My appologies James, I was working from memory of several days ago, ... This is the actual clipped text and letterhead...
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" Electric propulsion has many advantages for sailboats. Firstly, the electric motor is the auxiliary. It is meant to get the boat in and out of the harbor. As a motor sailor, an electric sailboat has better range than a diesel when equipped with an appropriate battery pack. There's hundreds of other reasons why electric propulsion makes more sense on a small sailboat than a diesel does. "
Next paragraph:
" But as the primary for a motor boat, it doesn't make so much sense. Done properly with all the safety equipment, a hybrid is much more expensive than a traditional diesel engine. This is because you now have 4 systems replacing one system. The diesel engine (one system) is replaced by a diesel engine, a generator head, a battery pack and a propulsion motor. "
I took this to mean the motor would not be used as a prime mover. My mistake. I meant no disrespect. As I am sure you would agree, there is more than one answer to the problem.
And all your other points are well stated. Thank you for being a part of the eBoat world.
Cheers mate,
Dan
----- Original Message -----
From: James Lambden james@electroprop.com [electricboats] <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Mon, 02 Apr 2018 00:45:27 -0400 (EDT)
Subject: Re: [Electric Boats] Converting from diesel power
From: James Lambden james@electroprop.com [electricboats] <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Mon, 02 Apr 2018 00:45:27 -0400 (EDT)
Subject: Re: [Electric Boats] Converting from diesel power
Not sure where I said that "They are for getting into and out of slips and docks" It doesn't sound like my writing and I think that this quote alone would probably be out of context.
The true story is much bigger than that.
The Motenergy Motors are very capable motors and are more than enough to run continuously and power a sailboat, if they are properly cooled with an efficient drivetrain.
The Motenergy ME 1115 is the motor that we use in the Electroprop Sailor and has been the an incredibly powerful and reliable motor.. At 48 volts the motor will turn at about 2100 rpm. At 96 volts it will turn at 4200 rpm and develop twice the power.
This motor must be cooled properly for extended, continuous use. Without cooling I would agree that it should be used minimally. I think 10 KW is a hugely overstated for this motor, especially considering most motors are at 48 volts. That would be a total of 208 amps and this motor is not capable of producing that kind of power for very long. I consider this motor to be 120 amps at 48 volts continuous, with proper cooling.
You also should look at motor current instead of battery current. A motor can overheat at 500 rpm if it goes over motor current. Yet at 500 rpm it may only be drawing 40 amps or less battery current. Its all about motor current which is determined by propeller, gear ratio and the hydrodynamics of the sailboat hull.
In the industry, continuous means a power level that can be achieved over the course of 1 hour. After about 1 hour we see that motors generally reach their temperature equilibrium.
The cooler these motors run, the more efficient they are. The Electroprop Sailor encloses the motor inside an enclosure that functions as a wind tunnel for cooling purposes. When the motor temperature reaches 165 degrees we turn on a big Spal fan which rushes air both over the outside case of the motor, and also air to pass through the motor to cool the windings. After all this work that we do, I still rate the Sailor drive at 6 KW, even though it will outperform any other drive system out there using this motor. The reason why the Electroprop Sailor will outperform the competition is because of the cooling.
This motor is commonly rated at 10 KW at 48 volts for other applications, but that rating is intermittent …... it probably would be very, very hot after even 5 minutes of operation at 208 amps, or 10 KW.
If you look closely at the motor ratings, I am pretty sure you will find that the motor is rated at 96 volts, not 48 volts. Maximum motor current is the same at any rpm for any electric motor. Motors are current limited. You can't make big power without big rpm in an electric motor and the only way to get big rpm is with big voltage.
Cooling is accomplished only by Delta Temperature. The Electroprop Sailor has air induction so is cooled by air coming through a 4 inch duct from cabin air and is not cooled by the hot air in an engine compartment. Cabin air can be as much as 100 degrees cooler or more than engine compartment air. If you don't have cooler air, you don't have any cooling, and any electric motor will overheat.
I have long said that these motors should be rated at continuous ratings, simply because these motors are used on a sailboat - continuously. I think that ratings should be looked at more closely. Ratings should include ambient temperature, and rpm of operation.
It means very little to have a motor rated higher than its continuous 1 hour rating, but that is what everyone wants to see. We are trained from the fossil fuel world to think that big horsepower is better. But with electric motors, horsepower means nothing if it is not delivered efficiently to the propeller. And horsepower will rapidly fall off over time if their is inadequate cooling. But because ratings is a game, you will find many more of these motors sold at 10 KW on the market, than at our far more realistic rating of 6 KW at 48 volts.
The maximum horsepower of a motor is determined by the electrical system fusing and not by the motor itself. The ME 1115 could put out 3 or 4 times its continuous rating for short burst of acceleration like you see in a car or a motorbike. Boats are a much different application. A boat will typically develop about twice the horsepower on a bollard pull than it will once the boat gets to hull speed.
Engineered properly, with proper cooling, and efficient power transfer, the Motenergy Motor is a workhorse that is capable of many years of reliable operation. This motor has done more for electrifying boats than any other motor ever made. It really is a brilliant design and incredible motor. But it should not be overstated as this is not fair to either the motor or the designer.
The Electroprop Sailor will push a 5 ton boat at 6 knots, or a 10 ton boat at 5 knots, all day long. If you are considering making a hybrid, the Sailor does not need to be derated for hybrid operation.
At about 40 lbs of weight, the Motenergy ME 1115 motor is a brilliant piece of machinery.
