What is aero engine thrust 15,400 lbs. The most powerful electric motor for a boat
So, you have decided to purchase a boat electric motor. But which model should you choose? What characteristics should it have?
Let's try to figure it out.
Unlike gasoline engines, outboard electric motors are divided by power, measured not in kilowatts or horsepower, but by the thrust (lbs) they develop.
Traction is the main characteristic of an electric motor, this is the force that this motor is capable of developing. Thrust is a constantly acting force resulting from the operation of an electric motor, it also depends on the shape, pitch and size of the propeller, as well as the speed of its rotation. In turn, the screws that are equipped with electric motors are designed to develop maximum acceleration immediately after starting the electric motor.
As a rule, the amount of thrust is indicated in its model name of the outboard electric motor. However, it should be noted that the American unit of measure is often used in the name - the pound, which must be multiplied by 0.45 (1 pound = 0.45359237 kg) to convert to the metric system we are used to.
Example: The Moratti Bady 30 electric motor has a thrust of 30 pounds or 13.5 kg.
The required amount of thrust of the electric motor is directly dependent on the displacement of your vessel. That is why, when describing the technical characteristics of a particular model of a boat electric motor, the maximum displacement and dimensions of the boats on which they are recommended to be used must be indicated.
For the convenience of determining the right electric motor thrust for your boat, the following chart has been compiled:
Using this chart is very easy. For example, your boat weighs 450 kg. With cargo, electric motor, fuel supply (battery), passengers, the weight (displacement) of the boat reaches 850 kg. We mark on the horizontal axis this value of displacement. Next, we find on the vertical axis the corresponding thrust value, which is measured in pounds, we get the value 40 lbs. An electric motor with just such a thrust will be optimal for your boat.
But what if we put an electric motor with more traction - will our boat go faster?
Let's try to answer this question. First, a little theory. First of all, it must be taken into account that the boat under the control of an electric motor moves in a displacement mode, that is, it is kept afloat due to the force of Archimedes, as a result of which it is partially submerged in water. In this mode, it is impossible to develop high speed due to the high water resistance.
The correspondence between the size of the vessel and the speed of its movement is determined through the Froude number (formula). For displacement ships, the Froude number is always less than one, usually 0.2-0.3.
The maximum speeds of boats moving in displacement mode are shown in the table below:
Now it becomes clear why electric motors are not for fast racing on water, but perfect option for lovers of quiet calm fishing.
Thus, by installing an electric motor with high traction performance on our boat, we can achieve an increase in speed by a maximum of 1-3 km / h, but this is at a significantly higher cost in the cost of both the electric motor and the battery. Moreover, thrust and speed are not linearly related - an increase in thrust by 30% increases speed by only 10%. And in any case, we will not be able to exceed the limits indicated in the above table.
Choosing an electric motor, you need to decide on its power supply - the battery.
All boat electric motors are divided into two power classes - 12 and 24 Volts. There are few options here - at 12 Volts we connect one battery, at 24 - two batteries are connected in series.
Batteries are divided into starting and traction.
Starter batteries are used in cars and to start outboard motors. Their task in a short time(at start) give out a significant current, then the internal combustion engine starts to work. If you use starter batteries as the main power source for electric motors, with a deep discharge, they are quickly discharged.
Traction batteries - specially designed for deep discharges, for the operation of mechanisms driven by electricity and are most suitable for powering boat electric motors.
When choosing a specific battery, you should be aware of how often you plan to use it. And of course, the price plays an important role. The car starter battery will last you 5-10 trips to the water. The traction battery will last much longer, although they cost 2 times more. But in this case, these costs are absolutely justified.
Determining the power of the battery is directly related to the thrust of your electric motor. The table below shows the operating time of a 100 Ah battery for different motors. 
That is, one charge of a battery with a capacity of 100 A * h, when operating it at 50% power to power an electric motor with a thrust of 35 LBS, will be enough for you for 6 hours of CONTINUOUS running.
Of course, these figures are indicative, as they do not take into account design features your electric motor and boat.
Motor control system.
The designers of leading manufacturers have tried to make it as easy as possible to control the outboard electric motor in order to allow you to fully concentrate on fishing. Users are presented with many accessories and additional devices.
You can choose manual or foot control according to your taste. Foot-operated motors are equipped with pedals with instant power switch and allow you to completely free your hands, but the pedals and wires clutter up the deck of the boat, which can be inconvenient if you are not fishing alone. "Handbrakes" have a telescopic tiller (with a variable angle for standing fishing) and push-button control.
