Rig tuning with a Loos gauge

Having the correct tension in stays and shrouds is important because a slack rig can impart shock loads to shrouds and chain plates as the mast flops from side to side; a too tight rig can cause structural damage.

A well tuned rig will have equally tensioned shrouds so that the boat will perform well on both tacks, the leeward shrouds won’t dangle flaccidly and the forestay won’t sag. She’ll feel right on all points of sail.

The rig on a cruising boat should be checked regularly to ensure good performance but also because it can be an indicator of something amiss – any unexpected change in a shroud’s tension should be investigated immediately.

Loos & Company makes two different classes of gauge for wire rigging – Standard and Professional. They also make two sizes of gauge for rod rigging.

The Standard range comprises two models, Type A(91M) covering wire sizes 2.5mm, 3mm and 4mm and Type B(90M) for wire sizes 5mm, 6mm and 7mm. These gauges are simple to use and accurate to 5% at mid range.

For more accuracy and convenience choose the Pro models: PT1M for 2.5mm, 3mm and 4mm, the PT2M for 5mm, 6mm and the lower tension end of 7mm and the PT3m for 7mm, 8mm, 9mm and 10mm wire. These gauges are a little more accurate, 3% at mid-range.

The Pro range is more convenient to use because the gauge is left on the wire whilst the turnbuckle adjustment is made whereas the Standard range gauges must be removed whilst the wire is adjusted.

Rod rigging can be accurately tuned with the RT10 and RT11 gauges.

On the Salty John website you’ll find an article on rig tuning using the Loos tension gauge, including suggested wire tension levels:


The full range of metric Loos gauges is available at the lowest prices in Europe from:


A tuned rig is a happy rig!