Tensioning the cap shrouds

Wire dia- Breaking load, meter, mm kN lbs

It is a fundamental requirement for all rig types that the cap shrouds are correctly tensioned. The cap shrouds are adjusted at the dockside, but final tuning is done while sailing. The table beside applies to standing rigging using 1 x 19 stainless wire. This is the most commonly used material for standing rigging. Your aim should be to tension the cap shrouds to 15-20% of the breaking load (the final check on tuning should be left until you are under sail). Then you know that the lateral staying is optimal both for the security of the rig and for sailing performance. There are measuring instruments of greater or lesser reliability for this purpose on the market. Seldén has developed a simple method of obtaining the information you need with material you probably already have. What you need to know is:• All 1 x 19 stainless wire stretches under load, but returns to its original length when the load is removed. 1 mm stretch per 2 m wire is equivalent to 5% of the breaking load, irrespective of the diameter of the wire. • A grp hull, on the other hand, changes its shape per-manently when the rig is put under load. This makes it necessary to set up the rigging again after some time. This applies particularly to new yachts. • At the dockside, both cap shrouds always have the same load. If you tension the starboard shroud, the port shroud is affected to precisely the same extent.

Ø 3 8 1,770 Ø 4 14 3,090 Ø 5 22 4,860 Ø 6 31 6,845 Ø 7 43 9,490 Ø 8 56 12,360 Ø 10 88 19,425 Ø 12 126 27,815 Ø 14 171 37,750 Ø 16 216 47,680 The breaking loads for various dimensions of 1 x 19 strand wire.

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