On masthead boats, the backstay adjuster is the primary device for changing headstay tension. A loose headstay makes the genoa full for drive in light air and chop, while a tight headstay flattens the genoa for heavy air speed. Furling systems require a tight headstay. On fractionally rigged boats, backstay tension contributes to headstay tension but is used primarily to bend the mast and flatten the mainsail. Use these sketches to develop ideas that may work on your boat.

 6:1 Right Angle: This simple 6:1 systems is used on smaller cruising boats.  

12:1 Cascaded Right Angle: A wire block is placed at the end of the backstay. A flexible cable runs over the wire block to form a 2:1 purchase, for a total power of 12:1.

4:1 Split Backstay: Tackle pulls the wire blocks down the backstay, pinching the legs together.  

 8:1 Split Backstay: A more powerful version of the split backstay adjuster uses a doubling wire running through a wire block for a purchase of 8:1

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  6:1 Double-ended Split: Double-ended split backstay adjuster leads the lines forward to cam cleats mounted just ahead of the helmsman.  

 Backstay Adjuster: Great for cruising boats! Small stay adjusters feature integral handles that fold out for easy adjustment.  

Backstay Adjuster with Winch Handle: A simple, powerful backstay adjuster without hydraulics. The stay tensioners accept a standard winch handle.  

2:1 Backstay Adjuster with Winch Handle : A stay tensioner with a split backstay. Replace the two lower legs of the backstay with flexible cable turned over a large block on the standing section of the stay. Size both block and wire to

Typical boat length:
Small Boat: 22' - 28' (6.7 - 8.5 m)
Midrange: 29' - 34' (8.8 - 10.4 m)
Big Boat: 35' - 42' (10.7 - 12.8 m)