Agenda. How a sailboat works What are you looking at? Modes of sailing A few boat handling tips Some resources

Transcription

1 Agenda How a sailboat works What are you looking at? Modes of sailing A few boat handling tips Some resources

2 The Sail is a Wing Like a wing in principle, lift is generated by both the shape (camber) of the sail and the angle of attack.

3 Sail Lift Vectors Sail Lift Forward Lift Lateral Lift 1. Lift is generated by wind over the sail (wing) 2. Can be broken into a lateral component and a forward component.

4 Keel Vector Keel Lift Keel Vector Keel Lateral Resistance Sail Lift Lateral Lift Forward Lift 1. The Centerboard provides resistant force opposite to lateral lift component. 2. Lift is also generated by the keel (and hull ) as the boat moves through the water.

5 Drag Vector Sail Lift Keel Vector Drag Vector Sail Drag Boat Drag 1. The boat produces drag as it moves through the water. 2. Depending on how they are set, a certain amount of drag is also produced by the sails.

6 Forward Movement: Sum of the Vectors Sail Lift Keel Vector Drag Vector Forward movement is what we get when we add the three vectors together.

7 Impact of the Change in Sail Lift An increase in Sail lift (without change in the other two vectors) results in an increased forward movement.

8 Increased Sail Lift + Keel Vector An increase in sail lift can also result in an increase in the keel vector. The centerboard increases resistance to the lateral movement and increased boat speed induces additional lift from the keel and hull. The result is even more forward movement!

9 What a Drag. However, any additional drag that s introduced has an opposing impact on the forward movement.

10 Over-Powered Boat heel minimizes effectiveness of hull and centerboard Increased drag from over-powered sails, loaded helm, and boat heel Significant increase in lift We need power to get the boat moving, but we are over-powered when the sails are set for more power than can be efficiently used. Significant increase in sail lift and increased drag (sails, helm, heel) with a minimal increase in keel vector (heel) results in negative impact to our forward momentum. Notice that the vector is also skewed to leeward!

11 Its all about balance! Weight Steering Sail Trim

12 Modes of sailing Directional adjust weight and trim VMG efficient trim and steering Upwind Reaching Downwind Comfort / Safety forget about efficiency Depowering Angle of sail

13 Angle of attack We frequently refer to keeping our most efficient trim and angle of attack upwind as staying in the groove maximum increase in sail lift, with minimal drag. The tell-tales and sail luff are our best indicators of angle of attack. Jib: both inside and outside tail tales Main: tell-tale off of the leech

14 Sail shape The two primary variables in sail shape are depth (camber) and draft (center of lift) position.

15 Depth and Draft Position Settings * * This is a little drastic on a thistle we probably wont see the draft move quite that far forward

16 Modifying Jib Shape Luff tension moves the draft (max camber) forward or aft: Eased luff for draft aft (better point) Trimmed luff for draft forward (wider groove) Indicator: crows-feet on the snaps Sheet Trim affects the depth(camber) and slot between the jib and main Eased for deeper camber and open slot Trim to flatten the sail Indicators: distance off-the-spreader, luffing main Lead position and trim depth (camber): Forward places trim emphasis on the leech twist Back places trim emphasis on the depth of the foot Indicators: top jib telltale

17 Modifying Main Shape Mast bend and foot tension changes the depth (camber): More bend will flatten sail quicker Tighter foot tension for flatter lower main Eased foot tension for deeper lower main Indicators: prominence of speed-wrinkles, size of main shelf Luff tension moves the draft (max camber) forward or aft: Eased luff tension for draft aft (better point) Tighter luff tension for draft forward (opened leech, less drag) Indicators: how far up speed wrinkles are visible, movement of main camber is apparent

18 What is twist? Relationship of upper batten to boom with respect to angle of attack Indicator of good flow is tell tales off of the leech of the main

19 How is twist used? In medium breeze with flat conditions, we can hook the leech and point the boat a little higher When overpowered, we can open the leech and spill off some of the power In light breeze or choppy conditions, we strive for the maximum power setting

20 Sail Controls Angle of Attack Mainsheet - changes the angle of attack for main by moving the boom in or and out Traveler changes the angle of attack for the main Jib Sheet - changes the angle of attack for the jib by moving the clew in or out Spin Guy changes the angle of attack for spinnaker by moving the pole forward or back

21 Sail Controls sail shape Main Halyard & Cunningham moves draft of main forward or aft Outhaul adjusts tension of the foot of the main to provide more or less depth Jib Halyard moves draft of jib forward or aft Jib Sheet Blocks control angle of sheets to help trim foot versus leech Topping Lift moves pole up or down to control where the spinnaker luff breaks

22 Sail Controls twist Mainsheet by pulling down on the boom as well as in, the main tightens the leech. Trimming the main hard will produce speed wrinkles and hook the upper batten inward Jib Sheet Blocks control angle of sheets to help trim foot versus leech. Moving the leads back in heavier breeze allows us to open the leech while keeping the sail relatively flat

23 What about the Vang? Upwind helps to depower the main by stretching the sail to reduce the depth (camber) Downwind when the boom is eased all the way out, the vang is used to adjust the twist (upper leech) of the sail

24 What s good for the main. is good for the jib The two sail must work together and must be trimmed in concert Twist also applies (to a lesser degree) to the jib The slot between the sails must be considered based on the conditions

25 Angle of Attack and Steering: Footing Sail faster (and lower) when: You need the extra power to fight through chop. You want to hold a lane on your current tack, and a boat to windward is threatening to roll over you. You re on a lift, sailing toward the next shift and/or better pressure. You are trying to cover the boat(s) to leeward, and she/they have their bow(s) ahead on your current tack. Pinching Sail slower (and higher) when: You have plenty of power and conditions are relatively flat. You want to hold a lane on your current tack, and a boat to leeward is threatening to pinch you off. There is better pressure and/or a lift coming from your windward side, and you can get to it faster by pinching. You want to tack, but first you must pinch off a boat on your windward hip that is preventing you from tacking.

26 What are you looking at? Telltales Telltales and flow link Telltales and sailing mode link Telltales video - link Wind and Waves Wind on the water - link Sail Shape Lines

27 What are you feeling? Heel Helm Lines Wind

28 What can you tell?

29 What can you tell?

30 What can you tell?

31 What can you tell?

32 What can you tell?

33 What can you tell?

34 A Few Tips Handling lines Safe wrap Don t hook with your little finger Cleats? Steering Tiller and sheet in same hand Steer behind your back Lightest helm possible Close reach for best control