Radio basics

Radio Control Boat Modeler, Apr 2002 by Eyrich, Rick, Boyd, Matt

Which system is right for you?

Once you decide to try RC model boating, you'll have to choose a radio system to control your model. If you already have a radio system, then the choice is simple; but if you're starting from scratch, there are a few things to consider. Matching your radio system to the type of boat you have is an important first step toward a fun and rewarding hobby. Let's see what's available.

WHICH RADIO TO CHOOSE?

To choose the correct radio gear, you first have to decide what your boating requirements are. Are you a go-fast kind of person, or do you want to build and run scale model boats and ships? Is electric power what you want, or will you be running nitro boats? Do you want to skipper a sailboat? All types of model boats require left and right steering control, but there are other important radio-system requirements to consider.

For your very first model boat, you should consider buying a model in which the boat and radio come packaged together. This way, most of the setup has already been done, and you can start experiencing the hobby right away. (See the "Almost-- Ready-to-Run Roundup" in the February 2002 issue.) Most basic boat radio systems are either 2- or 3-channel units and come in either a stick- or pistol-grip style. Pistol-grip radios are very popular with RC car modelers, and used ones can often be found at hobby shops for reduced prices. The square, two-stick radios also offer the same degree of control; the choice is up to you.

A 2-channel radio provides steering and throttle control. Slightly more expensive radios have a third, auxiliary channel that you can use to adjust or move other items such as the engine/fuel mixture in a race boat or the sail position on a sailboat. For the most part, if you operate a sport or race boat, the 2- or 3-channel radio will satisfy all your needs.

RADIOS FOR SCALE BOATERS

Scale modelers require more versatile radio systems, as several functions can be controlled when you operate a scale boat. If you plan to stay in the hobby for any length of time, consider at least a 4-channel stick radio. These radios are very similar to those used to fly RC airplanes except that they transmit on ground frequencies. The throttle and rudder controls are on the left stick, while the right stick offers two auxiliary channels to operate all sorts of functions. Turning lights on and off, activating horns and sound systems and raising and lowering anchors and cranes are just some of the things that can be done. If you have a tugboat, you may also want to operate a tow winch or a bow thruster. Military ships have guns and cannon; these can also be raised and aimed using the auxiliary channels. A stick radio can be used to operate dual-drive motors independently (using both sticks) to increase the model's maneuverability. If you have the right radio system, just about anything that moves or operates on a full-size boat can be duplicated with a scale boat.

BASIC SETUPS

Radios come with a variety of features and equipment, but all come with a transmitter, a receiver, a switch harness and a battery to power the receiver. Basic entry-level radio systems require you to supply the eight dry-cell (AA) batteries that power the transmitter and the four that power the receiver. More elaborate systems come with Ni-Cd battery packs and a battery charger. Though slightly more expensive initially, Ni-Cd packs last much longer and over time, save money because you don't have to keep buying new AA cells.

For a standard nitro boat (one with a glow engine), only two servos are needed: one for steering and another to control the engine's carburetor. With an electric-powered boat, the throttle servo actuates a mechanical speed control or a switch. tf you use an electronic speed control (ESC), it replaces the servo and plugs directly into the receiver. An advantage to using ESCs is that some have a battery eliminator circuit (BEC) that shunts power from the motor-drive battery to the receiver. Using a BEC-equipped ESC, you save the weight of both the throttle servo and the receiver battery pack. -Rick Eyrich

INSTALLATION TIPS

For the novice RC boater, installing and maintaining a boat's radio system can often be a tough nut to crack. Properly mounting servos, receivers and control linkages as well as using the correct radio accessories can greatly affect how well the finished boat will react to your commands. In most cases, radio-related headaches can easily be overcome, but for those tougher situations, a bit of extra work might be needed. To that end, here are some simple ways to subdue a few common radio-system problems that average RC boaters often encounter.

Servo mounts, Servos can be attached to the inside of a radio box in several ways, but it sometimes can be tough to mount them securely enough to hold up to the torque of the boat's rudder/throttle controls. You can use vertical plates, hardwood posts and even double-sided tape to hold servos, but one of the most dependable ways to hold them is with Aeromarine Laminates' servo trays. These aircraft-aluminum brackets allow you to mount servos in either an upright or a horizontal position; this comes in handy if your boat has a low-profile radio box. The Aeromarine trays are available for micro-, standard- and 1/4-scale servos.