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Old 05-31-2019, 04:48 PM   #121
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Love the name and I love the idea of someone trying to buck the herd and find a better way. I meet a guy (Capt. Jim) a couple years ago who did the great loop in an all electric boat and claimed to be the first one to do it and you can find him on face book under "pirates of the sun".

On that blister repair above, you need to bevel those edges out way more so the new glass can bond to the old glass.

Good luck and I will certainly be watching this one and rooting for you. There are tons of diesel electric vessels and to have the ability to go all electric with a diesel generator as backup would be a great vessel. Sleeping at anchor in A/C without the sound of a generator running sounds great to me!
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Old 05-31-2019, 06:53 PM   #122
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Keep the rudders

For what it's worth, my advice is to keep the rudders. With rudders and twin screws you could easily spin the boat port or strbd and walk the boat sideways port or strbd. with out rudders, all you could do is spin the boat and go frwd/bkwd.
Plus it would be much easier to control the boat during a tow.
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Old 05-31-2019, 08:35 PM   #123
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Are you fixed on Lithium batteries? Wait a minute, aren't Prius batteries NiMH?


Anyway, if you are open to LA (I know, it's old school), I have 64kw that I'll make you the deal of a lifetime on. Just send me a private message if interested. Transport would be the hardest part.
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Old 05-31-2019, 08:38 PM   #124
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Star-Lord, Electric Trawler Conversion

NVMD, question already answered.
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Old 05-31-2019, 09:27 PM   #125
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That Top Secret video that was posted was great. Thank you for posting it. Very inspiring. I will not add a mast to my boat. It will shade my solar panels.

Based on the specs mentioned in the video the Prius motors will be more than enough power for my boat. They each have a peak power of 50kW. 20kW continuous no problem with adequate cooling.

He also mentioned that there was a high voltage limit on European boats. I did not know that. My battery will be up in the 400V range.

My generator setup will also be a single stage conversion into the batteries which I guess is what he meant by a DC genset.

I will also have a bi-directional inverter which can both supply AC loads from the battery and also act as a battery charger when the boat is connected to shore power. I will be able to use the Prius inverter/motor controller components for this function.

The Prius inverter also already has a high power 12V DC converter since that is what powers the car's 12V system. Won't need to have two different battery banks.

The battery out of the Tesla Model 3 is around 75kWh and I see on Ebay for $12k. I better start saving up.
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Old 05-31-2019, 09:30 PM   #126
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For what it's worth, my advice is to keep the rudders. With rudders and twin screws you could easily spin the boat port or strbd and walk the boat sideways port or strbd. with out rudders, all you could do is spin the boat and go frwd/bkwd.
Plus it would be much easier to control the boat during a tow.
I'm glad you posted that. I was still secretly debating it. They are going back on.
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Old 05-31-2019, 10:18 PM   #127
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I'd guess that boat would eat about 30-40 shaft hp to go 7kts. A guess indeed, but probably close. So call it 20hp or 15kW out of each motor. Slower or faster changes that number significantly.

And yes about keeping the rudders. Aircraft with two engines can maintain heading with no vertical stabilizer or rudder just varying engine thrust. But somehow all (??) aircraft still have a vertical stabilizer and rudder. Heading stability is a nice thing.
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Old 06-01-2019, 06:30 AM   #128
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Having a rudder of sufficient size will allow you to operate with only a single prop being powered.

This might be efficient at slow cruise?

Twin engine aircraft need somewhat larger rudders to be able to slow down to near normal landing speeds , if operating on a single engine.
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Old 06-01-2019, 09:23 AM   #129
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With all of this weight exchange going on, have you considered the effect on the boat's trim and center of gravity? If you remove the engines and fuel tanks and pile in a bunch of batteries down in the bilges equivalent to the weight removed, you end up with a very "stiff" vessel which will snap your head off in a seaway. Not putting enough weight back on the boat in the boat could result in a very "tender" boat with possible dangerous roll characteristics. Just sayin....

On another front, since you are ging to have a diesel genny aboard, I have two comments.

First, if you elect to carry a significant load of fuel in the original tanks, NOT my recommendation, you will want to have a fuel polishing system because the generator will use so little fuel that you will have to care for the fuel in loooong term storage.

Second, could you clutch in the generator's crank shaft to the Prius input shaft via a clutch (assuming the electrical end's circuit breaker is left open) and drive the prop shaft? Just thinking about some elecrical side failure you could work around.

