First 31.7 Rig Tuning Guide.
This tuning guide is intended to get your First 31.7 rig set-up to a base set-up and is targetted at people new to racing the First 31.7. It is by no means definitive but provides a good start point.
The principles of rig tuning are straight forward, however, if you are at all unsure of what you are doing you should consult a professional rigger.
Knowing the pre-bend cut into you mainsail is key for the initial set-up of the rig. Here are some sailmaker target pre-bend numbers we are aware of but you should check with you sailmaker.
30mm – Quantum
50mm – Is a reasonable start point if you don’t know the pre-bend cut into your mainsail
65mm – Banks
100mm – North, Sobstad
One other key fact you need to establsh is how your bottlescrews are threaded. On Electra The Caps and D1s have left handed threads – tensioned counter-clockwise (thread looking from above) and loosened Clockwise, while the D2s are right handed thread.
When tensioning or loosening the standing rigging, it is best to do a couple of turns at a time on one side and then perform the same adjustment on the opposite side of the boat. This will ensure that you don’t over-stress or over-tighten the rig and keep the mast straight and in column.
The First 31.7 comes with two mast variants. The majority of boats are supplied with the LR rig (P=1080) and all the 31.7s I have ever seen have this rig. There is a larger rig HR or Lake rig with P=1120 of which I am aware there are a few in Finland. This guide is for the First 31.7 LR rig with some guestimates to help those with the HR.
1. Reset the mast tune
2. Set and Measure The Rake:
3. Centre the rig.
4. Tension First 31.7 The Rig
5. Check and adjust the Pre-Bend
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