Gemini 105mc conversion Diesel to EV?

[Brewgyver]

Originally Posted by harlem24

Why the F would one go 200 miles with 6kn on motor?
We are still talking sailboats, aren't we?

What Skipmac said, plus about a hundred other reasons.

A few obvious examples (well, obvious to most)

In some parts of the world, you may have to travel that far to meet visa deadlines, e.g. to get to a location where you can check out of country before you overstay your visa.

Illness or injury requires traveling to a location with medical facilities.

Mechanical failure requires traveling to get parts or repairs.

Traveling to a specific location to pick up or drop off visitors.

[Sailmonkey]

Originally Posted by harlem24

Why the F would one go 200 miles with 6kn on motor?
We are still talking sailboats, aren't we?

Ever been becalmed 300 miles from land with no wind forecast for the next 5-7 days?

[Mr B]

Originally Posted by harlem24

Why the F would one go 200 miles with 6kn on motor?
We are still talking sailboats, aren't we?

Four days at 7 knots, at 2500 RPM, Middle of the Coral Sea, Dead flat sea,
Not a breathe of wind,
I did want to get home, Which was still approx 1500 Nmiles to the south of where I was,
I had been on the boat 3 months at this time,
And I only need 3 knots of wind to sail, There wasnt even that,
And I still had to go thru Customs at Bundaberg first, Before going south to get home,

Sail boats need wind to sail,

[StuM]

Originally Posted by bouncycastle

The sum is simple total fuel in WOT is 0.6 gallons per hour convert its fuel energy in watts joules inputed versus work accomplished result three tons moved at 6 knots some 6 nautical miles

And therein is revealed your total misunderstanding and where your mythical "global efficiency" comes from.


The mass of the object the speed it is moved at and the distance it is moved are all essentially irrelevant to the question of energy efficiency unless you are moving it vertically against gravity.



Moving a mass a certain distance takes a certain amount of energy. The total energy required is not changed by the speed of movement.



To a first approximation, all of the work done in moving an object horizontally is used to overcome friction in all its forms.



Put the boat on land on low friction rollers on a smooth surface and it will take very little energy to move it 6 miles.


When trying to go to weather in a storm, the work done in remaining stationary is that required to resist the wind forces on the boat. No distance, but energy still used.

[sailingharry]

Stu,


I must say that your patience and effort in discussing this matter are exemplary! I'm a mechanical engineer, and so this stuff is obvious to the point of being boring. I can't keep up discussions with folks that can't even use correct units (which means almost every battery discussion drives me to drink, as folks talk about Ah out of their alternators, Amps/Hour consumption rates, and other mindnumbing misstatements).


Keep up the fight!


Harry

[Cadence]

Originally Posted by sailingharry

Stu,


I must say that your patience and effort in discussing this matter are exemplary! I'm a mechanical engineer, and so this stuff is obvious to the point of being boring. I can't keep up discussions with folks that can't even use correct units (which means almost every battery discussion drives me to drink, as folks talk about Ah out of their alternators, Amps/Hour consumption rates, and other mindnumbing misstatements).


Keep up the fight!


Harry

Maybe if they included how long the engine drove the alternator.

[bouncycastle]

Originally Posted by StuM

And therein is revealed your total misunderstanding and where your mythical "global efficiency" comes from.

Sorry to disappoint you I would not have the brain power to invent the term or idea "global efficiency"

I merely copy the guru of this idea Global efficiency such as in the 1980 era Burt Rutan of the USA https://en.wikipedia.org/wiki/Burt_Rutan a adventure manufacturer scientist type etc who in ~1982 was commissioned by Ford cars to make a electric car using lead acid battery with ~100 mile range .
The electric car story was coved in Popular mechanics ~1980 era
Rutan said gasoline cars are ~5% global efficiency and lead acid batteries are ~1% the power density of gasoline fuel .

So blame Burt Rutan and debate him on the subject that "Global efficiency is mythical" .

Bart Rutan also said after his twin engine plane flew non stop around the world how did you figure out everything from back of the envelop numbers . He replied he used his system of rules of thumbs and system of SWAG Scientifically Wild Assed Guess . You got to luv this guy .

These modern days There are newer terms that are used to replace " global efficiency like entropy and entropy Crisis often used by doomsayers that say our entire technological system is unsustainable when you go from oil extraction to final industrial outputs results
Global effeciency didn't have enough power to scare the masses I guess

The national transport and safety Board NTSB of the USA uses the term from fuel tank to wheel for automobiles and set it is approximately ~12% to replace the term global Efficiency .

The debate rages among experts who say that is only steady state ~55MPH testing on highway measures the NTSB uses

The argument is when real world result are done with town traffic highway mix the Tank to wheel results are closer to ~5%





So to keep you happy we can agree to a similar term to NTSB from tank to propeller results for boats and a attempted example that might help electrify a 10.5 metre cat will be supplied below

Originally Posted by StuM

The mass of the object the speed it is moved at and the distance it is moved are all essentially irrelevant to the question of energy efficiency unless you are moving it vertically against gravity.

