International One Metre
Irish National Class Association

You need a transmitter (Tx)2 channels (most use a 4 channel Tx), a receiver (Rx), a servo for the rudder, a winch for the sails and a battery pack to feed all the above with energy.

Rudder Servo

You may be surprised at how much pressure the rudder is under in some conditions.

So you need a rudder servo that is light, with metal gears, High torque and ideally waterproof.

A wide range of them do exist and one of the most popular, if you're using Futaba Tx, is the (here comes the techy bit)  P-S9202 with a torque of 7.1Kg/cm, water and dust resistant, dual ballraced, 0.21sec at 60 deg with a cordless motor. Pretty good starting servo for our IOM boats. Just plug it into your receiver and steer away !!!

Brushless technology has recently emerged and improved servos by increasing the life of the servo and for smooth operation.


Checkout my dedicated page on my servo rudder shortlist

The winch

Now you have the radio to steer your boat but nothing to adjust the sails to get it moving so the winch is absolutely vital as it will adjust the angle of your sails.

Now you know as stated above that the rudder is under high pressure but the winch requires to hold the sails regardless of the wind and so it needs to cope with even higher pressure.

Most common winch are built by RMG (AUS) , and KBits (UK), but also by Futaba, Hitec and Graupner.   Most RC Sailors use one of the first 2 winches. The RMG which uses a drum to sheet in and out whereas Kbits one uses an arm connected to a very powerful Hitec servo.

Great choice of product here again... they are all good but the choice is yours. Just plug it into your receiver and sheet away !!!

The battery

So now you can transmit and receive signals, steer your boat and control the sails or can you ??? Well the wind will power your boat to move forward but you need another power source to power all that equipment. To do that you need reliable, powerful batteries.


The old Nicad batteries were ok but suffered from memory problems which meant you had to cycle them or their lifespan would reduce seriously after a while. The Nimh were better, no memory effect anymore and you could find capacity up to 2200mah. But they could be heavy. The new Lipo (Lithium Polimer) Life (lithium sss) are now the reference for a number of reasons.


To start no memory nasty effects, you typically charge them at 1C or their nominal capacity so they charge very quickly, they hardly loose any power when not used, they are lighter but …


BUT they are not for home made - you need to buy good quality ones because they can explode. Don’t get me wrong they are safe if used properly (we use them for a few years now with no problems) but they require a lithium ready charger as they need to be balanced charged so all the elements in the batteries are charging simultaneously and you want to stay around during the charge just in case.


Ok but what type of batteries do I need ?


The voltage will ensure that enough “oumf” is going to all the various electronic equipments while the capacity (mah) will in a nutshell dictate how long you can sail (the higher the capacity the longer you can sail without changing batteries). The voltage will vary depending on the type of winch you use but for the capacity you'll have plenty with 700 to 1100mah to last you for up to half a day of great sailing, depending on the conditions and use.


Ok so far but how do I know what is good for my boat and my usage ?


In short look for a 2S (2 cells at 3.7v each) which will bring typically 7.4v and a capacity of 700mah min to 1200mah or more depending on your usage. The C number on the battery pack eg 20C is the max burst capacity the pack can deliver but in our utilisation this does not matter as we only use the battery pack to power to the electrics on the boat the boat speed will be obtained by the wind and the rig.


I personally use a lipo battery 2S 850mah of 48gr which typically gives me half a day of sailing with no worries but just in case I usually have 2 spares to rotate them.


In order to help each other we agreed that everyone in Ireland use Deans connectors which have the best connection rating so that if someone runs out they can use someone else battery…

Electrics
SKills.

Transmitter & Receiver

Your choice is simple as most RC sailors use transmitters from either Futaba, Hitec or Graupner.

In Ireland most RC sailors use the new 2.4 Ghz which once bound to its receiver will work better then the old FM technology in that there is conflict of frequency anymore and less interference too.


Again, keep it simple as there is no need to buy expensive programmable models with a zillion channels. A standard 4 channel like the Futaba Skysport 4 is sufficient. You will need to decide on the type of battery you will use as they come with a choice of AA size battery or with a battery pack. Make sure you get the model with the throttle on the left (it will be the channel you will use for controlling the winch and your sails). With more advanced model such as the 6 EXA you can actually change the mode of the transmitter so to have the throttle on the left, but this feature is not on all transmitter so watch out before buying.


Transmitters will normally come with their own receiver which you will need but most are sold with 3 servos and various bits. To cut down the cost some suppliers may sell the transmitter (Tx), the receiver (Rx) and a servo separately.


A new constructor is emerging and becoming more and more popular with its new technology. Spektrum build transmitters and receivers with a 2.4 Ghz technology. This technology removes the need to have numerous crystals as they will operate on their own unique frequency removing any chance of having frequency conflicts. Also it removes the occasional glitches you may experience with FM systems. More expensive but they seem to become the most popular one as more skippers migrate over to them.