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Old 17-08-2016, 06:26   #121
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Re: Lagoon 420 hybrid + modern tech

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What baffles me is why auto manufacturers haven't realized this key difference and started selling cheap small electric cars with 70-100mile range. What drives the price of electric cars thru the roof is trying to ask too much of the technology in terms of range. This forces them to use giant expensive battery packs, regenerative braking and a host of other features to try and match a technology they have no hope of matching.
Electric cars are cheap now!

I've owned my 2012 Nissan Leaf for almost 5 years. Works great, clean, 0 maint., and it looks like I'll get a new battery under warranty .

The resale value is crazy cheap $6-9k. Anyone can go out today by a $6K Leaf, drop a brand new $5k battery and have a perfect commuter for 5 years. $11K for you commute for 5 years, blows away gas, ROI. And probably 80% of commuters would be fine with 60-75 mile range.

Im sure that if you go the BMW I3 approach with a range extender it would translate right to these boat scenarios. Have a good sized Gen, good sized electric motors and keep a reasonable sized battery bank.

It's really just older thinkers that can't understand or believe it's possible. I've done it for 4.5 years and would never buy a pure gas car again.

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Old 17-08-2016, 06:39   #122
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Re: Lagoon 420 hybrid + modern tech

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Electric cars are cheap now!

I've owned my 2012 Nissan Leaf for almost 5 years. Works great, clean, 0 maint., and it looks like I'll get a new battery under warranty .

The resale value is crazy cheap $6-9k. Anyone can go out today by a $6K Leaf, drop a brand new $5k battery and have a perfect commuter for 5 years. $11K for you commute for 5 years, blows away gas, ROI. And probably 80% of commuters would be fine with 60-75 mile range.

Im sure that if you go the BMW I3 approach with a range extender it would translate right to these boat scenarios. Have a good sized Gen, good sized electric motors and keep a reasonable sized battery bank.

It's really just older thinkers that can't understand or believe it's possible. I've done it for 4.5 years and would never buy a pure gas car again.

I'm talking more about new car sales. When new, that leaf was probably $35k and was going up against $15k IC engine commuter cars. This is reflected in the low resale values.

The underlying issue that confuses me is the auto makers are making a similar mistake that the electric boat people are making (just with a different use case that is actually viable). They are claiming it can match an IC engine for capability. They spend a huge amount both in design and advertising trying to address range anxiety. When they should simply point out you have a 2nd IC engine car for long trips and we can give you a $15k electric commuter car for daily commuting that costs the same up front but will have drastically reduced fuel costs.

The volt is actually a great idea but again, they've tried to do too much and overpriced it. Far better they accepted a 20mile range and kept the price down in the mid $20k range (and included a real back seat). I think it would have sold like hotcakes and with the reduced electric capability it still would have allowed for 80-90% of miles under electric power. The BMW seems to be following a similar pattern.

If it wasn't for govt mandates forcing the issue, I believe you would see all the electric cars disappear. I also suspect this is part of the problem. They are designing to meet a mandate, not to meet what customers want.
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Old 17-08-2016, 06:57   #123
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Re: Lagoon 420 hybrid + modern tech

I'm pretty sure no automakers officially claim that an EV is the same capability of a gas car. Anyone with sense who buys an EV knows this.

Some buy EV's so they don't send gas dollars to foreign countries that want to kill us. If the US Gov. didn't do some investment/innovation/mandates then where do you think we would be as a country..?

I'd welcome some more mandates on diesel engines to the point that it spurs on advances in electrical motors, battery tech, super capacitor storage, solar etc.

Just look at what Tesla & SpaceX have been able to do with very little (relative to the over all budget) push from the Gov.
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Old 17-08-2016, 07:22   #124
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Re: Lagoon 420 hybrid + modern tech

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I'm pretty sure no automakers officially claim that an EV is the same capability of a gas car. Anyone with sense who buys an EV knows this.

