The transition from a gasoline engine to electric traction is not just a tribute to fashion, but a conscious step towards comfort and safety on the water. Electric motor It radically changes the feeling of the boat control, saving the owner from the smell of fuel, noise and the need for regular maintenance of the internal combustion engine. Modern models allow the clock to enjoy the silence of nature, which is especially appreciated by fishermen and lovers of a relaxing holiday.
But electrification requires careful planning, and you have a lot of technical issues to solve, from calculating the necessary requirements. traction And then we can get the battery capacity to the right control system, and errors in the design phase can cause the boat to fail to reach the right speed or to have a critically small range.
In this article, we will discuss in detail all aspects of the installation of an electric motor on the motorboatYou'll learn how to calculate power consumption, why 12 volts might not be enough for a body heavier than 500 kg, and what nuances are hidden in the specifications of the screws. Deep immersion in the topic will help avoid common mistakes and build a reliable power plant.
Advantages and Disadvantages of Electrical Traction
The key to electric motors is their quietness, and the lack of vibrations and hum allows you to sneak up on the fish as far as possible without scaring them. eco-friendliness These engines are undeniable: there are no exhaust emissions and the risk of oil or gasoline leaking into the water, making them ideal for use in protected areas.
⚠️ Attention: Despite the absence of exhaust gases, do not forget about the tightness of the battery compartment. LiFePO4 A lead acid battery may short circuit or chemical reaction with water.
On the other hand, there is a limitation on autonomyIf a gasoline engine can be refueled in 5 minutes and run further, a discharged battery requires charging time, which can be from 2 to 8 hours depending on technology and capacity. Also worth considering the initial cost: a quality kit (motor + battery + charger) often costs more than a new low-power gasoline analogue.
However, the reliability of the electrician is higher. electric-motor The lack of need to change oil, filters and candles makes operation predictable and easy, and for many users, this becomes a decisive factor in favor of switching to electricity.
Power calculation and selection of traction force
The key parameter in the selection is traction Unlike horsepower, thrust shows the real force with which the propeller pushes the boat forward. For lightweight inflatable boats (PVC), up to 300 kg, a 30-40 lbs motor is usually enough, whereas for metal or plywood housings, much more is required.
There is a rule of thumb: for every 45-50 kg of total weight of the boat (hull + motors + battery + people + cargo), 1 pound of thrust is required. motorboat With a flat bottom or a glittering body, that stock should be increased by 20 to 30 percent, and if you plan to go out in windy weather or against the current, the power reserve will become critical.
It is also important to pay attention to the work tensionLow-power motors run from 12 volts, medium-powered motors run from 24 volts, and high-power models require 36 volts or more. Higher voltages reduce the current in the circuit, which reduces wire heating and increases overall power. Efficiency systems.
Why not take the engine "back-to-back" in power?
If the engine is running at 100 percent of its power, it's going to be in a very short lifespan, and the electric motors are the most efficient and durable at 60 to 80 percent of their maximum thrust, and running at the limit causes the windings to overheat and the battery to run out quickly.
When choosing a model, you should also consider the type of propeller. For heavy boats, large-step propellers are better, but they require more energy to promote. propeller With a small step will provide better acceleration, but can limit the maximum speed.
The choice of a battery: technology and capacity
The heart of your electrical system is the battery. Traditionally, traction was used. lead-acid Batteries (AGM or GEL) that are cheap and reliable but have a high weight and low depth of discharge are highly discouraged from being discharged below 50%, otherwise the lifespan will be drastically shortened.
The current alternative is lithium-iron-phosphate (LI).LiFePO4They are 2-3 times lighter than lead, have almost 100% depth of discharge and can withstand thousands of charging cycles. resource It pays off in the long run.
Battery capacity is measured in ampere hours (Ah). To calculate the approximate running time, you need to divide the battery capacity by the current consumption of the motor. For example, a 55 lbs motor consumes about 50 amps. A 100 Ah battery (lead, usable 50%) will provide about 1 hour of full power or 3-4 hours of low speed.
| Type of AKB | Weight (approximate) | Depth of discharge | Duration of service (cycles) | Cost |
|---|---|---|---|---|
| Lead-acid (WET) | Heavy. | 50% | 200-300 | Low. |
| AGM / GEL | Medium. | 60-70% | 400-600 | Medium |
| LiFePO4 (Lithium) | Light. | 90-100% | 2000-5000 | High. |
When buying a lithium battery, make sure it has a low voltage BMS (Battery Management System) built in. Some cheap models don't turn off the discharge in time, which can knock the battery out.
