Harken Yacht Equipment Catalog OnLine

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Reference > Backstay Adjusters

On masthead boats, they are the primary device for changing headstay tension. A loose headstay makes genoas full for drive in light air and chop while a tight headstay flattens the genoa for heavier air. Furling systems need a tight headstay Many owners like to sail with a tight headstay, but want to relieve the load on their boats when they are not sailing. On fractionally rigged boats, backstay tension contributes some to headstay tension but is used primarily to bend the mast and flatten the mainsail. Some common styles of backstay adjusters are shown here. Use these sketches to develop ideas which may work on your boat.

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

Diagram Ref. Description Small Boat Part No. Midrange Part No. Big Boat Part No.

System 1

A Triple 344/ 2640 — —

B Triple 347/ 2648 — —

System 2

A Single 300 — —

B Triple 344/ 2640 — —

C Triple 347/ 2648 — —

System 3

A Single 304 304/ 308 —

B Fiddle 2655/ 2621 2621/ 1559 —

C Fiddle 2658/ 2624 2624/ 1556 —

System 4

A Single 304 308 —

B Fiddle 2655/ 2621 2621/ 1559 —

C Fiddle 2658/ 2624 2624/ 1556 —

System 5

A Single 304/ 308 304/ 308 —

B Single 2636 2600 —

C Double 2638 2602 —

D Stand-up 349/ 2652 2652/ 2600/ 369 —

E Cheek 350/ 2644 2644/ 2606 —

F Cam cleat 338/ 150 150 —

System 6

A Backstay adjuster — B1722/ B1834 —

System 7

A Backstay adjuster — B500/ B501 B502/ B503

B Winch handle — B8AL/ B10AL B8AL/ B10AL

System 8

A Runner — 737/ 1991/ 1853/ 3013 3013/ 1855/ 3019/ 3024

B Backstay adjuster — B500/ B501 B502/ B503

C Winch handle — B8AL/ B10AL B8AL/ B10AL

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

2. 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.

3. Tackle pulls the wire blocks down the backstay, pinching the legs together.

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

5. Double-ended split backstay adjuster leads the lines forward to cam cleats mounted just ahead of the helmsman.

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

7. A simple, powerful backstay adjuster without hydraulics. The stay tensioners accept a standard winch handle.

8. 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 match the strength of the back.

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