Many modern models are equipped with special systems for adjusting engine power depending on the speed of movement, which increases the output from one battery charge by four to five times. Autopilot and remote control systems for electric motors are also becoming commonplace.
How to care for a boat electric motor?
Store the electric motor, as well as batteries, in a clean and dry condition. If you have used it in sea water, you must first thoroughly “desalinate” - the motor, completely rinse in fresh water. If you are initially using an electric motor designed for use in salt water ( distinguishing feature for this type of motors - white color) flushing is desirable, the main thing is to monitor the condition of the anti-corrosion anode, which is always used when operating electric motors in salt water and is usually attached behind a screw on the motor housing, or above the deadwood. The anode surface must always be clean. The preferred storage of the motor is a dry and warm place.
Which boats are suitable for electric motors? And what is the average speed under them? How many hours does the battery charge last? Is it true that all boat motors are the same? Can they be considered as a replacement for the internal combustion engine? The standard pile of questions that falls on the head of anyone who plans to get an electric motor for their boat. So we decided to hit the test on the topic of the day. The idea is simple: take two inflatable PVC boats of different lengths, a couple of traction batteries and several outboard electric motors, and then test them on the water. The tasks are clear - answer the questions listed above.
What have we done?
We took boat electric motors four different manufacturers, the most widely represented on the market today - Minn Kota, Outland, Haibo and Flower. Additionally, we managed to test two models from the same manufacturer with different traction characteristics - Outland TP44 and TP34, in order to find out how they differ, except for the numbers on the case. Some of the outboard electric motors tested were brand new, others had been used for a long time. This did not bother us at all, but, on the contrary, even interested us. I really wanted to unleash one more question: how the performance characteristics of electric motors change with the passage of time. Then we went to the reservoir, where all this stuff was subjected to the most sea trials. Note that our goals were not to obtain dry statistical material. We wanted more - to form, based on the results, an informed opinion on how different outboard electric motors behave on different pvc boats.
materials
For tests, we chose two pvc inflatable boats from Mnev of the Cayman model. The first is 330 cm long, the second is 380 cm. There were good reasons for this.
Firstly, the Cayman is a very popular model that has been produced for the second decade - in general, a classic pvc boat with classic shapes and design (photo 1).
Secondly, this model has a lot of imitators among other companies, therefore, by choosing it, we automatically cover a wide range of boats found on our waters. It is no coincidence that these two sizes - 330 and 380 cm - are the most popular and versatile, applicable both on small forest lakes and in open spaces. major rivers or reservoirs. In addition, these are already serious, rather large pvc boats - it was curious how our outboard electric motors would cope with them.
For tests, we took two batteries with capacities of 95 and 100 A / h (photo 2), both acid and traction.
And if the “weave” was practically new - only a couple of fishing trips were registered behind it, then the “95th” was operated for more than three years and survived about two hundred charge cycles, almost half of its resource. Thus, we wanted to see how the characteristics of the tested outboard electric motors would change, coupled with such different batteries.
Speed measurements were made using a Garmin Oregon 200 household GPS navigator (photo 3), to determine the current and voltage values in the circuit while driving, we used a Ts4324 voltammeter (photo 4).
Place and conditions for testing boat electric motors
For testing, we chose a very popular resting place among Minsk residents - the Zaslavskoe reservoir, as it is also called - the Minsk Sea. So that the reader can imagine the possible wave height or wind strength, which, of course, left their mark on the test results, I will describe our sea. The area of its water surface is about 31.1 km2. In length - under 10 km, width - 4.5 km. Standard depths are 3.5 m, although there are also 8 m. On the day of testing, the weather was cloudy with a light northwest wind speed of 3-5 m/s.
About boat motors
Every self-respecting manufacturer of boat electric motors has in its lineup at least four models that differ in power, and, consequently, in traction characteristics, overall dimensions and weight.
So, the thrust of the smallest models in the line is less than 13 kg (about 0.38 hp) and they are usually designed for boats with a full curb weight of up to 600 - 800 kg, while the most powerful instances of outboard electric motors develop thrust up to 25 kg (0.85 hp) and can be used on ships with a displacement of up to 1.5 tons or more. We deliberately chose for tests electric motors with similar traction characteristics - these are light models for small and medium boats, with declared figures of 32 - 34 lbs, i.e. 14.5-15.5 kg.
Tested outboard electric motors at the first inspection
Boat electric motor Minn Kota Endura Pro 32(photo 6). Maximum thrust in the push 32 lbs = 14.5 kg (in 5th gear), power 0.43 hp, designed for boats with a curb weight of up to 680 kg, rod length 76 cm. Weight of the electric motor according to the "manual" - 7.3 kg. The number of gears is 5 forward + 3 reverse. The screw is two-bladed. Features: rod made of composite material. And, of course, one cannot fail to say that Minn Kota is a recognized trendsetter in this area. Hence the build quality and materials. The boat electric motor we tested has been in operation for more than three years. And, characteristically, no repairs are required to this day.
