Each year since the early s, more and more boats are built with bow & stern thrusters, boat owners without them are installing them to make their boats more maneuverable. While thrusters are extremely helpful for docking and navigating in close quarters, they are often “out of sight, out of mind.” Because their thrusters are often buried deep in the bilge, many boaters struggle to access them for maintenance or repairs.
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As a result, very few boaters perform any annual maintenance on their thrusters, aside from changing anodes each season. Like any other piece of equipment on your boat, thrusters require maintenance to operate at peak performance, and you don’t want your thrusters failing at the worst possible time.
That’s why we’ve put together five helpful tips for maintaining your thrusters and keep them running strong. Keep in mind, not all thrusters are the same, so it’s always best to consult your owner’s manual for tips specific to your brand and model of thruster.
While almost every marine enthusiast knows to replace anodes, this tip is still at the top of our list because it is the most important. An underwater thruster gear-leg with no anodes to protect it from corrosion will erode in a matter of days and can be dangerous to you and other boaters.
Anodes should be replaced yearly or when they are half-eroded. Prior to launch, use a wire brush to clean lightly eroded anodes and remove any oxidation after being exposed to air. When installing anodes, use blue Loctite, an instant adhesive, on the anode screw.
Any time the boat is out of the water, you should remove the props and scrape all marine growth off the gear-leg and propellers. Be very thorough in removing growth, as even barnacle feet left on the props will reduce performance and run time.
Be sure to grease the propeller-shaft with marine-grade grease before re-installing the propellers. The tunnel, gear-leg and propellers should also be painted with anti-fouling paint as the hull requires.
It is always important to make sure the batteries for your thruster are providing enough power. To ensure they are, it’s best to check the operating voltage. It is important to note that this check should only be conducted with the boat in the water, as running the thruster out of the water with no resistance will damage the motor.
“Operating voltage” is refers to the voltage reading after the thruster has been running for approximately 10 seconds. To check it, you will simply connect a volt-meter to the positive and negative terminals on the thruster motor. It’s usually easiest to perform this check with two people: one to operate the thruster from the helm, and the other to hold the volt-meter.
12-Volt thrusters typically run between 9.5V and 10.5V, while 24-Volt thrusters typically run between 18V and 21V. If the voltage is below 9V for 12-Volt thrusters or below 17V for 24-Volt thrusters, you have a low-voltage situation on the boat. Operating the thruster at low voltage will damage components on the motor, such as the solenoid. If that is the case on your boat, a qualified marine technician should look into the cause of low operating voltage.
Some older-models of thrusters require an oil bottle and tube to feed oil into the gear-leg. If you do not have an oil-fed gear-leg, you likely have one that is pre-filled and sealed at the factory and can skip this step.
Check the gear-leg oil feed tube for water. If the oil is milky, there is likely a water leak and the gear-leg should be serviced by a qualified marine technician.
Check the gear-leg oil reservoir level. If more bow thruster oil is needed, consult the owner’s manual and add the proper type of gear oil recommended by the manufacturer. In most cases, an 80-90 or 85-90 weight gear oil will work.
The gear-leg oil should be changed every two years under normal recreational use conditions. To change, remove the drain plug and allow fresh oil from the reservoir to flush out the used oil. Reinstall a new drain plug and gasket and top-off the reservoir as necessary.
Permanently sealed gear-legs do not require servicing.
Beyond inspecting the thruster itself, be sure to examine the compartment in which the thruster motor is mounted as well. The thruster motor creates heat with prolonged usage. It is important that there are no objects in contact with the motor.
Is the thruster compartment dry? If not, make sure to dry it and find the source of the water. The less moisture the better, so do not store any wet or damp items near the thruster motor. Look out for any marine growth inside the tunnel or on the propellers, this can lead to noisy bow thrusters.
Thruster motors can also create carbon dust, so if there is a thin black film or dust in the compartment, that’s perfectly normal, but you may want to wipe it up. You may also want to remove the motor cap and use a vacuum or compressed air to remove the excess dust that has collected in the motor itself. Please note carbon dust is harmful to breathe, so always wear a mask when vacuuming or blowing out the motor.
Lastly, check all the electrical connections and make sure they are tight and free of corrosion.
Following these tips annually will help ensure your thruster runs at peak performance all season long. Be sure to consult your owner’s manual for any maintenance specific to the make and model of the thruster on your boat.
