Kestrel 2000 Rig Tuning - October, 2018
In general, the Kestrel has several narrow grooves of adjustment to mast rake, pre-bend, spreader length and shroud tension that power up and depower the sail plan. There are more on-board controls than many other dinghies. Having and using equipment that can provide proper rig tension is crucial to setting up the boat for maximum boat speed.
The Position of the center of effort (CE, Sail Plan) in relation to the center of resistance (CLR, Centerboard and Rudder). This is measured from the top of the mast to the top of the transom on the Kestrel. Raking the mast aft (shorter distance from the top of the mast to the transom) moves the CE aft of the CLR. This will generate a slight weather helm causing the boat to sail higher naturally. Raking the mast back is better for higher wind speeds, or if you are struggling with the ability to point. Raking the mast forward (longer distance from the top of the mast to the top of the transom) moves the CE directly over the CLR or sometimes forward of the CLR. With the rake further forward the boat will not sail as high, but will sail faster and accelerate more in choppy sea states. The key is to find the balance point between sailing high and sailing fast.
The amount to tension of pressure measured on the shrouds. Rig tension helps control the mast bend. With more rig tension the mast will have more bend but will also be more stable. With less rig tension the mast will be straighter and our sail controls (vang, mainsheet, Cunningham) will have more affect on mast bend.
The length of the spreader itself. This is measured from the side of the mast to the bearing point of the shroud and the spreader end. The longer the spreader is the more stability it provides for the mast, makes the mast stiffer. This is a good feature for teams that are sailing heavier than the recommended crew weight, also better for sailing in lighter air conditions as it makes the mast stiffer and provides more power in the sail plan. Shorter spreaders will make the mast more bendy and de-powered. This is a good set up for lighter crew weights or over powering windy conditions.
The angle of the spreaders in relation to the mast. To measure spreader sweep you must tie a thin piece of line between the ends of the spreader tips making a extension line. Measure from the line down to the back face of the mast, this distance is the spreader sweep. The more sweep you have (larger number) the more the mast will bend de-powering the rig and sail plan. The less sweep (smaller number) the stiffer the mast will be, this is a good set up for heavier crews.
Pre-bend is the amount of static bend in the mast while the rig is under tension. This is measured from the main halyard pulled tight down to the gooseneck fitting. The distance from the main halyard and the back of the mast is the amount of pre-bend you have. More pre-bend will make the main sail flatter, less power. The less pre-bend means the mast is straighter and the main sail will be deeper and more powerful.
Suggested Tuning Numbers- North Sails UK
23’6”- Light to Moderate wind conditions
23’3”- Heavy air
425mm- Lighter crew weight, less than 320lbs
435mm- heavier crew weight, more than 320lbs
200mm- Lighter crew weight, less than 320lbs
190mm- Heavier crew weight, more than 320lbs
45mm- Lighter crew weight
40mm- Heavier crew weight
Increasing Light Air Performance-
What do we Change?
Sailing in light air is in many ways tougher than sailing in windier conditions. The breeze must connect to the sails to generate flow, once flow attaches it must move across the sails in order to generate pressure, this pressure puts force on the Centerboard and rudder generating lift. The lighter the breeze is the harder it is to attach flow on the sails thus making it harder to generate lift. We can make changes to our sail plan and rig tune in order to make generating flow and lift easier.
- Rig tune- Mast rake and rig tension are the two critical tuning features we need to focus on. Make sure that you are set up for a mast rake on the longer range of your scale. Having the mast raked further forward will help the sail plan generate enough power to create lift. Rig tension is also critical, pay attention to the leeward shrouds while sailing upwind. Make sure the leeward shrouds have little to no tension on them. You want them just starting to go slack while sailing upwind.
- Don’t try to point- Sailing high and slow is a death sentence in light air conditions.
Make sure that you are sailing with both tell tales streaming back maximizing the flow across the sails. Once you are going fast thru the water you will naturally generate lift for pointing ability.
- Sail Trim- Do not over trim the sails. Twist in the leeches of the main and match twist in the jib will help you generate flow across the sail plan, maximizing the flow helps generate lift. Once you are up to full speed, you can cheat a little height by trimming in (removing twist). Pay attention to your speed though, if you are slowing down, be sure to ease back out right away.
- Sail for the puffs- Sailing in pressure towards the next puff is critical to light air
performance. Keep you heads out of the boat and make sure you are sailing in the best pressure on the course and heading towards the next puff.
Rig Tune on the Water-
What to pay attention to-
While sailing upwind there are certain things you need to pay attention to. These items will help you balance the boat while sailing with as much speed as possible. If one of these items is incorrect the boat will be either out of balance, sailing low (not pointing), sailing slow (no boat speed), or a combination there of.