Boat electric motor Flover F33T(photo 7). Clean and jerk pull, of course, 33 lbs, that's 15 kg. Power 0.44 l. With. Designed for boats with curb weight up to 800 kg. The length of the composite rod is 75 cm, the declared weight is 6.8 kg. Number of gears 5/3. Two-bladed screw. The naked eye can see the external resemblance of Flover to Minn Kota (photo 8). Well, this is intriguing - will the similarity turn out to be only external? Features: the model has an LED indicator of the battery charge level (photo 9). Reviews about this option are very controversial - from enthusiastic to negative, due to the increase in electricity consumption by the electric motor. Flover F33T came to us in its original packaging.
Boat electric motor Outland TP 34(photo 10). Maximum thrust in clean and jerk 34 lbs = 15.4 kg, power 0.47 hp. With. The manufacturer claims that it is designed for a boat curb weight of up to 1100 kg. Claimed weight - 6.7 kg Rod length 78 cm. Number of gears 5/2. Two-bladed screw. At the time of testing, it was in operation for more than two years. There were no problems during use. Notice how the declared values differ allowable weight boats with which Outland TP 34 and Minn Kota Endura Pro 32 are applicable: almost twice the difference! 1100 vs 680 kg. This is intriguing, since the rest of the declared parameters for these two outboard electric motors, if they differ, are insignificant. It turns out that either someone is playing it safe, or someone gives unrealistic numbers - we hope this will become clear in the test.
Boat electric motor Outland TP44(photo 11). Maximum thrust in clean and jerk 44 lbs = 19.95 kg. Power 0.59 l. With. The maximum displacement of the boat is up to 1350 kg. The weight of the boat electric motor according to the passport is 9.55 kg. The design is similar to the younger model TP34. At the time of testing, the electric motor was in operation for an incomplete season, and did not cause any complaints. Of the features - a metal rod 91 cm long and a three-blade propeller, which indicates that the electric motor is applicable on fairly large boats with a high side. It is this unit that goes beyond the scope of the “light class” outboard electric motors chosen for testing.
Boat electric motor Haibo ET 34L(photo 12). Boat electric motor by design and appearance just identical with Outland. Moreover, we dare to assume that they were produced at the same factory - well, just twin brothers! Therefore, we were not at all surprised that the declared characteristics of these two electric motors are the same: maximum thrust in the push 34 lbs = 15.4 kg, power 0.47 liters. s, boat displacement up to 1100 kg. Rod length 78 cm, electric motor weight 6.7 kg. He fell into our hands used - about three years without complaints of ailments. The intrigue is that rumors are actively circulating in the Internet community that, allegedly, Haibo, when driving at the last, fifth speed, “does” all its classmates and even some electric motors, which is more powerful. This, of course, we will also clarify today.
Let's start the test of boat electric motors
To begin with, we weighed each of the tested outboard electric motors. Measurements were made on the Nevsky bench scales (photo 13) with a limit of 15 kg. As can be seen from Table 1, our results are slightly different from those claimed by the manufacturer. The most a big difference the Minn Kota Enduro Pro 32 has more than 700 grams lighter, and this, you see, is significant. Apparently, the Americans underestimated the lightness of the composite bar.
Why was it necessary to measure the current strength? Here's the thing: other things being equal, of the two outboard electric motors, the one that consumes the higher currents will be the fastest. That is, this table gives outlines for future speed tests and will allow in the future, coupled with the results of measuring the speed of pvc boats, on the efficiency of the tested outboard electric motor. What is worth paying attention to here?
Firstly, from Table 2 it can be seen that the values of the current strength in the corresponding gears for classmate electric motors, if they differ, are insignificant. This indirectly indicates that their speeds should be approximately equal, other things being equal. If a serious difference is found, it means that the efficiency of outboard electric motors is different.
Secondly, note that the Minn Kota Enduro Pro 32 in 5th gear draws almost the same current as the most powerful Outland ET 44 in 4th gear. Do you get what we're getting at? Let's see if they have the same speed.
Thirdly, Haibo ET34L and Outland ET 34 have identical current values. This is another reason to claim that these outboard electric motors have one parent.
Comparing the Minn Kota Enduro Pro 32 and the replica from Flover, you can see similar data. Differences occur only at the first, second and fourth speeds. At the same time, we must take into account the fact that Flover copies, most likely, the new AIA motor, which appeared in 2012, while we have Minn Kota's electric motor - three years ago.