Some buy EV's so they don't send gas dollars to foreign countries that want to kill us. If the US Gov. didn't do some investment/innovation/mandates then where do you think we would be as a country..?

I'd welcome some more mandates on diesel engines to the point that it spurs on advances in electrical motors, battery tech, super capacitor storage, solar etc.

Just look at what Tesla & SpaceX have been able to do with very little (relative to the over all budget) push from the Gov.
Not directly but car companies keep pushing range that exceeds typical usage by huge margins to address range anxiety but it's undermining their cost competitiveness.

I have looked at Tesla. Tesla would be bankrupt without the push from the government. It may be small in terms of the overall federal budget but it is huge relative to Tesla's budget.

The problem with govt mandates is they often have unintended consequences because they push companies to build to the mandate not to what the buyer wants. As a result they often don't solve the original issue that spurred the mandate in the first place.

The market is far better at making better products. If the goal is to cut petroleum usage, simply tack on a $2-3/gal tax. If you go back to when gas was $4/gal, suddenly the auto companies started to produce good quality compact cars that people actually wanted to buy. For the prior 3-4 decades, they were producing complete garbage in the compact car market and selling them at a loss to meet a govt mandate. Once the customer demanded a fuel efficient car, the market responded and did so very quickly.

But we are getting into a bit of thread drift. So far the govt hasn't paid too much attention to the infinitesimal percentage of fuel used by cruising sailboats. When you have cruisers bragging that they use less than 5 gal of diesel per year, there isn't much room to substantially reduce consumption if you truly hate the idea of using petroleum based fuels.
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Old 17-08-2016, 07:38   #125
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Re: Lagoon 420 hybrid + modern tech

Lots of companies would be bankrupt if the Fed's did not provide incentives. Think about Pharm for instance.

There's a big difference in an incentive, which is what Tesla benefits from, and a mandate. Then bring Taxes into it? Taxes are simply a penalty applied to everyone paying them and rarely spur innovation.

The gains by EV in the auto market will spill over into the cruising market as the new technology comes down in prices and becomes attractive to the market. Exactly as the cost of my new Leaf was 20% more than a similar gas vehicle. The benefits then out weigh the cost differential and we know those costs, in technology, go down over time.

I hope I get the chance to replace a diesel or two with electric motors when it reaches the point it did in my car.
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Old 17-08-2016, 07:43   #126
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Re: Lagoon 420 hybrid + modern tech

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Lots of companies would be bankrupt if the Fed's did not provide incentives. Think about Pharm for instance.

There's a big difference in an incentive, which is what Tesla benefits from, and a mandate. Then bring Taxes into it? Taxes are simply a penalty applied to everyone paying them and rarely spur innovation.

The gains by EV in the auto market will spill over into the cruising market as the new technology comes down in prices and becomes attractive to the market. Exactly as the cost of my new Leaf was 20% more than a similar gas vehicle. The benefits then out weigh the cost differential and we know those costs, in technology, go down over time.

I hope I get the chance to replace a diesel or two with electric motors when it reaches the point it did in my car.
I hope to see that day also. Not holding my breath but hope to see it.

As far as incentive vs disincentive vs mandate...in the end they amount to the same thing. The market doesn't care what you call them. It prices them in and reacts accordingly regardless if it servers the original intent.
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Old 17-08-2016, 11:50   #127
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Re: Lagoon 420 hybrid + modern tech

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This is a scenario where the instant torque of electric motors allows you to use substantially smaller electric motors.


LAMO. Now torque plays a role in choosing the appropriate HP? Pick one side of your mouth and stick to it. Exactly why every objection of yours has been a complete joke. Thanks for the laughs!
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Old 17-08-2016, 12:35   #128
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Re: Lagoon 420 hybrid + modern tech

Horsepower (HP) is very often misused and is really a poor measure for useful work. In terms of an engine, Hp refers to the TOTAL power expended.

Torque is a "Measure of Rotational Force" and is VERY applicable to thrust calculations.

A diesel engine is more efficient and therefore produces more torque for less HP than an average gas engine.

