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Old 26-09-2016, 17:44   #16
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Re: Boat conversions with Prius

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The Original Prius had a 40 hp electric motor, the next release was 44 hp, and the next was 57 hp.

An issue with trying to use one on a boat is they run off of very high voltage, in the hundreds of volts, up to 500 I think. I also think those motors are built into the transmission if you want to call it that, and the other is essentially the engines flywheel. It's not like you can take one out and bolt it to anything, I believe you would need the whole powertrain, Internal combustion engine and all.
Now the batteries are widely available and not real expensive, but I bet you can get an AH cheaper out of golf cart batteries and at voltages that are a lot less likely to electrocute you. I briefly considered using them as a house bank.

Those HP numbers may be for both electric motors? They are actually I believe permanent magnet AC motors that also will generate power. I'm not sure of its purpose but a Prius also has a large inverter, so large that it has its own cooling system, like a radiator with an electric water pump etc.
Then I'm sure the whole thing is computer controlled by a computer with way more power than what ran the Saturn V system.


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Old 26-09-2016, 18:06   #17
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Re: Boat conversions with Prius

You might get better results using a Tesla motor, and a reduction gearbox. Also, I believe there are diesel hybrids. Personally, I think the concept is great, but am less comfortable with the execution based upon what is currently available in engines, motors, and the batteries for power and storage for the motors.
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Old 26-09-2016, 18:48   #18
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Re: Boat conversions with Prius

The subject of putting an electric motor (and batteries) in a boat comes up often, meaning there are a lot of people out there who are more interested in tinkering than going boating.
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Old 26-09-2016, 19:11   #19
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Re: Boat conversions with Prius

Do not do it. I own one and work on it. The reverse in a prius is 100% electric motor and can not pull the care more than a about 1/2 a mile with fully charged battery. It goes that far and stops and revs the gas engine to charge the battery pack before moving again. Same goes for going forward with a dead gas engine.

Raid a golf cart for the motor you will be much better off. How do you plan on charging the batteries? Shore power is the only practical way. If all your sails and deck were solar PV panels that might work. A new type of sail cloth that is PV might be a really good idea.
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Old 27-09-2016, 09:07   #20
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Re: Boat conversions with Prius

Just as a note on electric boats. I believe it was Endeavour, Tamper area, that made one which looked like an early 20th century rich mans launch, fringed top and all.

As I recall, it went from Tampa to around Moore Haven on one charge and the destination was the Miami boat show. It was a prototype as I recall.
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Old 27-09-2016, 19:03   #21
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Re: Boat conversions with Prius

I own a Prius. The synergy is such that is most economical in city driving. The constant braking generates energy for charging, electromagnetic.
A64 explanation is best unless your last name is Tesla🤓
Now if your boat was larger , and it had a loading ramp, and you could drive it onto your industrial treadmill which powers your props or paddle wheels
However, I don't think putting on the brakes will create a similar effect

We put Deo Volente' to water on Friday . We have a Warp9 golf cart style motor belt drive to prop shaft. 50 dry cell batteries 58lbs each . Will have 5000watts solar. No sails or mast as yet, considering kite....

The Prius is a car not a boat.
Truly there are several good solar, hybrid,and battery operated watercraft presently in production . They fit different niches as for specific purpose.
You can search Torqeedo, Electoprop, and several others, there out there.
If you want a true cruiser and don't always want to rent slips and plug in to charge, you need to think out of the box and make sure you have plenty of checkbook. It's not for the faint hearted, even if you do most labor yourself.
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Old 28-09-2016, 08:05   #22
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Re: Boat conversions with Prius

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There's a big difference in Hybrid for cars and for water. For one, once the car is up to speed the energy required to keep it moving is low. For a boat that is not so, it just keeps needing energy.
This is why hybrid makes a lot of sense for cars but not for boats.
- It probably only takes 40-50hp to keep a prius at highway speeds but would result in horrible acceleration (think an old VW). With a hybrid, they can size the motor to match that for peak efficiency. Then the battery gives the extra power to get decent acceleration. Regenerative braking can boost the efficiency even further.
- A displacement cruising boat generally doesn't care much about acceleration, so you simply size the engine for efficiency at cruising speed. There isn't typically a lot of stop and go, so there isn't anything to gain and you also lose efficiency converting mechanical power to electric and back to mechanical.

Where a hybrid could make sense is for a short distance ferry. If you are crossing a river say 1/4mile wide, there is a lot of starting and stopping and acceleration holds a more important role.
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Old 28-09-2016, 08:29   #23
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Re: Boat conversions with Prius

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This is why hybrid makes a lot of sense for cars but not for boats.
- It probably only takes 40-50hp to keep a prius at highway speeds but would result in horrible acceleration (think an old VW). With a hybrid, they can size the motor to match that for peak efficiency. Then the battery gives the extra power to get decent acceleration. Regenerative braking can boost the efficiency even further.

You have the gist of it, but it goes even further than that. A Prius is not an Otto cycle engine, it is an Atkinson cycle engine, as insane as this sounds an Atkinson cycle engine has a longer power stroke than compression stroke, hint its done with valve timing, a problem with them is they have very little torque, which makes acceleration extremely weak , but nothing makes torque like an electric motor so that fills in the gap as you said
https://en.wikipedia.org/wiki/Atkinson_cycle That is how the thing can get good highway mileage too, I assumed its highway mileage ought to be less than a normal car as all the electric motors, batteries etc are just extra weight at steady state highway speeds

I've had a Prius for 6 yrs and the operating principle fascinates me, there are 5 different operating stages for example, and some of them seem to be illogical, yet it works.