Boat motor test for maximum speed
Recall that speed measurements were made using a Garmin Oregon 200 GPS navigator. Of course, we cannot avoid the errors of GPS devices for non-military purposes here. However, all subjects were in equal conditions. The measurements were carried out in the following way: the Cayman 330 pvc inflatable boat was equipped with a tested electric motor, after which it covered the distance between two given points on the reservoir. For the entire series of tests, these points, and hence the direction vector, remained unchanged - in our case, this is the distance from the pier to the island, which was equal to 0.34 km according to the navigator. Moreover, when moving from the pier to the island, the wind prevailed in the following direction, and back - back. This coast-island-shore route was overcome in each of the five gears in turn, and we placed the maximum speed (in km/h) during the passage of the track in Table 3.
All tests were carried out three times - with one, two and three passengers on board - these values correspond to the columns with a load of 80, 160 and 220 kg, respectively. For the sake of the purity of the experiment, we note that we did not take into account the mass of the battery and equipment in the boat, although this is still about 40 kg. In addition, we fixed the speed with and against the wind - and derived the values average speed, which you can also see in Table 4 for each case.
As it should have happened most powerful boat motor Outland TP44 also showed the highest speed in all tests. However, we were quite surprised by the fact that Haibo ET34L came close to it when loaded with 220 kg, and when loaded with 80 and 160 kg in 5th gear, it was even a little faster! It is also curious that the Haibo ET34L clone - the Outland TP34 model - showed worse results than the leaders. It turns out that the guts of Outland and Haibo are still different. In general, the results were pretty even. The only thing that goes beyond this beautiful range is the speed values we obtained for the Outland TP44.
Please note that when driving in all gears, with the possible exception of 3rd and 4th, the maximum speed values were fixed, paradoxically, at the same maximum load of the boat. How to explain it? It seems that the answer lies in a combination of reasons: starting from changes in better side in the hydrodynamic parameters of the boat when the optimal load is reached to the imperfection of measuring instruments and methods. In any case, we assume that the test conditions remained unchanged for all models.
The smallest model, Minn Kota Endura Pro 32, showed the slowest result, as expected.
Only Flover 33T was not mentioned. He has, in general, very good results. Boat speeds under this outboard motor are exactly where they should be: between the Endura Pro 32 on one side and the more powerful ET34L and TP34 on the other. Next, we repeated the tests of outboard electric motors, only on a larger Cayman 380 boat. We did this only once this time - with a load of 160 kg, in order to compare the results with a smaller boat.
What engine power is needed for a particular vessel and at what speed will this vessel move?
This question most often arises when fishing in waters where the use of gasoline engines is prohibited or when choosing a trolling motor on boats with an outboard or stationary engine with an angular column.
Let's start in order.
All electric motors do not have such a characteristic as the well-understood “Horsepower”.
Instead, such a concept as "traction" is used. Thrust is the force exerted by the motor. Visually, it can be measured quite simply.
We take scales (like a steelyard) and fasten the halyard from the boat to one side, and the halyard to the pier to the other side (the pier must be motionless). We start the engine and look at the readings of the steelyard - this is the thrust.
Example 1
Suppose your boat weighs 100 kg, add to this weight the load, engine weight, fuel weight, luggage and passenger weight. We get about 200-250 kg. On the horizontal axis, the graph starts at 500 kg.
We accept this value and on the vertical axis we find the required thrust of the electric motor (in pounds, as a rule, this corresponds to the numbers in the motor model). In our case, it turns out 33-35 LBS.
Example 2
Our boat together with the engine load weighs 1500 kg. We act in a similar way. We find on the horizontal axis the weight and the corresponding thrust value.
In our case, this will be approximately 55-60 LBS.
Motor thrust - determined.
But, two questions arise: how fast will the ship move and if you put a more powerful motor, will the ship move faster?
To answer them, let's turn to theory again.
First you need to understand that the electric motor moves the boat in a displacement mode. The relationship between the size of the boat and the speed of movement in the displacement mode is almost unambiguously established through the Froude number.
We will not give formulas, but for boats up to 7-8 meters long and with a displacement of up to 3000 tons, the maximum speed does not exceed 10 km / h.
We have reduced the table to the maximum speeds in displacement mode.
The choice of battery will ultimately be determined by the price and frequency of use. An ordinary car battery can be "killed" in 5-10 trips to the water.
The traction battery will last several times longer in this mode of operation.