The T200 and T500 are underwater thrusters designed to be rugged, powerful, and flexible in many applications like high-power ROVs, surface vessels, AUVs, as well as human-carrying applications like kayaks. This guide will show you how to operate, service, and troubleshoot your T200 or T500 thruster.
The following is some basic information to help you get familiar with the T200 and T500 thrusters.
This diagram shows the main components of a T200 or T500 thruster.
The front of the thruster is the side where the cable enters the nose cone.
The T200 and T500 are designed to optimize thrust and efficiency when thrusting in the forward direction. The thruster is thrusting in the forward direction when water enters from the front and is expelled through the back of the nozzle.
Forward Thrust: more thrust and greater efficiency
The thruster can also generate thrust in the reverse direction, although at slightly lower force and efficiency.
Reverse Thrust: Less thrust and efficiency
Forward and reverse thrust performance specifications are available in the T200 and T500 performance charts.
Every thruster includes both a clockwise rotating propeller and a counterclockwise rotating propeller. The propellers are labeled with “CW” (clockwise) and “CCW” (counterclockwise) for easy identification. Propeller direction can also be determined by viewing the thruster from the front nose cone and looking at the direction of the leading edge of the blades:
A clockwise propeller will generate forward thrust when spinning in the clockwise direction. Likewise, a counterclockwise propeller will generate forward thrust when spinning counterclockwise.
Both clockwise and counterclockwise propellers can generate thrust in the forward and reverse directions.
What is the other propeller direction for?
When a thruster spins, it creates torque. This torque can cause undesired rotation of the vehicle. To counteract this, opposite (counter-rotating) propellers can be used on pairs of thrusters that are on the same axis to cancel out their torques.
Instructions for switching the installed propeller are available in the Changing a Propeller section of this guide.
To operate a thruster you need:
The following diagram shows how everything is connected.
The thruster cable has three conductors that terminate in tinned wire ends.
Connect these three thruster wires to the three motor phase wires from the ESC. How you connect the wires is up to your preference. The wires can be soldered together or you can use connectors like bullet connectors or screw terminal blocks. The order does not matter, the thruster will spin with the wires connected in any configuration. If the thruster is spinning in reverse of what is desired, swap the connection of two of the wires.
After the thruster is connected to the ESC, connect the red (positive) and black (ground) ESC power wires to a power source. The power source voltage should be within the operating voltage range for the thruster you are powering, this is: 7–20 V for the T200 and 7–24 V for the T500.
When the ESC is connected to power you should hear three beeps in rising pitch indicating the ESC is receiving power.
T500 Voltage Limitation
The T500 Thruster has a maximum operating voltage of 24 V. The T500 can also be powered using a 6S Lithium-ion/Lithium polymer battery (maximum). Continuous full throttle use should be limited to 1 minute or less when the T500 is operated at 24 V or with a fully charged 6S Lithium-ion/Lithium polymer battery to avoid overheating the thruster.
Connect the white ESC signal wire to the signal source output. Connect the black (ground) ESC wire to a ground pin on the signal source device. Send a PWM signal of microseconds (µs) to initialize the ESC. The ESC must be initialized before it can accept any other throttle signals. When the ESC is initialized you should hear two more beeps. The first beep indicates the ESC detects a throttle signal and the second beep indicates that the correct µs signal is detected and the ESC is now fully initialized.
After the ESC is initialized, sending a PWM signal from µs to µs will control the throttle of the thruster:
While testing your thrusters, do not operate them for more than 10 seconds outside of water (while dry). The bearings require water for lubrication and may be damaged if the thruster is operated for an extended period of time while dry. You may also notice a clicking noise or that some thrusters are noisier than others. This is normal. Because of the tolerances of the plastic bearings and the metal rotor shafts, the rotor shaft can move slightly in the bearing causing variation in how different thrusters sound. Any noise is significantly reduced or eliminated when operated in water.
If you are having problems with thruster operation please refer to the Troubleshooting section of this guide.
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Pretty much anything that can output the correct PWM signal! The PWM signals used by the ESC are the same signals commonly used by RC receivers or to control servos. The following are a few examples of devices that can be used as a PWM signal source:
Blue Robotics Thruster Commander
The Thruster Commander is a great way to get started using our thrusters. We recommend it for first-time users and anyone who is not sure about what signal source they should use. It’s also great for controlling thrusters on a stand-up paddle board, kayak, fishing float, etc.
Flight control devices like the Navigator Flight Controller or Pixhawk Autopilots
These devices are used to control unmanned vehicles like ROVs, AUVs, USVs, etc.
