"Practical " Boat Owner?..

[Refueler]

hybrid seems to work well enough for cars, maybe the objections to hybrid yachts consists of more than mathematics, which appears to work in favour of one, but against the other.
maybe its ignorance?

im sure there is an engineer out there capable of deigning a funnelled turbine capable of being deployed at the stern

The Car hybrid is a poor example to use for a yacht system .. the Car system has recovery of energy to the battery system when running purely on fuel engine ... then when called on - the E-Motors are mostly supplemental to the fuel engine.

How would you do that on a yacht ?

OK .. Trains / Ships ... Diesel-Electric .. why ? Others have mentioned the efficiency aspect ... diesel is a workhorse that performs best when run at high loads and RPM ... it has good torque - but only when engine is at reasonable RPM, at lower speeds it fails ... but E-Motors torque is there at low and medium speeds ...
This is why Diesels on trains have typically been married to Hydraulic or Electric drive.
Ships are a slightly different proposition as 'Motor Ships' are prone to vibration - Boy - you have to see it to believe it !! .. so a combination of the E-Motor 'torque' advantage and that the diesel power source can be run at most efficient / least vibration ...

 

[geem]

The Car hybrid is a poor example to use for a yacht system .. the Car system has recovery of energy to the battery system when running purely on fuel engine ... then when called on - the E-Motors are mostly supplemental to the fuel engine.

How would you do that on a yacht ?

OK .. Trains / Ships ... Diesel-Electric .. why ? Others have mentioned the efficiency aspect ... diesel is a workhorse that performs best when run at high loads and RPM ... it has good torque - but only when engine is at reasonable RPM, at lower speeds it fails ... but E-Motors torque is there at low and medium speeds ...
This is why Diesels on trains have typically been married to Hydraulic or Electric drive.
Ships are a slightly different proposition as 'Motor Ships' are prone to vibration - Boy - you have to see it to believe it !! .. so a combination of the E-Motor 'torque' advantage and that the diesel power source can be run at most efficient / least vibration ...

It's an interesting subject. I recently watched a guy on utube with a diesel car test fuel consumption in different gears at 30mph over a standard distance. The highest gear, giving the least revs, achieved the best fuel consumption.
On a boat, the faster you go, the more drag you create and the fuel required goes up dramatically, as you approach hull speed. Electric boats have to motor slowly to keep this drag as low as possible so they don't use too much energy. This also works for diesel engines. You need little power at low speeds. The question then is how much power in reserve do you need for when going very slow doesn't work? We have plenty in reserve and the big 4.4L engine certainly doesn't hurt our fuel consumption.
Top gear once did a comparison between a Prius driving flat out around their circuit with a BMW 3.5L 5 series diesel just cruising along behind it at the same speed. The BMW used less fuel. A big lump of an engine doing the same speeds as a small petrol engined hybrid.
A boat builder friend of mine was building a large catamaran for himself. He was determined to go electric drive with lithium batteries and a diesel generator to charge up when he needed it. The idea being that a small generator would be more efficient fully loaded than running conventional diesel engines. In the end, he went for conventional diesel units in each hull. He just couldn't get the concept to stack up. He was a clever guy and he built the first two Gunboats in his yard in South Africa. He had all the right contacts and resources but he said it didn't stack up.
We met a couple of guys with electric drive boats. One was a Contessa 32 with a big solar array on an arch. The other was a 44ft American boat with a similar but larger solar array. Both were doing ocean passsges. They both cruised on their engines at circa 2 or 3 knots maximum because they were totally reliant on solar. Most of the time they had a range of less than 100 miles so dropping to 1 or 2 knots, the solar could keep up if it was sunny. It's a serious drawback on a boat doing ocean passsges. You are more akin to an engineless boat that a diesel equipped boat. Maybe saving some battery power so you have enough to enter harbour when you arrive. A diesel generator would help but you are really not any better off than just sticking with diesel propulsion in the first place.

 

[Refueler]

I'm no fan of the Prius .. but the test you refer to was with the early version which was shown on numerous occasions to have poor economy ... the later versions corrected this.

I drive a TDV8 4.4L Range Rover ... people ask me about fuel consumption .... the fact is - its better than the 3.6L version of same car ... its better than my petrol engine Volvo XC70 ...

