“The folding rule method”

The following materials are required: 1. A 2 metre long measuring rod (a folding rule is recommended)2. Adhesive tape3. Vernier callipers• Start with the cap shrouds only hand-tight. The rig is stayed with the lower shrouds and the forestay and backstay. • Tape the upper end of the folding rule to the starboard cap shroud. The lower end of the folding rule must be approximately 5 mm above the upper end of the wire marine terminal. Measure the distance between terminal and folding rule exactly. This is index 0, let’s call it point A.• Tension the starboard cap shroud until the distance is A + 1.5 mm between the terminal and the folding rule. Measure using the vernier callipers. • Leave the folding rule attached to the starboard shroud, and move across to the port side and tension the shroud rigging screw the equivalent amount. • At intervals, check the starboard side to see how much the folding rule has moved from the end terminal. When there is a gap of A + 3 mm, the cap shrouds are tensioned to 15% of the breaking load of the wire (3 x 5% = 15%).If the mast is not straight, adjust the lower shrouds, inter-mediate shrouds etc. There is more information on this in the chapter dealing with your rig type. The folding rule method can be used on other stays, such as the backstay and forestay (without jib furling system). It can also be used for Dyform- or rod rigging, but please take the difference in stretch into account compared to 1 x 19 wire.

2 m
A+ 3 mm A

Hint! Count how many turns on the rigging screw corresponds to 1 mm elongation (5% of the breaking load). Make a note of it. This is useful to know if you ever need to tension “another 5%”.

Stretch per 2 meter 1 x 19 wire Dyform Rod
5% of breaking load 1 mm 0.95 mm 0.7 mm

Incorrect. Correct.

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