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Aquaria 05-26-2010 05:58 PM

6 Attachment(s)
The discussion about electric engines in sailboat has started and some boat yards are beginning to equip their *(bigger) yachts with a hyprid engine system or (on smaller units and inshore sailboats) with an electric engine. The number of companies *in Europe, offering packages of complete engine systems is growing and that makes it interesting for owners of existing yachts to think about an electric engine when the old Diesel has to be replaced.

Our Volvo MD2B (25hp/18,3kw) was 36 years old. It was still running, but it showed clear signs of age - the stability of temperatur und rpm was decreasing and it was getting hard to get spare parts.

*Attachment 1360

After a long process of looking at the pros and cons we finally decided, that an electric propulsion system fits to the boat and – maybe even more important - to our „motoring habits".

The boat:

Centurion 32, a former IOR-half ton – therefor good sailing performance

weight of about 5,5 metric tons (fully equipped)

so far an 18,3kw diesel engine, with a real power potential of 7,3kw (the rest was heat and noise) due to an (estimated) efficiency of**40%

The motoring habits:

the main use of the engine is to get in and out of harbours, marinas and crowded anchorages

under rare occasions we use the engine to make the last miles into the harbour after the wind died and if it does not make sence to stay out at night

we never motor against wrong tides, winds or severe calms

if necessary, we look for a new destination instead of**starting the engine to meet once set schedules

we love to sail**at 2 to 3kn even under light wind conditions and if we use the engine a speed of not more than 4 knots is fine

we never use the engine for extended passage making

in the years of weekend sailing and**sailing vacation the engine runs about 40 to 50 hours in a sailing season (April to October)

during periods of living aboard we used 90 litres of Diesel in a year on two occasions (Northern Europe, Caribbean and back in 15 months and between Northern Europe and Gibraltar/Marocco in 12 months )

during offshore / ocean sailing we never used the engine for passage making. (Sooner or later, every calm ends – it's just a matter of time and patience and good books...) *The engine was never used for battery charging, which is done by shore power if available or otherwise by wind generator and solar panel.

The new electric motor system had to meet the following needs:*

- a power of about 10kw should be sufficient, creating a realistic power potential of 9kw (at *an efficiency of 90%).

- It should be poweful enough to move around savely in crowded marinas and to keep away from any dangers in tidal waters

- the new system including the batteries should equal the weight of the Diesel engine, gear box, starter battery and 60 litres of fuel.

- all components (especially all batteries) should find their place in the engine compartment to make sure that the trim is not influenced negatively.

- a driving range of about 15 to 20 nautical miles (as a relistic half distance between two ports in the northern European waters we sail during normal weekend / vacation settings, if not sailing over night) under engine

- we wanted to install the system ourselves – therefor we wanted to keep the existing traditional prop shaft arrangement

- under sails the motor should function as a generator

- the system should work on *12/24V and not on three-phase-curent, as bigger units use. *

While looking around searching for experience and manufacturers we soon found out that a sister ship, driven by electric power was already on the water in Norway:*Sy Ren Glede (and click on Last ned beskrivelse for a the description). This led us to the swedish manufacturer of innovative yacht equipment OzMarine. *

OZMarine**specializes on electric motors for sailing yachts and their package includes all parts to run the system, including the motor itself, made up by two electric motors set in line to drive the axle, the folding prop, axle, axle sealant, axle bearing, motor controller, charging electronic to use the motor as a generator, complete shore power system with 230VA/C battery charger and the battery control unit and the cabeling.*

Installation was easy and astonishingly fast.*

We removed the old engine (with the only outside help to hoist out the heavy old Diesel engine), cut back the old engine mount and rebuilt it as a fibreglass/wood-structure to fit the new engine.

Aligning the engine was easy, as the two el-motors are placed in a stainless steel frame that swings around a lateral axis. To define the correct elevation of the engine in relation to the prop shaft, stainless steel plates can be placed under the engine frame and finally the bolts that hold the engine to the mount are a little less in diameter than the holes in the engine frame, giving a little flexibility to work around the vertical axis.**And as the whole engine only weighs 32 kg it is no problem at all to successfully install the engine all by yourself!