Years ago - I had a 1.6L Mk2 Capri L ... then swapped it for the 2.0L JPS Mk 2 Capri S ... consumption was same or at times better. (Until I race converted it !! then it burned holes in the wallet below 100mph).

But this is not the matter I was referring to earlier ... I mentioned TORQUE .. something E-Motors are generally better at ....particularly under load ..

It may be a smaller engine but the matter is an important one for us in the model world .... and can lead to interesting discussions ... but one is - the matter of safety.

If you take a wet fuel engine and a comparable sized electric motor - which do you think is the most dangerous ?

It may surprise you that the E-motor is .... why ? In all aspects bar one - they are similar in that they have a meat cleaving prop rotating and waiting to devour anything that gets in its way.
Not advised - but lets say your finger or an object gets in the prop ..

The wet fuel engine will carve it up - but if it stops - you withdraw whatever you have left as engine has stopped.

Have same with the E-motor and it may stop - BUT unlike the wet fuel motor - its waiting to have another go ... as soon as it can - that prop will turn again as the E-motor just keeps ramping up its demand for power to turn .. it's torque increase is phenomenal until either motor burns out or power source fails.

 

[geem]

I'm no fan of the Prius .. but the test you refer to was with the early version which was shown on numerous occasions to have poor economy ... the later versions corrected this.

I drive a TDV8 4.4L Range Rover ... people ask me about fuel consumption .... the fact is - its better than the 3.6L version of same car ... its better than my petrol engine Volvo XC70 ...

Years ago - I had a 1.6L Mk2 Capri L ... then swapped it for the 2.0L JPS Mk 2 Capri S ... consumption was same or at times better. (Until I race converted it !! then it burned holes in the wallet below 100mph).

But this is not the matter I was referring to earlier ... I mentioned TORQUE .. something E-Motors are generally better at ....particularly under load ..

It may be a smaller engine but the matter is an important one for us in the model world .... and can lead to interesting discussions ... but one is - the matter of safety.

If you take a wet fuel engine and a comparable sized electric motor - which do you think is the most dangerous ?

It may surprise you that the E-motor is .... why ? In all aspects bar one - they are similar in that they have a meat cleaving prop rotating and waiting to devour anything that gets in its way.
Not advised - but lets say your finger or an object gets in the prop ..

The wet fuel engine will carve it up - but if it stops - you withdraw whatever you have left as engine has stopped.

Have same with the E-motor and it may stop - BUT unlike the wet fuel motor - its waiting to have another go ... as soon as it can - that prop will turn again as the E-motor just keeps ramping up its demand for power to turn .. it's torque increase is phenomenal until either motor burns out or power source fails.

Our 4.4L 86hp engine produces its maximum torque at 1200rpm. Almost at the bottom of the useful rev range. 1000rpm gives us 5kts in flat water. We dont run the engine any lower. 1200rpm is 6kts boat speed. The beauty of big engines is torque at low revs. The Perkins M92B was a development of the 4.0L M92. They increased cubic capacity/torque and improved fuel economy.
I was talking to the technical guy at Brunton propellers a few weeks ago. Our folding prop needed refurb. I was looking at option to refurb or replace. I asked him what the advantage was of the autoprop. He said it dropped the revs by 300rpm. I explained what engine we had and what revs we cruised at and that dropping the revs by 300 rpm wasn't an option for us since we were already very low reving. He agreed and said the autoprop was not the right solution for us. He said that our setup was excellent, although he would now sell us a 4 bladed prop since it would give us better reverse thrust.
There are so many variables when designing a propulsion system that it very hard to get the perfect set up. I am very happy with ours but it's not perfect. Mainly down to the prop walk and reverse thrust. Every other aspect of power and fuel economy is very good. Having a very low reving and relatively quiet engine is very nice

 

[trapper guy]

The Car hybrid is a poor example to use for a yacht system .. the Car system has recovery of energy to the battery system when running purely on fuel engine ... then when called on - the E-Motors are mostly supplemental to the fuel engine.

How would you do that on a yacht ?

