is around 50% efficient from electricity to propulsion.

Originally Posted by newhaul

A diesel will get you out of trouble if you find yourself in it.
.

Experience has shown this false and I got myself out of trouble without one.


The opposite is true: diesel is getting all of us into serious trouble:
https://youtu.be/Bik-ErDHrFk

[waterman46]

Originally Posted by seandepagnier

So once you have a repeller, it must be sufficient size for the speed, and then you will produce that much power, and it can be hundreds of watts at 2 knots if your repeller is 6ft diameter.

Hundreds of watts, say 746, is only one HP.
If your repeller is 6' diameter you won't be going 2 knots w/o one heck of a tailwind. At less than hull speed, for every watt you produce, you are slowing the boat more than 1 watt's worth of speed. And you simply could not sail upwind with that much drag - the boat would be making leeway like crazy.

In bad weather the sails are very powerful, and I clawed off many lee shores using storm jib beating in 40 knots. Counting on an engine to do this is poor seamanship and often boats are lost and talked about at length on this forum doing just this, rather than using sails!!

Nobody would argue that you can sail a boat anywhere, even upwind hundreds of miles, and more reliably than with an engine. Whether you choose to sail or motor is often just a matter of available time and discomfort, with many of us voting to sometimes make decisions that favor comfort or time.

You simply do not need to power against weather and this way of thinking needs a shift.

George Orwell had a lot to say about that attitude in his book "1984". Thinking will change, not by stating wild claims, but whenever a technology is *proven* useful for a given purpose.

[newhaul]

Originally Posted by carstendenmark

Newhaul : 5.5 knots @ 60 amps (40% left), 3.0 knots @ 10 amps (0% left). 200 AH bank of LiFePO4.

You really need to rethink your batteryand math paradigm.
Lfp dont go below 10% thats into rhe lower knees and not somewherebyou wantnto be .

Now your 60 amps for 2 hours is 120ah or 60% of a full battery and at best thats 11nm
Now the remainder 80ah at 10 amps and 3.3 knots is 8 hours at 3 thats 24 nm or a total of 35 nm and a completely dead lfp bank which being totally dead is now junk.
I dont see anywhere you are getting the 60nm you posted with a battery bank left to charge.

That being said your boat your choice and your money your choice.
My little md2 will push my 29 ft boat at 6 knots and with my 35 gallon tank i can run at that speed for about 3 days . Or 70 hours straight ( i burn just under 1/2 gallon an hour at top speed

[newhaul]

Originally Posted by seandepagnier

Current yacht propellers are around 20-25% efficient at best speed.

So where are the improvements?

1) much larger propellers needed
2) contra-rotating propellers
3) kort nozzles.
4) variable pitch, variable camber propellers

All of these can give potentially huge gains in efficiency. Try dividing the power requirement of an electric drive by 4, and it becomes much more interesting.

You seem to have an overall efficiency of around 25% which is a great start but huge improvements are possible. My motor is around 50% efficient from electricity to propulsion.


Experience has shown this false and I got myself out of trouble without one.


The opposite is true: diesel is getting all of us into serious trouble:
https://youtu.be/Bik-ErDHrFk

Wrong and lets not play the bs climate change card shall we .

If running your iron wind gets you into trouble you really should rethink being on a boat at all.