Actually to defy gravity with electric power is very education for all electric engine disciplines

My drones I make require some 98 watts to keep 1 kilo of craft hovering and to defy the 9.8 meters per second that the craft would fall if the engines quit .
The same rule applies to all drone or helicopters

basically it requires the ~90% efficiency electric motors attached to the ~90% efficient Lipo battery attached to the ~95% efficient speed controllers attached to 50% efficient propellers with other hard to figure out system losses returns about ~20% global efficiency while hovering in CALM WIND .

So the craft requires some ~500watts of power to stop the 1 kilo craft from falling and maintain a steady hovering flight .

To climb at 9.8 meters per second will require a net power of 98x2=196 watts and that requires with global effect of 20% a ~1000 watt system .

With gravity net power its easy to figure the forces net versus gross .

The kicker is when its a windy day and turbulence removes lift of the propellers .
Now the propellers efficiency is halved to 25%.

Then although net power to hover remains the same 98 watts the engine regime is constantly changing up and down from 500 watt up to 1000 watts
This means my global efficiency drops down to 15% when the engine produces 1000 watts
Now we can say the average global efficiency is less about 17.5%
Now in turbulence to climb at 9.5metres a second requires maybe 2000 watts .

So now we need to double the original power to climb and four times the power than the original still air hovering .
Typicaly the massive extra demands on power will heat up equipment like battery motor and wires and speed control dropping the efficiency to less than ideal due to excess heat build up .

If we don't plan for the types of changes in the system we can end up with underpowered badly functioning functioning electric power system .
Many of the above power rules also apply to land and water based electric driven projects

With land like electric cars and and electric boats the net power requirements can be harder to figure out but estimates can be figured out with simple tests like towing the object that needs electric power .

Yes if I spend mega bucks on state of the art stuff I can get north of 30% global efficiency for drones but my drone cost could be increased over ten times

I will supply a cat info details below

Originally Posted by StuM

Moving a mass a certain distance takes a certain amount of energy. The total energy required is not changed by the speed of movement.

In maths and Physics lingo you get one reply to that logic .
in the English lingo of the mere mortals on the street you get another logic reply
Too big a issue to tease out here at this time

Originally Posted by StuM

To a first approximation, all of the work done in moving an object horizontally is used to overcome friction in all its forms.

Agreed but my terms to define the forces and friction might differ to yours but the results will be the same

Originally Posted by StuM

Put the boat on land on low friction rollers on a smooth surface and it will take very little energy to move it 6 miles.

Water at slow speeds is a very low friction system

The original 1800 era ~40 ton plus sized canal barges required one horse to pull them at about ~2 MPH .
Today we tend to use power of ~50 to ~80 BHP to move these boats now normally empty of cargo as houseboats at a faster speed of ~5 knots often at steady engine regime of 30% power or demanding some ~20HP .
We can visably see there is a exponential demand for power requirement as we increase speeds
With TANK to Propeller efficiency in the order of ~10% steady state will drop a lot if stopping and starting in cases of multi lock system stop start demands .

Rolling resistance on electric cars tend not to increase in a linear or exponental way. All other friction like air drag for cars or water drag will increase with a increase in speed of a object like a car or boat .
Same if you put a boat on rollers there will be initial rolling resistance that remiss the same . We don't normally puts boats on rollers

Originally Posted by StuM

When trying to go to weather in a storm, the work done in remaining stationary is that required to resist the wind forces on the boat. No distance, but energy still used.

Again the definition of terms can vary
A boat at full power fighting a strong wind and achieving zero knots can in one set of terms tank to propeller in effect be defined as Zero efficiency and in another set of terms be some positive number in efficiency depending on what type of measures you chose to use

Hope that answers your questions

There is not a lot of info for Hybrids but this one suppose interesting info on diesel versus electric and how hybrids can fill some gaps . It is less interesting for multi hulls due to extra weight

https://www.yachtingworld.com/featur...-yachts-120908

I shall now try to ball park number figure out what is the NET power required to move a 4.5 ton 10.5 meter catermeran with a few sketchy numbers to work with supplied from this thread post NUMBER 55. by mikedefieslife

Details Prout 35 ft 10.5 meters 4.5 tons inboard 29 HP Yanmar prop 16/14 speed 5 knots 2.5 litres per hour
Missing info so have to guess from experience
Assumed information leg drive Z type Enfeild 2:1 gears ratio
link to Yanmar 29 hp engine specs
https://www.yanmarmarine.com/Product...E-426/#cat_9_2

download PDF for specs
https://www.yanmarmarine.com/theme/y...et_3YM30AE.pdf


Fuel consumption graph show 2.5 litres per hour at 2200 RPM
HP at 2200 RPM shows 10 HP or 7.46 kilowatts

