Why the slow progress on hybrid engine systems?

[Ric]

Why have hybrid engines been so slow to come to the sailing market, while they are being adapted with much alacrity by the road vehicle market? Over the past decade or so, a number of systems have come and gone, often from small companies which have not had the resources to overcome teething difficulties. None of the large engine manufacturers (except Nanni) have made any serious attempt to perfect the technology, and even Nanni seem to not be trying to hard.

Is there some compelling technical reason why this technology is so difficult to make work on the sailing boat market? The economies of scale of the vehicle market are clearly not the same in the boat market, but nevertheless I would have thought there would be more adaption by now.

I would really be interested in fitting a system if it could provide 220v ac while in diesel mode, provide regenerative power when sailing at hull-speed (but importantly have the possibility to switch back to low drag when in light winds), and be from a major manufacturer.

 

[NormanB]

Hybrid just makes no economic sense for a sailing yacht, given there is no economy of scale in terms of production & installation

You are going to need a whole load more batteries to give you any sort of range/utility AND you still need a Diesel engine and tank. The vehicle hybrid design ethos recognises you plug into the mains either en route or at the end of the journey - they all introduce range anxiety.

I think a custom pure electric could be an option for an owner who was prepared not to be able to motor for days at a time (doldrums) and could cope with an 'auxiliary' propulsion system that only had an endurance of say 10 hours/50 miles. The installation could take advantage of losing the Diesel engine and fuel tank while fitting batteries to suit trim. Solar panels and maybe waterborne generation (or regeneration) for topping up batteries whilst under sail. Wind turbine if you do not mind noise.

 

[michael_w]

Very hard to beat the energy density/efficency of diesel.

To my mind the hybrid route for cruising boats is a wholly unncessesary layer of complication, weight and expense.

 

[Poignard]

As shopkeepers used to say when you wanted something they didn't stock

"There's no call for it, Sir."

 

[reeac]

The main plus point of hybrid drive is regenerative braking which comes into its own with road vehicles in stop/start conditions. I can't see its relevance for sailing boats except for the rare few who would be willing to tolerate the drag entailed when in sailing modes itch sufficient wind. There is a secondary advantage for city centre busses where, with luck, the dirty diesel engine would only run when needed rather than all the time. At one time there was quite a fanfare from various cheerleaders about hybrid power for boats but they've gone strangely quiet now.

 

[Tranona]

This subject has been covered here extensively in the past. It is a mistake to try and make any comparison between automotive applications and marine. There is no advantage of hybrid power in auxiliary yacht applications and little in pure powerboat over straight diesel power.

Suggest reading the series of articles on the subject published recently in PBO which report on Nigel Calder's EU funded project. This covered the building and operation of a hybrid powered Malo 45 as a typical cruising boat. This is the minimum size of boat that could take a functioning hybrid system without compromising the main purpose of the boat. The findings are clear that there are no advantages over straight diesel and significant cost penalties.

The reason why no engine manufacturers have pursued the technology, despite several developing near production systems is that they see no demand for a product that show no advantages.

 

[charles_reed]

Hybrid power trains for road vehicles make some sense, where you need widely different power outputs for different road conditions - you have a small constant-speed engine driving an alternator with a battery pack acting as the reservoir for the different power requirements.
The whole thing was driven by Government tax systems driving for a reduction in CO2/mile.
Boats have no such widely varying demands and no tax system to tempt anyone in their right mind to develop such a system.

In any case hybrid vehicles are becoming yesterday's technology with the improvement in power/weight ratios in batteries and the spread of charging points favouring pure electric vehicles.

So an artificial inducement to consumers, to reduce CO2 emission/mile, catered for by an expensive and complex methodology which is already obsolescent.

 

[GrahamM376]

We will be well up that well known creek and will need a paddle if modern vehicle technology is applied to the marine environment. Fly by wire is already appearing on engine controls and is likely to create problems and much expense when it gets old and corroded. Sod the environmental arguments, keep boat engines as simple as possible and fixable at sea.

 

[JumbleDuck]

I can see two main ways in which hybrid power could work for cruising yachts. First of all, it gives the possibility of a very quick and easy way of getting power when it's only needed for a short time. No faffing about with seacocks, starter buttons, checking for water and all that guff; just push the lever and go. Its potentially a great solution for people who generally only want a quick burst of power for entering and leaving their marina. A friend of mine has an all-electric Victoria 800 and electric power works very well for this.

