In RC Hobby Intro Posted by Robert D May 11, 2014
Brushless RC boats
There are different groups and types of Radio Controlled Devices. Most obvious division is the vehicle used. There are cars, planes, boats and many other vehicles. You can divide them by gas used or motor type, or some other distinctive feature. You can also divide them by purpose they have.
When it comes to speed as important feature, boats have few similar characteristics. If we are talking about shape, they can be catamarans, deep-vees, Chris Craft, cigarette boats, or some other aerodynamic style. Materials must be high quality and durable to survive high stresses. Materials must be light, so there is less energy spent to move them.
Maybe most important detail, when it comes to speed, is a motor. After all, you must have a significant amount of energy to force 5 feet long boat to go faster than 100 mph. In this case, probably the best solution could be brushless RC boats.
Brushless RC boats are using the technology that turns whole electro motor theory upside down. In ordinary electric motors you have a rotor, or a spinning armature on the inside; and a stator, or permanent magnets on the outside. The armature is an electromagnet.
Once the electricity runs through the electromagnet, it creates a magnetic field that is attracted or repelled by magnets in the stator. If you change electricity flow, you change the polarity, and that causes armature to spin and produce kinetic energy that moves the vehicle. To change the polarity, this motor uses brushes that make contact with electrodes on the armature.
There are several disadvantages to this method. First, brushes wear off with time, which makes the motor less efficient. Then, motor makes noise and sparking when brushes continue to connect and disconnect from the armature. When the electromagnet is in the center, it is harder to cool the motor. The brushes are limiting the highest speed of the motor, as well as whole vehicle. Armature can have only that much poles, as the number of the brushes. That limits motor's ability to create energy.
Technical advance made possible to "turn the motor inside out". Now stator is an electromagnet, and you move permanent magnets on the rotor. There is no need to use brushes, which has several advantages. Motor is more precise because there can be much more electromagnets on the stator than in ordinary motor, and you can control them by the computer. These motors are easy to cool, quiet and with no sparkling, and with no brushes to wear off.
Only disadvantage brushless RC boats have is a higher cost, but you can compensate it by the higher efficiency of the motor. Therefore, brushless RC boats are much better choice than boats with conventional motors when speed is deciding factor.