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CarpeDiem wrote in another thread:

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I am interested to know how this technology has progressed and how it compares realistically now. When we replaced our Volvo 29hp 2 years ago, the cost of batteries/motor and the most efficient diesel generator was more than a replacement engine and we still needed to buy a sail drive.

The generators came in on paper a good few percentage points more efficient than the new engine which I liked.

But unless we committed to being a full time race boat out of and back to marina power only and made sure we never raced on a day with light winds that we'd need to retire, and find ourselves too far from home, I couldn't make electric cost effective once factoring in the diesel genny costs. 

Disclaimer: I run electricboat.co.nz up in Kerikeri. We sell electric propulsion systems and lithium batteries. We also do installations and run our own fleet of five electric hire boats so I'm well placed to answer the questions. I hope it's OK to post useful replies to questions here without being considered spam. If anyone buys anything from us as a result of reading my posts here then please mention crew.org.nz and we'll donate to the site.

So, some good questions!

How has the technology progressed? Electric motor technology is already mature and there's very little room for improvement. It's 100% reliable and highly efficient. It has been mature for 30 years or more. Electric launches were fashionable in the 1920s if you were wealthy enough. The inboard propulsion technology developed in submarines was already mature by the 1940s. Electric propulsion went out of fashion again for other boats to some extent as diesels got better. It remained popular on the inland waterways of Europe where pod type outboards took off in the 1950s (with the motor mounted underwater for direct cooling, no gearbox losses, a perfectly horizontal shaft and complete silence). That simple but highly effective technology has been continually refined ever since and is the basis of all modern electric outboards and smaller saildrives (apart from some really cheap rubbish). Using a pod drive outside the hull on a yacht frees up the internal space completely, there is no engine compartment and the batteries can go anywhere (preferably low down as ballast) so you can really get creative with the layout.

What we do see happening is prices are coming down as sales volumes are increasing exponentially. We are also seeing bigger and bigger pod drives, up to about 30hp equivalent this year. Larger motors still hve the motor on top, requiring a cooling system. We expect to see even bigger systems move underwater into a pod to eliminate the cooling system and make them truly silent. As production volumes increase, another new development is there are some cheap Chinese copies of the European motors coming out. ePropulsion is the best of those cheap copies but not good enough - if you are thinking of sustainability you need to buy something like a Combi which truly lasts a lifetime. If the motor will only last a few years then the emissions involved in manufacturing a new motor will negate the benefits.

Battery technology on the other hand is a fast-moving field. Currently two main options. Conventional lead acid batteries are still cheapest if you don't use the boat that frequently, don't need huge range and weight is not an issue (most non-racing displacement yachts). Lithium batteries are a topic in themselves and we sell some high quality brands. Watch out for the cheap rubbish - the battery management system is the important part and some of them don't even have one! Most lithium batteries on the market are technically illegal to use on boats in NZ and might invalidate the EWoF if the inspector is paying attention.

Every boat is different, but generally you can get a whole day of running time with a total system cost not much more than a good diesel install.

Then you factor in that this system will be virtually maintenance free for life - no fuel, parts, servicing or oil to pay for, ever.

We are currently doing a conversion on an H28 with a 5kw motor and 10kwh of quality NZ made lithium batteries. Total weight of the system about 160kg - less in total than the old diesel, gearbox, fuel tank and start battery. It'll have more power than the old diesel, especially low end torque and acceleration. You also have total control at low speed, there's no clunking into gear already at 1000 revs, you control it precisely from one rev upwards. It's always ready - no need to start it.

So for a typical cruising day sailor who will use 2kw of power at cruising speed that will give 5 hours continuous running time. How often do you need more range than that? For those rare occasions you can carry a portable suitcase generator which only costs $500. If you're ok spending a bit more and want something built in then we also have an extremely compact, silent lightweight 48v marine diesel generator. Kubota based and marinised in the USA. On the whole we try to discourage the use of generators for obvious reasons.

What's really needed is a small adjustment of mindset - if you've got sails use them. If not then cover the boat in solar panels. Your "auxiliary" motor is for getting in and out of marinas and sticky situations. If you want to go a very long way then wait for a wind. As a rule of thumb, your range under electric power will double if you reduce the speed by one knot. So reduce the speed by two knots if you have a long way to go. You can put enough solar on most boats to give you unlimited range at 3 knots on a sunny day, or massively extend your range at 5 knots. Rigging can interfere with this on a sailing yacht of course.