OK .. Trains / Ships ... Diesel-Electric .. why ? Others have mentioned the efficiency aspect ... diesel is a workhorse that performs best when run at high loads and RPM ... it has good torque - but only when engine is at reasonable RPM, at lower speeds it fails ... but E-Motors torque is there at low and medium speeds ...
This is why Diesels on trains have typically been married to Hydraulic or Electric drive.
Ships are a slightly different proposition as 'Motor Ships' are prone to vibration - Boy - you have to see it to believe it !! .. so a combination of the E-Motor 'torque' advantage and that the diesel power source can be run at most efficient / least vibration ...

so what is the problem with a twin system?
you power the boats momentum with the diesel and charge the batteries with the alternator, then when the batteries are charged you switch to the electric system...
all the time you are using the electric system you are saving diesel, which in turn makes the diesel more economical to run
not only can you use the alternator, but a shaft driven generator could be devised also, it could be adapted to drive the same prop and shaft using both systems

 

[trapper guy]

It's an interesting subject. I recently watched a guy on utube with a diesel car test fuel consumption in different gears at 30mph over a standard distance. The highest gear, giving the least revs, achieved the best fuel consumption.
On a boat, the faster you go, the more drag you create and the fuel required goes up dramatically, as you approach hull speed. Electric boats have to motor slowly to keep this drag as low as possible so they don't use too much energy. This also works for diesel engines. You need little power at low speeds. The question then is how much power in reserve do you need for when going very slow doesn't work? We have plenty in reserve and the big 4.4L engine certainly doesn't hurt our fuel consumption.
Top gear once did a comparison between a Prius driving flat out around their circuit with a BMW 3.5L 5 series diesel just cruising along behind it at the same speed. The BMW used less fuel. A big lump of an engine doing the same speeds as a small petrol engined hybrid.
A boat builder friend of mine was building a large catamaran for himself. He was determined to go electric drive with lithium batteries and a diesel generator to charge up when he needed it. The idea being that a small generator would be more efficient fully loaded than running conventional diesel engines. In the end, he went for conventional diesel units in each hull. He just couldn't get the concept to stack up. He was a clever guy and he built the first two Gunboats in his yard in South Africa. He had all the right contacts and resources but he said it didn't stack up.
We met a couple of guys with electric drive boats. One was a Contessa 32 with a big solar array on an arch. The other was a 44ft American boat with a similar but larger solar array. Both were doing ocean passsges. They both cruised on their engines at circa 2 or 3 knots maximum because they were totally reliant on solar. Most of the time they had a range of less than 100 miles so dropping to 1 or 2 knots, the solar could keep up if it was sunny. It's a serious drawback on a boat doing ocean passsges. You are more akin to an engineless boat that a diesel equipped boat. Maybe saving some battery power so you have enough to enter harbour when you arrive. A diesel generator would help but you are really not any better off than just sticking with diesel propulsion in the first place.

one clever guy tried it and failed?, better give up on the idea then.
thankfully thats not how the world works, and despite the early failures flight ultimately proved to be successful

 

[noelex]

you power the boats momentum with the diesel and charge the batteries with the alternator, then when the batteries are charged you switch to the electric system...

The alternator will use energy and therefore it will consume diesel fuel.

all the time you are using the electric system you are saving diesel, which in turn makes the diesel more economical to run

The energy has to be replaced. If you replace this energy using the engine or a generator you will consume more diesel.

 

[Refueler]

so what is the problem with a twin system?
you power the boats momentum with the diesel and charge the batteries with the alternator, then when the batteries are charged you switch to the electric system...
all the time you are using the electric system you are saving diesel, which in turn makes the diesel more economical to run
not only can you use the alternator, but a shaft driven generator could be devised also, it could be adapted to drive the same prop and shaft using both systems

No-one has devised a system to transfer energy 100% ... you will always have losses ... so if you use the diesel engine to a) move the boat and b) to charge the batterys, which would need to be far larger than most people have on board - there will be losses that are higher than if you just use the diesel to power the boat and charging a more normal battery bank.

Have you ever observed a change of alternator on an engine ? Swapping an alternator to a higher output version increases load on the engine and often a stronger or second belt is added .. you audibly hear the engine working harder ..
So in having that battery bank to move the boat - surely a larger battery bank to do it ... which in turns means a high output alternator ... which in turn means greater fuel consumption of the diesel when powering the boat AND the alternator ...