An Electric motor that is measured in Horsepower will always be FAR more powerful (Thrust OR Torque) and efficient that a comparable gas or diesel engine if you use just the HP figures.

You could also say that a electric motor of a given torque rating would have a far lower HP rating than an equivalent engine. Electric Motors are exceptionally efficient. Its the efficiency of the source of electrical power that is the area of concern. With a properly sized storage source (Battery Bank) to provide for short term peak usage, a generator would be sized to provide slightly more power than the average total use, and be able to do so while running at its peak efficiency.

To be fair, a more useful comparison would be an example of each for a given vessel size that provides comparable performance. Both types would be measured in TOTAL weight, Maintenance requirements over a set time. and Fuel Consumption.

From my perspective the Electric system would be sized and measured based on being driven by a generator ONLY. Solar and/or wind would simply be a soft bonus.

It is clearly possible to size a Marine Electric propulsion system that has its power supplied by a generator. Almost ALL new commercial and industrial marine drive systems are built this way due to gains in efficiency and maintenance requirements. The real key is having the system designed properly for the intended use. This is currently rare in recreational boating but is making great strides. You can easily make generalized statements that seem to confirm either side of this argument, however the march of technology is also clearly pointing towards Electric and Hybrid drive systems.

I for one will keep a close eye on the developments and would greatly prefer to use Electric-Hybrid once I have enough confidence and have seen more in general use.

These are of course only my opinions.
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Old 17-08-2016, 13:29   #129
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Re: Lagoon 420 hybrid + modern tech

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LAMO. Now torque plays a role in choosing the appropriate HP? Pick one side of your mouth and stick to it. Exactly why every objection of yours has been a complete joke. Thanks for the laughs!
Hey!!! Welcome back.

Let me explain the physics behind it since you don't seem to understand the difference:

When we rate a motor (electric or IC), that doesn't mean the full HP is used or even available all the time (it's not). It's typically rated by the peak continuous HP the motor can put out reliably. (You could pump more amps into an electric motor or bolt a turbo on an IC motor to force more HP but without modifications, you can seriously shorten the life if not destroy it within seconds.)

Electric motors can produce peak torque pretty much regardless of RPM.
IC motors have a torque curve and produce peak torque in a narrow RPM range. When outside that RPM range (such as when at idle), they produce significantly less torque.

While the motors have a rated HP, there is also the HP that is being produced at any point in time. That can be calculated as:
HP = Torque * RPM (using the instantaneous torque and RPM)

Coming from a standing start, this strongly favors Electric as they are at peak Torque from the instant power is applied to the prop. Depending on how the IC motor is optimized, it may only be generating 1/3 of it's peak torque at idle. It then takes a few seconds to spin up into an RPM range where it is putting out peak torque. As a result, motors of the same HP rating, the electric motor will initially accelerate faster because there is more HP initially available.

BUT, as the diesel spins up to a higher RPM both the RPM and torque are increasing which means the HP builds faster until it catches up to the electric motor and the total HP is the same when it reaches peak.

Remember, the electric motor as it spins up, is only increasing RPM not torque so the HP builds in a very linear fashion. The IC motor gains hp in more of a cubic fashion where it's slow at first and then very fast towards the end. (If you've ever tried to start out in 2nd gear with a stick, you can see this as acceleration is horrible from idle to maybe 1500 rpm and then suddenly you will feel a surge of acceleration as the engine starts building torque in addition to RPM.)

So how does this differ between a boat and a car:

As previously mentioned, for a small car, depending on aerodynamics, it may only take say 60hp to maintain freeway speeds (taking into account a headwind and climbing a moderate grade) but if you use a 60hp engine with only 1/3 of peak torque, and 1/3 of the RPM at peak HP, the engine is only generating maybe 7hp off the line. An electric motor with max torque is going to generate around 3 times the HP at the same RPM. It gets a little complicated as you have to take into account the clutch actuation with a IC motor and you can rev the IC engine to counter act some of the limitation but the electric motor has far more power off the line. So in the end the electric motor has roughly twice the power off the line.

