Sail Selection for the RC Laser

Choosing the Right Sail

When the ‘A’ (large; light weather) and the ‘B’ (middle-size) sails get near the upper end of their wind range, they develop a pronounced weather helm. This means that they drive the boat into the wind, sometimes overpowering the rudder and when sailing downwind the boat tends to ‘submarine’. For example, the ‘A’ rig has an upper range of around 8-10 knots.
To windward, the answer to this problem is boat speed. It is critical to keep boat speed up so that the rudder has maximum effect. This is done by making quick, complete tacks, and slacking the sail slightly after a tack to bring the boat up to maximum speed again. Only then can you afford to trim for windward sailing.

The idea is not to fall off to a beam reach, rather just a slight slackening of the sail after tacking and pointing a few degrees lower than you would expect. This is the same method used with any sail when tacking to get your boat back to speed. Remember that the cat rig needs to sail fast through the wind in order to develop its maximum pointing angle. Just remember boat speed, boat speed, boat speed – the faster you go, the higher you can point.

So you screw up and get in irons – now what? There is only one way out – and the manoeuvre is even more pronounced with the A rig. Hold the rudder full over, and keep it there. Don’t worry about which way you have turned the rudder, just pick a hard over position and hold it. The boat will start to back out of irons. At the same time slack the sail all the way out.

As the boat turns backwards, the sail will be flapping out to the beam. For the A rig, it takes a full beam reach (perpendicular to the wind direction) to regain control. So when your boat is beam to the wind, SLOWLY trim in the sail. SLOWLY!!! The boat will start to move forward, and soon you will have developed rudder control once again. As speed increases, trim the sail more until you are back sailing at speed to windward.

If you trim the sail too quickly, the sail just drives the boat right back into the wind because you have no rudder action to stop it. Then you get to start all over again.

Finally, and the ultimate determining factor of going to a smaller sail is your downwind performance. Most sails can be feathered to windward, but there is practically no way out when you turn downwind.

First of all, when the bow starts to dive, you need to steer back and forth rapidly. The change of angle of the bow, allows the lee bow to lift the bow and keep it afloat. If the wind is steady, this technique can keep you going, and the added speed developed will do even more to keep your bow up. However, when it is gusting, the approaching gust will often bury your bow before you can get your boat up to speed. Again, it is speed – a fast boat has more lift in the bow.

To recap, just about everything discussed here has to do with boat speed. To windward, keep the boat moving at all costs. Tack fast, slack momentarily, regain speed and then trim for weather sailing. If you get caught in irons, rudder hard over and hold, sail all the way out. When on a beam reach, trim the sail very slightly to get the boat moving, and regain steering control. Downwind, wiggle the bow to help with lift. When rolling out, or diving, is all you do, change down in sail size. 

Sail Shape

You will, with practice, learn how to set sail shape for maximum boat speed. In the meantime we suggest setting the outer boom slider (at the stern most corner of the foot of the sail) approximately 4.5 cm from the end of the boom. This setting, in conjunction with a suitable adjustment of the inner boom slider, should give a nice curve to the foot of the sail. Pulling the inner outhaul slider towards the mast will bend the mast thereby flattening the sail and vice versa. You will soon be experimenting with the controls to set your own favourite sail shapes for different wind conditions.
Some full size top Laser sailors are now sailing with a lot of camber set in the foot of the sail when sailing in light airs. This is contrary to the advice given by top sailors for other types of yacht or dinghy. Give it a go, you may be pleasantly surprised.
In heavy weather you may find it worthwhile flattening the sail a bit to improve air flow over the sail. As this has the added effect of tightening the sail leech (reducing twist) and moving the Centre of Area rearwards you have to watch what you are doing so as not to increase weather helm too much, and therefore the tendency for the boat to head up to wind.

When setting the sail on the shore be aware that the sail shape will change when the boat is on the water and the sail has wind pressure acting upon it. Always look to the sail shape ‘when sailing’ – not when the boat is static on the shore.

As you are probably now beginning to realise Laser sailing has more to it than meets the eye. So go out there and start practising. Are you up to the challenge?

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