Mostly we are sailing for pleasure not because we need to be somewhere at a particular time. Plan your trip around the wind and the capabilities of your propulsion system.

Electric propulsion is best suited to marina-based boats which can plug in to charge or designs which have space for lots of solar. We do have a client who just converted a sailing yacht which lives on a mooring and only has small solar panels. He is a real sailor so he only uses the motor to pick up the mooring or enter a harbour, otherwise he sails, heaves to or anchors.

Most people over-estimate the power requirements of electric propulsion. Electric motors are much more efficient and most diesel installs these days are very over powered - as you push hull speed you just waste power making more waves and don't actually go any faster. Our hire boats run happily all day long and some of them have enough solar that they usually come back with full batteries! It's unlikely you really need a generator. If you do need one then you may only need a cheap little thing.

Silent electric motoring is a pleasure like sailing, you'll want to slow down and enjoy the relaxing experience. A blaring, rattling, vibrating, smelly diesel means you just want to get home quick and turn the damn thing off!

Also bear in mind that internal combustion engines will likely be illegal within 10 years and diesel fuel taxes will be astronomical even sooner, so re-powering with a diesel now just doesn't make sense. With electric you might have to think a bit more about planning your itinerary for the next 5 years. After 5 years I think battery prices and weight will have come down so much that you can upgrade your batteries and have all the range you want. For this reason, most customers who are not weight sensitive are choosing lead acid (which will easily last 7 years of moderately frequent use). Commercial users and racers are mostly going with lithium due to the cycle life and the weight respectively.

An electric propulsion system can cost the same as a diesel system or up to three times as much depending what you spend on batteries. For a vessel which is in daily use, the system will generally pay for itself in savings on fuel and maintenance within 1-2 years. All commercial vessels should be electric already for this reason alone. In large areas of the Netherlands internal combustion engines have been banned for 10 years or more. There are tens of thousands of electric boats there and nobody is looking back. NZ is very, very late to the party!

So coming back to your system CarpeDiem, not enough detail to be sure but you were probably specified something way more expensive and complex than you needed. Using a 10kw pod motor ($15-25,000) in place of your saildrive the installation cost is negligible, just bolt it on and there's nothing inside the hull except batteries, control box and charger. You could have a battery bank for $7000, $14,000 or $28,000+ depending on range requirements. From $1500 for a charger. From $400 for a portable emergency genset. So a complete system to replace a 29hp saildrive inboard starts at well under $25,000. All ballpark figures only of course.

As an aside, we are developing our own NZ made 5kw propulsion systems and looking for a shaft drive yacht or displacement launch around 24-33ft as a test bed if anyone is interested? We'd provide free mooring for the winter in Kerikeri while we work on it and you get the motor very cheap afterwards if you want it, no obligation.

 

 

 

 

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5 hours ago, syohana said:

CarpeDiem wrote in another thread:

Disclaimer: I run electricboat.co.nz up in Kerikeri. We sell electric propulsion systems and lithium batteries. We also do installations and run our own fleet of five electric hire boats so I'm well placed to answer the questions. I hope it's OK to post useful replies to questions here without being considered spam. If anyone buys anything from us as a result of reading my posts here then please mention crew.org.nz and we'll donate to the site.

So, some good questions!

How has the technology progressed? Electric motor technology is already mature and there's very little room for improvement. It's 100% reliable and highly efficient. It has been mature for 30 years or more. Electric launches were fashionable in the 1920s if you were wealthy enough. The inboard propulsion technology developed in submarines was already mature by the 1940s. Electric propulsion went out of fashion again for other boats to some extent as diesels got better. It remained popular on the inland waterways of Europe where pod type outboards took off in the 1950s (with the motor mounted underwater for direct cooling, no gearbox losses, a perfectly horizontal shaft and complete silence). That simple but highly effective technology has been continually refined ever since and is the basis of all modern electric outboards and smaller saildrives (apart from some really cheap rubbish). Using a pod drive outside the hull on a yacht frees up the internal space completely, there is no engine compartment and the batteries can go anywhere (preferably low down as ballast) so you can really get creative with the layout.

