Tuning Tips for the RC Laser
Guidelines by Jon Elmaleh
as edited by Abigail Kelly and Steve Lang
The incredibly good design and engineering of the RC Laser leaves the skipper with a relatively small range of performance adjustments. Because there are so few, they are fairly critical. What follows are basic guidelines to help you achieve greater performance from your RC Laser.
Adjusting sail shape is very important especially with respect to foot curve and leech twist. Knowing how much of each is based on practice and competition. Basically, in a light wind, more foot curve and a less leach twist are best. In a heavy wind, aim for less foot curve and more leech twist.
How are these sail adjustments made?
At the aft end of the boom are two sliders. The forward one is for tensioning, the aft slider adjusts the angle of outhaul tension on the sail. If you slide the aft slider forward, the tension angle is more down than out. So tensioning in this position tightens the leech, and allows the foot to curve away from the boom (foot curve). This produces draft that powers the boat in light wind.
As the aft slider is moved further aft, the angle of tension changes to distribute the tension more equally on the leech and the foot of the sail. In this position, a puff of wind bends the mast causing the leach to twist spilling air – which helps the boat stay upright. The lower section of the sail stays properly trimmed to help power the boat through the puff.
What is the proper amount of foot curve for a given wind condition?
A good indicator is boat balance (helm pressure). If the boat is able to sail itself to windward with little or no steering correction (neutral helm), then the foot curve is about right. Too much weather helm (the boat rotating into the wind) indicates that you need to flatten the foot curve. A leeward helm (the boat falling off the wind) shows a need for an increased foot curve.
Sailing in choppy water
Increasing leech twist helps prevent stalling the sail as the boat pitches through the waves. Because waves do not always relate to current wind velocity, this is a tricky setting to make. Don’t worry about a little windward helm in choppy conditions since it helps you find the wind.
Proper boom position
Most top sailors agree that sailing upwind with the boom just inside the aft corner of the stern is the proper location. Pulling the sail further inboard (pinching) produces a boat that goes upwind at a closer angle, but it travels much slower through the water. This position is only useful for short distances to get around a mark or obstacle. With the boom just inside the aft corner of the boat, you will find the RC Laser develops the best speed, and angle to windward.
Electronic boom positioning
It is often difficult to see the position of the boom from shore while you are sailing. Therefore, the following electronic and sheet adjustments allow you to know where the boom is by the position of your transmitter controls.
With the radio system on, place the sail control lever (left) all the way down (the full-in position). Set the fine tune slider next to the control lever, in the middle of its range.
Now adjust the length of the mainsheet (black string) so that the boom is positioned just inside the corner of the transom (should be done with the sail mounted).
The idea is that when you sail to windward, you push the sail lever all the way down and put the fine tune slider in the middle. That is your base position where your sail will be properly set for most of your windward sailing.
If you need to pinch up to pass an obstacle or a mark, move the slider down and it will bring in the sail to the centerline of the boat. If you have been slowed by waves, tacking, or another boat, you may want to push the fine tune slider up to let the sail out a little as you foot off to gain speed.
In light winds do not tension the outhaul to the point where it bends the mast. At the opposite end of the scale, when the wind is blowing hard, slide your aft slider all the way aft, and you will tension the sail so that there is little or no foot curve. Tension the outhaul to bend the mast so it pretty well fills out the luff pocket (leading edge of the sail). Obviously there is a lot of variation based on the wind speed.
When to Switch Sails?
Basically, when you begin to dive while sailing downwind, you should switch to a smaller sail. Many sailors carry big sails too long, and their performance is compromised by loss of control. There is very little difference in boat speed between sail sizes in the crossover wind ranges and keeping control is often the deciding factor. Experience will help you determine the best time to change.
Concentrate on steering your boat in a straight line – remember the shortest distance between two points is a straight line. Over-steering is a common mistake in model sailboats. Focus on smoothing out your steering and you will earn big rewards in performance.
Also remember that every time you turn sharply, the rudder acts as a brake, slowing your boat speed.
Tuning is done by degrees. Shades of adjustment make a difference. Tuning is not a mystery, but one that takes practice until you find the groove. These guidelines are just that, the parameters within which you will find the right combination to get the very best performance from your boat.
On the other hand, you can have a perfectly tuned boat and move your thumb in the wrong direction and . . . J So don’t fret over tuning, follow the basic guidelines and it will come to you.