Don't forget that temperature In winter or cold water, lead batteries are less efficient, while lithium-iron-phosphate models remain stable, although charging them at negative temperatures without heating is prohibited.
Connection schemes and chain protection
The installation of the electrical part requires strict adherence to safety rules. Basic rule: the cable cross section must correspond to the current consumption. For powerful motors (50-80 lbs) at 12 volts, the current can reach 60-80 amps, which requires the use of copper wires with a cross section of at least 16-25 mm2 (AWG 6-4).
An essential element of the system is switch-off Or a fuse that's as close to the battery as possible, which will protect the boat from fire in the event of a short circuit, and it's also recommended that you use special sea connectors that are resistant to corrosion and splash.
⚠️ Warning: Never use household extension cords or thin wires to connect the motor. High current heats them instantly, melts the insulation, which can lead to ignition. Use only specialized marine cable.
Additional devices such as pedals or remote devices are often used to control speed. handleWhen installing them, make sure that the joints are leaky. All contacts must be soldered or pressurized and protected by shrinkage.
☑️ Electrical circuit inspection
Features of installation on transom and nose
Installation electric-motor The slinging of a motor boat has its own specifications, and unlike light inflatable boats, where the motor is hung on a cylinder, it requires a rigid mount, often using special brackets or transition plates if the standard transom does not allow the motor to be secured with a standard clamp.
When installing it is important to set deepening If you lift the motor too high, it will capture air (cavitate), lose efficiency and create noise. If you lower it too low, water resistance will increase. The optimal position is when the propeller is 15-20 cm below the bottom of the boat.
Trolling motors on metal or fiberglass boats often require special areas, which frees up the transom for the main motor or fishing. motorboat With high sides, the bow control may be less convenient due to limited visibility.
Fastening elements must be made of stainless steel; constant contact with water and salt (at sea) or just moist air will quickly destroy the ordinary metal; Regularly check the tightening of the bolts, as vibration when the screw is working can weaken them.
Proper entrapment of the screw and the use of stainless fasteners are two main conditions for durability and efficiency of the electric motor on a rigid body.
Operation and extension of battery life
It's important to drive your electric motor for a long time, and the power of the handle is bad for the controller and the battery, and smooth acceleration and braking are good for you. charge It reduces the heat load on the system.
After every run into the water, especially if you've used salt water, the motor needs to be rinsed with fresh water, the salt deposits on the screw and the lower unit upset the balance and cause corrosion, and it's also worth lubricating the moving parts with a special lubricant that is resistant to washing.
Battery storage requires special attention. Lead batteries cannot be left empty - they sulfate and fail. Lithium batteries are best stored at 60-70% charge in a cool place. Be sure to complete a full winter storage before long-term winter storage. charging.
How to extend the time on one charge?
Use an anchor cable or GPS anchor to avoid wasting energy on holding your position in the wind. Drive 60-70% of the power is the most economical mode. Avoid frequent acceleration to maximum. Keep your propeller clean: algae fouling reduces efficiency by 15-20%.
Can I charge the battery directly on the boat?
It depends on the type of charger. Most modern smart charging systems are safe to connect while the battery is installed on the boat, as long as ventilation is provided (for lead batteries, hydrogen is released when boiling), however, for lithium batteries, it is better to remove them or use chargers with the appropriate profile and temperature compensation.
What to do if the motor starts vibrating?
Vibration is most often caused by winding a fishing line onto a propeller shaft or damage to the blades. Stop immediately and check the propeller. It can also be caused by the screw itself being unbalanced after hitting a rock or driftwood. In rare cases, vibration indicates wear on engine bearings.
Adhering to these simple rules will allow you to enjoy quiet and eco-friendly navigation for years to come. Electrifying a boat is an investment in comfort that will seem more justified with each season.