What we do see happening is prices are coming down as sales volumes are increasing exponentially. We are also seeing bigger and bigger pod drives, up to about 30hp equivalent this year. Larger motors still hve the motor on top, requiring a cooling system. We expect to see even bigger systems move underwater into a pod to eliminate the cooling system and make them truly silent. As production volumes increase, another new development is there are some cheap Chinese copies of the European motors coming out. ePropulsion is the best of those cheap copies but not good enough - if you are thinking of sustainability you need to buy something like a Combi which truly lasts a lifetime. If the motor will only last a few years then the emissions involved in manufacturing a new motor will negate the benefits.

Battery technology on the other hand is a fast-moving field. Currently two main options. Conventional lead acid batteries are still cheapest if you don't use the boat that frequently, don't need huge range and weight is not an issue (most non-racing displacement yachts). Lithium batteries are a topic in themselves and we sell some high quality brands. Watch out for the cheap rubbish - the battery management system is the important part and some of them don't even have one! Most lithium batteries on the market are technically illegal to use on boats in NZ and might invalidate the EWoF if the inspector is paying attention.

Every boat is different, but generally you can get a whole day of running time with a total system cost not much more than a good diesel install.

Then you factor in that this system will be virtually maintenance free for life - no fuel, parts, servicing or oil to pay for, ever.

We are currently doing a conversion on an H28 with a 5kw motor and 10kwh of quality NZ made lithium batteries. Total weight of the system about 160kg - less in total than the old diesel, gearbox, fuel tank and start battery. It'll have more power than the old diesel, especially low end torque and acceleration. You also have total control at low speed, there's no clunking into gear already at 1000 revs, you control it precisely from one rev upwards. It's always ready - no need to start it.

So for a typical cruising day sailor who will use 2kw of power at cruising speed that will give 5 hours continuous running time. How often do you need more range than that? For those rare occasions you can carry a portable suitcase generator which only costs $500. If you're ok spending a bit more and want something built in then we also have an extremely compact, silent lightweight 48v marine diesel generator. Kubota based and marinised in the USA. On the whole we try to discourage the use of generators for obvious reasons.

What's really needed is a small adjustment of mindset - if you've got sails use them. If not then cover the boat in solar panels. Your "auxiliary" motor is for getting in and out of marinas and sticky situations. If you want to go a very long way then wait for a wind. As a rule of thumb, your range under electric power will double if you reduce the speed by one knot. So reduce the speed by two knots if you have a long way to go. You can put enough solar on most boats to give you unlimited range at 3 knots on a sunny day, or massively extend your range at 5 knots. Rigging can interfere with this on a sailing yacht of course.

Mostly we are sailing for pleasure not because we need to be somewhere at a particular time. Plan your trip around the wind and the capabilities of your propulsion system.

Electric propulsion is best suited to marina-based boats which can plug in to charge or designs which have space for lots of solar. We do have a client who just converted a sailing yacht which lives on a mooring and only has small solar panels. He is a real sailor so he only uses the motor to pick up the mooring or enter a harbour, otherwise he sails, heaves to or anchors.

Most people over-estimate the power requirements of electric propulsion. Electric motors are much more efficient and most diesel installs these days are very over powered - as you push hull speed you just waste power making more waves and don't actually go any faster. Our hire boats run happily all day long and some of them have enough solar that they usually come back with full batteries! It's unlikely you really need a generator. If you do need one then you may only need a cheap little thing.

Silent electric motoring is a pleasure like sailing, you'll want to slow down and enjoy the relaxing experience. A blaring, rattling, vibrating, smelly diesel means you just want to get home quick and turn the damn thing off!

Also bear in mind that internal combustion engines will likely be illegal within 10 years and diesel fuel taxes will be astronomical even sooner, so re-powering with a diesel now just doesn't make sense. With electric you might have to think a bit more about planning your itinerary for the next 5 years. After 5 years I think battery prices and weight will have come down so much that you can upgrade your batteries and have all the range you want. For this reason, most customers who are not weight sensitive are choosing lead acid (which will easily last 7 years of moderately frequent use). Commercial users and racers are mostly going with lithium due to the cycle life and the weight respectively.

An electric propulsion system can cost the same as a diesel system or up to three times as much depending what you spend on batteries. For a vessel which is in daily use, the system will generally pay for itself in savings on fuel and maintenance within 1-2 years. All commercial vessels should be electric already for this reason alone. In large areas of the Netherlands internal combustion engines have been banned for 10 years or more. There are tens of thousands of electric boats there and nobody is looking back. NZ is very, very late to the party!