Attachment 1361

Attachment 1363

Attachment 1362

We installed six VRLA-Gel batteries (100Ah)

- to get the necessary weight to replace the Diesel engine,

- to place them in the engine compartment and not anywhere else unter the bunks to maintain the trim and to keep the cabeling short,

- to reach a range under engine of about 20nm without draining the batteries more that 50% (this is not much but it perfectly well fits into our traditional motoring habits)*

First trials met our expectations.*


6 months in tidal waters, out of that one month cruising, at night in marinas using shore power. On one calm day 23nm over ground, going with the tide under engine, otherwise weekend sailing.*

- the engine reacts powerful and fast – good for crowded marinas and anchorages.

- at a "cruising speed" of almost 4 knots under calm conditions (which is perfectly enough for us) it consumes about 60A . That gives a range of about 18 nm at a consumption of 300Ah – using *50% of the total battery - capacity.*

- under full speed (at 24V) the speed is 5,8 knots, which can be maintained for nearly 40 minutes. Enough time and speed to escape from risky situations, without abusing the batteries

- normal motoring in and out of a marina can be done with a power consumtion of 12 to 16 Ah.

- charging under sail is possible with up to 10A under ideal conditions (wind generator, solar panel and using the engine as a generator).

- If shore power is available the charging is done by a 50A-automatic charger.

Attachment 1364

But for two reasons we decided to complete the system with a Honda i10 Generator:

for the most unusual case of being in the need to use the engine for more than the 18 nm, we can take the generator to recharge during motoring: with an input of 50A and a consumtion of 60A we will be able to extend the range by the factor 6, that makes 108 nm under engine. We NEVER motored this far in our whole sailing life! So, the chance that we actually have to use the Honda for motoring (in a "hybrid"-configuration) will be almost zero.

Attachment 1365

As we plan to do more extended sailing outside European waters and thus far away from 230V shore power, the generator will be the only source to guarantee the possibility of intelligent and complete charging (bulk at 14,4V at a maximum current; absorbing at 14,4V at a gradually decreasing current and finally at floating charge at 13,8V). Other sources on board (wind gen, two solar panels and engine functioning as generator) will charge the batteries, but only to the level of 13,8V.

The new feeling of motoring:*

In former times we experienced the ideal situation of sailing and the necessity of motoring. Now the motoring is the extension of light wind sailing without sails: No noise, no diesel fume.

And as the reaction of the el-motor is faster and more poweful, it is much easier (and safer) to move around in crowded marinas. And all that without any noise!*

And just these days we completed the first battery-cycle (646Ah used) after 350 days of use with 8 months in the water, regular weekend sailing and a 4 week sailing vacation.

The two extremes of the reactions of fellow sailors:

- very much interested as this will be the future on our boats

- no way, I need my strong diesel to work against all tides, winds and eventualities and new engine should be stronger as the old one...

How do we think after the first year?

- like explorers in new territory*

- No real engine any more: we sail further in into the harbours, marinas and on anchorages, if the traffic permits

- feeling a little anxious when thinking of sailing long distances again in the future without our traditional Diesel engine (but in the 60ies and 70ies of the last century the blue water sailors did the same with small or no engines and also made it far beyound the horizons!)


SY Aquaria

MMNETSEA 05-26-2010 11:56 PM


Really interesting ! Congratulations! My first reaction was to see an opportunity for use in a light weight catamaran with 2 sets of motors & batteries plus the advantage of space for additional solar charges.


delatbabel 05-27-2010 12:05 AM

Great post, thanks for the information and links.

I have a 1982 built steely with a Vetus engine c.a 1991. It runs well but has over 5000 hours on the clock now. Its replacement will be electric. I may be tempted to keep the large in-keel diesel tank and install a small diesel generator in the engine bay with the electric engine. That way I reduce the need to carry petrol, a dangerous fuel to have on a boat at sea.

