Electric inboard engine, equivelant diesel inboard.

[BurnitBlue]

I get the impression that a small inboard diesel like Yanmar 1gm10 would give the same or better performance than a typical electric motor. For instance on a passage of, say, 200 miles which would arrive first. Assume similar 35 foot cruiser. Same start same weather start. So what tactics would make a difference?

 

[RAI]

Same zero emissions requirement?

 

[BurnitBlue]

Same zero emissions requirement?

Compared to the enormous power of a US milltary transport taking off, you may consider them both almost zero

 

[dunedin]

I get the impression that a small inboard diesel like Yanmar 1gm10 would give the same or better performance than a typical electric motor. For instance on a passage of, say, 200 miles which would arrive first. Assume similar 35 foot cruiser. Same start same weather start. So what tactics would make a difference?

Kind of meaningless question unless define power of your "typical" electric motor. They come in all sizes to power model yachts to enormous cruise liners.
Plenty of yacht electric drives of 10-15kW (13-20hp), and many bigger ones also available. But few if any yachts have a range more than 50 miles or so in pure battery mode (huge range if a serial hybrid with DC generator).

 

[Tranona]

Add to that a 1GM does not have enough power to give more than say 3 knots in flat water. Not sure what you are trying to establish. As said while you can easily get enough power from an electric motor to match a diesel in a boat you cannot use it because you cannot store enough energy in the batteries.

 

[BurnitBlue]

Add to that a 1GM does not have enough power to give more than say 3 knots in flat water. Not sure what you are trying to establish. As said while you can easily get enough power from an electric motor to match a diesel in a boat you cannot use it because you cannot store enough energy in the batteries.

I am not sure what I want from this thread because I know nothing about electric propulsion on a yacht. I know the vast range of power options from the diesel engine makers but that the window of acceptance is actually quite small among cruisers. Maybe 30 hp. So the first casualty may be lower electric hp power to accomodate the weight and cost of a very heavy battery bank and charge controllers. So I started low with the yanmar 1gm10.to give and electric system an affordable alternative.

The end result is that the electric yacht can arrive in harbour with flat batteries facing a full day to plug in and get charged up. While the 1gm10 has full batterries with a ten minute stop for fuel and ready to go. Eric Hiscock sailed his 6 ton Wanderer lll twice Round the world with a dodgy 4hp two-stroke Stuart Turner inboard.

I grew up with the early catamarans equiped with a single 9hp outboard on a bracket. Todays catamarans have 30hp in each hull. I am drifting away with my own thread but perhaps getting cöoser to why I want to know more. So a single lightweight 1gm10 inboard diesel could be better than a complex electric system.

 

[Fr J Hackett]

I am not sure what I want from this thread because I know nothing about electric propulsion on a yacht. I know the vast range of power options from the diesel engine makers but that the window of acceptance is actually quite small among cruisers. Maybe 30 hp. So the first casualty may be lower electric hp power to accomodate the weight and cost of a very heavy battery bank and charge controllers. So I started low with the yanmar 1gm10.to give and electric system an affordable alternative.

The end result is that the electric yacht can arrive in harbour with flat batteries facing a full day to plug in and get charged up. While the 1gm10 has full batterries with a ten minute stop for fuel and ready to go. Eric Hiscock sailed his 6 ton Wanderer lll twice Round the world with a dodgy 4hp two-stroke Stuart Turner inboard.

I grew up with the early catamarans equiped with a single 9hp outboard on a bracket. Todays catamarans have 30hp in each hull. I am drifting away with my own thread but perhaps getting cöoser to why I want to know more. So a single lightweight 1gm10 inboard diesel could be better than a complex electric system.

It would certainly be cheaper.

 

[penfold]

Small reliable lightweight diesels suitable for powering a 35' AWB have been available for over 5 decades, there are essentially no off-the-shelf battery electric systems available to do the same task yet and finding a contractor to build you one will require a low-ish 5 figure sum. Ask the same question in 10 years and the answer will be different.

 

[BurnitBlue]

Small reliable lightweight diesels suitable for powering a 35' AWB have been available for over 5 decades, there are essentially no off-the-shelf battery electric systems available to do the same task yet and finding a contractor to build you one will require a low-ish 5 figure sum. Ask the same question in 10 years and the answer will be different.

