The Basics
Model boats offer a wide range of entertainment, from the sheer speed and action from racing boats to the complete relaxation from sailing and most scale boats, this sport is for everyone.
Boats can be classified into three categories for easier referencing.
Sailboats:
Sailboats get their power from the force of the wind that is caught in large sails and move the boat in the same manner as a full-size sailboat. R/C sailboats range in size from less than twenty inches long to over 6 feet high (40 inches long) above the water!
Scale Boats:
A scale boat is a replica of a full-size boat. The greater the skill of the builder, the more the model can resemble the original. Some have features like planked decks, working lights, chrome or brass deck fittings; even cloth flags and ladders.
Racing Boats:
There are three main types of racing hulls: three-point hydros, tunnel hulls, and V-hulls. The different types of hulls require different water conditions. Tunnel hulls and hydros run best on smooth water where they can "Get on step" and plane properly across the water. Hydros have a surface running propeller which, at full speed, is half in and half out of the water kicking up the famous "rooster tail" of water behind the boat. Deep-V hulls have a submerged propeller and can slice through waves without much reduction in speed.
Construction Basics
Wood, fiberglass and plastic are the basic boat construction materials. Wood construction varies from pre-formed panels to actual hull planking which is hard and time-consuming to create, but with beautiful and realistic results. Fiberglass boats build faster (some come with the hull and deck separate and some pre-joined) and often have molded-in scale detail. ARF boats (Almost-Ready-to-Float) are primarily made of durable ABS plastic with pre-joined hull and deck and come complete with running hardware, motor and decals. They are a great way for beginners to get launched into R/C boating quickly and affordably. RTR boats (Ready to Run) come built and are ready to run (of course) and are for those who have no time to build it themselves or just don't have the skills to build it (no pun intended).
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Hulls
Hulls have to be the most important part of the boat. They keep the water out (most of the time) and the RC gear in. Some come pre-built and ready to use whale others need to be sanded and painted. Some more experienced modelers actually build their own hull, a very difficult and time-consuming procedure.
Racing Boat Hull Types
Three-Point Hydros
Three-point hydros are what people think of when they picture racing boats. Along either side of the boat are two long hulls (sponsons) which stop about half way down the boat. The stern of the boat is farther aft. When moving, three points of the boat (the stern and the rear of each of the two side hulls) are all that is in the water, hence the name three-point hydro.
Tunnel Hulls
Tunnel hulls are a variation of the three-point design. However, the sponsons extend the complete length of the hull similar to a catamaran. The effect is that the hull is partially supported by a cushion of air trapped beneath the boat. This helps the boat to move faster by requiring less hull for flotation.
V-Hulls
V-hulls, like the famous "Cigarette" off-shore racing boats, are mono hull boats and their hull is in the shape of a V - usually 150 degrees or less. They are noted for their ability to slice through rough, choppy water so that the speed of the boat is maintained.
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Hardware
The hardware of the boat consists of the propeller, drive shaft, rudder, most of the things to control it. It is not required if you are just using the model for display, but is if you want to put it on the water. Some models come with the hardware, a lot don't and require you to figure out what works best.
Hardware isn't as confusing as you think!
The running hardware of the boat can be a complete mystery to the newbie. The power produced by the inboard engine is transferred to the propeller by a drive shaft. It exits through a "stuffing box" (a tube filled with grease) which lubricates the shaft and keeps water out of the hull. Some stuffing boxes include needle bearings for better performance.
Some boats use a flexible drive shaft where the propeller and rudder are mounted behind the boat and power is transferred from the engine to the propeller by a flexible cable which exits through the bottom of the boat. This eliminates the use of universal joints beneath the water.
Beneath the hull are additional fittings. A strut, which supports the drive shaft, also provides a solid mounting for the propeller and absorbs the thrust from the propeller, transferring it to the boat. Immediately behind the propeller is the rudder for steering the boat and the water pick-up tube. Water expelled by the propeller is caught by the tube and routed through the engine's water jacket to cool it. The heated water is then expelled overboard.
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Radio Gear
Radio gear is also required if you want to put the model on the water and choosing the right one can be a difficult task. You need to get the radio transmitter, receiver, servos, and batteries for them which can all add up! You need to look at your needs to select the right gear; "do I want to go fast?", "do I want something easy to use?", when you figure out what you need, it is a lot easier to find it.