So coming back to your system CarpeDiem, not enough detail to be sure but you were probably specified something way more expensive and complex than you needed. Using a 10kw pod motor ($15-25,000) in place of your saildrive the installation cost is negligible, just bolt it on and there's nothing inside the hull except batteries, control box and charger. You could have a battery bank for $7000, $14,000 or $28,000+ depending on range requirements. From $1500 for a charger. From $400 for a portable emergency genset. So a complete system to replace a 29hp saildrive inboard starts at well under $25,000. All ballpark figures only of course.

As an aside, we are developing our own NZ made 5kw propulsion systems and looking for a shaft drive yacht or displacement launch around 24-33ft as a test bed if anyone is interested? We'd provide free mooring for the winter in Kerikeri while we work on it and you get the motor very cheap afterwards if you want it, no obligation.

 

 

 

 

Great information there, many thanks, I'm just waiting for a reasonably priced 2hp electric outboard.

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Snap. I’m looking at Torqeedo and ePropulsion units - they both seem to have pros & cons. I’m thinking to put one on the tender for our regular short distance boat-to-beach hopping around the anchorage. But having a petrol o/b on the rail for occasions we need more power / speed / endurance.

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8 hours ago, syohana said:

Electric motor technology is already mature and there's very little room for improvement. It's 100% reliable and highly efficient. It has been mature for 30 years or more.

Actually, not totaly so. The advancement in motor technology is still continuing. Advancements have been in the magnetic design part. This is what has given Elon Musk such an advantage in the Industry the blistering power/speed his cars deliver. Once that technology comes to other markets, we are likely to see some big gains again. It's all to do  I do have to say, that guy seems to have some mega talented people on his payrole.
There are still big improvements in battery technology sitting on the Horizon. But still a way off being seen on any shop shelf yet. One really exciting design is the Solid state battery. Many major Car makers have given up trying to invent a battery. Instead they are pouring huge amounts of cash into a couple of Industries that have some realy exciting designs. They will be major game changers. But when we will see them, I have no clue.

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Lots of good information thanks.

Re the pricing, my D1-30 Volvo was $20k. It was a drop in replacement including saildrive. The electric set up was going to be $30k for parts and we had unknown labour and building costs to modify cabinets and make custom mounts etc, electrician costs were extra. It was recommended we go to a shaft drive which required Hull modifications. I didn't see it happening for less than $40k when all was said and done.

So it was $20k more. In diesel/maintenance costs that is probably around 10yrs projected. If done at todays prices it's 20 years but I accept that the levies on diesel will go up. 

Finally our use cases didn't fit without a 20kw generator which threw the cost through the roof.  That old priority called work gets in the way of being able to just float off Cape Brett for 24hrs waiting for the wind cause you and the crew need to get the boat home for work commitments.  Year on year we've found ourselves becalmed and unable to sail for a long period.  Eg, this year we spent 14hrs motoring home after Coastal Classic and 8 hours motoring home after BOI race week. The alternative is everyone misses work for an extra day or we leave the boat at the extra expense of going up to collect it and missing more racing cause the boat isn't home.

So I get what you're saying about "just change the way you use the boat" but for a like-for-like replacement it seems that electric on a monohull still isn't there without a diesel generator? 

So that was my experience, I realise it won't be everyone's but I just couldn't justify the expense to be able to have a like for like replacement and continue to use the boat the way we currently do.  Something needed to give. 

Some questions.

For replacing a 20kw (29hp) diesel what sized motor would you recommend? (We were recommended 15kw to be able to motor at our current speed of 6.5knots which is below Hull speed) 

Why are some Lithium batteries illegal on NZ boats? Which laws are they breaking and how?

These boats you have being motored all day and coming back with batteries nearly full, how many kW of solar do they have?  What size boats? 

Are you aware of drop in replacements for sail drives? (everyone seems to want you to switch to a shaft). 

Thanks

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Thank you syo.

I looked at it about 5 yrs ago and it sounds like things have improved since .

If you have the time and inclination what would you suggest to replace 90hp diesel? 100mile range@4kn 25mile @5.5. Then the biggie, not ever likely to be on a marina so how long to recharge?

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6 hours ago, Frank said:

Great information there, many thanks, I'm just waiting for a reasonably priced 2hp electric outboard.

We have one Torqeedo 1103C left in stock, that's equivalent power to a 3hp petrol outboard. Priced only a little higher than the Chinese ePropulsion clone but it's actually made in Germany and to a very high quality.