Yttrill 05-27-2010 10:32 AM

Any thoughts about what happens to an engine when things get wet?

MMNETSEA 05-27-2010 11:32 AM


Originally Posted by Yttrill' date='27 May 2010 - 05:32 PM (Post 1274956338)

Any thoughts about what happens to an engine when things get wet?

Hi, are you referring to a diesel engine, or an electric motor ? Wet with what ? where ?

Aquaria 05-27-2010 11:36 AM


Originally Posted by MMNETSEA' date='27 May 2010 - 01:56 AM (Post 1274918217)


Really interesting ! Congratulations! My first reaction was to see an opportunity for use in a light weight catamaran with 2 sets of motors & batteries plus the advantage of space for additional solar charges.



you might already know the french catamaran Lagoon 420 that does not have a pure electric engine but is equipped with a hybrid solution: a diesel generator and two electric engines.

The big andvantage of hybrids are indeed that you are mor flexible running under engine: Short maneuvers in harbors are done only by electric engine but you are still able to do longer distances at better speed and the last but very big advantage of the diesel generator is its better ration of size/power to charging capacity.They charge the battery bank much more economically than any traditional diesel engine with an alternator. The address I came along was that of Fischer Panda , a company that specializes on diesel generators and takes part in developing hybrid solutions.

I did not have the room to install a hybrid engine like that and I thought that with the good sailing abilities of AQUARIA a pure electric solution should be feasable. And indeed, I did not yet had to use the Honda generator for recharging while under way.

delatbabel, good idea! As the diesel generator will be of much smaller size as the original engine, you will be able to place it somewhere else in the boat, add more batteries and place the very small electric engine where the diesel was!

... and the contact with sea water is an important point!

I distinguish between two incidents:

- a splash of salt water can be indeed a bigger problem to an electric engine than to a traditional diesel. The swedish company OZMarine even sells these motors in watertight capsules - but then you have to start thinking about cooling the engine. Technically no problem but a bigger installation and a matter of costs.

As my new engine is placed way back in the engine compartment and as I never had salt water from above in my engine room as long as we have the boat (20 years), I decided to live with that risk. (But you might have noticed the fresh water pressure pump next to the engine: I am not at all comfortable with that so close to the engine. We hardly ever use it as we prefer hand- of foot pumps but I think of moving it elsewhere next winter.)

-and rising water from below: there is no big difference to the diesel, because the air intake of the engine was only 10cm higher than the level of the new installed el-engine.


SY Aquaria

MMNETSEA 05-27-2010 12:09 PM


Your solution appears to be a far better setup than that installed in the Lagoon 420. I can't remember the total weight of their Electric Motor + Diesel + Batteries + Controls etc., but it has not been a success in terms of sales and performance. Their electric motors alone appear to be very much larger.

It would be interesting to show a setup ( with same prop-shaft kw output) of the Lagoons hybrid, alongside your installation.


Aquaria 05-28-2010 01:50 PM


Originally Posted by MMNETSEA' date='27 May 2010 - 02:09 PM (Post 1274962143)


Your solution appears to be a far better setup than that installed in the Lagoon 420. I can't remember the total weight of their Electric Motor + Diesel + Batteries + Controls etc., but it has not been a success in terms of sales and performance. Their electric motors alone appear to be very much larger.

It would be interesting to show a setup ( with same prop-shaft kw output) of the Lagoons hybrid, alongside your installation.



the Lagoon 420 has indeed a totally different arrangement (and philosophy). The two power battery banks (each with 6 x 210Ahrs) weigh about 800 kgs and the Onan diesel generator (21kw) might weigh about 340 kgs.

I am not sure if the two battery banks placed under the bunks in the aft cabins equal the weight of the traditional two engines - but 400kg seem to be a little much for that size of one modern diesel engine. And the generator used in the hybrid version is alot bigger than the standard generator, adding more weight to the boat.

On Aquaria I tried to equal the weight of the former engine, fuel and starter battery with the new system (but I must admit, that the little Honda with its 13kg is not included *>/doh_icon.gif...)