Yes, a ferry and a tug boat are two examples of efficient hybrid boats, both sit for extended periods where a small engine can run at its most efficient load charging batteries and the batteries can be used to provide the relatively short blast of power when needed.
Back in the 70's I believe the Russians built city buses that were hybrids and got phenomenal mileage, or that may be Urban myth.
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Old 28-09-2016, 08:43   #24
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Re: Boat conversions with Prius

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You have the gist of it, but it goes even further than that. A Prius is not an Otto cycle engine, it is an Atkinson cycle engine, as insane as this sounds an Atkinson cycle engine has a longer power stroke than compression stroke, hint its done with valve timing, a problem with them is they have very little torque, which makes acceleration extremely weak , but nothing makes torque like an electric motor so that fills in the gap as you said
https://en.wikipedia.org/wiki/Atkinson_cycle That is how the thing can get good highway mileage too, I assumed its highway mileage ought to be less than a normal car as all the electric motors, batteries etc are just extra weight at steady state highway speeds

I've had a Prius for 6 yrs and the operating principle fascinates me, there are 5 different operating stages for example, and some of them seem to be illogical, yet it works.

Yes, a ferry and a tug boat are two examples of efficient hybrid boats, both sit for extended periods where a small engine can run at its most efficient load charging batteries and the batteries can be used to provide the relatively short blast of power when needed.
Back in the 70's I believe the Russians built city buses that were hybrids and got phenomenal mileage, or that may be Urban myth.
In principal, you could use an Atkinson in a cruising boat and get similar benefits but that's nibbling at the edges. The big advantage for a prius is in stop&go traffic using the hybrid functionality. Standard econoboxes with standard engines can come darn close to a prius in terms of freeway MPG.

The main reason you don't see them in other uses (such as cruising boats) is there isn't a big market for them with really only the prius using one. In theory, it would be a good option for a cruising boat as acceleration isn't critical. This is unlike your standard 20-40hp diesels which are adapted for a wide variety of uses from generators to tractors to fork lifts to....
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Old 28-09-2016, 10:19   #25
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Re: Boat conversions with Prius

A hybrid boat may make sense but it has to be done right from the start. I can imagine a setup where you have lead acid batteries integrated into the keel, an electric motor/generator combo with a custom propeller that can both drive the boat and generate power while under sail and an auxiliary generator to charge the battery pack (may be solar as well but the contribution will be tiny).

It is a more complex setup vs. the mature propulsion train today but few people thought electric cars will be competitive 20 years ago. The benefit for the sailboat is that weight is not a problem (you need to have the keel anyway) and free power is available to charge the batteries (wind). Now, if you were to experiment building such a boat I would do the following, say for a 30 ft boat with a 4400 pound bolted iron keel.

1. Replace the keel with a similar sized keel with integrated lead acid battery cells. You have to use cells vs. complete batteries due to the shape of the keel. Wire everything correctly and design a system to monitor and top off the batteries with water. I would put 50 kWh capacity, approx. 3000 pounds , approx. $5,000 for the batteries plus another $5,000 to design and build the keel enclosure.

2. I do not know about motors but the Prius may work plus you can reuse a lot of the electronics for charging/discharging. This will not be a 12V system but much higher and possibly AC. The propeller will be expensive as well.

What will 50 kWh give you? Well, you need 4-5 hp to move the boat at 3 knots, 10 hp at 5 knots. So, you will get about 7-8 hour range at 5 knots.

It is not a bad project but you need some serious motivation and time to do it. May be you can sell the idea to the big sailboat manufacturers.

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Old 28-09-2016, 10:25   #26
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Re: Boat conversions with Prius

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........... May be you can sell the idea to the big sailboat manufacturers.
Or sell the idea to Prius and they can start building electric boats.
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Old 28-09-2016, 10:26   #27
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Re: Boat conversions with Prius

I looked into this when designing a boat (before I found exactly what I wanted for sale in Los Angeles). My solution was diesel-electric. A single diesel engine with two electric motors.
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Old 28-09-2016, 11:20   #28
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Re: Boat conversions with Prius

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I looked into this when designing a boat (before I found exactly what I wanted for sale in Los Angeles). My solution was diesel-electric. A single diesel engine with two electric motors.
Put one engine fore and one aft, you have a ferry. It could be a weight consideration? DC motors are generally not light. I know only one diesel but larger to achieve the same HP plus the weight of the generator. Include the efficiency loses. Diesel electric is generally for response of control.

I think if I were to sacrifice loses, I would go hydraulic Pumps and motors are lighter.
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Old 28-09-2016, 11:35   #29
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Re: Boat conversions with Prius

Really not trying to be sarcastic, but your not going to exceed the efficiency of a direct drive Diesel for propulsion, and your best use of Solar power for propulsion is sails.
I get 6.5 Nautical miles per gallon with my boat, with fuel costs being what they are, I'd never break even on a Hybrid conversion.
There are some large Yachts, I think one J boat has a huge bank with the idea of electric propulsion to get them out of the Marina and then they run the generator most of the day so that they can go silent by running off of batteries at night?
Think WWII Submarine, but you get a lot of weight, takes up a lot of room, cost a fortune to buy and maintain, and likely your less efficient than simply staying Diesel.

But if your fabulously rich, you can talk about your "green" boat I guess?
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Old 28-09-2016, 11:44   #30
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Re: Boat conversions with Prius

this will be fun to watch.......
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