Congratulations on sparking one of the longer threads I have seen here.
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Old 06-01-2019, 01:41 PM   #130
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I don't own a Prius but I do own a RAV 4 hybrid which uses Prius hybrid technology. I don't know current Prius technology but I do wish they had used a lithium battery in the RAV 4 instead of the old battery technology. I do understand due to price point why they didn't use lithium. How about using used Tesla batteries? I do wish the Chinese would come out with a drop in replacement lithium battery for RAV 4 and Prius's.

On a side note: I was reading the Chinese are big into electric technology and it is expected there will be a glut of Chinese electric cars in about three years. What is important in this scenario is the price point which is purposely lower than all the offerings out there from the big manufactures we know and sometimes hate. Before anyone reacts, this is identical with Toyota creating a glut of Corollas back in the late 60's and early 70's; people loved them because they were reliable, and significantly cheaper than what was out there at the time.
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Old 06-01-2019, 07:55 PM   #131
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First congrats on the electric boat build. Second definitely keep the rudders, the boat will be un-drive-able without them. Ive had to skid steer a 36 ft boat when the steering failed, (the rudders were still there, just not moveable), it was terrible except at low speed, without them you have a large spinning top.

I converted a smaller boat to electric, and have 7kwh of batteries on board, and am disappointed in the range. Unlike a car which requires much less energy (amps) to maintain speed as it does to accelerate, and boat requires a constant energy outlay to maintain speed.

I would like to buy a Prius or Volt pack, and install it, you mentioned knowing how to hack them?

A 70 mile range with 12 hour charging would be enough for coastal cruising I think.

You could install a bigger generator, and maybe keep up with battery drain at low speeds.

I've thought of doing something similar, and even bought a boat hull with defunct engines, which unfortunately meant when it was hit by a hurricane I was unable to move it, and the last time I saw it was in pieces in the middle of a freeway.

Maybe the next one...
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Old 06-01-2019, 08:00 PM   #132
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The gear reduction seems like it might be the perfect ratio needed for maximizing available power of the motor.

The electric motor stator and rotor bearings and all the gear reduction components are all part of the same assembly housing.

You could save weight by removing the gear reduction components and making a direct connection to the motor via the engine center shaft. In this case you would be at 25% of the available torque and spinning the motor very slowly.
To drive a car requires low torque, high rotation, and they still use a reduction gear. Boats require high torque, low RPM, Yes you need a reducer.
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Old 06-01-2019, 08:02 PM   #133
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This weekend I uncovered a serious blister and delamination problem with my hull. Right now I am planning to try and fix the situation. However, once I have all of them exposed I may need to rethink this donor boat. I am not happy right now. I don't know how bad it is yet.

I think I got one of the Gulfstars with the poor quality layer bonding.

Attachment 89568
Attachment 89569
Attachment 89570

Not the first boat with blister issues, fixable, but it will be a headache. they often come back.
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Old 06-03-2019, 06:02 AM   #134
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First congrats on the electric boat build. Second definitely keep the rudders, the boat will be un-drive-able without them. Ive had to skid steer a 36 ft boat when the steering failed, (the rudders were still there, just not moveable), it was terrible except at low speed, without them you have a large spinning top.

I converted a smaller boat to electric, and have 7kwh of batteries on board, and am disappointed in the range. Unlike a car which requires much less energy (amps) to maintain speed as it does to accelerate, and boat requires a constant energy outlay to maintain speed.

I would like to buy a Prius or Volt pack, and install it, you mentioned knowing how to hack them?

A 70 mile range with 12 hour charging would be enough for coastal cruising I think.

You could install a bigger generator, and maybe keep up with battery drain at low speeds.

I've thought of doing something similar, and even bought a boat hull with defunct engines, which unfortunately meant when it was hit by a hurricane I was unable to move it, and the last time I saw it was in pieces in the middle of a freeway.

Maybe the next one...
We are on the same wavelength.
Prius batteries are not good for this use. Chevy Volt battery may be.

If you are considering electric boat then you may check out EVTV.me
These guys use to only convert cars to electric but lately have been doing solar energy storage products using Tesla Model S batteries. They configure the 24V modules into a 100kWh 48V block. Their software guy is interfacing directly with the Tesla Battery Management System (BMS). I think they sell the interface. There are many very long and dry videos but you could contact them with your questions.

I have seen boats and cars converted using Chevy Volt batteries. There are numerous tear down videos and how to on YouTube.

Lithium batteries are tricky because you have to monitor every single serial node voltage to ensure each stay in safe operating range. If you over charge or over discharge a single cell it can be catastrophic. There is no inherent cell leveling or trickle charging like in Lead Acid batteries.