Due to the fact that the cost of traction batteries is 2-4 times higher than the starting ones, but at the same time they last 5-10 times longer, it makes sense to spend money on them if you go out on the water more often than 5-10 times a day. year.
What capacity battery is needed for the selected motor?
The question is directly related to the traction characteristics of the electric motor. Data for different motors and battery life with a capacity of 100 Ah are shown in the table below:
| LBS | 10% power | 25% power | 50% power | 75% power | 100% power |
| 30 | 17.5 | 11.67 | 7 | 4.67 | 3.5 |
| 32 | 16.5 | 11 | 6.6 | 4.4 | 3.3 |
| 35 | 15 | 10 | 6 | 4 | 3 |
| 40 | 13 | 8.67 | 5.2 | 3.47 | 2.6 |
| 44 | 12.5 | 8.33 | 5 | 3.33 | 2.5 |
| 46 | 12.5 | 8.33 | 5 | 3.33 | 2.5 |
| 50 | 12 | 8 | 4.8 | 3.2 | 2.4 |
| 110 | 10.5 | 7 | 4.2 | 2.8 | 2.1 |
| 165 | 10.5 | 7 | 4.2 | 2.8 | 2.1 |
These data are indicative and, in most cases, depend on the design features of the electric motor.
And the last. How to determine how low our battery is on the water?
The easiest option is to install a voltmeter.
Voltmeter readings will serve as an indirect indicator of the degree of battery discharge. For traction batteries, devices have been developed (the principle of a voltmeter), which already have a scale calibrated in percent of the battery charge.
This option is the most preferable, since each time recalculating the voltage into the residual capacity is a tedious process.
Devices of this kind are available in two versions: portable or built into the dashboard. For small boats, it is preferable to use a portable version.
For boats that have a dashboard, it is naturally better to install it permanently in this panel. This is due to the fact that the batteries for powering the electric motor, as a rule, are removed in the hold part (in lockers, below deck). Access to them becomes limited.
Look like that's it. We chose a motor, a battery and ensured its charge and control.
Now - on the road! Happy sailing!
Hello readers! Have you ever thought that one unit of measurement can be used in different contexts and mean different things. Don't be afraid, I'm not crazy and I'm not trying to blow smoke in my eyes, today we will look at the value of lbs what is it? Where can you most often find such an abbreviation and what does it mean.
Lbs as a unit of measurement
The first time I got acquainted with the Lbs indicator was completely by accident. If you read my blog, you probably know that I am fond of sports and have been doing it regularly for more than a year. And as soon as the first electronic balance I couldn't resist purchasing them.
Opening the box, pressing a few buttons (I don’t remember exactly how old I was then), I turned on the scales and immediately decided to use them for their intended purpose. Imagine my surprised eyes when the number 170 appeared on the screen. I was shocked, and only after a few seconds I realized what the catch was. The scales were not set to Kg, they showed pounds. And how to translate lbs into kg was not clear.
Convert to kg
- Pound (from Latin pondus - weight, weight) - a unit by which mass and weight are measured.
- The classic pound used in America and England is equal to 16 ounces or 453 grams;
- A troy (English pharmacy) pound is equal to 12 troy ounces or 373 grams.
- The Latin word "libra" means a unit that preceded the pound, in English-speaking countries the abbreviation lb is still found. Many of you have probably heard about the monetary unit of the pound sterling, which means the symbol £, which also goes back to the word "libra".
To convert Lbs to kilograms, you need to multiply the number of pounds by 0.453 kg.
Most often, this abbreviation is used in such concepts:
- Location-based service - a type of information and entertainment service based on determining the current location of a mobile phone.
- A measure of weight is lbs (the correct designation in singular and plural is lb).
- Lectori benevolo salutem. (L.B.S.) Greeting to a supportive public (Latin.) A formula of authorial etiquette that was used many years ago.
What is lbs tracker
Location-based service is an information and entertainment service based to determine the current location of a mobile phone. The visualization capability of a modern mobile phone (often used in a smartphone) will allow displaying on the screen, which will allow the tracker to be used to solve a variety of business, navigation and entertainment tasks.
LBS does not have to use the technological features of GLONASS, GPS or other satellite systems to determine the location. The place where it is mobile phone, for example, can be determined using pre-known information data about where the base stations of GSM, UMTS, etc. mobile networks are located, as well as through information about the location of the Wi-Fi access point.
In this case, in each case, the same method for calculating the position is used - a reverse geodetic resection.
GPS And navigation
Today, the GPS-monitoring system performs the function of a reliable tool to control and optimize the operation of transport. It allows you to get reliable information about where the car is located, how many kilometers it has traveled, what is the fuel consumption, etc. Do you use the GPS service? I think all readers of this article will answer: "Yes."
