Hybrid diesel electric propulsion

[JumbleDuck]

One possible benefit with hybrid propulsion (with electric or hydraulic drive) ...

As above, this does not address the basic problem of storage and range.

It doesn't have to, because he wrote "hybrid", not "electric".

 

[Tranona]

One possible benefit with hybrid propulsion (with electric or hydraulic drive), providing the motor attached to the prop is small (light) enough) would be the ability to retract the prop and shaft when not motoring. Either a outboard pivoting in a well (or on the transom) or a vertical lift with a curved "box" under the prop that aligns with the hull when retracted. Efficiency will drop a little, but the removal of the need for a shaft through the hull or a large hole for the sail drive seal has attractions. The well would extend above the waterline in a large enough boat, lowering the probability of failure leading to sinking.

I suspect this is actually of little benefit as the number of singings due to shaft failure (dropping out) or sail drive seal failure appears to be negligible - I have heard of one of each, and the latter was due to a cat grounding.

So just an idea for cold rainy nights.

Such things have been tried in the past but tend to suffer from two main issues. First is efficiency losses and second is complexity. Self contained electric drive pods (miniatures of the types used in big ships) have been available for some time - Mastervolt have a range but don't seem to be visible in the market. Hydraulic drives have been around for years and are used in hire boats built for the French canals. Big advantage for them is the placement of the engine under the boarding platform so not compromising the accommodation. Power requirements are modest so the efficiency losses are not such a problem as they would be in a seagoing vessel.

Hybrid power has also been used in catamarans in the charter market, but quickly discontinued for the reasons above - no real benefit over "conventional" saildrives which are smaller, lighter and simpler for similar power.

 

[DownWest]

It doesn't have to, because he wrote "hybrid", not "electric".

Ah, sorry..

 

[JumbleDuck]

Ah, sorry..

Nae problem. On the whole I tend to agree that all-electric propulsion is likely to stay niche, though I expect cheaper versions of Torqeedos to eat internal combustion alive for the dinghy market.

However, as with cars, I think hybrids could do quite well. Most of us need auxiliaries for three things:

(1) short trips into and out of harbour - ideal for electric

(2) long plods on calm days - ideal for a small diesel

(3) medium term blatts to out of something nasty or round a headland - ideal for electric+diesel together

Current small marine diesel technology is out-of-date and dirty. When it gets outlawed, as will happen, the combination of small, clean modern diesels with modern batteries will be am attractive alternative to lugging a ruddy great engine around, just in case. The old-timers will stick to what they know, of course, but they can't stop the market moving on.

 

[Tranona]

Nae problem. On the whole I tend to agree that all-electric propulsion is likely to stay niche, though I expect cheaper versions of Torqeedos to eat internal combustion alive for the dinghy market.

However, as with cars, I think hybrids could do quite well. Most of us need auxiliaries for three things:

(1) short trips into and out of harbour - ideal for electric

(2) long plods on calm days - ideal for a small diesel

(3) medium term blatts to out of something nasty or round a headland - ideal for electric+diesel together

Current small marine diesel technology is out-of-date and dirty. When it gets outlawed, as will happen, the combination of small, clean modern diesels with modern batteries will be am attractive alternative to lugging a ruddy great engine around, just in case. The old-timers will stick to what they know, of course, but they can't stop the market moving on.

That is a good summary of the requirements of many weekend sailors. However getting from there to a functioning product that meets those requirements is an enormous leap and there is nothing on the development horizon that will make it possible.

As I have said many times just about all of small marine engine requirements are met as spin offs from industrial engines and while the current engines may be less environmentally friendly as they could be, hybrids are unlikely to be the future as most industrial applications do not have that slow/high speed mix.

If drawing from the automotive world, hybrids are using petrol rather than diesel for power generation and some propulsion. In effect packaged versions of what some hobbyists use for their "electric" boats - that is recharging their batteries with a small petrol generator. Others such as the original Hybrid Marine system used a 1GM mounted remotely to charge the battery, but never got past the prototype stage. Yanmar themselves built an integrated diesel/electric power plant but again it never went past the trials stage.

One can see a place for an integrated petrol (or even diesel) electric hybrid the size of existing diesels but it would be a brave manufacturer to invest in such a beast for the tiny marine market.