I suppose the complete system will be packaged in a plastic box with a plug and play shaft sticking out ready for a propellor. One advantage of the DIY systems today is that the motor can be the sole occupant of the engine bay with the rest of the gubbins spread out somewhere else.

 

[Tranona]

I suppose the complete system will be packaged in a plastic box with a plug and play shaft sticking out ready for a propellor. One advantage of the DIY systems today is that the motor can be the sole occupant of the engine bay with the rest of the gubbins spread out somewhere else.

These already exist as packages. See here epropulsion.uk and here fischerpanda.co.uk/products/Pod_Motor_Electric-Fischer_Panda.html for examples offering both pods (like saildrives) and for shaft drives. Other makes such as Oceanvolt (as used by Sailing Uma) and Eleco also available.

A number of small scale specialist builders and one or two mainstream performance boat builders have offered boats with these systems and there have been a variety of retrofit including the E propulsion dealer in UK who has fitted a pod drive to his Sadler 29. This oceanvolt.com/testimonials/salona-46/ is probably the best known example of a biggish cruising boat with electric power.

Electric powered cruising boats all share the same characteristics. They are extremely expensive - not so much the motor but the batteries and management systems. The Sadler 29 installation cost over £10k for a very basic system. The Salona sells at a 20% premium over the diesel equivalent. While some systems have an element of regeneration (which starts to produce useful power at about 6 knot) they are dependent on shore power. While the motor is capable of producing enough power to get hull speed it uses electricity at a fast rate. With a typical battery installation that will fit in the space where the diesel engine and fuel tank were you get a range of between 50-80 miles at cruising speeds of maybe 4 or 5 knots. Increasing range requires more batteries at huge cost and space.

Generalisations but capture the current offerings. Inevitably this means they are only feasible for marina based day or weekend sailors and that is the type of boat that is being made using electric. Cornish Shrimpers at one end and billionaires Spirit weekenders at the other. Ocean cruisers, particularly American like the owners of Uma are also enthusiastic users (mostly home brewed systems) if they are prepared to limit their use to emergencies or just at either end of a passage.

There is nothing new about electric boats. They actually predate IC engined boats and have always been popular for day cruising on inland waterways like the Thames where 6 or 8 hours use in the day can be recharged overnight. However even though many coastal and offshore sailors who are prepared to frequent marinas for shorepower on a regular basis could live with the limitations not many are prepared to pay the premium either for the retrofit or a new build. This will only change when the poor energy storage density of batteries is improved. Same problem as with cars but without the potential demand to justify the R&D. Small boat propulsion has always been an offshoot of automotive and industrial developments, now mostly industrial where there is little pressure to go electric so doubt there will be any major advance until the next phase of automotive development has stabilised and manufacturers start looking at other uses for the technology. Definitely not in my lifetime though!

 

[dunedin]

Small reliable lightweight diesels suitable for powering a 35' AWB have been available for over 5 decades, there are essentially no off-the-shelf battery electric systems available to do the same task yet and finding a contractor to build you one will require a low-ish 5 figure sum. Ask the same question in 10 years and the answer will be different.

Not true. Various suppliers now offer these - notably Oceanvolt saildrive systems in the 10-15kW (15-20hp) range suitable for a 35-40 foot yacht. A number of builders now offer these as options on new build, and people like Sailing Uma have retrofitted (with supplier financial assistance, I suspect, in their case).

But cost and range remain the big issues. Most of the new build ones I have seen are serial hybrids, with 48V DC generators to give huge range (but even more cost)

 

[Bouba]

At the moment....the best uses for electric motors are in fast day boats...often with exotic foils to increase speed and decrease drag... the other scenario is canal and river and lake boats...when speed is not essential but range and quietness are appreciated.
Whenever you plan to go electric, think first about charging....the road charging network is growing at a phenomenal rate globally...not so much with marinas. But boat usage is different from cars...you may only use a boat every so many days therefore slow charging won’t impinge on your enjoyment.
Probably best to think about solar arrays...so catamarans could be good candidates

 

[Boathook]

Probably best to think about solar arrays...so catamarans could be good candidates

Yes cats would be good but the solar panels would need to be able to stand constant 'use' from being stood on to have items dropped on the them. I possibly have the space on my cat but do walk on most areas to sort out sails, etc or just sit in the sun .....

