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Optimist Tuning Guide - Grogs 11/07 UAE race coach Page 1 optimist tuning guide

Optimist Tuning Guide - Grogs 11/07 UAE race coach Page 1 optimist tuning guide p r e p a r e t o p e r f o r m Oppie Tuning Tuning the oppie is very subjective, it is tailored to the individual sailor, their weight, strength, style of sailing against the factors of sea state, wind speed, equipment and I even take into account the child’s mood. I know this sounds like a daunting black art but I can give you some very precise tips to mix with your own experience and experimentation is a very thrilling part of coaching this technical dinghy. The tuning tips in this guide are meant for children to perform and for parents to provide the guidance allowing the sailor to develop their own tuning skills. Tip 1: Tune with critical passion. You have a phenomenal engine that needs to be adjusted for speed, millimetre differences make huge changes to sail shape and rig performance. Learn to take time and patience tuning your rig, be very critical it will put you in a league of your own and you will out perform most of your competitors. The sail is a beautifully cut piece of cloth that must be kept in its shape for maximum performance and you will notice if you lay the sail on the floor the front edge (the luff) is far from straight. The biggest problem we have tuning the oppie rig is how to put a curved sail on a straight mast, a mast that will bend depending on the wind and a sailor’s weight and strength. All of the sail adjustment points can be altered on the water but it is much easier to do it on the beach anticipating the conditions we are going to experience once we’ve launched. Class Rule: The maximum distance between the sail and spars at attachment points is 10mm – the width of your little finger Optimist Tuning Guide - Grogs 11/07 UAE race coach Page 2 Tip 2: Most of our tuning effort should be focused on the luff of the sail and how it lies against the mast. On the boom the ties once set can be left and just checked occasionally to make sure they are not coming undone. Also the Throat Check once correctly adjusted for sail height at the rigging stage can be left and only periodically inspected for chaff and wear. (See rigging section to explain the names of the sail and strings!) Optimist Tuning Guide - Grogs 11/07 UAE race coach Page 3 optimist tuning guide p r e p a r e t o p e r f o r m Curved Sail - Straight Mast (maximum distance between the sail and spars at attachment points is 10mm) 4mm 2mm 1mm 1mm 2mm 4mm Mediu m Wind some mast bend 3-5m m 3-5m m Strong Wi nd lots of mast bend 0-3m m 0-3m m Sail T ie s 8mm 4mm 2mm 2mm 4mm 8mm Light Wind no mast bend 5-10m m 5-10m m Thr oat Fo ot 1mm 2mm 2mm 2mm 2mm 1mm Here are some tuning figures I use for the Olimpic radial sails, I haven’t specified the exact wind strengths in precise terms because the sail set up will depend on a number of factors not only wind speed and type of sail, but sailor’s weight, ability, sea state and even air temperature (A hot day in Dubai against a cool day in the UK has a density difference equivalent of climbing up a 5000’ mountain and the difference in the amount of pressure in the rig is remarkable) The bottom line is one of how much power is coming out of the rig and how much of it can we control, the more excess we have the further right in the diagrams we go. A light child in flat water will be on strong wind settings before his bigger competitor. Optimist Tuning Guide - Grogs 11/07 UAE race coach Page 4 optimist tuning guide p r e p a r e t o p e r f o r m Luff Tuning Light Airs: The sail is not pulled in hard so the mast will not bend, for the sail to keep its beautiful design curves we must adjust all the attachment points to allow the sail to find its natural shape. The throat and foot are eased to the maximum 10mm, the sail ties adjusted individually to follow the cut of the luff. The boom is lifted to ease the tension in the front of the sail by twisting and shortening the goose neck strop making the luff fuller. The outhaul is eased to allow the foot of the sail to scallop to give belly to the sail and also allow it to flop over the boom easily when tacking. Increasing Wind Strength: If we don’t adjust the sail for the conditions as the strength in the breeze increases so we need to adjust the rig accordingly. The mainsheet will be pulled harder, the unstayed mast will bend, the sail will mis-shape and the power will be unbalanced. When we tune, the throat and foot need to be brought closer to the mast and the ties adjusted so that the bending of the mast on the water does not distort the sail. The front of the sail can be flattened to control it’s power by taking twists out of the goose neck strop allowing the boom to drop and luff tensioned. The outhaul needs to be progressively tightened as the breeze builds, flattening and depowering the rig. Tip 3: A sail tuned for fullness has a greater curve to the sail providing power in light wind, waves, and for heavier sailors. But it has a big downside, a more rounded sail prevents you from pointing as high as a flatter sail. Light sailors often sail higher and faster because they don’t need such a powerful (curved) sail and can flatten the rig allowing them to point higher before the sail stalls. Its all about critical angles of attack and the point at which lamina airflow breaks down because it needs more energy to flow around the surface with a greater curvature. What we need to know is that there is an optimum balance depending on conditions for power (full sail) vs height (flat sail). Optimist Tuning Guide - Grogs 11/07 UAE race coach Page 5 The Sprit The sprit is the greatest tuning tool. It is always rigged on the starboard side so that on the start line you aren’t disadvantaged by having the spar disturb the airflow over the critical lifting section of the sail. Tip 4 : WHEN ON THE WATER THE SPRIT MUST BE CONTINUALLY ADJUSTED FOR THE CONDITIONS Ace sailors alter the sprit tension around the course as they race. With practice it’s very easy to adjust and if done at the appropriate time then the sailor will not loose any ground making the change and only gain hull speed after. So how much sprit tension should you have? Well the sail is the biggest and best signpost for telling you how much sprit you need and it also advertises to the world if you are an ace sailor or not. The simple answer is if the sail looks right the tension in the sprit is right. Here are a few pointers: - Never should there be vertical creases in the sail when sailing it means the sprit is too tight. This often happens in light wind, if the sprit is not eased for the reach and run vertical ceases appear, these kill the airflow and destroy the sails performance, you will go slower than anyone else who has adjusted their rig. - Horizontal creases aren’t nearly so bad and means the tension across the sail is loose so the sprit needs to be tightened. Often we would sail with slight horizontal ‘speed creases’ as this means the sail is at its most efficient. optimist tuning guide p r e p a r e t o p e r f o r m horizontal creases (sprit loose) perfect vertical creases (sprit tight) Optimist Tuning Guide - Grogs 11/07 UAE race coach Page 6 optimist tuning guide p r e p a r e t o p e r f o r m Kicking Strap Often poorly adjusted, the kicking strap is critical to the curve at the back of the sail (the leech). Too much kicker and the leech is hooked acting as a brake and stalling the airflow, too little and the boom lifts, the leech twists, depowers the sail and off the wind forces the boat to roll to windward easily resulting in a capsize. So how much kicking strap? The kicking strap should always be adjusted to take up any slack in it once the sail has been sheeted into its normal position for beating. As the breeze builds so the mainsheet uploads/Management/ optimist-tuning-guide.pdf