Conversion to Electric Power for a 32ft Sailboat

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thesaintlyone

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Hello

During my random google searching I came across the concept of adding brushless Electric power to a sailboat motor!!! Apparently whilst the initial outlay is not cheap the future running costs are very viable as long as the set up is correct and there are a number of blogs and articles
where people have done it quite successfully here www.electricyacht.com So I have a couple of questions

1) Has anyone done it already on here and if so any advice
2) How Much Does a Conversion Rely on the Existing Engine if any, I am considering adding this to a potential new project Boat that currently does not have an engine installed.
3) Any Further Advice/Suggestions

Regards
 
Masses of info around which I'm sure others will direct you to! I think that there was a big article in a recent PBO which would be worth you searching for. There have, as you say, been a lot of successful conversions ( although a caveat to that is that most people who have invested lots of time and money on a project may have a biased view on it!!)
I think that new developments in the power generation and battery storage will make it more viable as time goes on.
 
The article referred to above was, I think, from Nigel Calder, who was building electropower into a new Malo. In his case he wanted it to provide off-grid independence.

His conclusion seemed to be that the installation is not too problematic, but that the stumbling block is obtaining a sufficient supply of electricity without resorting to a hydrocarbon generator (in which case you might as well have a hydrocarbon engine). Photovoltaics require an unfeasible amount of deck space, wind is unreliable, towed generators won't keep up with consumption when motoring in insufficient wind to sail, fuel cells are expensive initially and more expensive to run, and the battery capacity required is heavy on weight, space consumption and expense.

It's worth adding that Calder had access to expertise from Malo in the installation, and from the various manufacturers involved, because they have a vested interest in establishing a yachting market for their kit. Even so, his conclusion was that it is not practical for extended, off-grid sailing.

(that's my recollection of the article - actually, I think it was a two or three part series - others might have different memories of it)
 
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Quite a bit in canal fora. How are you going to recharge?
IIRC, there are slim donut shaped motors that can fit behind a conventional engine on the prop shaft, assuming the gearbox is suitable.
Downside? I’ve seen several half finished electric projects for sale for comparative pennies. Upside? You could buy one as a starting point!
 
There was also a yacht at SIBS a few years ago which had huge batteries and an electric auxiliary, American perhaps? Anyone else remember more?
 
Plenty of electric launches have been built successfully over the years.
But they don't need much power or range.

The starting point should be an analysis of what power and range you will need.
Then you need to either generate or store that or some combination of the two.

Electric power to get 500m in or out of a marina is perfectly feasible.
What is feasible beyond that, and whether you really want to give up a diesel engine is a matter of setting the requirements properly.
 
The drive part is easy and there are off-the-shelf products that will fit as long as you have a shaft drive and the stern gland isn't too close to the gearbox.

The problem is the power supply, and as far as I know nobody has cracked this for a boat used in the same way as a normal yacht.

Pete
 
A pal of mine has converted a Victoria 800 (posh version of a Victoria 26) to electric power, using a Lynch motor. In principal it seems very nice, but it's taking a lot of fine tuning to get the combination of prop and drive right. Battery capacity is an issue, but he has just replaced 250Ah (I think) of lead-acid with the same in Li-ion which extends the range by a factor of two. That's still only an hour or two at full whack, but he only plans to use electric for entering and leaving harbour. I would want enough oomph to get through the Crinan Canal, myself, as a bare minimum.
 
JumbleDuck said:
Battery capacity is an issue, but he has just replaced 250Ah (I think) of lead-acid with the same in Li-ion
Click to expand...

Hmm. My service bank for a conventional 34-footer is 420Ah. I'll admit that's on the large side but still, having only around half of that for both service and propulsion seems far too small.

Pete
 
There were all kinds of numbers associated with it but it boiled down to that there needs to be significant improvements in battery technology to make it viable. It seems to just about make the grade for very short trips and marina use where the diesel engine would be inefficient but for general use the diesel wins. You can store more energy, more easily in the form of diesel. It doesn't seem to solve a problem since you can't be self sufficient unless you are hardly ever using the engine and so you need to charge up from power produced from burning stuff at a power station. With the additional loses it seems neither environmentally friendly or practical for most uses. It may change in the future as technology improves though.
 
thesaintlyone said:
Hello

During my random google searching I came across the concept of adding brushless Electric power to a sailboat motor!!! Apparently whilst the initial outlay is not cheap the future running costs are very viable as long as the set up is correct and there are a number of blogs and articles
where people have done it quite successfully here www.electricyacht.com So I have a couple of questions

1) Has anyone done it already on here and if so any advice
2) How Much Does a Conversion Rely on the Existing Engine if any, I am considering adding this to a potential new project Boat that currently does not have an engine installed.
3) Any Further Advice/Suggestions

Regards
Click to expand...