Arduinos, Raspberry Pis, and other types of microcontrollers and SBCs
These can be used for a multitude of projects, from human-operated vehicles to fully autonomous vehicles.
RC transmitters/receivers
These are a good choice for adding simple wireless controls to a vehicle. Just remember, they don’t work underwater!
Simple Servo testers
Probably the most simple type of signal source. Servo testers work well for testing thrusters (go figure) or as a super simple, single-input control method.
We have several other guides that explain how to control the ESC and thruster using different devices in greater detail:
The thrusters have two mounting options:
The mounting hole pattern and thread size for each thruster are provided below.
The T200 also has an optional mounting bracket for situations where it is not convenient to use the default mounting location. This bracket is not compatible with the T500 thruster.
Refer to the table below for tool and screw sizes. All hardware is 316 stainless steel.
Every thruster includes both a clockwise rotating propeller and a counterclockwise rotating propeller. Changing the installed propeller is quick and easy. Refer to the Thruster Tools table for exact tool sizes.
1. Use a Phillips screwdriver to remove the four nozzle screws from the nozzle then pull the nozzle away from the rest of the thruster.
2. Remove the propeller screws using a hex driver and pull the propeller off of the rotor.
3. A different propeller can now be installed onto the rotor.
4. Follow the directions in reverse to reassemble the thruster.
You may have to take apart your thruster occasionally for cleaning and maintenance. Follow the instructions below to disassemble your thruster. Refer to the Thruster Tools table above for exact tool sizes.
1. Use a Phillips screwdriver to remove the four nozzle screws from the nozzle then pull the nozzle away from the rest of the thruster.
2. Use a hex driver to remove the two nose cone screws.
3. Remove the nose cone. Take notice of how the thruster cable bends and exits the nose cone on the opposite side. This is important when reassembling the thruster.
4. Rotate the propeller by hand until the shaft collar set screw lines up with the notch in the stator base. Use a hex driver to loosen the set screw.
5. Do not pry up on the shaft collar to remove it. Instead, pull the propeller away from the thruster core to separate it from the stator.
6. Use a hex driver to remove the propeller screws.
7. With the propeller screws removed, you can separate the propeller from the rotor. Your thruster is now completely disassembled.
1. Install the propeller onto the rotor using the propeller screws and a hex driver.
2. Ensure the shaft collar is in the stator base then install the propeller and rotor onto the thruster core.
3. Use a hex driver to tighten the shaft collar set screw onto the flat side of the rotor shaft.
4. Install the nose cone onto the core making sure the cable exits the nose cone on the opposite side. Do not bend the cable in the other direction.
5. Install the nozzle using the nozzle screws and a Phillips screwdriver.
Operating in environments with a lot of sand, silt, sediment, ferrous particles, or other abrasives will scratch the protective coating on the rotors. Heavily damaged coating will eventually cause the rotor to corrode and seize the thruster.
When a thruster is connected to an ESC, the ESC can use it as a “speaker” to play a series of beeps. These beeps provide information about the status of the ESC and are useful for troubleshooting. Both the Basic ESC and Basic ESC 500 have slightly different beeping patterns.
Basic ESC
1. At power on the ESC will beep three times in rising pitch. If you do not hear these beeps:
2. If any throttle signal is detected the ESC will then beep one time. If you do not hear this beep:
3. If the initialize/stop signal ( µs) is detected the ESC will beep one final time indicating that it is fully initialized. If you do not hear this beep:
Basic ESC 500
1. At power on the ESC will beep once. If you do not hear this beep:
2. If the initialize/stop signal ( µs) is detected the ESC will beep three times in rising pitch indicating that it is fully initialized. If you do not hear these beeps:
A great way to troubleshoot a problem is to swap components with other known-working components and observe whether the problem stays in place or moves with the component. To troubleshoot a thruster using this method you will need an different thruster and ESC set that you have confirmed is working normally.
1. Swap the problematic thruster with a thruster that you know works well. That is, connect the problematic thruster to the ESC that was connected to the working thruster and connect the working thruster to the ESC that was connected to the problematic thruster. If the problem follows the thruster, you know that the thruster is defective. If the problem stays with the ESC, move on to the next step.
2. Swap the signal sources of the ESCs. If the problem follows the problematic ESC, you know the ESC is defective. If the problem stays with the signal source, then there is a problem with the signal source.
We’re always trying to make our documentation, instructions, software, and user experience better. If you’d like to leave feedback about how we can make this guide better, let us know here.