Having the correct rig tension is important because a loose rig is slow and can impart shock loads to shrouds and chainplates as you tack; an over 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.
You don’t need a tension gauge to set up the rig – there are methods whereby you can measure the change in length of the shrouds and stays as the turnbuckles are tightened, and there’s always the tune your rig like a guitar technique: “Twang! That sounds about right”.
But the Loos tension gauge gives you a quick, accurate check and that will encourage you to test often, making sure all is well.
For racers who set their rigs to suit the prevailing conditions a Loos gauge is an important tool in their race-winning armoury. There’s a link on the website to the North Sails catalogue of tuning guides – your boat might be in there and, if so, you’ll get information on the best Loos settings for all your wire.
There are Loos gauges for wire rigging from 2.5mm up to 10mm and for rod rigging of all sizes. You can get them all at Salty John.
So, you can’t tuna fish but you can tune your rig – with a Loos tension gauge.