The philosophy: The batteries drive two 10kw electric engines out of the battery banks that are linked together to provide 72V and the generator takes over automatically when the the batteries are drained 80%, or so. * Possible distances under electric engines alone are 2 hours at 4,5kn (and of corse less when going faster...). So, *this is indeed a hybrid engine.

And as this boat of tremendous size (42ft cruising catamaran) and 16 tons of weight is of a totally different dimension of what we are using (32ft monohull with 5,5tons) it is hard to compare: *We use one electric engine of about 10kw, under economy speed (which is at 12V) we go 3,8kn, but can do that for 5 hrs, reaching a distance of 18nm in dead calm, flat seas.

And the whole system is set up much easier, no electronics involved (except for the battery monitoring). As I cannot access the online manual section of OZmarine right now I cannot show my setup at the moment. I keep trying over the weekend or will dig in my paper manuals and will be back with that beginning next week.*

Now we go out sailing!


SY Aquaria

* *

Aquaria 05-31-2010 03:39 PM

4 Attachment(s)

Originally Posted by MMNETSEA' date='27 May 2010 - 02:09 PM (Post 1274962143)


It would be interesting to show a setup ( with same prop-shaft kw output) of the Lagoons hybrid, alongside your installation.


Here are two diagrams for further explanation of how our OZecoDrive system works:

The central unit...

Attachment 1368

...* is the OZquickShift, which drives the whole system. The attached picture shows the units rear *with all cabeling installed (but with the cover for protection removed and as this unit is fastened to the inside of the cockpit bulkhead, the control lever will be mounted on the cockpit's side).*

A very simple system, no electronics are involved to run the engine. But due to this very basic principal the system has only 7 speed positions (snap positions of the speed**lever):

-2: *** Full astern thrust (24V)

-1: * * Normal astern thrust (12V)

*0: *** Neutral position. The motor is disconnected from the system

+1: ** Propeller charging position

+2: ** Low speed ahead (8V – therefor the installation of a resistor in the system)

+3: ** Economy speed (12V) producing in my case 3,8kn under calm contitions

+4: ** High speed (24V) producing in my case a speed of 5,8kn.

This unit also holds the two main switches. If they are turned off, the whole system is off, there is no reaction when moving the speed lever.*

(But OZmarine is providing an electronic speed control lever if one wishes to set the exact speed, but then the whole system is different, as this works with 24V from the beginning)

Attachment 1369

The el-motor, two battery banks, the AC-charger and the OZecoCharge unit (controlling the motor when working as a generator) are directly connected to the OZquickShift unit.

The OzecoCharge unit is a semi watertight box we installed in the cockpit locker for water protection but with easy access as it has a knob for adjustment, so that the system provides just as much „load“ to charge the batteries without the folding prop collapsing.

The AC-charger is permanently connected to the ships AC-system, so it can be provided with power either by shore power cable or we connect the Honda Generator into the AC-system, if no shore power is availabe. And here lies the compromize in my system: The AC-charger is a little small with 50ah charging capacity and 600 + 100ah Battery capacity. But as the Honda EU10i generator has an output of 0,9kVA and the AC-charger takes 0,825kVA, it fits perfectly well into our system. And the AC-charger cannot be any bigger as we are not able to manage the next bigger generator (of almost twice the weight!) on our „small“ boat. *


Attachment 1370

As we have solar panels and a wind generator connected to an own charging control (Marlec HRDX), I connected this system also to the OZquickShift. Initially I connected it directly to the battery power banks, but that led to the situation that the battery monitor registered the loading current as an „output“, forcing the monitor to give wrong information about the state of charge of the battery banks *- the most valuabe information!!!

Attachment 1371

The batteries are linked together in two banks with three 100ah batteries each, providing the regular 12V and only in the positions -2 and +4 *(on the speed lever) the two banks are linked together via the OZquickShift to provide the 24V for the motor. The battery monitoring unit (BTM-1) which was part of the whole package (and not optional as stated in the description) is linked into the system as shown: quite interesting solution, no shunt needed.*

The big advantage about this system is the fact that you never have any cables carrying more than 12V – a big safety factor when working on the system!