I'm not convinced .. sorry.

 

[geem]

so what is the problem with a twin system?
you power the boats momentum with the diesel and charge the batteries with the alternator, then when the batteries are charged you switch to the electric system...
all the time you are using the electric system you are saving diesel, which in turn makes the diesel more economical to run
not only can you use the alternator, but a shaft driven generator could be devised also, it could be adapted to drive the same prop and shaft using both systems

Where do you think the energy came from to charge the electric drive batteries? You burnt diesel running a large alternator. That energy wasn't free.
A propeller optimised for driving a boat does not make a perfect generator for charging batteries. You can only optimise one aspect of the propeller design.
What we see all over the tropics is diesel driven catamarans with 2 to 5kw of solar array. They have electric cooking, air-conditioning, and run every aspect of their life from solar. This is the best use of solar and you still get energy efficient diesel propulsion. These boats have no gas onboard so over the course of a season, their overall energy demand is low.

 

[rogerthebodger]

When you run a diesel or petrol engine all you are doing is converting the chemical energy in the fuel into mechanical energy and then converting the mechanical energy into electrical energy which will charge the battery converting to chemical energy then converting the chemical energy back to electrical energy which is converted into mechanical energy to drive the boat along.

Each time you convert energy from one type to another type there will be losses in the conversion these loses in most cases it is heat like in the diesel / petrol engine the heat created by the engine is just thrown away into the sea water cooling the engine.

Even transformers have losses which is again heat. Batteries also create heat in the conversion process.

So, each time you convert one type of energy to another type there will be losses in the form of heat.

It's called conversion losses of efficiency

 

[ylop]

This idea arguably came from our very forum. About 20 years ago there was a discussion about working on old boats. I (and possibly others ) suggested that it would be a very good idea for PBO to obtain and old boat and renovate it. In this way products and ideas could be demonstrated and recommended or not, in a very elegant and useful manner.

I pitched the idea to the then editor, suggesting suggesting PBO obtain a cheap boat, I would do the work record it, write it up (fees were paid at that time) and the finished thing could be sold at a profit - it would pay for itself. The reply was dismissive, I remember one of Elaine Bunting's phrases:

"...........PBO has no budget for buying boats....."

Seemingly that was that. A couple of years later they bought their first old boat for restoration.

I think it was an idea that had merit, although it often felt to me that it had taken over the magazine - by the end I was feeling, "are they still bloody doing that boat up", which is probably a true reflection of real life. I suspect a bigger problem than "no budget for buying boats" was no budget for keeping boats - and lets face it that is the downfall of every £1 boat purchase.

Does that really stack up? ... ... Where is the benefits?

The Car hybrid is a poor example to use for a yacht system .. the Car system has recovery of energy to the battery system when running purely on fuel engine ... then when called on - the E-Motors are mostly supplemental to the fuel engine.

How would you do that on a yacht ?

You are right that just because it "works*" in cars doesn't mean it necessarily works in boats, but I'm not sure I understand your point - there are boat hybrid systems around. Charging on solar, plugging in, regen whilst sailing and/or the "generator". That certainly may not be more efficient multiday motoring but for a typical sailing yacht the cost of diesel is rarely the driver for considering these changes. For the way a lot of people actually sail it might actually be good. Whilst some might claim they are doing it for environmental reasons, but I can see that sailors typically want peace and switching to electric might provide more of that. I suspect though that real advantages will come, not from retrofitting to old boats, or even as options on new boats - but when naval architects really get their head around the options - where you can put the weight, the noisy bits, etc and how that then influences internal layouts and even hull shapes.

*I'm not actually sure it achieves quite what the manufacturers or regulators set out to do in cars either. I know of many "company car" hybrids which benefit from the theoretical environmental benefits to get more attractive taxation but are driven by people who aren't paying for the fuel so don't use them to the best of their ability. Inner city NOx emissions might be improved, but motorway CO2 get worse etc.

 

[ylop]

When you run a diesel or petrol engine all you are doing is converting the chemical energy in the fuel into mechanical energy and then converting the mechanical energy into electrical energy which will charge the battery converting to chemical energy then converting the chemical energy back to electrical energy which is converted into mechanical energy to drive the boat along.