The GPS monitoring system is convenient not only for drivers, but also for company managers, because based on the analyzed data, you can make an important management decision, coordinate work on more high level, and dispatchers and forwarders will be able to see the real and most relevant picture in order to promptly respond to any non-standard situation.
But what if the key technology to determine location, GPS, is no longer functional, or has been adversely affected by the driver himself and did it on purpose? In such a force majeure situation, the only alternative is the LBS monitoring system, which has recently been supported in many existing systems.
Principle of operation
According to the principle of operation, LBS monitoring resembles GPS, but the signal source is not a satellite, but the nearest GSM station of a mobile operator.
Therefore, if for some reason the GPS signal is lost, you will quickly determine the location of the transport wherever there is a cellular network (and the more sticks on the phone that indicate the signal, the more accurately you can determine the location).
Monitoring is also used to control the movement of objects in places where the GPS signal is not available: it can be an underground parking, a tunnel, a concrete garage.
It is not as realistic to determine the coordinates as accurately as possible using LBS technology than using GPS. It all depends on the coverage density and the base station network, what the current local radio conditions are and the cell configuration.
For example, in the central large European town, the coordinate error can vary in the range of several tens of meters, on the outskirts and in small town- up to hundreds of meters. In villages or deserts, accuracy may be reduced by several kilometers. But, according to my personal observations and calculations, the data from the cell site will allow you to accurately show on the map which road the object was traveling on. The accuracy of the run, of course, cannot be calculated, but the approximate location, as well as the approximate trajectory of movement, can be shown realistically.
Useful addition
We can come to the conclusion that, despite the fact that the functionality of LBS monitoring is inferior to GPS in terms of specifics and accuracy, as you probably already noted to yourself, it can be considered a worthy assistant and a “second possible option” if suddenly the GPS signal is absent or interrupted by interference .
Therefore, if you do not want your cars to be overlooked, always keep your finger on the pulse - feel free to find on the Internet how to set up the LBS detector correctly. You can monitor in manual or automatic mode.
By the way, LBS services are also actively used in the Yandex.Traffic app. If a person’s location is constantly updated, and a few minutes ago he was in the middle of the road and does not move, he should only sympathize: a friend is in a kilometer traffic jam.
Various schemes have been invented in the world to track the situation on the road: operational reports, cameras and detectors that automatically analyze the picture, and, of course, the software that LBS services use.
If you have any questions on this topic, please write in the comments. I will be glad if you become a subscriber. See you soon!
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What is the most powerful electric motor for a boat? The one that draws more power from the battery? Or maybe one that easily pushes even a heavy boat forward, consumes little current and runs on batteries for a long time?
What is the power
The propeller converts the energy of the engine into force, which, overcoming the resistance of water and air, moves the boat forward at a selected speed. Part of the energy is lost in this case, and the power used to move the ship is always less than what the engine consumes. Rt - water resistance; Pe - effective (towing) power; Pt - power on the propeller; Pv - power on the shaft; Pb - engine power. T - thrust; V - speedA single criterion for comparison is important. The power measured in different places differ significantly from each other. Motor developing 4 hp on the shaft. with., on the screw gives out only 1 hp.
Outboard motor manufacturers use different types power. There are shaft power, power consumption and even thrust. Therefore, before comparing various electric motors for boats, you need to bring the available data to a "common denominator"
Power consumed, on the shaft and on the propeller
Power consumption- often used as a characteristic of an electric motor for a boat (power \u003d current x voltage). Expressed in watts or horsepower. Manufacturers of gasoline or diesel outboard motors do not use this type of power. However, for an internal combustion engine, the power consumption can also be calculated by multiplying the calorific value of the fuel by its consumption.
Shaft power- used by manufacturers of outboard gasoline outboard motors. This type of power is calculated in the same way as a car (power = torque x angular velocity). It is measured in horsepower or watts. Shaft power takes into account losses in the gearbox, but does not take into account losses on the propeller, which range from 20 to 70%.
Power on screw– has been a generally accepted characteristic of the engine in shipbuilding for more than a hundred years. It takes into account all power losses and determines the energy transmitted to the boat by the engine.
During the rotation of the propeller, a lifting force is generated on the surfaces of the blades. The component of this force directed along the axis of movement of the boat is called thrust or thrust. It characterizes that part of the lifting force that pushes the ship forward.
The net power produced by a boat propeller is equal to its thrust multiplied by the boat's current speed. In the characteristics of electric motors, manufacturers always indicate maximum value traction. It is impossible to draw a conclusion about the power of the electric motor on the propeller without installing sensors and taking measurements. 