Ozmarine suggests that you can use the power banks also for your consumption. We don't do that. We still carry a consumer battery and for charging, this battery is connected to the 2nd outlet of the AC-carger and also to the Marlec HDRX unit 2nd outlet. The OZecoCharge (using the prop for charging) unit is only charging the power banks. (But we could charge the consumer battery with the OzecoCharge by just connecting the power- and *consumer battery via the battery main switch!)*

All in all its a very simple system, therefor it was easy to install all by ourself *and we understand every single part in the system! The accompanying installation manual in english was easy to understand, the two drawings of the setup are taken from this manual.


Sy Aquaria*

Silver Raven 06-10-2011 01:13 AM


Here are two diagrams for further explanation of how our OZecoDrive system works:

Uwe. Re; 'e-propulsion'. Year old subject however I'd like to re-visit it & get an update, Please. Can't thank you enough for this whole subject. Richards questions & your answers are the most comprehensive & informative discussion regarding 'marine electrical propulsion system(s)' I've ever read, anywhere. So many Thanks to both of you.

Now Uwe, a year more down the track, give us an update, Please ! ! How would your evaluate the system as a whole? Are the batteries standing up? Are they above or below your expectations of longevity & cost? In regard to Sir Richard's question - Re; total weight of the complete system(s) for use in a light-weight catamaran or trimaran - How would you evaluate it's possibilities as overall weight to efficiency is also a serious consideration with your yacht? Richard - did you come up with any answers? Is the 'MEPS' that Uwe has refined a weight/power/cost viable proposition as against a diesel system? I'm sure others will be interested in the overall view from you two. In particular - my case - is 2x 9.9 hp o/b's - gross weight is aprox. 350 kilos incl. 100 ltrs fuel (30 hrs @ 6 to 8 kts in adverse conditions) enclosed in fire & explosion-proof housed areas (which is easy for me to build & cost effective). And - all of that for only $12K AUD (8688 Euro - Gawd that's expensive). Having said all that, it would cost/weigh 1/2 that for only 1 motor. I don't need to go that fast but it's the most cost effecive - rpm/speed/fuel consumption in my case. Like Uwe (with his beaut 1/2 ton 'sailing' yacht) - weight & placement is very important, as I too like to go sailing not motoring. In that case - Richard - what do you think about only 1 engine in 1 hull? The weight balance could be equalled by water & provisions in the other hull or do you feel that would compromise handling too much? As I see it I could then move all the weight away from the back of the boat to a better balanced position & keep all that weight low in the hulls? - using the 'long-tail' shaft principle, possibly. Yes - No ??? Don't want to go down the 'Lagoon' path = 2-hulled motorboats c/w expensive flag-pole fitted at little gain & twin, big,heavy expensive diesel motors. No I'm not trying to start a fight with anyone I just want to sail & be able to go to windward c/w c/b's down, not sideways without using any motor(s). Thanks guys (cobbers in OZ-speak). Good sailing & cruising fun to all. Ciao, james

Aquaria 06-22-2011 05:40 PM

"How would you evaluate the system as a whole?"

Richard, there are two aspects to your question:

- The system as such, its technical setup and transparency in the eyes of a non-expert and the ease of maintenance.

- Its practicability and every day use.

Simplicity, and transparency of the system*

As it is a system that we installed all by ourselves, we know all the components and how they work together in the system right from the beginning. Here it helped too, that the whole system was designed to be geniuosly easy. That has been a big advantage in the initial trouble shooting and still is in the every day use over the last two years. The point is: there is nothing much that can break down:

- the rugged industrial type electric motors

- the ruggedly built mechanical main unit (OzquickShift) with the speed lever and then

- the peipheral (electronic) parts: the AC-charger, the OzecoCharge-unit and the battery monitor, that are not vital parts for the actual function of the motor

We are much more relaxed to motor with this system than we have before: starting the diesel in time, watch the cooling water come out, watch the temperature, checking the amount of fuel and oil beforhand and so on...