100% theory distance traveled per hour by prop with 14 inch pitch = 12.7 nautical miles
distance covered in reality with losses = 5 nautical miles
efficiency of prop =~40%
total fuel 2.5 later is 25 kilowatts energy input per hour
efficiency of engine from graph at 2200 RPM 32%
kilowatts power used by engine 32% equals = ~8 kilowatts
assume losses of the Z drive 10% so 8000 watts minis 800 watts = ~7200 watts
7200 watts sent to prop losses 60% means prop gives 2900 watts

Tank to prop efficiency 25000 watts versus 3000 watts ~= 8%

Throw in rough seas and speed drop to 3.5 knots tank to propeller efficiency ~5%%

Therefore the NET power to drive the two hulls at 5 knots is ~3000 watt or 1.5 kilowatts per hull in calm weather probably 5000 watts in knots in rough conditions


Electric power plant with ~30% global efficiency in calm conditions suggests 10 kilowatt electric power to drive two hulls at 5 knots or two ~6 kilowatt motors

That is the power plant found in 36 foot cat from oceanvolt 36 ft cat

https://oceanvolt.com/testimonials/ic36/

typical with cat at 2,5 knots power requirements will be 1/3rd of speeds energy demands of 5 knots or 500 watts per hull or 1000 watts Total

efficiency of lower power demands from electric props at 2.5 knots greater and effiency from batteries and electric demands can be expected so global effiency closer to ~ 40% might occur at 2,5 knots A solar cell set up giving 1 kilowatt of power average for 6 hours can assist battery and extend range in calm conditions

In rough conditions 2000 to 3000 watts would probably be needed to maintain speeds of 2.5 knots

Thats what the numbers tend to look like is my SWAG


Hybrids might help solve issues examples below

https://www.yachtingworld.com/featur...-yachts-120908

Hope this can help OP on the way and methods to solve the issues even if my mathematics are a bit off if the Z Drive is 1.64: 1 ratio instead of 2:1

Its possible the Z drive is another make that uses similar to sail drive 2,64:1 ratios or2.5:1
Also the source of data Mikes boat could be using 2400 RPM or more or even less and not 2200 RPM and that fuel demand is more like ~3 litres fuel per hour and not 2,5 litres per hour .

The Z drive gear box efficiency is not known but high figures of losses from 5% to 15% are frequent with gear boxes of complex bending designs like Z or or stern drives compared to straight through shaft systems so 10% is estimate of losses couldn't find any data on Enfield Z drive

cat with Z drive efficiency is not known to be very good as prop is too close to surface of the water and any waves kills the prop efficiency quickly

Props under the two hulls tend to be higher efficiency often closer to ~50% and single larger prop is more likely to be the more efficient again ( assuming the props are not simplex folders which are often less efficient than fixed prop types )

Composite prop types tend to bee best at speeds less than 3 knots and help electric power global efficiency returns

For me the best option is to replace Diesel engine as is and put up as many solar cells panels on the decks etc and run a high quality folder electric propeller under one hull not use a battery solution and in calm weather for daylight hours some six hours drive the boat at some 2 knots would be the cheapest practical solution

just my two cent

[StuM]

Originally Posted by bouncycastle

Sorry to disappoint you I would not have the brain power to invent the term or idea "global efficiency"
...
just my two cent

I can't be bothered with dissecting that ramble.


Suffice to say that you've grossly over valued it.

[Brewgyver]

At the risk of injecting religion into the thread,
AMEN to that!

[ssmoot]

Originally Posted by Dirk01

And DON'T USE EV-batteries! They are not imanent safe and in case of a thermal runaway they not burn the boat only.

Don't use NCA Tesla batteries for sure. Very dramatic when those things pop-off. Especially with this amount of power demand since you won't have the original thermal management (liquid cooling) in place.

Leaf batteries? Go for it. Those are tanks.

I personally think the insistence on LiFePO4 is a bit too conservative. There are cheaper, denser, better suited chemistries available today. It's basically what Torqeedo uses in their new packs.

Nothing inherently wrong with LiFePO4 if that's what rocks ya. Besides the weight penalty and price anyways. But there's no reason not to expand your search a little either.

[bouncycastle]

Originally Posted by ssmoot

Leaf batteries? Go for it. Those are tanks.

Any spec sheets on them last I recall they are 3.7 volt LiPo 20 amp and any EU sales outlets that sell single packs ???

[Jean Michel]

Have you made any progress?
I also have a 105 and thinking of a conversion to EV. Weight is a factor for sure and probably will need a back up system when recharging off shore or no sun is not available. I currently use 2 Honda gen EI2000 in tandem to keep my system afloat when sun is deficient in winter month. Heading for the sea of cortez.
in any case, we could look at it as a join project to reduce cost and share knowledge?

[DecarbPeter]

Thanks to BouncyCastle for their terrific, if complicated, essay re. electrifying Gemimi 105's. Is there a later forum that continues and enhances that discussion? We would like to hybridize and solarize an existing cat of 30-35', ideally with plyglass hulls for low weight and to extend my long cohort of wooden boat enthusiasts.

At this point in life we also need to let go of full sail rigs, and don't want a lot of shadows on the solar panels anyway.

Thanks for any and all leads!