We also have Combi outboards from the Netherlands which are bulletproof, solid aluminium, no plastic parts. they will run for longer than the whole lifetime of a petrol outboard before the first quick service to change seals and bearings. They cost a little more to buy but the lifetime cost is far less than any other petrol or electric outboard, especially if you use them every day. Lifetime means not just your lifetime but the grandkids lifetime too!

You do need to overcome that initial big spend but then you reap the benefits of zero maintenance and no fuel or oil to buy. If you use it every day it can pay for itself in one year. You can keep the initial spend down by using lead acid batteries if the boat will take the weight.

 

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2 hours ago, wheels said:

Actually, not totaly so. The advancement in motor technology is still continuing. Advancements have been in the magnetic design part. This is what has given Elon Musk such an advantage in the Industry the blistering power/speed his cars deliver. Once that technology comes to other markets, we are likely to see some big gains again. It's all to do  I do have to say, that guy seems to have some mega talented people on his payrole.
There are still big improvements in battery technology sitting on the Horizon. But still a way off being seen on any shop shelf yet. One really exciting design is the Solid state battery. Many major Car makers have given up trying to invent a battery. Instead they are pouring huge amounts of cash into a couple of Industries that have some realy exciting designs. They will be major game changers. But when we will see them, I have no clue.

Of course there can still be improvements but the technology is mature so they are incrementally tweaking details. The motors are already 85-95% efficient so there's no room for a big leap but there are still incremental improvements happening in motor design, such as higher power at lower voltage allowing safe DIY installation of bigger motors.

The big leap will be in battery technology as you say. You can install an electric motor now and be happy that it will be future proof and last a lifetime, but you may want to upgrade the batteries in a few years.

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SyOhana - a couple of questions for you:

"Most lithium batteries on the market are technically illegal to use on boats in NZ and might invalidate the EWoF if the inspector is paying attention." - I have Lithium batteries and I am horrified to hear this, can you explain why?  And why would an EWoF inspector be looking at my batteries?

"NZ made lithium batteries" - I was not aware of any battery manufacturers here in NZ?  I'd like to support if possible.  I know there are people who assemble batteries into packs, is that what you mean?

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1 hour ago, CarpeDiem said:

our use cases didn't fit without a 20kw generator which threw the cost through the roof.  That old priority called work gets in the way of being able to just float off Cape Brett for 24hrs waiting for the wind cause you and the crew need to get the boat home for work commitments.  Year on year we've found ourselves becalmed and unable to sail for a long period.  Eg, this year we spent 14hrs motoring home after Coastal Classic and 8 hours motoring home after BOI race week. The alternative is everyone misses work for an extra day or we leave the boat at the extra expense of going up to collect it and missing more racing cause the boat isn't home.

Apart from being bad practice to ever sail to a schedule, you still didn't need a 20kw genset. Just back off the throttle by 1 knot on those long passages and your power consumption will halve. Back off another knot and it will halve again. Enjoy the silence! even with a diesel you'll see the same in terms of fuel consumption. Not sure how big your boat is but I bet you would never actually use 20kw except bashing directly into a strong headwind at full speed. That's masochism not sailing! 

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Are you aware of drop in replacements for sail drives? (everyone seems to want you to switch to a shaft). 

You should probably have been recommended a pod drive rather than a shaft drive. They are still quite hard to source in larger sizes but it can be done.

A pod drive does cost a little more but not if you'd have to put in a new propeller shaft. A pod drive can replace a saildrive.

We do also have drop in replacement conventional saildrive options with the motor inboard and a conventional technodrive leg with 90 degree gear at the bottom. Have a browse on our website. I'd always steer people towards a pod rather than a conventional saildrive for the reasons listed in my first post and because a saildrive has gears it it so there are a efficiency losses.

Remember that pod drives can bolt onto the hull absolutely anywhere so another option would be twin 5kw pods, one each side and fit a blanking plate where the old saildrive was in the middle. Twin motors allow you to spin on the spot and provide redundancy, plus you'd save the cost of a bow thruster if you were considering having one. You can even build a pod drive into the rudder if you want to get creative!

I can't imagine why you would need a 20kw genset, that would be very heavy and bulky. A 20kw generator would provide enough power to propel a 20 tonne displacement boat at hull speed without draining anything from the batteries.