Communication and support from Ozmarine in Sweden*

In the very beginning we had problems with the OZecoCharge-unit, charging the batteries by the electric engine functioning as a generator: the prop was milling but there was no input. The experts from Ozmarine in Sweden suggested that the OZecoCharge-unit might be the problem – we met in Gothenburg (had been sailing there anyway) and got the unit exchanged, even though the Ozmarine company was closed down for summer holidays. Perfect service, they came down to our boat!*

Then the charging unit worked fine for a while, but suddenly quit its job again a couple months later. Ozmarine again helped instantly, took the OZecoCharge-unit back, re-tested it, found out that it worked fine and came up with the right suggestion, that proved to be the problem, that there were some little parts in the OZQuickShift-unit that they had worked over in the meantime and that should be exchanged. They sent me these little parts and I was able to replace them within ten minutes – I just needed a screw driver to get this job done! Since then everything works fine and besides that no other problems occured!*

Mainenance and use

It's very easy, practically there is nothing that needs to be maintained! After a day of sailing (and motoring into the marina) you plug in the shore power cord and the 230V charger takes care *of filling up the batteries again. *The progress can be watched on the battery monitor.

In general we are taking the batteries in closer focus now: recharging them at every chance given. That is quite easy when having access to shore power, but needs some taking care of if no shore power is availabe. And as we try to use as much renewable energy as possible, we use our two solar panels alot, which we can move around freely to avoid any shades and to position them as good as possible towards the sun. One example: motoring 2,5 miles up a river consumed 27Ah, there was no shore power availabe on the pontoon but with the two solar panels we gained back**about 18Ah during the remaining 5 h of sunshine on the same day and on the next morning another 10 Ah in two hours, being able to leave again with full battery-banks.


Are the batteries standing up? Are they above or below the expectations of longevity/cost?

This question cannot be answered fully yet, as we just consumed 1150 Ah within the last two years, i.e. we**just start on the third cycle of the 600Ah battery bank.**This is not much and needs to be explained: The boat has been in the water for about**7,5 months per year and we are on the boat almost every weekend. On 4 to 5 weeks per sailing season we are on more extended cruises. These last two years we sailed almost 1400 nm, using the motor to get in and out of 44 marinas, harbours an anchorages. In the average we use 6 to 12 Ah leaving or entering a harbour, on only one occasion we drained the batteries down to 87% (makes a consumption of 102Ah). And I must say that the every day use out of battery bank C is also metered over the battery monitor – so the above mentioned 1150 Ah are**for motoring and living. Tied up to pontoons we use the AC-charger as a converter 230V/12V – therefor the input/output-level to the batteries is even and the consumers do not really add a whole lot to this sum.*

Without shore power the solar panel(s) and the wind gen feed the systems and there can be times of more consumption or more input. But our experience shows that the over all input is higher than our consumption – a result of a surprising amount of sunshine and many daylight hours here in northern Europe and of passing depressions with the accompanying winds even in summer. In fact, the over all input is quite alot higher - so we are even able to feed the surplus into a peltier-cooling box (2,5Ah) during the day, once the batteries are fully charged. And that happens quite often, so the beer is very cold when the sun sets.*

Concerning the batteries there are two other aspects that needed to be watched closely:

The charging capacity and the safety on board.

Our charging capacities range between a few amperes (depending on wind and weather situation) and 50A by the 230V-charger. (It does not make sence to leave the wind gen running or the solar panels out in the sun, when the AC-charger does its job, as the high voltage under charging (14,4V) makes the HDRX-controller regulate the input down to zero.) *With a total capacity of 700Ah the maximum of 50A is a little below the recommended 10% of the total battery capacity that define a good charging capacity. We were not able to install more and therefor had to look for a battery type with the smallest rate of self-discharge to be sure not to use all the charging capacity (when the batteries get older) to work against that: it had to be either an AGM--* or a GEL-type battery and the experience of the first two years show that even the charging capacity provided by renewable power is enough to recharge the banks to the regulating cut in voltage of 13.8V, *and beyond, up to the maximum charge voltage 0f 14.4V (regulated by the Marlec-HDRX-charge controller). We have to see how things develope, when the batteries get older and have more cycles on their back... But an aging is not yet seen: The CEF ( charge efficiency factor – the battery's total efficiency: more Ah must be charged into the battery than has been used) is still at the *Gel-battery's optimum of 94%, as two years ago! *This is no surprize regarding the fact that we just started on the third battery cycle. *

