December 7th, 2016

Really Useful Sailing Tips – Sail Trim

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Really Useful Sailing Tips – Sail Trim

Even if you are only cruising, trimming the sails correctly will make your boat speed more efficient, reduce leeway and generally give a more comfortable ride. Here are some valuable sail trim tips.
Tip 1 – General Sail Trim

Powering up your sails is all about angle of attack. At zero angle of attack the sail is luffing. Trim in to increase angle of attack and increase power. Ease the sails out and power is reduced. Angle of attack is also controlled by the helmsman. Bear off to increase power, and head up to reduce power. This works for reaching and close hauled sailing.
Tip 2 – Sails – flat or deep?

A key source of power is the amount of draft or depth in your sails. Sail depth controls the power, acceleration and drag of the sail. More depth creates more power and acceleration while a flat sail has less power and less drag. A deep sail is best for punching through waves and chop, or for accelerating after tacking. A flat sail will be faster in smooth water. In strong conditions it’s best to have a flat sail. If your lee rail is in the water you are overpowered and will have lost speed.
Tip 3 – Sails – Twist

Twist is also a source of power. Effectively a sail is twisted when it is let out at the top but pulled in at the bottom. Using the mainsheet, kicker and traveller together you will achieve the required twist. There tends to be stronger wind flow at the top of a sail. Twist can be fine tuned to match actual conditions. Less twist is good for pointing higher, more twist is good for speed and acceleration. In overpowering conditions power can be reduced by easing sheets and reducing twist – this works well in lumpy waves. In smooth water it’s better to flatten the sails. Keep both main and genoa in matching formation to maintain a consistent slot between the sails, maximising efficiency.

Tip 4 – Preparing to hoist the spinnaker

Before hoisting the spinnaker check that the pole is in the right position and that the guy has plenty of turns around the winch. Make sure the sheet is not too tight, and that the halyard goes right to the top of the block on the mast. That way when the spinnaker fills it will be set correctly right from the start, with only minimum adjustments needed. The boat won’t lurch around and it will be easier on the helm.

Tip 5 – Spinnaker hoisting
Setting a spinnaker can be hassle free with a bit of forward planning, preparation and crew co-operation. Always make sure the spinnaker is properly packed in the bag so it comes out with all three corners free and untwisted around the body of the kite. Larger spinnakers can have wool tied around the first few feet of the head to ensure a clean hoist. Make sure each crew member knows what they have to do, one each on the guy, sheet, halyard and topping lift/downhaul. Don’t try setting a spinnaker in strong winds unless you have practised in light airs first and sorted the process –otherwise it will end in tears!

Tip 6 – Spinnaker setting

The spinnaker should be kept as symmetrical and as rounded as possible (so the maximum area is ‘presented’ to the wind). The spinnaker pole is critical to achieving this, so the pole should always be level with the clew it is attached to (it may be lower in light winds and higher in moderate winds), therefore it may need to be adjusted at the mast as well as at the clew end. The pole should also be at right angles to the apparent wind direction – that is the wind coming across the deck. Both clews should be level with each other.

Tip 7 – Spinnaker drop

When dropping the spinnaker make sure the halyard is free to run. Coil it loosely around the winch then move it to the deck and turn the coil over so it runs free from on top. Make sure someone is holding the lazy guy (or sheet on a smaller boat) and is ready to gather then drop 50% of the halyard quickly to take the power out of the sail. Control the rest of the drop to the speed that the crew gather it in. Lastly, drop the pole forward and down on to the deck and tidy everything up. Don’t forget to repack the spinnaker ready for the next hoist!
As with all these things practice makes perfect and you will soon get a feel for the correct sail trim for the conditions.
Happy sailing!