In reality if people do have a genset then they use it as a range extender, drawing from the batteries and the genset together at full speed, or providing unlimited range at an economic cruising speed (say 4 knots) to get you home.

If you had a shaft drive then I would recommend a parallel hybrid where your diesel engine drives both the propeller shaft directly and the electric motor attached to that prop shaft generates, propelling the boat and charging the batteries at the same time. Much better than a series hybrid and a fraction of the cost. Unfortunately we don't have a saildrive option for this yet but we are working on it (our own 50ft catamaran has saildrives and we want parallel hybrid on one side, electric drive on the other).

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For replacing a 20kw (29hp) diesel what sized motor would you recommend? (We were recommended 15kw to be able to motor at our current speed of 6.5knots which is below Hull speed) 

How long and heavy is your yacht (displacement tonnes NOT registered tonnage which has more to do with the amount of wine barrels you can carry)? We don't know whether you actually need 29hp or whether you use 60% of that power just to make more waves after you already reached hull speed? Do you ever run your diesel flat out pedal to the metal or are you really only using half or quarter of those horse power? Do you want to motor into strong headwinds and big seas or are you a gentleman who doesn't go to windward?

Quote

Why are some Lithium batteries illegal on NZ boats? Which laws are they breaking and how?

The one which catches out even the quality brands is the NZS3004 requirement for the visual AND audible alarm which sounds in advance of any situation which might cause the battery to disconnect. Most batteries panic and shut down immediately when things go wrong. We can retrofit a compliance unit to Torqeedo batteries.

The enertec Juice batteries we supply are a real quality product and the whole BMS is actually designed in New Zealand with all custom made circuit boards, not just assembled from off the shelf parts. The programming can be customised and it's NZS3004 compliant out of the box. We use these on our own boats where weight is an issue and lead acid for the boats which can take the weight.

Quote

These boats you have being motored all day and coming back with batteries nearly full, how many kW of solar do they have?  What size boats? 

Our "English River Launch" is a Frolic 21 with 640 watts of double glass solar panels built into the canopy. On a sunny day she comes back with batteries full. She has been souped up 2.5kw lynch motor which is overkill. She can tow two of the other boats at hull speed! The original motor would have been 1.5kw. We have to limit her to 1kw so the customers can't exceed the 5 knot speed limit. As there's usually a bit of stopping and starting and most people don't run flat out, she usually comes back with a full battery and if not then it gets filled up during the turnaround time between hires.

Our Ruban Bleu has no solar, just 220kg of old fashioned wet lead acid traction batteries. She is limited to 1.1kw and with the same usage pattern above she will go all day and still have plenty in reserve, charge overnight.

Our 4m catamarans have a single 300w solar panel. the 1.1kw max motors but only use about 500w at normal cruising speed. Again, the usage cycle means the solar panels keep up providing you park them facing the right way during turnaround time.

They have one 5kwh enertec Juice lithium battery weighing 53kg so at cruising speed 500w power consumption they can run 10 hours non stop so we can tolerate a few cloudy days without have to charge.

On cloudy days they all have enough battery capacity to run all day and charge overnight.

The takeaway here is that electric propulsion needs a lot less power then you'd think if you just converted diesel HP to electric KW. Our 21ft boat cruises on about half a kilowatt at 3-4 knots and uses about 1.25 kilowatt at 5 knots. You can use all 2.5kw at just over 6 knots with all that extra power being wasted to make more waves, not going much faster.

Same principle applies to diesel. A 6hp used to be considered adequate for a 32ft yacht. Now people put in 30hp in the same boat so they can make more waves and burn more fuel without going much faster. Diesels like to be run flat out, they hate being at low revs all the time so this trend really isn't good for the motors either.

 

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6 minutes ago, Dtwo said:

SyOhana - a couple of questions for you:

"Most lithium batteries on the market are technically illegal to use on boats in NZ and might invalidate the EWoF if the inspector is paying attention." - I have Lithium batteries and I am horrified to hear this, can you explain why?  And why would an EWoF inspector be looking at my batteries?

"NZ made lithium batteries" - I was not aware of any battery manufacturers here in NZ?  I'd like to support if possible.  I know there are people who assemble batteries into packs, is that what you mean?

See my reply to CarpeDiem above. We sell enertec Juice lithium. The LiFePo4 cells are quality imported items but the BMS and display is their own design with all custom circuit boards and software. Another nice feature is NMEA2000 connectivity.