Unclear about what you intend doing. Do you want electric power only? or are you considering a hybrid? Both are feasible, but the former totally impractical unless you have regular and frequent access to a power source to recharge your batteries. So fine if you day sail and return to a marina with shorepower every day and you just want power to get you in and out, but useless if you want to cruise independently.

Hybrid is more feasible. However as the Nigel Calder series of articles referred to earlier conclude it is neither efficient or economic in the typical duty cycles of a cruising sailboat - even a large and power hungry one such as his Malo 45. Large sums of money have been thrown at trying to develop hybrid power both by governments (EU in Calder's case) and engine or electrical manufacturers such as Yanmar and Mastervolt, but have failed to produce a commercially viable system.

The basic problem is that hybrid power works well if the requirement is for large amounts of electrical power, for example in cruise ships, where propulsion is a minor part of the power requirement. So cruise ships have massive oil fired generators and some of the electricity is used to run steerable pods for propulsion and manoeuvring in port. Contrast this with container ships of similar size where the main power requirement is propulsion and a simple diesel engine to a single screw is used.

With a 32' yacht the main power requirement (apart from the wind) is for propulsion and one of the big constraints is space. Batteries are an inefficient storage medium for energy compared with storage in liquid form, so pure electricity is only of limited value. So if you want to increase range of electric power by recharging batteries on board you need a diesel engine anyway, so why then inefficiently convert the energy to electricity before you can use it to provide propulsion when it can be used directly for this purpose?

A 32' sailboat typically will use an engine 150 hours a year, consuming less than 2l an hour, so 300l a year. Hybrid efficiency is less than 100% (see Calder's articles for further explanation) so hybrid power will actually increase fuel consumption, not reduce. Then consider the practicalities of installation. Most yachts of this size have difficulty in making space for a diesel auxiliary, and adding an electric motor, either serial or parallel greatly increases bulk and weight. Similarly of you want to increase storage capacity to increase running time under electricity alone, where do the batteries go?

So, not difficult to see why virtually nobody has produce a hybrid powered yacht of any kind, never mind one that is efficient or has any practical advantage over simple diesel power.
 
JumbleDuck said:
A pal of mine has converted a Victoria 800 (posh version of a Victoria 26) to electric power, using a Lynch motor. In principal it seems very nice, but it's taking a lot of fine tuning to get the combination of prop and drive right. Battery capacity is an issue, but he has just replaced 250Ah (I think) of lead-acid with the same in Li-ion which extends the range by a factor of two. That's still only an hour or two at full whack, but he only plans to use electric for entering and leaving harbour. I would want enough oomph to get through the Crinan Canal, myself, as a bare minimum.
Click to expand...

250Ah at 12V is 3kWh or about 4hp-hr at 100% efficiency.
How long is your Crinan Canal?
Remember that a 1 horsepower horse used to tow a 70ft canal boat at about 2 knots (?)....
But only on flat water at well below so-called hull speed.
Our modern yachts are very short and power hungry?
 
Let's put some numbers to this...

I have an 80-litre diesel tank, which is on the small side for a modern boat. According to Wikipedia, the energy density of diesel is 35,800 kilojoules per litre, so I have 2,864,000 kilojoules in my tank.

A watt for a second is a joule, so a watt-hour is 3.6 kilojoules, and the 12v amp-hour we're used to measuring our batteries with is 43.2 kilojoules. So I have 18,144 kilojoules in my rather oversize battery bank, assuming I could use it all, which I can't.

The normal rule of thumb is that you should only use half the amp-hours in your lead-acid battery to avoid damaging it. So we're down to 9,072 usable kilojoules in the battery.

I find lots of different figures for the efficiency of engines and motors, but I'm going to take 40% for the diesel and 90% for the electric. This is probably erring in favour of the electric motor. Both will presumably be subject to the same losses in the prop, shaft, etc so I'm ignoring those.

I'm actually going to pretend the motor is 100% efficient to allow for expensive deep-cycle batteries that you can drain below 50% without damage. So I still have 9,072 usable kilojoules in my battery, but now "only" 1,145,600 usable kilojoules in my diesel tank.