I have a homegrown BMS that is still under development so I can't offer a solution at the moment.
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Old 06-03-2019, 06:39 AM   #135
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With all of this weight exchange going on, have you considered the effect on the boat's trim and center of gravity? If you remove the engines and fuel tanks and pile in a bunch of batteries down in the bilges equivalent to the weight removed, you end up with a very "stiff" vessel which will snap your head off in a seaway. Not putting enough weight back on the boat in the boat could result in a very "tender" boat with possible dangerous roll characteristics. Just sayin....

On another front, since you are ging to have a diesel genny aboard, I have two comments.

First, if you elect to carry a significant load of fuel in the original tanks, NOT my recommendation, you will want to have a fuel polishing system because the generator will use so little fuel that you will have to care for the fuel in loooong term storage.

Second, could you clutch in the generator's crank shaft to the Prius input shaft via a clutch (assuming the electrical end's circuit breaker is left open) and drive the prop shaft? Just thinking about some elecrical side failure you could work around.

Congratulations on sparking one of the longer threads I have seen here.
I am concerned about the weight distribution. I have been reading about the Center of gravity, Center of buoyancy, and the Meta Center where the force lines intersect.

The solar panels I want to install may also make the boat top heavy.

My first concern is will the boat float safely with the engines and generator removed so I can tow the hull to my house to begin adding components. I guess each motor and transmission is over 1500# each.

With regards to generator and hybrid drive. If you have an electrical failure on an electrical boat you are probably dead in the water. However the Prius is already a hybrid so I can use the gas engine of the prius to charge the battery when stopped or to supplement torque while cruising in the normal Toyota mode of operation.

This is done with the Prius Synergy Drive which is an elliptical gear they call the Power Split Device connecting two electric motors and the engine. The engine is connected to the planet carrier, the smaller motor (generator) is connected to the sun gear, and the larger motor is connected to the ring gear.

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The ring gear of the PSD is then connected 4:1 to the axles.

So Yes to your question. In theory you could lock the sun gear and then torque would pass to axle via the engine shaft. However there are no clutches inside the transaxle so this would be tricky. One trick is to electrically short the winding of the generator which would brake and hold the sun gear so torque could pass to the axle without electrical motor operation.
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Old 06-03-2019, 06:47 AM   #136
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Old 06-03-2019, 06:49 AM   #137
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This company just had an unveiling in my area yesterday.
https://www.novaluxeyachts.com

"Solar electric yachting at a never before price point". I think I saw something like a 4day recharge time on solar in their specs. They seem to offer many different boat styles. I think they may be just getting started.

I was busy grinding blisters off the bottom of my project so I didn't go.

I am trying to reconnect with a guy I met last year at a party. I think he is the first owner of their sea trial prototype. I wasn't doing an electric boat at the time we met but he was very excited about the torqueedo motors and BMW battery combination.

The dinghy costs is $30,000 so I don't think I will ask their prices for their boats.
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Old 06-03-2019, 08:43 AM   #138
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Modifying the Prius gasoline engine for marine use is a rather work-intensive task to do it right. Cooling and exhaust systems will be very different from the car systems.

Then you have to have gasoline fuel tanks with the safety issues with that.

Might be simpler to source a single purpose electric motor and maybe upgrade to a larger diesel genset. Or maybe you can extract the motor from a prius transaxle.
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Old 06-03-2019, 09:10 AM   #139
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Modifying the Prius gasoline engine for marine use is a rather work-intensive task to do it right. Cooling and exhaust systems will be very different from the car systems.

Then you have to have gasoline fuel tanks with the safety issues with that.

Might be simpler to source a single purpose electric motor and maybe upgrade to a larger diesel genset. Or maybe you can extract the motor from a prius transaxle.
You are correct. This is an interesting brain storming. There are many different ways to skin this cat.

I see one approach for me is to install two Prius transaxles with MG1 and PSD removed from housing since may not be used. Use MG2 only and gear reduction to drive the propeller shafts.

Then add a small battery (maybe the prius battery 200V 1.5kWh at first if I have it laying around) and the diesel generator that is already on board (if it works). I should be able to rectify the genset AC output into my DC bus for both motors using the left over electronics for MG1 that I am not using.

This would be the least expensive way for me to make the boat move in theory which would be a huge milestone.
This may be a usable boat at this point with the generator always running.

Second step: add solar
Third step: bigger battery (big bucks)
Fourth step: try and utilize the MG1 generator aspect of the Prius for next designs that would not use the extra genset hardware.
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Old 06-03-2019, 10:40 AM   #140
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WOW what are you planing on doing with all the motor parts ??????
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