Thrust is determined by testing in which the boat is connected to the pier with a dynamometer and an electric motor is forced to push it forward. The test is carried out on calm water, in calm weather, at a sufficient depth and distance from the shore. For boat electric motors, thrust is most commonly reported in pounds-force (lbs).
| Name | Torqeedo Travel 1003 СS | Minn Kota Traxxis 55 |
 |
 |
| Power consumption, W | 1000 | 600 |
| Working voltage | 29,6 | 12 |
| Screw power, W | 480 | - |
| Thrust, lbs * | 68 (* 102 lbs trolling motor manufacturer's method) | 55 |
| Full efficiency, % | 48 | - |
| Weight without batteries, kg | 8,9 | 13,6 |
| Weight with battery, kg | 14,9 | - |
| Maximum boat weight, kg | 1500 | 1500 |
Gasoline and electric boat engines
Boat electric motors can develop the same thrust as internal combustion engines with significantly less shaft power. This is due to the different shape of the torque curves of electric and gasoline engines. With an internal combustion engine, the torque curve has a pronounced peak, due to which the maximum torque is available only in a limited range of shaft speeds. The dependence of torque on revolutions of the electric motor is much flatter and it is sufficient at any speed.
Maximum torque and power are important characteristics of an engine. Torque determines the ability to accelerate quickly and pull a load, while power (referred to weight) top speed. The torque depends on the number of revolutions of the shaft. At different types engines, this dependence has its own form. In an electric motor, the rate of energy conversion from the battery is not related to the shaft speed. In internal combustion engines, with an increase in the number of revolutions, pressure and temperature increase and reach an optimal combination at a certain speed, which accounts for the peak torque. The flat torque characteristic allows you to install more efficient propellers on boat electric motors. The propeller efficiency of some small boat electric motors is three times higher than that of gasoline outboard engines of the same class.
To make it easier for the user to compare outboard motors with shaft horsepower to electric motors, Torqeedo has introduced the concept of "equivalent horsepower". labeled “3 HP equivalent” delivers the same propeller power as a 3 HP outboard gasoline engine. Although in this case the power consumption and the power on the shaft of the electric motor can be significantly lower.
| Torqeedo Cruise 2.0 | Typical boat motor | Outboard gasoline engine 5 hp | |
| Power consumption | 2000 W (2.7 HP) | 2000 W (2.7 HP) | — |
| Shaft power | — | — | 3700 W (5hp) |
| Power on screw | 1112 W (1.5 HP) | 660 W (0.9 HP) | 995 W (1.4 HP) |
Loss of power in the boat electric motor
The overall efficiency of the power plant on a ship with an internal combustion engine is 5-15%. For a boat with an electric motor, such an indicator is an unaffordable luxury. It is considered that a boat electric motor works efficiently if, taking into account the losses on the propeller, its efficiency is about 50%. In this case, the efficiency of the electric motor must be at least 80%, and the propeller must be at least 63%.
Comparison of the efficiency and power of electric boat motors and small outboard gasoline engines. The full efficiency of a gasoline engine is 5-15%. The efficiency of typical boat motors is about 20%, Torqeedo boat motors are about 50% System voltage
The power loss is proportional to the resistance of the conductor and the square of the current flowing through it. If the current doubles, the losses increase by a factor of four. If the current increases tenfold, the losses increase by a hundred. You can reduce the current and losses by increasing the voltage in the circuit.
The current voltage of powerful boat electric motors is 48 volts, but 24-volt electric motors are also suitable for small boats. At a current of 50 A, the maximum power of an electric motor in a 12-volt system will be 600 watts, and in a 24-volt system - 1200 watts
The second way to reduce losses in the DC circuit is to increase the cable cross-section. Properly selected cable increases the efficiency and safety of the electrical system, eliminates localized overheating and reduces energy losses. For example, the maximum current 2.0 is more than 80A (power consumption 2000W at 24V). If you connect an electric motor to batteries located at a distance of five meters from it, with a cable with a cross section of 25-35 mm², then the loss will be 17 W, which corresponds to 0.8% of the total power or 3.4 W per meter of cable.
electric motor
Electric motors used in boat electric motors can be divided according to several criteria:
- Method for creating an alternating magnetic field
- Method of excitation of the main magnetic flux
- Design
An alternating magnetic field in the electric motor is created using mechanical or electronic switching. In a classic motor, the fixed brushes slide along the rings located on the shaft and switch the direction of the current in the windings depending on the position of the rotor. The brush assembly converts direct current from an external source into alternating current and serves as a mechanical inverter. Over time, the brushes wear out, begin to spark, and additional resistance arises at the point of contact with the rings. Losses reduce the efficiency of the motor and increase the current it consumes.