The Basics
For most boats, a 2-channel radio is required. There are two different styles of radios to choose from - two-stick and pistol-grip with trigger. The choice depends on your own personal preference.
For the casual captain, just a basic 2-channel radio will do just fine and will require around 12AA batteries (or just 8 with BEC-equipped models). Remember that fast racing boats put a tremendous strain on the steering (or rudder) servo. Choose a heavy-duty servo for this application.
2-Stick Radios
The two-stick radio is easy to use for a boat - even though they aren't controlled by a steering wheel. The two-stick radio helps you develop the same automatic reflexes for steering and throttle. This enables you to make an easier transition if you choose to fly airplanes later on. (With a pistol-grip radio, some relearning will be required.) In addition, the two-stick radio is also the least expensive of the two types of radios.
Pistol-Grip Radios
The pistol-grip radio with steering wheel offers the unique feeling of real driving control and is the more popular option. Turning the wheel of the transmitter duplicates the steering techniques of full-size boat. The shape of the transmitter is similar to that of a pistol; the wheel is located on the right side of the radio and the throttle is controlled by the left index finger in the trigger position. It's a very comfortable and convenient method of control, but more expensive.
Radio Modulation
Frequency (Channel Number): Like all radio equipment, an R/C system broadcasts its signal at a specific wave rate and this is known as its "frequency". Just as commercial radio stations that you listen to each operate on their own frequency, so do R/C transmitters. There are several different frequencies to choose from and these are now referred to in the R/C industry by "Channel Number". This channel number is easily confused with the number of control channels used in the model but the two are quite different -
the channel number that your transmitter broadcasts on (e.g., channel 56 or channel 80) refers to its frequency, not the number of model features it can control. If there was only one R/C frequency or channel number available, only one person in any given area could operate their model - just as if there were only one TV channel, you would only be able to choose one show to watch! By having a number of different channels available, many models can fly, race or skim along the water at the same time.
-AM: Stands for Amplitude Modulation which transmits by a variation in the amplitude of signals, it is subject to interference more than FM.
-FM: Stands for Frequency Modulation which transmits signals by variations in frequency, reduces the risk of "glitches" due to signal interference.
-PCM: Stands for Pulse Code Modulation uses binary code to digitize the signal, providing the most accurate signal possible.
Surface Use Only: (75 megahertz, Channels 61-90): Cars, boats, and other non-flying models must use one of these channels. Radios designed for cars/boats exclusively with a steering wheel or pistol grip control are only available on these channels.
All Uses: (27 megahertz, Channel Code A1-A6): Although legal for all models, we suggest that you use 27 megahertz only for surface models. This is because of the possibility that some unseen operator may innocently be operating a surface model on the same channel within range of your model airplane which would cause interference and a possible crash. Note: countries outside the United States may offer different frequency allocation schemes
Servos
A servo contains an electric motor and is the "muscle" that moves the rudder or other control surfaces. They can also be used to control the mechanical speed control (if equipped) and other accessories (horns, winches, etc.)
Radio Gear Definitions
-Battery Eliminator Circuitry (BEC): A circuit that eliminates the need for a receiver battery.
-Dual Rates: A dual rate switch on the transmitter can reduce the amount of servo travel. This makes the controls less sensitive. The aileron and elevator control channels are the most common channels with this feature, although some radios will also have a rudder dual rate switch. Select low rate, and a over responsive model can be made easier to control. Since beginners tend to over-control the model, low rate can also tame their models.
-Frequency Modules: A frequency module plugs into the transmitter and enables you to change the channel number your radio broadcasts on. Some new frequency modules also allow you to now dial in the frequency virtually eliminating the frustration of not being able to fly if someone else is also on your frequency.
-Fail Safe (FS): This feature automatically returns a servo or servos to neutral or a preset position in case of a malfunction or interference.
-Servo Arms : Connect the servo to either a pushrod or cable. Adjustable servo arms are available for some radios which can be made shorter or longer.
-Servo Gear Sets: Servo gears can be damaged in a crash and the loss of just a few teeth can render the servo useless. A replacement gear set lets you fix the servo yourself. It's very handy to have extra gear sets!
-Servo Case Sets: A cracked or broken servo case can let dirt, water or fuel into the sensitive electronics of the servo.
-Servo Connectors/Adapters: Most manufacturers offer servo plugs that are compatible with their radio systems. This allows you to adapt other brands of servos to your radio system or repair damaged plugs.