A typical modern compact car will have somewhere on the order of 90-150hp IC engine. Let's say 120hp, and that means 14hp off the line. Since you can get the similar off the line power from a 60hp electric motor, the 60hp electric motor is plenty for both accelerating from a stop and for cruising down the freeway. It serves both key use cases.

As a result for the use case of a small passenger car, an electric motor has a big advantage over an IC motor (ignoring fuel storage).

With a displacement cruising sailboat, sailboat, the situation is a bit different.

Let's say you need 20hp to maintain your desired cruising speed under a headwind and waves.
- Once up to speed, both the IC and electric motors are putting out the same HP, so as long as both are using appropriate gear ratios, the same torque and RPM are applied to the prop shaft and can turn the same prop at the same speed.
- Assuming the IC motor has been properly selected, cruise speed has the motor operating close to peak torque when at cruise speed.
- The electric motor is also operating at the peak torque and once gear ratios are accounted for, Torque and RPM of the prop shaft are the same.

So for maintaining cruise speed, there is no significant difference between IC or electric motors in terms of the power they produce.

For acceleration there is still a benefit but most cruisers simply don't place a lot of value on acceleration. Once you get out of the marina, whether it takes 5 seconds or 20 seconds to get up to 6kts, really isn't that important.
- Also unlike a car where the car must accelerate if the drive wheels turn (assuming you don't spin the tires), propellers always start out spinning faster than the theoretical distance they should drive the boat. There is always some slippage before the boat starts moving forward. What this means is it's much easier to get the propeller moving and within a second or so, the IC motor is moving up the torque curve more quickly as the motor doesn't have to wait for the boat to accelerate, just the prop. By the time the prop starts developing a real strong bite on the water, the IC motor has already climbed a good ways up the torque curve and can produce a significant percentage of peak HP.
- While there is that rare save a botched docking maneuver moment, it's really very rare to use more than 10-20% throttle when docking. Usually, if you hear someone firewall the throttle, the situation has already turned to poo.

So while you do get a bit of a boost accelerating with an electric motor, it's not something that drives the HP selection process. The end result is it's the cruising speed HP requirements that drive the motor HP selection on a displacement cruising boat and that HP is the same regardless of electric or IC.

It doesn't matter what speed you select. If you only want to cruise at 3kts in dead calm conditions, you might be able to drop the requirement to 5hp, but otherwise it's pretty much the same. I've actually played with this scenario as I have a 5hp dingy outboard that is stored on a spring loaded outboard bracket. Flat out it will get the big boat (34' cat) up to around 3kts. Docking, it needs more like 50% throttle but most of the issue is the prop is set up for a small higher speed planning dingy and the bracket doesn't get the prop deep in the water, so it doesn't do a good job transferring the power to the water. A dedicated drivetrain would be much better.

I hope that helps you to understand the difference. I've glossed over a few technical details that don't really change the outcome but add a lot of complication (example: how power transfer with a IC motor spinning at low RPM with a clutch differs from an electric motor that starts from zero RPM with the clutch fully engaged).

This is where the frustration with "magic electric HP" comes from. People take the advantages electric motors have in an automotive use case and mis-apply them to a displacement boat use case.

If you think there is a different use case for a displacement cruising boat, let's discuss it.
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Old 17-08-2016, 13:55   #130
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Re: Lagoon 420 hybrid + modern tech

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Horsepower (HP) is very often misused and is really a poor measure for useful work. In terms of an engine, Hp refers to the TOTAL power expended.

Torque is a "Measure of Rotational Force" and is VERY applicable to thrust calculations.
This is incorrect unless you include RPM. A diesel spinning at 2500rpm generating 200ft-lb of torque will easily generator more thrust than an electric motor spinning at 100rpm generating 2000ft-lb of torque.