Each time you convert energy from one type to another type there will be losses in the conversion these loses in most cases it is heat like in the diesel / petrol engine the heat created by the engine is just thrown away into the sea water cooling the engine.

Even transformers have losses which is again heat. Batteries also create heat in the conversion process.

So, each time you convert one type of energy to another type there will be losses in the form of heat.

It's called conversion losses of efficiency

Absolutely, the ultimate question for efficiency is:

Does:

Chemical (fuel) --> Kinetic energy (prop) with the necessary range of speed/power etc translate to more or less efficient than:

Chemical (fuel) --> Kinetic --> Electrical --> Chemical (battery) --> Kinetic (motor) --> Prop

because the losses are optimised for each stage to be ideal. I don't know. It gets more complex is you add in:

Prop (regen) --> Kinetic --> Electrical --> Chemical (battery)
Solar --> Electrical --> Chemical (battery)
Wind --> Electrical --> Chemical (battery)
Electrical (grid) --> Chemical (battery)

A full analysis would need to understand the issues Dunedin highlighted like - the ideal prop for regen is not the same as one for drive. A huge solar array will add weight and windage etc...

BUT it is quite clear that PBO is not wide of the mark by having articles on this topic as clearly some people have some interest in it.

 

[rogerthebodger]

Yes there needs a detailed analysis of the various setups.

Adding solar input which is in effect free electrical energy

The one downside is the unlike road cars that have energy recovery recovering the momentum energy which is not generally available in boats.

sailing boats need less chemical/ electrical energy due to the capture of the wind energy to drive the sailboat along

 

[trapper guy]

is propane free? no, is diesel free? no, petrol free? no
so why apply a metric to electrical generation that doesnt get applied to other forms of energy?

there is just this obstacle in peoples minds when it comes to generating electricity for some reason, i dont understand it.

lets apply the same argument to a horse and cart...
put hay in a horse, which produces reciprocal energy, convert that to rotary energy...
OOH BUT THERE ARE LOSSES IN THE SYSTEM! ITS GOING TO COST ME MORE HAY!

in terms of work done, the extra hay was clearly worth it, as civilisation was built using the horse and cart.

apply your logic and we neednt ever invented the cart!
why was the dynamo ever invented, when we clearly have more learned people in todays society.
the extra energy involved in pedalling that bike was clearly nonsense and not worth the light output from the lamp!

so a paddle wheel dropped into the water, may slow a boat by half a knot, but if the result is cost free electrical generation for 30kts, it a win? surely?

the paddle would still generate when the boat was moored up, unless you happen to live in an anomaly spot on earth where water doesnt flow 24hrs a day, every day, just like wind or solar are not available 24hrs a day, any day.
so lift the paddle out of the water when sailing? ill wait for the ridiculous objections why that would induce losses into the system

 

[trapper guy]

Yes there needs a detailed analysis of the various setups.

Adding solar input which is in effect free electrical energy

The one downside is the unlike road cars that have energy recovery recovering the momentum energy which is not generally available in boats.

sailing boats need less chemical/ electrical energy due to the capture of the wind energy to drive the sailboat along

no solar is no more free than any other form of generation, it has to pass through through the charge controller, there are losses in that system!
then you put it through the inverter to bring it to 240volts, losses in the system!

somebody in science one said in an isolated system the energy remains constant, but never said anything about the energy in an open system.

but yall keep applying the rule for the isolated system to the open system!

and i dont agree that a boat requires less chemical/electrical energy, when it comes to work done, boats are vastly more inefficient than road cars.
if i run my car engine for an hour, i can push that mass over 60 miles, if i run my boat engine for an hour, on a good day i can push that mass a whooole 7kts?

 

[RunAgroundHard]

I don’t think many anre arguing that electric energy on a boat will not become a primary source of energy. Some don’t believe it will be. The discussion is around current applications and the usefulness to users.

Personally, all electric sailing boats, in the majority of usage categories, is coming. You only have to be aware of the technology improvements in alternator charging, solar power management, battery storage, turbines to see that progress and efficiency is relentless, as is demand. Even energy efficiency has moved on a pace with LEDs and induction hobs being examples compared to their contemporaries.