I have not heard of a boat actually failing an EWoF for this reason yet but they might start checking, especially as a knee jerk reaction if there was a death, collision or wreck in NZ due to the battery cutting out at the wrong time without warning (whether that be propulsion failure or just the nav lights went off). 

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1 hour ago, Black Panther said:

Thank you syo.

I looked at it about 5 yrs ago and it sounds like things have improved since .

If you have the time and inclination what would you suggest to replace 90hp diesel? 100mile range@4kn 25mile @5.5. Then the biggie, not ever likely to be on a marina so how long to recharge?

As I said to CarpeDiem, it's more about specifying the right motor for your boat than replacing a 90hp diesel which might not be right and you're probably never running it flat out.

Please tell me more about the boat and the drivetrain. For 100nm range and no marina berth you probably want some sort of hybrid and plenty of solar. You can do it all electric but it will be very spendy on batteries for that range.

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1 hour ago, syohana said:

Can't imagine why you would need a 20kw genset, that would be very heavy and bulky. 

We were told to over spec the generator so it was never running at full output? It was described as a range extender and battery charger. I could see it only being used a few times a year. However, if we had gone down that path we'd also have removed the Lpg and gone full electric cooking and water heating so it would of been a bit more than just a range extender on long cruises. 

20kw genny was matched to a 15kw motor. 

1 hour ago, syohana said:

How long and heavy is your yacht (displacement tonnes NOT registered tonnage which has more to do with the amount of wine barrels you can carry)? We don't know whether you actually need 29hp or whether you use 60% of that power just to make more waves after you already reached hull speed? Do you ever run your diesel flat out pedal to the metal or are you really only using half or quarter of those horse power? Do you want to motor into strong headwinds and big seas or are you a gentleman who doesn't go to windward?

Lwl is 10m. Weight is 5200kg. We cruise at 6.2knots which is 2200rpm.  If we take the engine to ~2800rpm we hit Hull speed at ~7.1knots.  At that point we have 300rpm in reserve, the engine maxes out at 3100rpm iirc but we don't go there. 

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40 minutes ago, CarpeDiem said:

We were told to over spec the generator so it was never running at full output? It was described as a range extender and battery charger. I could see it only being used a few times a year. However, if we had gone down that path we'd also have removed the Lpg and gone full electric cooking and water heating so it would of been a bit more than just a range extender on long cruises. 

20kw genny was matched to a 15kw motor. 

Lwl is 10m. Weight is 5200kg. We cruise at 6.2knots which is 2200rpm.  If we take the engine to ~2800rpm we hit Hull speed at ~7.1knots.  At that point we have 300rpm in reserve, the engine maxes out at 3100rpm iirc but we don't go there. 

Sounds about right. I run our D1-30 at about 2200 rpm and sit at about the same speed, maybe a tad more. Need those extra horses to get in and out of Whitianga harbour against big tides.

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1 hour ago, CarpeDiem said:

We were told to over spec the generator so it was never running at full output? It was described as a range extender and battery charger. I could see it only being used a few times a year. However, if we had gone down that path we'd also have removed the Lpg and gone full electric cooking and water heating so it would of been a bit more than just a range extender on long cruises. 

Bad advice IMHO. Diesels like running at about 80% of their full capacity, a 20kw genset would be specced so that the diesel in it is running at about 80% when producing the full 20kw electric output. If you don't run it at full output (and you never would even with propulsion, cooking and an electric heater all at once) then the exhaust gets all clogged up with soot.

 

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20kw genny was matched to a 15kw motor. 

15kw is overkill for this size boat. 5kw is adequate to reach full hull speed in calm conditions. The rest is extra power to push into strong wind and waves. Nice to have in reserve but not often used.

If you need a genset at all then the genset should be 5kw for unlimited range at hull speed or 3kw as a range extender or to get you home with unlimited range at reduced speed. If you need extra power to bash into a strong wind then you can draw down the batteries.

 

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Lwl is 10m. Weight is 5200kg. We cruise at 6.2knots which is 2200rpm.  If we take the engine to ~2800rpm we hit Hull speed at ~7.1knots.  At that point we have 300rpm in reserve, the engine maxes out at 3100rpm iirc but we don't go there. 