- Rig tension/Head Stay Sag- Rig Tension and Headstay sag can be the number one cause of speed and height issues. If you are sailing in light air conditions and the rig is too tight you will not generate enough headstay sag making the jib too flat and less powerful. On the other side, if you are sailing in over powered conditions and the rig is not tight enough, the headstay will have too much sag making the jib too deep pulling the bow down when the main is eased. This causes leeward helm and more heel angle. Really focus on the leeward shroud tension and the amount the headstay is moving. In light air you want a loose rig and more sag in the headstay, in heavier air you want a tighter rig and no movement in the headstay. Adjust this according to the wind conditions.
- Main sail shape- As the wind speed varies the depth of the main sail should change as well. A deeper sail shape will generate more power and more weather helm, and flatter main sail shape will de-power the boat making it easier to sail the boat flatter and minimizing weather helm. As it gets windier and you apply vang to help bend the mast and de-power the boat (flatter main) you may invert the main sail at some point. This is slow and a change needs to be made. Be on the look out and observe your main sail shape. If you feel like you need more power or point, make the main deeper, if you are over powered and struggling to keep the boat flat, make the mainsail flatter with vang, Cunningham and outhaul.
- Mast Ram (What does it do?)- To refer to main sail depth, the mast ram as a direct effect on mast bend which affects the main sail depth. If you need more depth and power in the main use the mast ram to make the mast straighter. If the main sail is inverting, that means the mast is over bent, apply mast ram to get the mast straighter. The mast ram is a tool used to make the mast straighter to make the main sail deeper, create more headstay tension, and to make the rig more stable (less bounce, keeping the energy for propulsion rather than exhausting the power through rig flexing of the mast, shrouds and headstay).
- Mast Rake- As you are sailing against other boats you should be paying attention to your relative performance against them. If you are lower (less point) but are faster, consider raking the mast further aft, this will give you the ability to point more. If you are higher and slower, consider raking the mast forward to generate more power to sail faster.
Keys to sailing fast upwind-
- Balance- Sail the boat flat and balanced, no helm one way or the other. Neutral helm and flat boat makes a fast boat.
- Changing gears-As the wind speed varies from puff to lull make sure you are making the appropriate changes to your sails set up. If the wind speed drops, make the sails fuller and more powerful, as the wind speed increases you will need to make the sails flatter and less powerful. The goal is to make the boat balanced all the time.
- Anticipate-In order to make the right changes and keep the boat balanced you need to anticipate what is going to happen next. Will the breeze increase or die? Will the puff knock or lift? Make your correction before the change happens.
Sail Trim- Main
The main sail trim gives the boat the ability to sail high, pointing. The main can also generate too much helm. Being aggressive with main sail trim is critical to the boats balance and performance.Set the sail up for the average wind speed- Through rig tune and sail depth, set your main sail up for the average wind speed so you can focus on using the main sheet to adjust the boats balance.
Keep the boat flat- As a puff approaches the boat be ready to ease the main sheet out. Keep the boat flat by easing the main out. As that puff goes away be ready to trim the main back in to avoid heeling the boat to windward.
Be aggressive- Be aggressive with main sail trim adjustments. In light air make sure you are eased for power and twist, but when the boat sails into a puff you can trim the main in to create height without loosing speed. In windier conditions, keep the boat flat by easing.
Sail Trim- Headsail
The headsail provides the ability to balance the boat as well. While the mainsail will create weather helm if trimmed in, the jib will create leeward helm when trimmed in. If both sails are trimmed equally, the boat will be balanced, and neutral helm will be achieved.
Pay attention to the main sail trim- If the main is eased in a large puff and starts to backwind, the jib may need to be eased slightly as well to keep the sail plan balanced. If the main is eased and the jib remains trimmed in the boat may experience lee helm.
Leech profile- by placing a tell tale on the upper leech of the jib you will be able to see how the flow of the breeze is exiting the sail. You want the tell tale flowing back all the time. If that is stalled, you need to ease the sail out, or move the lead aft to open the leech.
Boat Balance with Crew Weight-
In all conditions the crew weight placement in the boat is very critical. You have the ability to move fore and aft in the boat as well as side to side. The goal is to sail the boat as balanced as possible while sailing as powered up as possible. Being aggressive with crew weight means paying attention to heel angle at them same time as sail trim. If you can hike harder and minimize the amount the sails are eased to keep the boat flat that means you will sail faster.