A diesel engine is more efficient and therefore produces more torque for less HP than an average gas engine.
The efficiency difference is not related to torque. It is mostly about the higher compression ration and longer stroke extracting more energy from the fuel. The higher torque is mostly incidental.

An Electric motor that is measured in Horsepower will always be FAR more powerful (Thrust OR Torque) and efficient that a comparable gas or diesel engine if you use just the HP figures.
Again, if HP is the same and they are running at the same RPM, torque will be identical. This is by definition.

Efficiency gets complicated as you have to account for the source of the electricity. If the electricity comes from a diesel generator and then is stored in batteries before being converted to electricity, it starts out roughly the same efficiency and then loses at each conversion.


You could also say that a electric motor of a given torque rating would have a far lower HP rating than an equivalent engine. Electric Motors are exceptionally efficient. Its the efficiency of the source of electrical power that is the area of concern. With a properly sized storage source (Battery Bank) to provide for short term peak usage, a generator would be sized to provide slightly more power than the average total use, and be able to do so while running at its peak efficiency.

No the electric motor HP rating is simply torque * RPM. Without knowing the RPM of both motors, you can't say which one is generating more HP.

To be fair, a more useful comparison would be an example of each for a given vessel size that provides comparable performance. Both types would be measured in TOTAL weight, Maintenance requirements over a set time. and Fuel Consumption.

I agree whole heartedly with this and since HP requirements are defined by cruising speed, if you put in an electric motor half the HP of a diesel, you do not have comparable performance.

From my perspective the Electric system would be sized and measured based on being driven by a generator ONLY. Solar and/or wind would simply be a soft bonus.

Agreed. For most practical purposes solar/wind don't provide enough power generation to move the needle unless you get into the prototype boats that have an insane impractical field of solar panels.

It is clearly possible to size a Marine Electric propulsion system that has its power supplied by a generator. Almost ALL new commercial and industrial marine drive systems are built this way due to gains in efficiency and maintenance requirements. The real key is having the system designed properly for the intended use. This is currently rare in recreational boating but is making great strides. You can easily make generalized statements that seem to confirm either side of this argument, however the march of technology is also clearly pointing towards Electric and Hybrid drive systems.

This has been discussed on other threads. The main driver for diesel/electric drivetrains for trains and large ships has little to do with efficiency.
- On trains, it eliminates what would be a massively large and complex transmission. Look at the old steam engines to see all the moving parts. Steam engines benefited from a similar torque pattern to electric motors. A steam engine can apply power from zero RPM (not sure if it's peak torque). That doesn't work so well with a diesel that must be spinning when you engage forward gear. The electric part of diesel electric basically provides a controlled transfer of power on start up.
- On large ships, it's usually cruise ships. Most freighters still use a single engine with direct drive. The main advantage is it allows them to maneuver in tight ports with little or no tug assistance. Unlike a freighter that may go a week or more between ports of call, cruise ships enter and leave ports almost daily.

I for one will keep a close eye on the developments and would greatly prefer to use Electric-Hybrid once I have enough confidence and have seen more in general use.

These are of course only my opinions.
Hybrid really won't change much. Diesel propulsion on cruising boats is already very efficient and it's easy to store enough fuel for a very long range. With a hybrid you still need to store the same diesel fuel and for steady state power supply typical of a cruising boat, they are actually less efficient.

It's electric storage (ie: batteries) that we are waiting on. If someone comes up with a battery that will store even 25% of what an equivalent weight and volume of diesel does, you will see a rapid conversion to electric propulsion. While there is lots of talk, I haven't seen any new battery technology that is anywhere close to this.
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Old 18-08-2016, 00:51   #131
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Re: Lagoon 420 hybrid + modern tech

Having read loads of these threads it seems to me that to embrace electric you should probably do the following:

Start with a great sailing catamaran. I mean something that can sail in anything from 3 to 50knts+ of wind.

Accept that you are going to be sitting there and not moving if you have no wind. So no timetable and no 'I must be there on Friday'. Your route planning for long journeys has to be more 'flexible'. This obviously doesn't matter for daysailors.