James Lambden
The Electric Propeller Company
625C East Haley Street,
Santa Barbara, CA
93103
805 455 8444
james@electroprop.com
www.electroprop.com
The Electric Propeller Company
625C East Haley Street,
Santa Barbara, CA
93103
On Apr 1, 2018, at 5:45 PM, DAN HENNIS dhennis@centurytel.net [electricboats] wrote:
These "sailboat" motors are light duty. Like James from Electro-prop as indicated, "they are for getting into and out of the slips and docks." Full displacement hulled tugboats have a bit more resistance than the average sailboat. 10 Kw BLDC motors are still light for the job.. (IMHO)Dan----- Original Message -----
From: Michael Ryan mryanqld@gmail.com [electricboats] <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Sun, 01 Apr 2018 19:21:39 -0400 (EDT)
Subject: Re: [Electric Boats] Converting from diesel powerHi KimI have a similar hull, displacement 1.4 tonne, waterline lenght 16' slightly narrower beam and the same submerged depth. The hull was originally powered by an inboard Bukh 10HP. I have the 10kw Sailboat Thunderstruck Kit, I have only recently received it and will be several months away from installing it. I had my prop scanned and the marine engineer advised I needed at least 8kw, I believe that the 5kwSailboat Thunderstruck Kitwould have been adequate. This user group states that 1kw per 1000 pounds is adequate.I have had considerable trouble trying to decipher the electric motor manufactures data sheets and performance curves. The performance curves or graphs are straight forward for a small marine diesel and it easy to determine the stated fuel consumption, power output and torque across the full RPM range. Not so for the information supplied by electric motor manufactures at least for me an electrical engineering novice. I am not alone though as a search on the web through electric vehicle user groups confirms the electric motor manufactures data sheets and performance curves are indecipherable or hard to understand for most people.I decided to install the 10KW ME1115 instead of the5KW ME1305motor simply due to the vagaries and conflicting advice on sizing a suitable motor to power my boat. The reasoning being that a little extra power is better than pushing a smaller power motor to its limitations. I will be swinging the biggest propeller that fits into the hull aperture with a pitch of about 7/8 the diameter. I intend to control the motor speed at near full power by changing the load on the motor via the reduction ratio. The goal is to obtain at least hull speed at about 75% of the maximum RPM with the lowest possible current. It will of course take sea several trials and ratio adjustment to get this right!A 10kw
motor is more powerful of course at higher voltages and current than the 5kw
motor but it may not use any more current to produce my more modest power requirements. This means for a given propeller speed the 10KW motor should not consume much more power than the 5kw motor. A larger motor will obviously dissipate heat
better and have a much longer service life. Disadvantages of the bigger motor
are the increased cost of the motor/ controller, some extra weight and a
slightly bigger space footprint required. The ME1115 motor supplied by Thunderstruck was fitted in the Zero motor cycles several years ago and produced over 50hp at 102 volts. I will running 48 volts way under the maximum voltage for this motor. The Sevcon controller supplied with the 10kw kit is rated at 550 amps which again is well under my expected maximum current draw
An interesting
specification of these Motoenergy motors is their volt/RPM constant. This is a nominal number
that helps dictates an optimum operating speed. The ME1305 is wound with 20
turns of wire per phase and the ME1115 with 28 turns of wire per phase. But the
supplier information states that both motors are designed to turn at a given
voltage with the volt/RPM constant of 50. At 48v both motors, maximum speed
should be around 2400RPM. I suspect that ME1115 may have a higher constant of
65 which is 3100 RPM. I will start somewhere around 2.5:1 reduction to get my propeller shaft maximum of 1000 RPM.To sum up I believe the extra $400 or so dollars for the 10kw kit was worth it.
On Mon, Apr 2, 2018 at 6:03 AM, oak oak_box@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
Kim,I would be inclined to suggest the Torqeedo 4R Electric Outboard, rated at 10hp. I would think it would push your 16' tug to 4mph just fine. However - the problem would be that you would have to find a way to mount an outboard - which would probably mean you'd have to make a motor well in the bottom of the boat.The $5000+ plug and play systems might be overkill for what you need? Though by the time you put everything together, it does get pricey.Good luck!John
On Sunday, April 1, 2018, 2:50:04 PM CDT, KIM GYE kimgye@shaw..ca [electricboats] <electricboats@yahoogroups.com> wrote:Hello. I am a new member and would welcome advice regarding converting my boat (a home built 16' tug) from 25hp diesel to electric drive. I am having trouble figuring out what size motor I need as I don't have displacement info on this boat etc. She weighs about 3000lbs. Beam at waterline is 7'. Length at waterline is 16'. Submerged depth is 2' not including keel/rudder. The motor is old and probably would honestly rate at 20 hp. My hull speed is 4 knots max and I attain that using only 1200 rpm. Motor max rpm under load is about 2200 .
I have looked at plug and play systems from the bigger companies but they are $5500 us and up which is above my budget for a drive system before batteries. I have found two companies that have sail boat systems for about $1600 us (Thunderstruck and Electricmotorsport) they are both in California. Does anyone have any advice or can point me in the right direction? Thanks in advance.
Kim
Sent from my iPhone
--Kind regards Mick 0414 264 312--Dan HennisCTR ServicesP.O. Box 25414237 FR 1155Cassville, MO 65625-0254417-396-0228
--
Dan Hennis
CTR Services
P.O. Box 254
14237 FR 1155
Cassville, MO 65625-0254
417-396-0228
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Posted by: DAN HENNIS <dhennis@centurytel.net>
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