 

[Bouba]

Yes cats would be good but the solar panels would need to be able to stand constant 'use' from being stood on to have items dropped on the them. I possibly have the space on my cat but do walk on most areas to sort out sails, etc or just sit in the sun .....

Well here is the thing....if your coach roof has a large array of panels...enough to supply two electric motors, constantly...then you would never need sails

 

[Tranona]

This has already been tried, most recently by Jimmy Cornell but not lived up to the promise. While it is possible to generate enough from sola and regeneration to power the engines you still need big battery capacity to to store until you need it. Where it falls down is that a cat big enough to do this will also have huge domestic demands which could be met by solar if it was not needed for propulsion. You can't have both with current battery technology.

Hybrid works well on cats by using a generator to power the domestics and electric for propulsion. Just like the grown up versions of floating holiday homes - cruise liners.

 

[RAI]

Compared to the enormous power of a US milltary transport taking off, you may consider them both almost zero

Then the diesel wins hands down.

 

[lustyd]

At the moment....the best uses for electric motors are in fast day boats...often with exotic foils to increase speed and decrease drag... the other scenario is canal and river and lake boats...when speed is not essential but range and quietness are appreciated.

Or from another perspective, they are ideal for long distance sail cruising. Unlimited range using Solar and regen is better than the very best range from any diesel yacht.

 

[Tranona]

Or from another perspective, they are ideal for long distance sail cruising. Unlimited range using Solar and regen is better than the very best range from any diesel yacht.

Not sure about that. See post#15. This is exactly what Cornell was trying to demonstrate - it failed, even by his own standards. You cannot generate enough from solar and/or regeneration even to keep pace with engine usage alone, never mind contribute to domestic use. Add to that even if you store the energy limitations of batteries reduce the range under power alone to around 50 miles. so, assuming you are able to store the maximum, which will mean limiting your domestic use the only way your range would be better is in terms of the number of 50 mile bursts in your passage.

The reality is that battery energy storage is not sufficiently dense to run both engines and domestics, nor to give a working range under engine of above 50 miles or so.

 

[lustyd]

This is exactly what Cornell was trying to demonstrate - it failed

It failed because his method was flawed, not because it doesn't work. You won't get far by whipping a car, you need to change your approach to adopt new technology.

Add to that even if you store the energy limitations of batteries reduce the range under power alone to around 50 miles

Not even close to the range of even modest electric yacht installations in 2023.


Anyway, my point remains, if you're mid-pacific in the doldrums and run out of diesel you're permanently out of diesel. Not so with Solar/electric

 

[dunedin]

Yes cats would be good but the solar panels would need to be able to stand constant 'use' from being stood on to have items dropped on the them. I possibly have the space on my cat but do walk on most areas to sort out sails, etc or just sit in the sun .....

Yes offshore cats are an ideal use case. Lots around like this now

Not sure about that. See post#15. This is exactly what Cornell was trying to demonstrate - it failed, even by his own standards. You cannot generate enough from solar and/or regeneration even to keep pace with engine usage alone, never mind contribute to domestic use. Add to that even if you store the energy limitations of batteries reduce the range under power alone to around 50 miles. so, assuming you are able to store the maximum, which will mean limiting your domestic use the only way your range would be better is in terms of the number of 50 mile bursts in your passage.

The reality is that battery energy storage is not sufficiently dense to run both engines and domestics, nor to give a working range under engine of above 50 miles or so.

Partially correct I think. It was the domestic power demands that scuppered Jimmy Cornell’s attempt.
His fast cat could easily do the 8kts plus needed to get effective regeneration under sail (which most smaller monohulls cannot, hence the infinite range is largely a myth for old/conventional monohulls).
But the twin freezers and all electric cooking was too demanding - and even, he noted, a crew who had dietary preferences that meant two different meals needed to be cooked each day.
I strongly suspect if he had a gas cooker on board his voyage could have continued (but then eventually was cancelled for reasons entirely unrelated to electric demands or the boat).