 

[rotrax]

I happened to be holding First Mates hand at the dentist earlier today and happened to pick up a copy of " Waterways World " the canal boating magazine.

An ad for hybrid drive gave one useful feature not mentioned here, the ability of the generator to provide 8KW's of 240v electricity for lighting, heating, cooking and pumps as well as providing high rate charge, if required, for the propulsion battery bank.

I installed an 8KW Westerbeke genset on Jarrow Lily last year. The power is from a 3 cylinder 900cc Mitsubishi diesel. Very efficient, but in my installation at present, quite noisy. Dealing with that soon.

I can see it being good for inland waterway use, but far more refinement required for use in yachts.

 

[Blue Sunray]

 

[DownWest]

I happened to be holding First Mates hand at the dentist earlier today and happened to pick up a copy of " Waterways World " the canal boating magazine.

An ad for hybrid drive gave one useful feature not mentioned here, the ability of the generator to provide 8KW's of 240v electricity for lighting, heating, cooking and pumps as well as providing high rate charge, if required, for the propulsion battery bank.

I installed an 8KW Westerbeke genset on Jarrow Lily last year. The power is from a 3 cylinder 900cc Mitsubishi diesel. Very efficient, but in my installation at present, quite noisy. Dealing with that soon.

I can see it being good for inland waterway use, but far more refinement required for use in yachts.

Waterway are more like the cruise ships. Electrical power is the priority over propulsion and, I imagine, easier to keep quiet compared with diesels and shafts, so as not to annoy the steerage class..

 

[earlybird]

Why would the average yachtie wish for a hybrid drive system? In the road vehicle world, consumer adoption of such systems is driven by legislation stemming from air quality problems experienced in centres of population.
No such driving force is on the horizon in the sail-boating world.
My 18kW diesel is fuel efficient, cheap(ish) to buy and maintain, weighs ~150 Kg including fuel for 50 hrs operation and I expect 20+ years of very reliable operation with the pattern of use outlined by JD, with the proviso that motoring in a prolonged calm sees the engine operating, at a guess, at 70-75% of its rated output, ie not too low.
After those 20+ years, I might be able to replace it with an up-to-date version, incrementally more fuel efficient, marginally cleaner combustion and slightly lighter in weight. Indeed, legislation might then demand reduced emissions, But what advantage would be gained by introducing the cost, weight, complication and conversion inefficiencies of an electric motor/generator and batteries into the drive train?

 

[JumbleDuck]

That is a good summary of the requirements of many weekend sailors. However getting from there to a functioning product that meets those requirements is an enormous leap and there is nothing on the development horizon that will make it possible.

On the contrary, battery technology is bounding ahead and, most important, control systems for hybrids are now mainstream and constantly improving. When I was at university in the 80s there was a long running series of final year projects around a hybrid car which at that stage had a Hillman Imp engine as the prime mover (the lead academic had worked for Rootes Group...). Every year groups of students made small advances, mainly on monitoring and control systems, but they were hampered by the technology of the time. Newer developments like DC used to create variable frequency AC for synchronous motors were a distant dream then; now it's off the shelf stuff.

As I have said many times just about all of small marine engine requirements are met as spin offs from industrial engines and while the current engines may be less environmentally friendly as they could be, hybrids are unlikely to be the future as most industrial applications do not have that slow/high speed mix.

Which of course makes them less suited for marine use and ideally suited for hybrids in which the prime mover can operate at maximum efficiency whenever its running. That's why Calmac are going hybrid - it's a larger scale, but the principles are just the same.

One can see a place for an integrated petrol (or even diesel) electric hybrid the size of existing diesels but it would be a brave manufacturer to invest in such a beast for the tiny marine market.

I agree, up to a point. The marine market is small-ish, but it bears a high premium. And remember, the hybrid package is going to be a 15hp diesel plus electrics replacing a 30hp diesel. We'll all have 'em, one day.

 

[JumbleDuck]

I loves me them Botnia Targas. One day ... I think I'd want more than five hours on battery, though.

 

[JumbleDuck]

But what advantage would be gained by introducing the cost, weight, complication and conversion inefficiencies of an electric motor/generator and batteries into the drive train?

In ten years time your boat will have a great wad of lithium-ion storage and a nice meaty alternator to charge it. The additional cost of an electric motor (or motor-generator, saving you the alternator cost) will be relatively low and give you a nice, quiet alternative to diesel and twice your installed power for a few hours if you really need it. What's not to like?

