Basic Tuning
TUNING & SAILING YOUR RAINBOW
INTRODUCTION
Greatest enjoyment is gained from your National Rainbow when you attain performances comparable with the leading boats in your fleet. The following suggestions are some basic principles. However, it must be stressed that your own theories should be tried, as only by doing this will the already high performance of the Rainbow be improved.
HULL
lt is most desirable to build your boat close to the minimum hull weight. Equally important it is necessary to make it rigid and strong. Therefore it follows that only by taking extreme care with every piece of material used and using good workmanship will these requirements be attained.
lt follows that a boat built strictly to the specifications will be easier to tune as you can then follow, with confidence, the "tricks" as used by the experts.
The general layout of the cockpit should be designed to suit individual ideas. If you are intending to have a light crew it is advisable to sheet your main on a hawse located at the centre of the cockpit. Keep it as simple as possible and only use gadgets and ideas that are really necessary to the efficient working of the boat.
Chines may be either rounded or left sharp to suit individual taste. Naturally the outside hull surface should be perfect.
CREW
The two man crew must be quick thinking, agile, strong and have the will to win. It has been found that an all-up crew weight of 114-133 kilo is the most successful for varied conditions.
The crew need only be formed by average sized people, but the forward hand should be the heavier member of the crew.
All these points are desirable, but teamwork will make the difference between winning and losing, and this only comes after much practice.
SAILS
It is not necessary to have a large wardrobe of sails. The Rainbow sets a mainsail, a jib and a spinnaker. One of each is quite sufficient for successful racing. A properly designed mast which flexes above the hounds (Where the rigging wires come together to support the mast) will automatically spill the excess wind out of the mainsail in hard breezes.
A simple axiom with sails is the heavier the crew the more airflow is necessary.
Full-length battens, or soft mainsails are optional. The soft type is fast becoming popular, due to simplicity to rig. There is little to choose between these types of mainsail, as both perform well in all conditions.
The jib is perhaps the most important sail on a Rainbow a boat with a perfectly setting jib will always be well to the fore of the fleet if sailed correctly.
It is only necessary to have one spinnaker on a Rainbow which should be as large as the rules permit.
With modern Mylar and Dacron it is important to look after your sails, as any handling at all tends to crease the cloth. This roughens the surface and ultimately breaks down its stability, density and strength.
SAILING TO WINDWARD
Below a breeze strength of 9 knots the Rainbow should be sailed with the windward chine just out of the water and the crew well forward. However, above this strength of breeze the boats can plane(1) to windward if carefully handled some skippers forsake a little of their pointing ability to achieve this extra speed to windward.
The trapeze allows the crew member to be fully supported by the rig as they place their feet in the gunwale and extend their weight out beyond the side of the boat. This extra power makes this planning possible. The decision whether to point close to the wind or ease sheets a little and plane is a matter for careful experimentation. Crews will adjust their decision as conditions change, but practice racing against other Rainbows will refine each crew's decision making.
REACHING
Unless the breeze is very light the whole idea of reaching is to make the boat plane at maximum speed all the time. Because of its speed, you will find that the boat reacts very easily to your rudder movements and although you must steer the boat to take the best benefits of waves and wind, do not be too severe on that rudder otherwise you are applying a brake, and a high speed planning hull requires very little effort to stop it in its tracks. It is most important to keep your Rainbow flat.
With the spinnaker set, your Rainbow should be almost perfectly balanced, requiring no severe movement of the rudder.
RUNNING
Once again because of its light weight the boat must be sailed delicately in that every wave can be put to some purpose. Your position of weight fore and aft will come from experimentation and as each set of conditions applies, so you will find the correct position for the crew. It is usual to move the crew aft as the breeze freshens.
The Rainbow is renowned for its speed on a three-quarter or shy run. In hard breezes the boat should be made to plane at maximum speed all the time. This can only be done by driving the boat to leeward in the hard puffs and heading to windward as the gust dies. If you make your Rainbow plane ten metres further than any other boat you will be well to the fore in a large fleet, but once again this can only be achieved by practice and teamwork.
For off the wind sailing a boom vang is a necessity.
GENERAL
The National Rainbow is basically a one design class and everybody has a chance of winning. If you have a carefully prepared hull, your sails correct and a keen crew, you should be well to the front of the Rainbow fleet. If you are not, it could be for any of the above reasons and since it is a restricted class, the opportunity exists for you to find out the weakness, overcome it and stay with the fastest boats in the field.
No matter how efficient your hull, sails and gear, unless you sail the boat properly you can jeopardise all the work that you have put into your Rainbow.
Simple operations like going about, handling the spinnaker and working sheets, determining the speed of your boat and practice is absolutely necessary to obtain the best results.
(1) Planning - Originally called aquaplaning or hydroplaning, this refers to boats traveling at speeds where their passage through the water generates lift. This lift reduces the resistance to the boat's forward motion allowing it to travel at far higher speeds.