-Servo Extension Cable: (Aileron Extension): These cables simply increase the distance between a servo and the receiver. Note: Very long servo leads may cause radio interference. Chokes or radio noise traps may be required.
-Y-Harness: Two servos can be plugged into one channel with a Y-harness. The two servos will then operate simultaneously. It is most often used in areas where the strength of one servo is not adequate.
-Servo Trays: Servos can be mounted in a tray which provides for easy installation and good vibration protection. Many different styles are available to fit various installations (see picture below). If all your models are outfitted for the same servo tray, transferring components between models is easy.
-Trainer Cord: Required to connect the two transmitters with trainer systems. Note: Be sure to check your instructions for proper connection and for compatibility with other radio systems.
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Speed Controls
Speed controllers come in two forms;
Electronic and
Mechanical and are used to control the speed of only electric motors (not gas). Electronic speed controllers (ESC's) control the speed of the motor by digitally controlling (from your radio) the amount of power to send to the motor. Mechanical speed controllers do the same, but use a resistance board and servo to control it.
Mechanical Speed Controllers
The mechanical speed controller uses a servo and a resistance board to control the speed of the boat. Most only offer three-speeds in forward and one in reverse. They are very bulky and use more energy then a electronic speed controller, but are a lot cheaper.
Electronic Speed Controllers
The ESC (Electronic speed control) replace the mechanical speed control and servo providing enhanced power efficiency and precision in an your electric R/C boat. In addition, they are lighter and easier to use which improves the performance of some electric models. They are a lot more expensive and delicate.
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Motors
R/C boats are powered in a variety of ways. Sailboats, for example, need no power source other than nature. But they’re the exception. All other R/C boats require something to propel them into action.
Choosing the Right Power!
You can power your boat with an electric motor (or motors) and battery packs. Because boats have adequate interior space to accommodate two batteries, running times of 1-2 hours can be achieved with some models. Electric racing boats can go 20-25 mph and run for 4-8 minutes.
Gas power offers superior performance and realism in terms of speed, sound and smoke! An outboard engine is easy to install: just bolt it on, hook it up and it's ready to go. Inboard engines require running hardware, a flywheel and water-cooled cylinder head. Newer inboards are now coming with integrated pull-start units which makes firing them up a snap! Gasoline engines are not as common as glow engines, as they are normally used for airplanes, helicopters, etc.
Engines
Most gas R/C models use a 2- or 4-stroke glow engine, sized specifically for that model. Typically, they range in displacement from .049 cu. in. to 1.2 cu. in. (80cc to 20cc) — a variety that satisfies virtually any model’s power requirements.
Glow engines cannot be operated with the same gasoline you’d get at a filling station pump. They require a special fuel, called “glow fuel.” It contains methanol as the base, with varying amounts of nitromethane to increase the energy that the fuel can provide. Oil, pre-mixed into the fuel, lubricates and protects your tiny engine as it pounds out amazing power.
Two-stroke vs. four-stroke
Engines come in either 2-stroke or 4-stroke forms.
Two-Stroke means that the engine “fires” (ignites the fuel in its combustion chamber) with every revolution of the piston. Generally, they’re a good place for new gas modelers to start. Two-strokes are easier to operate, less vulnerable to problems if misused, and deliver more power for their size and weight.
Four-Stroke engines fire once with every two revolutions. They consume less fuel, sound more realistic, and provide more torque — but cost more, are harder to adjust and require more maintenance.
Engine Care
If you take good care of your engine from day one (which is not difficult at all), it will reward you with a long life of optimum performance. Here are some tips to help:
Keep the engine clean from dust, dirt, water, etc.
Keep your engine dry (or dry it off if it gets wet).
Use an after-run engine oil.
Use a brand-name fuel that contains at least the amount of oil recommended by the engine manufacturer.
Use fuel with the proper percentage of nitromethane, as recommended by the engine manufacturer.
Electric Motors
Some people find it easier to install an electric motor in their model. The electric motor will run on about 6-7 cells and uses a speed controller to adjust the speed. They require less maintenance then gas motors and they are quick, quiet, easy to build and comfortable for the beginning R/Cer to navigate. The electric cars are powered with a rechargeable nicd battery that can be charged in as little as 15-20 minutes. A boat with a stock motor will provide about 6-8 minutes of run time; with a couple of
batteries and a 15 minute charger, your electric boat is ready for hours of use (just remember to monitor the motor and electronics' heat).