 

[laika]

People are only motivated by their own personal interests and there is little demand for electric power through choice as it fails to satisfy wants which are what motivates peoples' purchase decisions.
[...]
If we were denied IC engines yachting as we have come to know it over the last 60 years will cease to exist as it is so dependent on diesel power. Typically a cruising yacht spends as much as half of the time on passage under engine, and it is engines that have made such boats viable for everyday leisure use.

With apologies to the OP for thread drift..allow me to segue back from hybrid to all electric as that actually interests me more. No-one is going to dispute that the technology isn't cheap(/practical) enough for the mass market today. I was talking to the Torquedo folks about their inboards. They didn't seem to think the amount of time in generator mode to yield an hour of propulsion made it an attractive proposition, never mind the eye-watering price (the battery can be more than the motor) but were pretty upbeat about the next few years. So are we just disagreeing about the adoption timeline? 20 years from now I expect any new boat to be using electric power, topped up either from shore power or the prop in hydrogenerator mode. It's likely that I'll be an early adopter in 5-10 years' time.

Most of us need auxiliaries for three things:

(1) short trips into and out of harbour - ideal for electric

(2) long plods on calm days - ideal for a small diesel

(3) medium term blatts to out of something nasty or round a headland - ideal for electric+diesel together

Good summary. Point 1 is mainly what I need an engine for. Torquedo's systems can already deliver this charged from shorepower (obviously not so good for those on midstream moorings) but the batteries are ludicrously expensive. This is an obvious area where we'll directly benefit from investment in the car industry.
Point 3 shouldn't be a problem if we have battery capacity and re-generate power from sailing. Still needs development but look at the difference between the power output of a watt&sea and the hydrogenerators of 10 years ago. We could also address this by changing the expectations of where we can get in a day's sail, sailing for the sailing rather than the destination and respecting lee shores and giving hazards more room. Point 2 will likely be an issue for longer and require changing expectations, perhaps more to what they were when an "auxiliary" was a seagull.

As Jumbleduck points out, hybrid addresses the areas that hydrogenation doesn't currently solve but it still leaves me with an engine I'd rather not have.

Early adopters would be people like me willing to change their expectations. I dislike using my engine. I don't like the noise. I'm not good with mechanics (I'm better with electrics) and I dislike the idea of the pollution it causes. ("bunny hugger" I believe is the epithet forumites tend to apply to people who walk to the bottle bank). The barriers for me right now are the cost and size of sufficiently capacious batteries, cost of the engine itself and impractically slow recharging in turbine mode.

Let's face it, lots of people thought it was the end of everything when Dylan went electric...

 

[earlybird]

The additional cost of an electric motor (or motor-generator, saving you the alternator cost) will be relatively low and give you a nice, quiet alternative to diesel and twice your installed power for a few hours if you really need it. What's not to like?

Ok, you've persuaded me! I'm thinking of ripping out my Beta 25 and replace it with a Beta 14 plus a 10hp electric motor/generator together with a few £K's worth of batteries. Not quite the suggested 50/50 power split, but near enough and I've saved every bit of 20kg on the diesel weight to set against all the electrical gear. My "all-day" motoring speed might still be ~6kts, albeit at WOT rather than a comfortable 75% max revs, and never mind the change from a smooth 3 cyl. engine to a less smooth 2 cyl. job. Just imagine how quiet and smooth my manoeuvering in the marina will be!
A problem now arises! How big should the prop. be? Matched to the 14hp/ 3600 rpm of the diesel or for the 24 hp of the total system power?
The only way of putting 24 hp through the smaller prop is by over-speeding the diesel engine to which it is coupled. On a big prop, the little diesel will struggle by itself, I won't get my comfortable 6 kts cruising speed.
Pity boats don't have multi-speed gearboxes and climb hills as road vehicle do. Shall I look for a variable pitch prop. or scrap the whole project?

 

[JumbleDuck]

Let's face it, lots of people thought it was the end of everything when Dylan went electric...

Isn't he still trying to blag a motor sailor?

Ok, you've persuaded me! I'm thinking of ripping out my Beta 25 and replace it with a Beta 14 plus a 10hp electric motor/generator together with a few £K's worth of batteries. Not quite the suggested 50/50 power split, but near enough and I've saved every bit of 20kg on the diesel weight to set against all the electrical gear.