From the system you were specified I thought you might have a 40 footer. Your diesel is about 20hp at 2200 RPM if it was producing maximum torque but I suspect that your propeller is not big enough for it to produce maximum torque at that RPM. Your 29hp diesel may never actually put more than 10hp into the water. Quite likely the propeller was specified for the original ~10hp motor the boat had when it was new so the prop isn't capable of delivering much more than 10hp considering that your new motor runs at the same RPM as the old one.

6.2 knots is not an economical cruising speed, it's close to a maximum speed. Depending on your waterline length that's probably pushing hull speed (28ft waterline=7 knot hull speed) and wasting a lot of power making waves. At 5.5kn you'd use half as much fuel/electricity.

 

 

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38 minutes ago, syohana said:

Your diesel is about 20hp at 2200 RPM if it was producing maximum torque but I suspect that your propeller is not big enough for it to produce maximum torque at that RPM. Your 29hp diesel may never actually put more than 10hp into the water. Quite likely the propeller was specified for the original ~10hp motor the boat had when it was new so the prop isn't capable of delivering much more than 10hp considering that your new motor runs at the same RPM as the old one.

She has had a Volvo 30hp engine since new. First one was a 30hp Volvo 2003. We replaced it with the 29hp D1-30.

The propellor is also Volvo and we took that off the old saildrive system but Volvo signed off on it being the correct size for the boat/engine.

Wow, only 10hp?  That surprises me. 

Thanks - food for thought. 

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1 minute ago, CarpeDiem said:

Wow, only 10hp?  That surprises me.

My 930 was running a 9.9 Yammy Hi Thrust and it would push her into a near cyclone with minimal lose of speed. Nothing with an inboard could touch us.

I have no problem at all believing the 10hp comment ;)

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15 minutes ago, CarpeDiem said:

She has had a Volvo 30hp engine since new. First one was a 30hp Volvo 2003. We replaced it with the 29hp D1-30.

The propellor is also Volvo and we took that off the old saildrive system but Volvo signed off on it being the correct size for the boat/engine.

Wow, only 10hp?  That surprises me. 

Thanks - food for thought. 

Sorry I misread 10m LWL as 10m LOA hence my discussion of 28ft waterline. 10hp may be a bit low. I overstated your cruising speed being too high, you're probably not pushing hull speed hard at 6 knots but 5.5 is still much more economical.

As a rule of thumb we recommend 1kw per tonne of displacement to get the boat up to hull speed in calm conditions. Most of my analysis was based on the displacement rather than the length so the suggested 5kw electric power remains valid but a 10kw or 15kw would not be a bad idea to give you extra power in reserve for bad weather. There's not a huge difference in cost between 5kw and 10kw motors.

Your prop is sized so as to never overload the engine at any RPM (as evidenced by your ability to take the motor to the maximum RPM). If it is sized correctly to not overload the motor at 3200 RPM then it cannot deliver the maximum rated horsepower at a mid range RPM. I still reckon you're not putting much over 10hp into the water at 2200rpm because 10hp should be enough to get a 5 tonne boat up to hull speed.  After that more horsepower just makes more waves.

 

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21 minutes ago, KM... said:

My 930 was running a 9.9 Yammy Hi Thrust and it would push her into a near cyclone with minimal lose of speed. Nothing with an inboard could touch us.

I have no problem at all believing the 10hp comment ;)

Yep, and outboard horsepower is even more overstated by the manufacturers than inboard horsepower! "Hi thrust" is the key here, you had the right propeller to get all of the available power into the water.

Diesel props are often undersized due to constraints of hull clearance or so that the engine isn't overloaded with a big alternator and fridge compressor hanging off it. Or they are sized for a maximum speed rather than a maximum thrust. They could be "one size fits all" so the standard prop on a 30hp diesel might be sized for the hull speed of the longest boat you'd reasonably fit that motor into.

Or, if they sized the prop specifically for your boat then perhaps they specified it so that the maximum rpm would correspond to the maximum hull speed, knowing that you'd never need all your horses at any RPM. Theoretically, having that reserve torque means you could potentially tow a second boat while maintaining exactly the same RPM and boat speed, the only difference would be your fuel consumption. Such behaviour might require a bigger prop.

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This horsepower inflation thing has been going on for a while. One horsepower used to be considered adequate for a 40 tonne coal barge....*

116dcb1b09277d112a18cc955562cdb9.jpg

 

* Propeller sizing was not a problem back then and the transmission was nearly 100% efficient. The emissions were still undesirable.

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