I'm sure a real engineer could come up with some better figures, but you can see the problem. My batteries weigh almost twice what my fuel tank does (66kg vs 120kg), but contain about a hundredth of the usable energy.

Pete
 
prv said:
Hmm. My service bank for a conventional 34-footer is 420Ah. I'll admit that's on the large side but still, having only around half of that for both service and propulsion seems far too small.
Click to expand...

I think he'd agree. However, batteries weigh a lot and space is limited. The advantage of Li-ion is that they can be discharged just about flat, which gives effectively twice the capacity per unit volume and four (?) times the capacity per unit weight. 250Ah of Li-ion is the equivalent of 500Ah of lead acid, which ain't too bad. Of course 12V x 500Ah = 6kWh = 8 hp-hours, which I can get out of 2 litres of diesel with my 1GM10 ...
 
prv said:
2-horsepower horse. James Watt underrated the horse for marketing purposes to make his engines look better :)

Pete
Click to expand...
Probably scrawny underfed ponies, not nice fit Shire horses?

Racehorses probably good for a few kW, but won't work a 12 hour shift.
 
prv said:
2-horsepower horse. James Watt underrated the horse for marketing purposes to make his engines look better :)
Click to expand...

2/3 hp. Watt measured horses as capable of doing 22,000 ft-lbf / minute and defined the horsepower as 33,000 ft-lbf / min.

The transmission system for horse tracking - a rope, basically - is as near 100% efficient as makes no difference, while a propeller is a lot less efficient.
 
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Tranona said:
Unclear about what you intend doing. Do you want electric power only? or are you considering a hybrid? Both are feasible, but the former totally impractical unless you have regular and frequent access to a power source to recharge your batteries. So fine if you day sail and return to a marina with shorepower every day and you just want power to get you in and out, but useless if you want to cruise independently.

Hybrid is more feasible. However as the Nigel Calder series of articles referred to earlier conclude it is neither efficient or economic in the typical duty cycles of a cruising sailboat - even a large and power hungry one such as his Malo 45. Large sums of money have been thrown at trying to develop hybrid power both by governments (EU in Calder's case) and engine or electrical manufacturers such as Yanmar and Mastervolt, but have failed to produce a commercially viable system.

The basic problem is that hybrid power works well if the requirement is for large amounts of electrical power, for example in cruise ships, where propulsion is a minor part of the power requirement. So cruise ships have massive oil fired generators and some of the electricity is used to run steerable pods for propulsion and manoeuvring in port. Contrast this with container ships of similar size where the main power requirement is propulsion and a simple diesel engine to a single screw is used.

With a 32' yacht the main power requirement (apart from the wind) is for propulsion and one of the big constraints is space. Batteries are an inefficient storage medium for energy compared with storage in liquid form, so pure electricity is only of limited value. So if you want to increase range of electric power by recharging batteries on board you need a diesel engine anyway, so why then inefficiently convert the energy to electricity before you can use it to provide propulsion when it can be used directly for this purpose?

A 32' sailboat typically will use an engine 150 hours a year, consuming less than 2l an hour, so 300l a year. Hybrid efficiency is less than 100% (see Calder's articles for further explanation) so hybrid power will actually increase fuel consumption, not reduce. Then consider the practicalities of installation. Most yachts of this size have difficulty in making space for a diesel auxiliary, and adding an electric motor, either serial or parallel greatly increases bulk and weight. Similarly of you want to increase storage capacity to increase running time under electricity alone, where do the batteries go?

So, not difficult to see why virtually nobody has produce a hybrid powered yacht of any kind, never mind one that is efficient or has any practical advantage over simple diesel power.
Click to expand...
 
Thanks for all the Replies and information I think the consumption figuesfor deisel given have been very useful.

The plan when I can secure the boat (currently looking at an abandoned part completed project boat that is solid and has great resale value) sorry I cant be more specific yet dont want to loose this opportunity.
The boat has had its engine removed for whatever reason and I have two options either new/Reconditioned deisel volvo around 28hp or an electric only conversion as the economy of a hybrid is not an option.
Was probably interested in the suitability and alternative options but I think im swaying more towards another diesel engine

Regards
 
JumbleDuck said:
1.5hp. Watt measured horses as capable of doing 22,000 ft-lbf / hour and defined the horsepower as 33,000 ft-lbf / hour.

The transmission system for horse tracking - a rope, basically - is as near 100% efficient as makes no difference, while a propeller is a lot less efficient.
Click to expand...
That would make dobbin 0.66hp?
 
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