You'll have the batteries anyway, so "all the electrical gear" is a 7.5kW electric motor.

My "all-day" motoring speed might still be ~6kts, albeit at WOT rather than a comfortable 75% max revs, and never mind the change from a smooth 3 cyl. engine to a less smooth 2 cyl. job. Just imagine how quiet and smooth my manoeuvering in the marina will be!

You might have a smooth little 3 cylinder 14hp diesel ... as the demands on them change the technology will respond, and engine made for use in hybrid systems (industrial and other) will probably be rather different from what we are used to nowadays.

A problem now arises! How big should the prop. be? Matched to the 14hp/ 3600 rpm of the diesel or for the 24 hp of the total system power?

Is your current prop matched to the ~15hp you'll use when cruising or fr the ~30hp you have available? It's the same problem, and if your answer isn't "Brunton Autoprop" it's probably wrong.

 

[earlybird]

.
Is your current prop matched to the ~15hp you'll use when cruising or fr the ~30hp you have available? It's the same problem, and if your answer isn't "Brunton Autoprop" it's probably wrong.

But you're selling the hybrid system as allowing a small engine enabling "long plods on calm days". What you will finish up with is a not-so-small engine working its inefficient socks off to match its bigger brother. I really can't see the benefit given current or near future state of play. And I may not want a Brunton prop! Or an electrical system that I use once in a blue moon. Why not the slightly larger engine in the first place. I can fully replenish its energy storage in about 10 minutes as well.
BTW have you seen BBC Business News re Nissan being looked into by the ASA re electric car claims? Don't believe everything you read from the manufacturers.

 

[Tranona]

Which of course makes them less suited for marine use and ideally suited for hybrids in which the prime mover can operate at maximum efficiency whenever its running. That's why Calmac are going hybrid - it's a larger scale, but the principles are just the same.



I agree, up to a point. The marine market is small-ish, but it bears a high premium. And remember, the hybrid package is going to be a 15hp diesel plus electrics replacing a 30hp diesel. We'll all have 'em, one day.

This is already available today - and has been for several years. Many engine builders/electrical suppliers Yanmar, Beta, Mastervolt for example have already offered hybrid engines for yachts. However, they are fundamentally inefficient - converting energy from fuel oil and then propulsive power is wasteful. Calder's work has shown that it only becomes vaguely efficient if the proportion of hours spent at low speed is high and/or the requirement for electricity generation is high. Exactly why Calmac are using hybrids (just as the IOW ferries have been diesel electric for as long as I can remember).

Yacht use is exactly the opposite. A few minutes at low speed followed by hours of constant power running and electrical requirements that for most can be provided as a by product of propulsion plus for heavy users supplemented by renewable resources.

So, as earlybird says there is zero demand from users for a product which is in almost every way inferior to what is now available - and he forgets to add currently at a price premium of over 100%. None of the developments on the horizon are going to change that significantly and nobody serious is going to invest in R&D for the tiny yacht market. So it will have to be a spin off from another market. Given that it took almost 70 years from invention of the diesel engine to it becoming practical for propulsion of small yachts I doubt either of us will live to see either hybrid or electrics replace diesel for yacht auxilliarys.

 

[Vicarage]

Late the party I know, but came across this on google. We're in the process of designing a 22m sail training yacht, which will almost certainly be diesel/electric.
For us, we would be running a genset almost all the time anyway, to provide 240V power to all the systems (fridges/freezers/cooker/microwave/lights/pump/nav kit, etc etc). It seems to work out more economical to simply increase the size of the genset slightly, and then take the power to the electric motor when required.
We can then have two generators sited dead amidships in the deep bit of the bilge, with no shaft run issues, and with 100% redundancy.
We don't need great heaps of batteries as we'd be running the generator throughout, and 240V means we can have an electric galley and remove the need for any gas aboard. Probably doesn't count as a hybrid, though the generator would be quieter and more eco than a propulsion engine.

 

[earlybird]

Why would that be, given the conversion inefficiencies of the electric drives?

 

[pvb]

We can then have two generators sited dead amidships in the deep bit of the bilge, with no shaft run issues, and with 100% redundancy.

What would connect the motor to the prop?