jaydee1976
Member
but DIY is much cheaper, and you only really use motor power in and around marinas, I actually sail off my swing mooring under sail and very rarely use my electric drive on my other boat..
Potential liveaboards
- Thread starter Laffan78
- Start date
Tranona
Well-known member
Maybe you only use your engine sparingly (which in itself is not a good as that is the prime cause of short engine life), but that is not what most people do. Engines are used just as much for generating electricity and heating water as propulsion. For all the reasons explained above simple non regenerative electric propulsion is impractical for most cruising boats.
I think your 99% is totally unrepresentative. The typical coastal cruising yachtsman uses the engine between 40-60% of the time. There are many examples of this being proved by people that keep detailed logs of their passages. It changes of course if you go ocean voyaging, and although many have cruised without engines at all they always find it very limiting when they want to interface with the land. Equally many have tried the DIY route that you advocate and most have failed to meet their objectives. You cannot argue with the physics of energy density, energy requirements and weight that clearly show that you cannot get speed and range above a very low level on a cruising yacht. The energy requirement is high, irrespective of where it comes from, the energy density of batteries is low. Read the thread I referred to earlier to get a flavour of what you can do with electric. Then look at the cost, almost half of which is batteries to give the same energy as 15l of diesel. For that you get 50 miles at 5 knots or 10 hours running time. that installation uses the very latest in motor and regeneration technology, but even then the regeneration is minimal as to get any even with a dedicated regeneration propeller you need to be travelling at 6 knots. As others have found you will not get regeneration with a conventional propulsion propeller.
So you might be able to get a range of 25-30 miles at 3-4 knots which is OK if all you do is go in and out of the marina and hook up to the mains every time you dock, but this is severely limiting for anybody who has ambitions for serious cruising. And don't forget you also have to run the ship's 12v systems.
I think your 99% is totally unrepresentative. The typical coastal cruising yachtsman uses the engine between 40-60% of the time. There are many examples of this being proved by people that keep detailed logs of their passages. It changes of course if you go ocean voyaging, and although many have cruised without engines at all they always find it very limiting when they want to interface with the land. Equally many have tried the DIY route that you advocate and most have failed to meet their objectives. You cannot argue with the physics of energy density, energy requirements and weight that clearly show that you cannot get speed and range above a very low level on a cruising yacht. The energy requirement is high, irrespective of where it comes from, the energy density of batteries is low. Read the thread I referred to earlier to get a flavour of what you can do with electric. Then look at the cost, almost half of which is batteries to give the same energy as 15l of diesel. For that you get 50 miles at 5 knots or 10 hours running time. that installation uses the very latest in motor and regeneration technology, but even then the regeneration is minimal as to get any even with a dedicated regeneration propeller you need to be travelling at 6 knots. As others have found you will not get regeneration with a conventional propulsion propeller.
So you might be able to get a range of 25-30 miles at 3-4 knots which is OK if all you do is go in and out of the marina and hook up to the mains every time you dock, but this is severely limiting for anybody who has ambitions for serious cruising. And don't forget you also have to run the ship's 12v systems.
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Kelpie
Well-known member
I really, really, wish that were true.
In an ideal world I would have unlimited time and be able to choose perfect weather windows.
But everyone uses their boat differently. I am very interested in electric propulsion, I think we will see more and more of it in the future, but as has been said countless times already it won't work for everyone without changing the way they use their boat.
jaydee1976
Member
I know my system works but yes i agree everyone is diffrent in how they use there boats, I have been many miles with mine with no issues and its not my first electric drive... but i do agree with range but i dont use mine much and am never in a hurry so i just sail stress free with no worries. I have no hook up as my boats were all set up for 12 volts for house batteries and 24 or 48volt for the drive motor.. I also can see in a motor boat it will restrict your cruising as well but a sailing boat is just that asailing boat there is many sailing boats around with no engines but i do agree if you just out for a weekend and have to be back by sunday then electric drive is no for them but those like sailing UMA and many others who are not in a rush to go anywhere then electric drive with regen does work... but I do think hybrid is the way forward as you get best of both worlds
Mistroma
Well-known member
I imagine that the fact you are posting in the liveaboard forum will mean that you will only find a small number able to manage with electric propulsion. Energy storage density is very important unless you use virtually no energy.
You said that you don't have a power hook up and I'm guessing you don't have a diesel generator to charge AGM batteries. How do you charge the batteries? Towed, wind or solar? Most liveaboards find it a struggle just keeping domestic batteries charged.
Tranona
Well-known member
Hybrid is a red herring, just like it is for road vehicles. Just does not make sense for a yacht when the prime demand is for propulsion and electrical power is minor and secondary. Why go to all the complication of a diesel engine and an electric motor as alternatives for propulsion, also using the diesel to generate the electricity for the motor with all the losses involved? Connect a diesel direct to the prop and use the surplus energy to provide electricity for the boats domestic and navigational needs as now, supplemented by solar and wind/water generation. Hybrid only makes sense when non propulsion power demands are greater than propulsion. That is why cruise liners use diesel electric, because the propulsion energy demand is a fraction of the demands of the hotel ship.