And regarding the safety we had no other choice than using GEL-batteries, because:

- the gassing of 7 batteries in a small engine compartment while charging was not acceptable – it can be dangerous!

- on a sea going sailboat it's theoretically possible that you heel more than wet-cell- batteries can cope with.*

Even though the charging is done with an automatic charger/charge controller, we don`t leave the boat unattended, while charging with high Ah input. Every few months we check the batteries on tightness and we occasionaly check the historical data on the battery monitor.

With either shore power or by solar panels/wind generator/prop generator the batteries are *more or less constantly charged, when we are on board. When not on the boat the wind generator keeps all battery banks fresh, which works quite well: the least recorded voltage after 6 days was 12,76V on the power bank A/B, and 12,64V on the comsumer bank C (this battery is quite a bit older), most times it was more, depending on the wind situation of the previous days.*

Total weight of the complete system(s) for**use in a light weight catamaran or trimaran – How would you evaluate its possibilities as overall weight to efficiency is also a serious consideration with your yacht?

The restrictions in weight have been a vital factor in planning the system and are on all smaller boats. These restrictions yielded into the two facts we have to live with now (but we knew before):

- the restricted range in distance (about 18nm) and

- in cruising speed (that is on the long run *lower than initially stated: 3,8kn with very fresh batteries and clean hull. More realistic is a maximum speed of 3,5kn in calm conditions ...( I can hear some reader's groaning, but again, since we have an absolutly quiet motor, motoring *for us is almost like light wind sailing!). *

Extending the range and/or raising the cruising speed results in more battery capacity and bigger electric motors (running at other currents than 12V) – all demands that end up in a different (maybe bigger) system.*

I liked to have a diesel generator instead of**the petrol generator, but a diesel generator demands a fixed installation and is way heavier than the mobile generator. Besides not having the room for the installation it would have ment a reduction of battery capacity – finally making up another system: a diesel-electric power system (hybrid), I did not intend to install. (Not to mention, that these systems are rather expensive: you need the electric motor(s), the batteries, peripheral components AND a diesel generator and they are quite expensive and again you have to care for a diesel engine!

On bigger boats or even on catamarans with two diesels this could be different:*

Diesel generators are generally not as big and heavy as marine diesel engines, as they work more efficiently when just producing electric power. That leaves enough space to install the necessary battery capacity.*

The situation might be even better on catamarans with two engines: one hull is equipped with the lighter diesel generator and some batteries to equal the weight of the former engine, the other hull could host**just batteries. (It is not a good idea to just stow water and provision in the other hull to make up the weight of an engine and that can be reduced to zero on a long trip, unless you constantly restow wile under way – if there is still so much to restow at the end of a trip to equal the weight in the other hull.)

Light weight catamarans (with one engine nacelle in the center) and trimarans seem to be a different task... with even more constrains concerning weight space available...

Now give me some more weeks of extended cruising to gain more practical experience which I love to pass on later.


Sy Aquaria

Aquaria 06-22-2011 08:54 PM


Originally Posted by Silver Raven (Post 1307668386)

Uwe. Re; 'e-propulsion'.


Ciao, james

Oh no, mixing up names>/doh_icon.gif

Sure, it was you, James, that brought up these great questions to Richard and me...

I should go sailing!