In a brushless motor, the alternating field creates a current drawn from a high frequency DC-AC converter. Brushless motors have no losses due to brushes, they are more efficient and do not need to be serviced.
There are two ways to create a primary magnetic flux in the motor - using permanent magnets or current in the field windings. Motors with electromagnetic excitation are cheaper, but compared to permanent magnet models, they are heavier and take up more space. Losses in the excitation coils reduce the efficiency of the motor and increase its energy consumption.
Section of the boat electric motor Torqeedo Travel 1003 CS. On the left is the bell of the outer rotor with permanent magnets, inside of which there is a stator with windings. The green board in the center is an electronic switch that replaces the brushes and rings. Structurally, brushless motors come with an internal or external rotor. In the traditional version, the rotor rotates inside the stator. Due to this, the engine cools better, but creates a relatively small torque.
In modern engines, the rotor is outside the stator. Magnets are placed on the rotor, and windings on the fixed stator, which create an alternating magnetic field. The torque of an external rotor motor is twice as strong. Since the surface area of the outer rotor is larger, twice as many magnets fit on it, further increasing the torque. The moment increases even more when rare earth magnets are used instead of conventional ferrite ones.
In powerful boat electric motors, a synchronous brushless motor with permanent magnets with an external rotor is installed. It generates more thrust than a conventional trolling motor, weighs less, draws less current and lasts longer on battery power.
Screw
High efficiency has a screw with a large diameter, pitch and low rotation speed. However, only a motor that develops high torque can work with such a screw. In this case, the difference between the largest and smallest torque values of the engine should be minimal.
Most of the propellers of gasoline and electric motors used on small boats are based on tests conducted back in the 1940s-1960s of the last century. General principles the designs that appeared then are systematized in the form of tables and graphs and are still used by manufacturers.
Another approach is used in the development of propellers for Torqeedo electric motors. First, a three-dimensional model is created on a computer, and then the pitch and curvature of the screw profile are optimized for each section, taking into account the conditions of water flow around the diameter that change along the diameter. Screws of this type are called screws with variable pitch and profile. Their losses are less, and the efficiency is higher.
Battery for electric motor
The optimal source of energy for a modern outboard electric motor is a lithium battery. Compared to other types of batteries, lithium batteries store more energy, provide high discharge current without loss of capacity, and withstand many more charge-discharge cycles.
| Power consumption, W | 1000 |
| Screw power, W | 480 |
| Comparable in terms of power on the screw outboard gasoline engine, h.p. | 3 |
| Comparable thrust outboard gasoline engine, hp | 4 |
| Maximum overall efficiency, % | 48 |
| Rated voltage, V | 29,6 |
| Static thrust, lbs | 68 |
| Static thrust, calculated according to the method of manufacturers of trolling electric motors, lbs | 102 |
| Built-in lithium battery capacity, Wh | 915 |
| Total weight, kg | 14,9 |
| Weight without batteries, kg | 8,9 |
| Built-in battery weight, kg | 6,0 |
| Deadwood, see | 62,5 |
| Standard screw (v - speed km / h at p-power W) | v9/p790 |
| Maximum propeller speed, rpm | 1200 |
| Control | Tiller |
| Forward/reverse. variable speed | Yes |
| Built-in computer with display and GPS | Yes |
However, unlike lead-acid batteries, lithium batteries require a complex electronic control and balancing system. However, the failure of the BMS components in itself creates a problem for the safety of the battery. To avoid unforeseen situations, critical BMS parts in lithium boat batteries are duplicated. Just like it is done in automotive, aerospace or medical technology.
In the industrial production of lithium boat batteries, only cylindrical cells in a metal shell are used, which are welded together and then installed in a plastic or metal case. For high-quality batteries, the housing has an IP67 protection class. The waterproof housing protects the BMS boards from corrosion and prevents the formation of electrolytic gas.
Convenient boat motor
High specifications a boat motor is easier to evaluate when it is convenient to use it. A modern electric motor on a boat is controlled by a microprocessor, so all information about its condition exists in digital form and is easy to present to the user. 
Part common system boat motor control is BMS. She knows everything about the battery. What charge is left in it? What is its temperature? What current does it give? The collected data is shared by the BMS with other system components, which use it to calculate the boat's current speed, power consumption, and remaining range.
The user receives the information processed by the on-board computer on the display. The remaining range in miles or kilometers changes in real time. When the battery runs out, the computer beeps and warns that it is time to turn the boat around and return to shore or slow down to increase the range.
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