There is no development going on anywhere that I have seen for hybrid propulsion for boats, and even in the automotive field the development is in systems that boost the power of the IC engines rather than providing meaningful electric only propulsion. Doubt we will see any new hybrid cars after the current types have worked their way through. None of the existing automotive technology has transferred to marine applications. the only viable examples in yachts have been generators charging batteries to provide the energy for electric drives. over complicated, bulky, heavy, expensive and a nightmare to maintain as the charter operators who bought Lagoon 420 hybrids found out 10 years or more ago.
There is no development going on anywhere that I have seen for hybrid propulsion for boats, and even in the automotive field the development is in systems that boost the power of the IC engines rather than providing meaningful electric only propulsion. Doubt we will see any new hybrid cars after the current types have worked their way through. None of the existing automotive technology has transferred to marine applications. the only viable examples in yachts have been generators charging batteries to provide the energy for electric drives. over complicated, bulky, heavy, expensive and a nightmare to maintain as the charter operators who bought Lagoon 420 hybrids found out 10 years or more ago.
Kelpie
Well-known member
Although it does give the option of running entirely on electric power for shorter journeys. Which for both yachts and road vehicles may be quite useful, depending on usage.
(e.g. for me, a 5 mile electric range would cover about 90% of my road journeys; enough range to get me on and off a mooring would cover 100% of my day sails).
Mistroma
Well-known member
Still not expecting many liveaboards are planning to fit electric propulsion. Probably the audience least likely to be early adopters.
Gary Fox
N/A
A few, very rich, fanatically green canal narrowboatists are choosing it. They are misguided because their minimal running hours and low power mean that making and scrapping their hi-tech batteries will damage the environment more than the equivalent diesel emissions.Still not expecting many liveaboards are planning to fit electric propulsion. Probably the audience least likely to be early adopters.
There's a hybrid powered Wylo gaff cutter, project-managed by Steve Sleight RIP, and the owner had blue water ambitions when I spoke to him. I wonder how it's working out?
Yes, leccy power is a nonsensical fantasy for liveaboard cruising yachtsmen, I don't even know why it's on this thread really.
Mistroma
Well-known member
I had not thought about narrowboats. They can simply stop and tie up or usually drift into a bank if power is lost. Not a big safety issue. I like to have confidence about arrival time if I'm rounding a headland with little wind or wind on the nose and 50-60nm from really good shelter. It wouldn't be good to have limited range under power when there's a Medicane closing on an erratic path.
Tranona
Well-known member
Same with me, even though I don't live on an island where 5 miles is a long journey! However in normal times I would not be able to visit my daughter in Reading in something like a Nissan Leaf on one charge, particularly i winter. Even a nice F Pace would struggle if I went to my other daughter in Kettering! Apart from the range, the Leaf costs over twice what I paid for my car (with a range of 400 miles) and the Jaguar 5 times! However both of these are a vast improvement on what was available electric 10 or 15 years ago.
As was discussed on the Salona thread electric is in its infancy for yachts with most advocates being at the marginal mad professor stage of development. Personally I doubt it will move quickly from this stage for yachts simply because of the size of the potential market (or lack of) and the basic constraints of power and energy density if you want to be independent of shoreside charging.
Tranona
Well-known member
I saw that when it was new. Good example of what I called the mad professor approach. Yanmar 1GM in the forecabin acting as a generator and a complicated electronic system to try and balance the loads from the electric motor on the battery. Not dissimilar to the much better executed system in the Lagoon 420 that failed to make any impression on the market. Who needs all that complication on a simple bluewater cruiser.
Why is this subject here? Because it is this sort of thread that draws in the mad professor types!
Laffan78
New member
It has got a bit out of hand hasn't it? ? I don't actually mind, as although I was thinking of trying to fit an electric motor in the macwester from the original post, I quickly realised it wasn't realistic. For all the same reasons people have mentioned here. That being said, it is an interesting concept and I would like to know more. So, everyone please carry on!
Laffan78
New member
Thanks everyone for the helpful advice, especially as to what boats to look for.
I like the look of the etap 28s that someone mentioned. I think I'm looking at one of the 27 footers, sabre, halcyon, or vega seems like the best choice. Might have to save a bit more than I thought or get lucky finding one that needs a suitable and manageable amount of work. I recently found out a vivacity has 6ft headroom. Although, it's a bit smaller than I'd like, could be a back up though, anybody got any experience?
In response the the electric power subplot that's pretty much taken over, graphene batteries?