Accept that you are more tidal bound than most due to less energy density and probably less grunt at the top end (as most electric engines seem to be spec'd with less WOT power than their diesel counterparts).

Accept that when others might be able to turn on the engines and head straight into strong head winds and nasty seas, you'll be uncomfortably beating.

Accept that to go full electric and have something vaguely useful it is going to be a lot more expensive but if you are going to build a custom boat from the ground up to be a an excellent sailor and be fully electric, you are probably going to be able to take the financial hit.

I just feel you'd have to have the mindset that your an almost engineless boat with strong bow thrusters (not actual bow thrusters but real engines but to think like they are) for short-term manoeuvrability.

If you (and those willing to sail with you) have a similar mindset (and accept any additional risks this entails) then go for it.

Personally, (and I want to emphasise that this is my personal opinion here) going hybrid is not worth it. Accept the consequences and costs and go all the way or don't bother.
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Old 18-08-2016, 18:27   #132
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Re: Lagoon 420 hybrid + modern tech

See comments below in red.....
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Having read loads of these threads it seems to me that to embrace electric you should probably do the following:

Start with a great sailing catamaran. I mean something that can sail in anything from 3 to 50knts+ of wind.
Some would say that is the point of cats in the first place, but condomaran owners have different priorities, and that's fair enough. But no, EP is suitable for many types of boats.

Accept that you are going to be sitting there and not moving if you have no wind. So no timetable and no 'I must be there on Friday'. Your route planning for long journeys has to be more 'flexible'. This obviously doesn't matter for daysailors.
No again. If you design your EP system to use the advantages of solar, you can motor on EP on just the solar input (during the day, of course), then draw down on battery at night or run the range extender generator. A good hull design for sailing would expect about 5 to 6 knots of cruising if you invest in solar. With the prices dropping for good panels, this is an excellent investment compared to costs of diesel and maintenance.Plus the secondary benefits of silence and no fumes.

Accept that you are more tidal bound than most due to less energy density and probably less grunt at the top end (as most electric engines seem to be spec'd with less WOT power than their diesel counterparts).
Not really. EP pushes against wind and tide just as well, maybe even better at low RPM's than diesel. As for top end grunt, look at the video on the OceanVolt site for a 10kW EP cat pulling against an identical 22.5kW ( 30 HP) diesel cat at WOT. The EP boat easily tows the diesel boat. And no, it is not trick photography, it was taken by the chartering company of their identical boats. And by the way, that chartering company reports that their costs and propulsion maintenance on the EP boat is WAY LESS than their diesel boat. see Videos of electric motor systems in boats

Accept that when others might be able to turn on the engines and head straight into strong head winds and nasty seas, you'll be uncomfortably beating.
The only difference here is that you will be motoring uncomfortably into the same seas!

Accept that to go full electric and have something vaguely useful it is going to be a lot more expensive but if you are going to build a custom boat from the ground up to be a an excellent sailor and be fully electric, you are probably going to be able to take the financial hit.
True, the initial capital expenditure is more than diesel but this is paid off with lower fuel costs and MUCH lower maintenance costs.

I just feel you'd have to have the mindset that your an almost engineless boat with strong bow thrusters (not actual bow thrusters but real engines but to think like they are) for short-term manoeuvrability.

If you (and those willing to sail with you) have a similar mindset (and accept any additional risks this entails) then go for it.
What risks are you referring to specifically? The risks of impellor failure and diesel fuel bug clogging up filters when you hit rough water are real.

Personally, (and I want to emphasise that this is my personal opinion here) going hybrid is not worth it. Accept the consequences and costs and go all the way or don't bother.
Personally, IMHO hybrid offers so many advantages that it is totally worth it. Many other designers and boat builders have examined the issues and come down to the same conclusion. But maybe you are right, and they are all wrong. Maybe, but I doubt it. see Boatbuilders
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Old 18-08-2016, 22:35   #133
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Re: Lagoon 420 hybrid + modern tech

Much of the equation that hasn't been applied is the displacement of the boat. In my boat it is trivial to push the 5400 lbs with dual Ray Electric Outboards running from mostly solar during the day. It would hardly dent the 20 kwh lithium battery pack.