Secondly, it gives the possibility of a fairly small and light diesel for long distance auxiliary use while keeping the possibility of an hour or two of much higher power when you really need it. Dodging a ship, for example, or getting round the Dorus Mor. Lots of boats have twice as much power installed as they need for 90% of the time.

The big question is whether hybrid systems can be cost effective at that scale. At the moment the answer is that they are not, because a suitable battery capacity is either prohibitive heavy if lead-based or prohibitively expensive if lithium based. When an watt-hour in Lithium costs less than an watt-hour in lead (and it will) things may change.

Even then, however, I suspect that the system development expense will be too much for marine engine companies. If Kubota come up with a hybrid base for industrial use (diesel meets steady compressed air demand, electric kicks in at times of high drain) then that, too, could change the economics of the proposition.

There will always be people who dismiss hybrid technology because it wouldn't suit their personal and current needs, but then there are people who dismiss sails on precisely the same grounds.

If I could buy, for £5k, a diesel electric hybrid which gave me 5kW continuous diesel power and a further 5kW of electric for an hour, I'd be very interested indeed. It would suit my sailing extremely well.

 

[Heckler]

We will be well up that well known creek and will need a paddle if modern vehicle technology is applied to the marine environment. Fly by wire is already appearing on engine controls and is likely to create problems and much expense when it gets old and corroded. Sod the environmental arguments, keep boat engines as simple as possible and fixable at sea.

Exactly, I am more than a competent diesel man BUT when the car starts playing up then forget it! Computer and thousands of pounds worth of software needed to fix. Was talking to Dr Diesel in Oswestry, far more experienced again than me but he said that even the injectors now are throwaway items! a certain Van, alloy head and interference fit "injectors"had a ten to. puller on them, wouldnt budge, £3k for a new head and injectors. So they start fitting that shite in our boats, what happens halfway across the oggin and the electrics decide to go on strike! Ah, got to go to the main dealers sir! Yeah! Right!
S

 

[dunedin]

The automotive hybrids only exist in any numbers due to
(A) huge pressure on the manufacturers to develop them and therefore billions of investment dollars
(B) typically loss leading sales prices - but currently still much higher than equivalent diesel/ petrol cars
(C) big government subsidy per car - was it circa £5k per car

The boat industry simply doesn't have that sort of mega bucks funding to develop and sell the technology

Oh and even with the green conscious prepared to pay extra for their cars, the depreciation rates of most of the hybrid cars are devastating currently

 

[NormanB]

Of course having said all of that - a draconian change to emissions legislation AND applying that to leisure craft could create the conditions for change (or the collapse of leisure craft industry).

 

[JumbleDuck]

Of course having said all of that - a draconian change to emissions legislation AND applying that to leisure craft could create the conditions for change (or the collapse of leisure craft industry).

I doubt we'll get away with crude, particulate belching diesels for long.

 

[Boo2]

Is there some compelling technical reason why this technology is so difficult to make work on the sailing boat market?

In one word : "batteries". The energy storage capacity of current battery technologies is so low compared with liquid fuels that it's a non-starter.

I'm interested to know what you see as the utility of hybrid systems anyway ? If you were thinking that a generator of sufficient power to propel a boat would generally be useful, consider :

A 35 hp diesel is 26kW at full power. Say that an electric motor is twice as efficient (something of a best case) then you need a generator of at least 13kW to propel your boat at the same speed as a 35hp diesel. But 13kW is way over what you need in general use, that's 4 electric kettles at full blast continually. So you would only ever run the generator at full power (= max efficiency) when you are motoring, the rest of the time the generator would be operating below maximum efficiency. So really it makes far more sense to buy a generator sized for the required electric power and a separate diesel to power the boat. So that's what people do.

If your idea is to power the boat from batteries that you charge via solar or a wind turbine then the energy density of batteries is not really up to it : 13kW is 260A at a safe 50V or 45A at an extremely lethal 300V. So you'd need a 2600 Ah battery bank to run the boat for 10 hours in the first case or 450 Ah in the second case. And the same current to recharge it taking a further 10 hours. So just not practical IMO at this time and I would not have a 300V dc power source on my boat, thanks.