I like the look of the etap 28s that someone mentioned. I think I'm looking at one of the 27 footers, sabre, halcyon, or vega seems like the best choice. Might have to save a bit more than I thought or get lucky finding one that needs a suitable and manageable amount of work. I recently found out a vivacity has 6ft headroom. Although, it's a bit smaller than I'd like, could be a back up though, anybody got any experience?
In response the the electric power subplot that's pretty much taken over, graphene batteries?
RupertW
Well-known member
The issue is recharging much more than the batteries (although better batteries will help weight of course). Although there is no need for diesel or petrol for battery charging or water heating or tender journeys any more if you are somewhere sunny the need for propulsion and range is still crucial as you may want to motor longish distances if there is no wind and you don’t want to wait a week.
So I have about 500 miles range in tank and jerrycans which I can refill in 20 minutes. Recreating even half that for electric propulsion isn’t possible without batteries taking over the boat, although if you are a marina based day sailor with a small boat then it’s expensive but entirely practical.
Laffan78
New member
RupertW
Well-known member
Yes but the same problem remains - charge from where?
Laffan78
New member
Yeah, I see where you're coming from. But here's my thinking on why electric motors will become more realistic going forward.
A graphene power bank equivalent in size to a lithium one you'd need to realistically run an electric motor would give you around 40-100hrs of running the motor, by my quick calculations. If you're cruising then, firstly, that is far superior to diesel, and you're just not likely to burn through enough to flatten the battery anyway. So, I think, as long as you have the money and the deck space for sufficient panels, then solar would be able to top up the batteries sufficiently on a day to day basis. Also, going back to regen, the oceanvolt motors do provide a significant amount of charge above 6 knots. Plus, the rate is exponential. So, I think there is a space for electric motors within the sailing community, but only once battery technologies catch up to the power requirements, (grabat are going to start producing their batteries in March of this year) and only for the few that fit the requirement profile, and can afford it. I can see blue water catamaran owners spearheading the trend. They have the space for solar, can reach greater speeds for regen and are terribly expensive, meaning owners with money. Also, most new battery technologies are being produced with cars in mind - low voltage, high capacity cells wired in series to achieve the high range they're claiming. so it will no doubt take a shift in design to apply them to boats but, I don't think that will be an issue once the technology is in production.
Whether that will, could, or should, be applied to coastal cruising and day sailing in the future, who knows. You could argue that the limited use of the motor I.e. Not every day of the year, would add validity to its use. It will take people trying it to find out. I for one, however, have no intention of going down that rabbit hole any time soon and will be looking for something with a working engine, as has been suggested, before anyone starts.
RupertW
Well-known member
On the graphene side - say I do a typical 120 miles at 5 knots motoring, so 24 hours - I’ve often done longer in a flat calm. So with my 45hp motor running at cruising speed thats 14Kw, so over 24 hours that’s 336 KWhr. For that I will need (using the 24/4 rough ratio to allow for daylight hours with less sun at either end) I need 56,000 W panels on the boat. I need a bigger boat.
Mistroma
Well-known member
Yes, I said in post #25 that energy density was a big problem at present. Diesel has about 100 times the energy density of many batteries. It has about 5-10 times the energy density of hydrogen (compressed or liquid). These are ballpark figures but enough to give an idea of relative positions.
Of course ICE isn't very efficient at extracting the energy even though we recover a small amount to heat water instead of throwing it away. That closes the gap considerably, making liquified hydrogen a possible replacement (purely on energy density, not practicality). Batteries still have a long way to go.
Assuming we solve that problem you then run into the re-charging issue already mentioned. Wind, wave and towed generation aren't really able to produce the required amount of power consistently. Solar is probably the best option to look at briefly.
Current panels are probably around 7m2 per kW. My boat has a 36kW diesel and even using only 10kW output would need a 70m2 panel, that's close to 8 x 9m and only vaguely feasible for a multi-hull.
Of course you really need a much larger panel because a 1kW panel does not produce anything close to 1kW. However, lets ignore that not so minor problem and assume we could magically capture all of the energy. It won't happen as there's a theoretical limit around 87% and current panels have a much lower theoretical limit of around 33%.
An impossibly 100% efficient panel would be around 10m2 to output 10kW. I might manage that on my boat if I could remove the mast and totally cover it with panels. Unfortunately, that only gives me power during the day and that is limited when cloudy. I'd really need about twice that area to allow for travel at night plus some for domestic use. It doesn't allow for running at full throttle for hours to reach shelter in an emergency.
Not sounding good so far, especially considering that I'm assuming a level of efficiency about 3 times the theoretical limit for current panels (theoretical, not actual). It isn't even practical for a multi-hull with current technology operating at its theoretical output. We need a step change in panel and battery technology to make it anywhere near viable.
It sounds as if we'd also need to combine it with swappable battery packs to reduce the gap between usage and generation. A bit like topping up your fuel tank, just pull in to a facility and swap for a fully charged pack. It would be quicker than re-charging but a real pain unless you designed the boat with that in mind.