Aquaria 12-20-2012 12:36 PM

1 Attachment(s)
3 year Experience with our electric engine
... clicking my way all the way down in the history of the battery monitor we get the information that our OzEco-Drive from Oz Marine, Sweden (now GreenStar Marine | The electric propulsion system of the future ) has been in use for about 1300 days. After these three and a half years, three summers sailing and two winters on the dry it is a good time to pass on some experience.
We have been sailing 2900 nautical miles, thereof 370 miles under engine passing the Kiel-Canal 6 times, but in the serial-hybrid configuration with support of the Honda 230V AC-Generator. Canal passages need a lot of patience, as the speed is only between 3.5 and 4 knots. Even on canal passages the wind becomes a crucial factor: on two occasions we decided to wait for a day because of fresh head winds that easily reduces the speed to 3 knots or even less. Here are the limits of the engine providing just 0.6 KW at 12V.
Things look different when using the motor on 24V. A lot of power adds to the safety when moving in an out of the locks and when coping with commercial traffic. Then the el-motor is putting its power much faster to the folding prop.
73 harbors and anchorages have been visited - this made up the main use of the motor. We never used the el-motor for passage making at sea. But we used it for crossing shipping lanes under light wind conditions, motor-sailing with a speed of 5 knots instead of two knots under sail alone. It adds to our safety. Under such circumstances we use the engine more often than the diesel engine in the past.
The highest amount of energy ever used at one time were 100 Ah but this in connection with passing the Kiel-Canal with head winds. This was one sixth of the total battery capacity. Going into and out of harbors we use about 6 Ah and even this is decreasing over the years as we are learning again to do the most maneuvering in the harbors under sail, just using the engine for the final adjustments of speed when entering the berth. After leaving harbors we charge the batteries with our wind generator ( Rutland 910 upgraded to a 913-model: ) and two solar panels (50Wp).
Attachment 1978
Most times just one panel is in use. Depending on sun and wind, the batteries are back at 100% of charge after about 2 hours or less when under way. Therefore the second solar panel is seldom in use. So, even under way the batteries were most times fully charged and the surplus of incoming energy is used to run the refrigeration, as we don't have any other energy-hungry equipment. In harbor we use shore power and the 50A Battery charger takes care of the batteries.
We did not use the OzecoCharge-unit so often. Charging the batteries with the folding propeller is very effective under fresh to strong wind conditions we measured inputs of up to 18A at a speed of 7 knots - but under wind conditions(30 to 40 knots of wind) we gladly do not have to cope with every day. Under normal wind-conditions we more likely harvest up to 10A and light to moderate winds create an input of maybe 2A - not enough to justify a reduction in speed of up to one knot.
Looking back on our energy needs we can say that the total battery capacity of 600Ah was a good choice. The batteries have now, after these three and a half years, completed 7 cycles this is far less, to what we originally thought we might use. And as all consumers are monitored by the battery monitor, the actual number of electric energy used by the engine is even way less than those computed 4200 Ampere-hours. So, we are still rather relaxed about the battery condition after these two and a half years: The low number of cycles in combination of a low number of Ah used in every single event, and the quick recharge of the battery banks after every use will sum up in a much longer life span than we initially expected. The calculated Charging-Efficiency-Factor (CEF) is still at 92% - another sign that the batteries are still in a very acceptable condition.
Over the years more electric power systems appeared on the marked. Very different systems though with different philosophies of power management many of them using higher Voltages that 12V with a higher speed-potential. We enjoy the ease of handling a 12V-system, accepting the rather moderate normal speed of less than four knots.
A perfect propulsion system when going out and back for a day sail or a weekend cruise. We even find it a good system for cruising and passage making with an occasional overnight sail in coastal and offshore waters, BUT we never cruise on a tight schedule, as passage making under engine is not possible (better done with a hybrid-solution). Now we are on the edge to test our electric engine system as live-aboards doing ocean sailing. No hundreds of liters of diesel guaranteeing a range of several hundred miles under engine at hull speed
But it is just half a century ago that ocean passages and blue water cruises were done with sailboats with a small or even no engine at all. What was possible back then should be possible today

We will report.

SY Aquaria

reefhunter 01-15-2013 01:23 PM

What's the weight difference btwn the diesel engine (30 hp) and the generators and battery setup?

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