Hike in a position that is comfortable for you. Hiking hard is fast and means that you do not have to de-power the boat as much, but if you are getting tired a few seconds after hiking hard, you will tend to move around too much disturbing the boats balance. Hike in a position that you can stay in for a few minutes.
Fore and aft position in the boat is just as critical. Pay attention to the way the water is flowing off the back end of the boat. You want to see smooth water coming off the transom. If you see allot of disturbed water, or water flowing upwards the transom, you need to move forward in the boat. Look at the bow wake as well, you do not want to be plowing water. Sit as far forward as you can with out digging the bow into the water.
Move your weight around to provide balance in the average wind speed. Adjust sail trim in puffs and lulls. The idea here is to minimize the amount of pitching the boat is doing. A stable platform is the fastest, rocking and pitching is wasted energy.
Keys to sailing fast Downwind-
- Know where the breeze is coming from and trim the boat properly. In lighter air conditions you will not be able to sail directly downwind, you will need to sail angles in order to keep your boat speed up. Always match speed with your competition before matching their angle, if sailing faster than your competition then sail lower and away.
- Sail in pressure. When sailing downwind you want to position yourself in front of the puffs. If pressure is coming from one side or the other, meet the puff, don’t sail too much extra distance to get to it.
- Sail the boat flat and balanced, use crew weight to turn the boat vs. rudder.
Sail the boat in front of the pressure and meet the puff.
Sail Trim- Main
Keep the main projected and at 90 degrees to the wind direction. If changing course,
the main trim needs to change as well. Don’t forget about the main
Pay attention to the top batten position. If the sail is too open (twisted) pull vang on to get the top batten 90 degrees to the wind direction.
Remember to remove Cunningham once sailing down wind, let the tack of the main float up to make the sail deep and powerful in the middle.
Sail Trim- Spinnaker
Keep the sail full and out in front of the boat, hold the guy from the extension in front of the twing block for faster adjustments.
Communicate the pressure or load in the sail. If the pressure or load is decreasing then inform the skipper and change your angle (sail higher) for more load. If the pressure or load is increasing, then inform the skipper and sail lower.
Pay attention to the boat balance. When the boat wants to pitch to windward during a larger puff, trim the leeward sheet rather hard in order to prevent the spinnaker from rotating too far to windward. The sail should stay directly in front of the boat.
During gybes, leave the pole alone and focus on keeping the spinnaker full through the gybe. Once the boom comes over, hand off the sheets to the skipper and switch the pole.
Pull the centerboard up at least half way in order to balance the helm and prevent the boat from tripping on the center board.
Pay close attention to fore and aft weight. In lighter air its ok to get really far forward to get the transom out of the water, pay attention to the bow wake though, do not push water
Sailing on a reach with the spinnaker-
Tips for sailing fast on a reach-
- Keep the boat flat and on its lines (water line level). Fore and aft weight is just as important as side to side weight.
- Be aggressive with sail trim and driving angles. The boat will power up and de-power more frequently and more aggressively. Keep the boat powered up and use every puff to get as low as possible, sail back up in the lulls to keep the boat moving fast.
- Sail for the puffs.
Sail Trim- Main
- The main sail controls most of the heel angle on the reach. If the boat is heeling to leeward, ease the main aggressively and then try to drive the boat down once it gets flat. As the boat wants to heel to windward, trim the main back in aggressively to keep the boat flat, as you trim the main in, sail up to power the boat back up.
- The boom vang is a primary control for leech tension on the reach. If the vang is too tight, the boat will tend to heel more and not accelerate in puffs, if the vang is too eased the boat will be slower in general. Proper vang trim is critical to boat balance. Trim the main in so it is not luffing, set the vang tension to the power needed to keep the boat balanced.
- To get the boat to accelerate in the puffs, pump the main as the pressure builds in the sail. Ease aggressively after the pump to keep the boat flat, the boat will accelerate into the puff and surf or plane.
Sail Trim- Spinnaker
- Do not over trim the spinnaker on a reach, over trimming will back wind the main and cause the boat to heel to leeward too much. Always maintain a 2-4” curl in the luff of the sail.
- Be aggressive with pumping the sheet. As the pressure builds in the sail from a puff, pump into the pressure build and then ease again aggressively to a 4”curl. This will promote planning and or surfing.
- As the spinnaker trimmer, you must be aggressive with body weight placement in the boat. As the boat wants to plane, move aft to get the bow to pop out, then move forward again to keep the transom out of the water and keep the boat on the plane longer. In lighter conditions be aggressive with side to side movements, keeping the boat flat.
Sail Trim- Jib
- Keep the jib sheet eased enough to luff the top half of the sail, but the bottom half is still full and drawing.