Boo2

 

[JumbleDuck]

A 35 hp diesel is 26kW at full power. Say that an electric motor is twice as efficient (something of a best case) then you need a generator of at least 13kW to propel your boat at the same speed as a 35hp diesel. But 13kW is way over what you need in general use, that's 4 electric kettles at full blast continually. So you would only ever run the generator at full power (= max efficiency) when you are motoring, the rest of the time the generator would be operating below maximum efficiency. So really it makes far more sense to buy a generator sized for the required electric power and a separate diesel to power the boat. So that's what people do.

You wouldn't use the electric drive to propel the boat continuously. You'd use it on its own for short trips (getting out the marina) or to boost the power from a small diesel for short periods (getting round a headland against the tide).

Agreed about current battery technology.

 

[Mistroma]

You wouldn't use the electric drive to propel the boat continuously. You'd use it on its own for short trips (getting out the marina) or to boost the power from a small diesel for short periods (getting round a headland against the tide).

Agreed about current battery technology.

Problem with restricting how people would be able to use the technology is that it reduces the number of people who'd consider buying it. You will get investment if millions want (or will be forced) to use a particular technology but unlikely to get investment if only a tiny fraction of owners would be interested.

I agree that cost and energy density (batteries vs. diesel) are big hurdles. However, power would still be coming from a combustion engine and increase in efficiency of a hybrid system wouldn't be huge. So perhaps not as green as might be thought.

Getting power from solar panels is a non-starter for normal cruising.
e.g. Collecting 100Ah per day with 12V batteries amounts to 1.2 kilowatts.

Someone mentioned 13kW for propulsion and that would mean a day of solar charging would give about 5 minutes running from above. I doubt any yacht would be able to fit enough solar panels to run for even 1 hour each day (even with a completely lossless battery charging system).

You could use a wind gen. to store electrical power from wind for use in calm conditions, but it would be massive and unlike the tiddly units currently fitted. You'd probably need to ditch the sails and remove the mast to make room. .

 

[rob2]

It just isn't cost effective to install a bank of rechargeable batteries with a short finite life (3 -5 years) to propel a boat for a few minutes each trip! The problem is compounded by the fact that you're not really being "green" as the manufacture of the batteries, solar panels and motors is a dirty process (though removed from the boat itself) as is the generation of the mains you'll end up using to get it up to full charge. A hybrid installation really needs to be incorporated into the design of the boat as the batteries will be a considerable part of the ballast - how many sailing boats could accomodate such an extra loading along with all the other gear carried without compromising the stability and sailing characteristics?

Rob.

 

[JumbleDuck]

A hybrid installation really needs to be incorporated into the design of the boat as the batteries will be a considerable part of the ballast - how many sailing boats could accomodate such an extra loading along with all the other gear carried without compromising the stability and sailing characteristics?

This is where lithium batteries win - they are much lighter than lead acid.

 

[Tranona]

You wouldn't use the electric drive to propel the boat continuously. You'd use it on its own for short trips (getting out the marina) or to boost the power from a small diesel for short periods (getting round a headland against the tide).

Agreed about current battery technology.

That is exactly how the hybrid system on a Toyota for example, works, and that in urban buses. Short term electric only power, recharged by IC engine or used together to boost power for high speeds. However, that has the advantage of regenerative power generation so reducing energy storage requirements.

This works well when the duty cycle is dominated by low speed stop start running. Very different from duty cycles for a yacht auxiliary, but possibly suitable for mixed use MOBOs as in the hybrid Greenline 33. However it still carries a massive cost, space and range penalty with the only real gain being a short period of quiet running.

A hybrid in a small yacht magnifies those penalties, particularly space for minimal gains. Two things to look at to illustrate - first compare the size of a 6.5KW diesel generator with a 10hp engine and box and work out what you are going to sacrifice in space to fit it, never mind the space required for th additional battery capacity. Then consider that the typical annual engine usage of a yacht is equal to less than 4000 miles mixed driving of which maybe 10% is in and out of a berth then you realise how little value there is in the electric element hybrid power.

 

[earlybird]

Mastervolt sells Li ion batteries. Vital stats. are:-
Capacity 5kWHrs; Weight 58 kg; price ~ £4.7k.
The spec. seems to advise discharging only to 20%, so at that, you might get about 4 hphrs at the prop. shaft.
Cf. a small outboard with a full tank.