Home
Club Frequency Allocation
Racing
Members Boats
Club Headquarters
Championships 2005
EQUIPMENT
Entry Forms
MYA Radio A Class National Championships 2005
The 2005 RA World Championships in Pictures
RA World Championships 2005 - More Pictures
Vane A Nationals 2006
PRACC 2006 - Gosport Round
Links for Gosport Model Yacht & Boat Club
Event Calendar
Mail Form
|
Equipment Requirements
Besides your boat, you will need Radio Control Equipment in order to effect and maintain control over it. When a yacht is out on the water, although it might not always look as if it is going very fast, a yacht ‘out of control’ can cause serious damage to itself and/or other boats.
The main elements of the Radio Control system are
The Transmitter
The Receiver
Rudder Servo
Sail Winch(es) |
Transmitters
There are a number of variations in the design of transmitters although the function of them is largely similar. The differences really come down to the levels of sophistication that are built into them. Some are almost miniature computers and allow the user to programme in settings such that if the transmitter is used for different boats at different times, the user does not have to set the settings each time a boat is changed. They are typically about 20 cm wide, 15 cm tall and 5 cm deep with an antenna which may extend to as much as 1 metre or more. Some form of protection should be placed on the end of the antenna in order for others to be able to see it more easily and to help avoid accidental injury such as it being poked in someone else’s eye.
Most transmitters essentially use two channels for control:-
1 Control of the rudder for steering
2 Control of the sails via cords known as ‘sheets’
|
A Computer Style Transmitter
 A transmitter with primarily two channels but capable of being programmed to retain settings for up to 6 different models. |
A standard type 2 channel Transmitter
A transmitter with primarily two channels but which may need some changes to its settings if it was intended to be used for different models. |
Multi Channel Transmitters
 | Some transmitters utilise more than 2 channels although this does depend upon the class of yacht being raced as some class rules only permit a maximum of 2 channels to be used. Bigger yachts, such as the A Class however are permitted to have each sail independently controlled. If the user chooses to adopt this method of control, at least three channels will need to be capable of being operated.
A transmitter with several channels, whilst more typically used with scale models for controlling a number of different functions e.g. lights, sound etc. this type of transmitter is regularly used in the likes of the A Class yachts as the ‘twin sticks’ enable the user to maintain control over the sails separately. |
|
Protecting Your Transmitter
It must be borne in mind that regardless of the cost of these units which can vary from as little as just a few pounds up to several hundred pounds, they are still precision electronic units and need to be looked after carefully.
When transmitters are used to control boats, water is never far away!!
Transmitters and water do not mix well!!
Radio Controlled sailing is undertaken in most weather conditions and users will frequently be seen with ‘muffs’ or some form of protection form the elements. They also help to keep fingers warm in cold conditions!
Most transmitters are powered by batteries typically rechargeable cells producing about 10 volts (8 cells at 1.2 volts nominal). A well charged set should permit the transmitter to be used for a day’s sailing although it is important to turn off the transmitter when it is not being used in order to conserve battery power.
|  |
|
Frequency Crystals
 A key part of the transmitter is its crystal which determines the precise frequency at which it is transmitting signals. There are a range of crystals available such that in theory as many as perhaps 40 boats or models can be controlled at the same time without them interfering (clashing) with each others instructions. Interference can have catastrophic consequences as the user will effectively lose control of his model. |
Receivers
 | This is typically a small unit approximately 5 cm x 2 cm x 1.5 cm that picks up the signal from the transmitter, converts that into instructions to the servo and/or winch and then passes that information to those units in order to make them operate. The receiver contains a crystal that determines the frequency of transmission that it will pick up. The crystal in the receiver must obviously match that in the transmitter.
The receiver requires power to operate, typically 4.8 – 6 volts. It may have its own prime source of batteries and then also distribute power as well as the instructions to the servo/winch or it may receive its power from the winch. The main advantage in utilising the power from a winch is that the winch normally operates with a higher voltage but typically contains a voltage regulator component that reduces the voltage level going to the receiver. If power is supplied to the winch from the receiver, there is the danger that the receiver may be overloaded or that the voltage going to the winch is lower thus making it slower to operate.
|
|
Protecting Your Receiver
| Apart from interference from another transmitter, the receiver’s worst enemy is moisture. In order to afford the best protection they are sometimes enclosed in for example a simple balloon although it is equally important that the balloon is removed after use to ensure there can be no build up of condensation. Moisture inside a receiver invariably brings control difficulties and loss of control with electrical shorting and even fire in worse cases. |  |
|
Rudder Servos
Servos are relatively small (4 cm x4 cm x1.5 cm) components that react to the instructions sent from the receiver. The result is the servo forn (or head) turns in a clockwise or anti-clockwise direction and through the linkage to the rudder, causes the rudder to turn with the intention of steering the boat. The amount of rotational travel should be in proportion to the amount of stick movement on the transmitter, typically a full throw of the stick generating something in the region of 60 degrees of movement off centre to either side.
Whilst it is possible to pay perhaps almost up to £50 or so for a servo, a much cheaper alternative, sensibly looked after will normally do the job just as well. They can be bought for probably under £10 but the secret is again to make sure they are kept as dry as possible. Even though they appear to be a sealed plastic container, moisture has an annoying habit of getting to the electronic elements. A smear of grease or silicone around the joints of the casing will help but especially if silicone is used it must not be allowed to come into contact with the rotating head.
|
Servo to Rudder Linkage
This is normally effected via rod or wire and can be done in basically one of two ways. There will normally be s servo horn fixed to the top of the servo which acts as a lever when the servo head is rotated.
It must be borne in mind that the rudder will be required to move both left and right and that if a single rod link is used, there will be occasions when the linkage is under pressure (when it is pushing) or under tension (when it is pulling).
To even out the effects that these differences can bring, where space and layout of the boat componenets permit, it is better to use linkages from both ends of the servo horn so that the pressure is equalised.
Remember to use good quality materials for the linkage and where possible include some form of adjustment capability. Stainless steel or brass are normally the most suitable metals to be used in view of their resistance to rusting but some plastic parts can be very useful.
|
Sail Winches
You will need some type of winch to control the sails.
There are two principal types of winch:
The Lever Arm and The Drum.
The Lever Arm type winch is in many ways similar to a rudder servo except that the arm on the top of the servo (the horn) is considerably longer to enable sufficient movement to be obtained when the servo is operated. Unless some form of gearing is introduced to the mechanism, there needs to be sufficient 'throw' from the lever arm such that from either of its extreme positions the line going to the sails (known as sheeting) permits the sails to move from a fully 'sheeted out' to 'close hauled' or 'fully sheeted in' position.
When you consider the considerable forces that may be needed to pull in a sail which has a strong breeze behind it, it follows that a servo required to operate a lever arm winch needs to be much more powerful than the standard type that could control a rudder.
The Drum winch has a circular 'drum' to which the sheeting is attached. Unlike the conventional servo, the head of the servo (which it resembles very much in appearance and size) can rotate through 360 degrees. Indeed drum winches customarily enable rotation through up to as many as 5 or 6 complete circles thus enabling closer control of the length of sheeting available to control the position of the sails.
Drums have varying diameter sizes and very often the winch servo itself has an adjusting screw that permits the user to set the number of turns that it should complete from its two extreme positions.
Whilst similar pressures are likely to be exerted upon the sails for a given wind speed and direction, because of the degree of pull needed to control the sheeting, a drum type winch does not necessarily need to have as much power as a lever arm type.
|
|