Calculating Scale Model Speeds
If you are building a scale model (A scale boat is a replica of a full-size boat) you need to purchase a motor that will give the model a "scale like" speed. Most ships don't go 50-knots and neither should yours. To achieve a scale speed, you must gear down the 12,000rpm (around there) offered by most motors to a slower 150-750rpm. Gearing down a motor (as opposed to the direct-drive system) will also use less battery power. A suitable motor size can be calculated from the formula below:
Model Name:- Scale: _:__
Fill the Letters in with Information from your Model
Installed power per screw (propeller): A
Top Speed (Meters/sec): B
Screw Dia. (Meters): C
Number of Blades: x
Number of screws: v
Screw pitch (not required): h
Screw revs: y
Calculation Method
1. Model Scale D
2. Prop Shaft dia. L
2a.Scale Speed vo
3. Scale Power per screw (P):
Securing the Motor
This is very important. If the motor is not securely attached, it will vibrate itself loose. You may also want to attach a rubber bed to the joints to minimize vibrations and noise. The motor should be installed under a hatch or point of easy access for maintenance and the motor shaft, coupling, and propeller shaft should be carefully aligned before the motor is installed.
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Batteries
Batteries power the electric motor and come in two forms, primary cells, and secondary cells. The two are very different and should be noted. Secondary batteries come in two forms, Ni-Cad and Sealed Lead Acid type. The biggest difference between the two is that the Ni-Cad's are smaller, while the Sealed Lead Acid's are much larger and mainly used for model ships.
Primary Cells
Primary cells produce electricity from an chemical reaction when they are connected to a circuit. These are also known as disposable and are not used for powering a model, but sometimes the radio transmitter and sometimes the receiver.
Secondary Cells
Secondary cells can be charged with a battery charger. They are divided into two kinds: the Sealed Lead Acid and Ni-Cad types.
Ni-Cad batteries are the most common, used to power the electric boats and even the radio transmitter and receiver. They fit almost anywhere in the hull (but must be securely fastened to prevent shifting) and also serve as ballast for the model.
Sealed Lead Acid batteries are large (somewhat smaller then the ones found in cars) and can be mounted in almost any way (even upside-down) because they are completely sealed, not needing to be topped up of liquid inside. They need a specialized charger (NOT the one for cars) and are mainly used for large model ships to serve as ballast (as well as the power source).
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Props
The propeller is a very important aspect of racing boats. You need to pick one with the right pitch, etc. to get that small advantage in the races. Most models have only one propeller, located right on the keel while some have twin screws (props), located on either side of the keel.
One or Two?
For most racing and sail boats (for auxiliary power) will only need one propeller, but scale models (where the full size boat has this feature) should be built with two props simply for the scale effect. The same goes with the number of rudders on the ship.
The Propellers Pitch
Props are designated by these two numbers, for instance 10 - 6. The first number is the prop's length, 10". The second number is the pitch or angle of the blades. The 6 represents the distance the propeller will move forward in one revolution, in this case 6".
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Detailing
This is to add items to the vessel to make it look more realistic. You would add railings, seats, anchor winches, etc. by either hand crafting or modifying pre-made accessories to fit on the model. You can also add lights, sound units, smoke generators, etc. (which can be found at HarborModels.com) for a good price.
Lights, Camera, Action!
Lights are the most popular auxiliary function you can put on your scale model. Port and starboard navigation lights, masthead lamps, search lights, deck lights, cabin lights are all great ideas to bring out more beauty and realism to your boat. They are readily available at most model shops (one listed above) and some are ready to use!
Sound Systems
Adding a horn, engine sound, bell ring, etc. can really bring out the realism in your model too! They are somewhat easy to install and usually require radio channels to turn them on and off.
Other Details
Water discharges, working anchors, fire monitors, and rotating radar scanners are also great additions to your scale model.
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Miscellaneous Information
Miscellaneous topics that you may find interesting.
Training Others
When you are teaching newbies how to navigate a model, it is very effective to allow two transmitters to be connected by means of a trainer cord. The instructor can pass control over to the student's transmitter so that he can navigate. If the student gets into trouble, the instructor can regain control instantly. This feature is normally found on more advanced radios and requires you to purchase two (plus a trainer cord) instead of one.
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