The math is simple even on a bad solar day. When I'm cruising at 4 knots using 40 amps 20 each motor and the 2160 watts of solar are producing 10 amps I'm burning 30 amps. I have 400ah usable lithium batteries. I could hold that speed for a maximum of 13.3 repeating hours.

On a good solar day if I'm making 25 amps at 48volts nominal cruising at my 4 knots still I just ran all day and hardly used any energy. Could it cross an ocean though?

transatlantic21: The world's first crossing of the Atlantic on a solar boat well I'm pretty sure I could considering they did it with lead acid but more solar. I on the other hand would utilize my generators.

So far in my limited testing the design and planning has worked well. All systems function to compliment the end result. Safe efficient low cost catamaran propulsion.

While I can only dream of doing a 300 nm shakedown cruise I did a number of cruises down the river and up the river. Once even to the mouth of the Fraser and back against what must have been at least 4 knots of current. I think it was even windy that day.

If the Lagoon lead acid dies and the owner drops 10 bills on lithium batteries he will have a much better system and certainly enjoy the solar recovery and energy storage solution they provide. Just attach as much solar as you can and you will probably never end up running the generators. I would go with 40 kwh of lithium batteries though if you can do it. That should be plenty.

I know a cat that is going to launch one day with over 40 700 ah lithium batteries in three banks. Just an absurd amount of power. Here is my Catamaran in the limited trials I did with it this year.


And my channel for other bad videos.
https://www.youtube.com/channel/UC6B...lf_id=0&view=0

Whereas none of the big diesel powered boats even moved from the dock. Usability certainly comes into play here especially with the price of diesel. A simple day trip up and down the river might run over 500 plus wear and tear and heaven forbid the chance of a break down.
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Old 18-08-2016, 23:58   #134
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Re: Lagoon 420 hybrid + modern tech

Hey BigBeakie,

You'd probably find that we are not a million miles away on what we think, just that for me to go electric, I'd probably take the chance and not have the generator.

I do think you are being a bit ambitious with your 5-6 knots on solar alone. 4 knots might be feasible in calm waters but you certainly aren't doing 5-6 knots directly into any sea state Moderate and above on solar alone.

Let's talk specifics, assuming a 45' cat with 3kw solar and 2x 15kw OceanVolt engines and 16x 160Ah lithium batteries.

Are you saying you'd have a 30kw generator to enable indefinite running of the engines?
A smaller generator to top up the batteries with reduced range?

I just find it helps to talk specifics so we can see where the difference lies.
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Old 19-08-2016, 01:59   #135
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Re: Lagoon 420 hybrid + modern tech

Quote:
Originally Posted by PacificGreen View Post
The math is simple even on a bad solar day. When I'm cruising at 4 knots using 40 amps 20 each motor and the 2160 watts of solar are producing 10 amps I'm burning 30 amps. I have 400ah usable lithium batteries. I could hold that speed for a maximum of 13.3 repeating hours.

On a good solar day if I'm making 25 amps at 48volts nominal cruising at my 4 knots still I just ran all day and hardly used any energy. Could it cross an ocean though?
The math may be simple to you, but it is very hard for me to make sense of. In your first paragraph, you are quoting Amps and Amp hours for current draw and batter bank without telling us the Volts and you are not telling us the size of your motors. If your 2160 watts is producing 10 Amps, that implies up to 216 Volts.

You then talk about 25 Amps @ 48 Volts nominal which is only 1200 Watts.

To assist in understanding your figures, could you please tell us:

1. What voltage is your 400Ah battery pack?
2. What is the voltage of your motors?
3. What is the KW/HP rating of your motors?


Edit: I missed the first sentence about 200kW lithium bank.
From that it appears that your 400AH is @ 48V
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