I probably have 25 years of sailing left, before I stop. If the last 25 years technology progress is anything to go by, a future upgrade to my boat, will likely result in an all electric boat. Like shoveling coal into a steam boiler’s furnace, diesel and gas power will be a quaint technology that we will laugh about.

 

[rogerthebodger]

no solar is no more free than any other form of generation, it has to pass through through the charge controller, there are losses in that system!
then you put it through the inverter to bring it to 240volts, losses in the system!

What I mean solar is free is that other the capital cost of the solar setup there is no cost in collecting the solar energy.

There is inefficiency in the conversion of solar radiation into electricity. Once the electricity is collected any conversion to a different form of energy will involve some losses. Those losses will be heat which is termed low grade heat that could b used but its not normally easy to use.

I use some of the waste heat from my engine to heat water and there have been discussions on using excess solar electricity to heat water but it's so low-grade heat but not very effective.

We have water heating direct from solar to heat out swimming pool and to help heat domestic water but again its low-grade heat so not very effective

 

[geem]

I don’t think many anre arguing that electric energy on a boat will not become a primary source of energy. Some don’t believe it will be. The discussion is around current applications and the usefulness to users.

Personally, all electric sailing boats, in the majority of usage categories, is coming. You only have to be aware of the technology improvements in alternator charging, solar power management, battery storage, turbines to see that progress and efficiency is relentless, as is demand. Even energy efficiency has moved on a pace with LEDs and induction hobs being examples compared to their contemporaries.

I probably have 25 years of sailing left, before I stop. If the last 25 years technology progress is anything to go by, a future upgrade to my boat, will likely result in an all electric boat. Like shoveling coal into a steam boiler’s furnace, diesel and gas power will be a quaint technology that we will laugh about.

I guess if you have a day sailer and all you do is potter out of the harbour and go for a sail, then electric propulsion where the power comes from shore power to charge the batteries, all makes sense. No argument there. Where it doesn't make sense is on ocean going vessels that actual crosses oceans. It can be done but motoring in calms at 5 or 6 knots for 24 hours or more will be impossible to achieve. Something that is easily done with a diesel engine. We have about 1000nm range under power.
Most monohulls have limited space for solar. 1000w being about the maximum for most boats. The power for electric drive has to come from somewhere. Towed turbines can make some power. My own produces about 10A at 12v on a nice sailing day, but it is a drop in the ocean when you consider that the loads on the boat for autopilot, fridge/freezer, electronics, nav lights, electric cooking, etc will take all of that solar and water turbine output. You still have to charge up that battery for motive power. As soon as you introduce a generator for charging you are back to diesel power, albeit driving electric motors.
You can accept that you need to use the boat differently but that isn't comparing apples with apples. We can motor at 5 or 6 kts for days. This gets us out of bad weather or into harbour before night fall or simply motors us through a large high pressure system. These options may disappear with all electric drive

 

[flaming]

Of course the difference with the way an offshore electic powered boat would work is that currently when your fuel is gone, it's gone. In the electric boat a few hours of sailing at decent speeds and the turbine has topped the range up again. Sure in the middle of a massive high that's not a huge amount of use, but everything has upsides as well as downsides.

If the shift away from ICE in all forms of transport means that cruising boat designers are actually required to consider how their boat performs in the 4-8 knots true wind range, instead of just assuming the owner will fire up the donk, then I'm all for it.

 

[geem]

Of course the difference with the way an offshore electic powered boat would work is that currently when your fuel is gone, it's gone. In the electric boat a few hours of sailing at decent speeds and the turbine has topped the range up again. Sure in the middle of a massive high that's not a huge amount of use, but everything has upsides as well as downsides.

If the shift away from ICE in all forms of transport means that cruising boat designers are actually required to consider how their boat performs in the 4-8 knots true wind range, instead of just assuming the owner will fire up the donk, then I'm all for it.

Regardless of how a boat sails in the 4 to 8kts range, when there is no wind and you need to be some place, you motor. When there is 4 kts of wind and a big swell, you motor because you can't keep wind in the sails. I know it has its applications but there will always be a place for diesel power