Simple rig set-up
Some boats have designer’s recommendations for mast rake, bend and rig tension – if yours is one of them, follow the instructions. The rest of us are obliged to make it up from scratch – so where do you start?
While some professional riggers might be able to assess the tension in a wire with a carefully calibrated shove, the rest of us need a bit of help. You can either buy a rig tension gauge (we tested several in April 2016) or measure the extension of the wire. This latter method works on the basis that, for 1x19 rigging wire, an elongation of 1mm over 2m equates to 5% of the break load of the wire. Seldén have a good explanation on their website – search ‘Seldén rig set-up’. The tension you are aiming for will vary from boat to boat and between types of rigging wire, but a gauge will make it much easier to keep the tension even on opposite shrouds.
For the initial set-up the boat should ideally be floating level – it makes it much easier to see whether, despite the measurements, everything looks right. I find it’s best to be on a finger berth, which allows you to get off the boat to assess whether the mast is upright.
Make sure that the mast is upright
If you’re starting from scratch, begin by centring the mast in the boat. Leave the lowers fairly slack and use the main halyard to measure to the chainplates on each side. You can then adjust the bottlescrews to make sure the cap shrouds are of equal length. If your boat is symmetrical, the mast will be upright. If your mast is keel-stepped, insert the chocks in the partners now before you apply rig tension. Finally, tighten the cap shroud bottlescrews hand-tight, making sure you put the same number of turns on each.
Set up the mast rake
Next, set the mast rake. If you have a setting from the designer, use it. If not, you’re most likely looking for a rake of between 1° and 2°, or 1:60 to 1:30. So for a 9m mast, you would expect the offset between masthead and mast foot to be between 15cm and 30cm. Measure it by hanging a weight from the main halyard and measuring the distance between the weight and the mast foot. If it’s windy, hanging the weight in a bucket of water will help damp the swing of the halyard.
Pull on a little backstay before using the forestay bottlescrew to move the masthead fore or aft and adjust the rake. The backstay helps the masthead to move – with no tension, the forestay will simply become slack as you back off the bottlescrew. Steeper rakes tend to go with fractional rigs, but this is by no means a rule – you may need to experiment to find what works for your boat. Increasing the rake will increase weather helm, and vice versa.
Tension the cap shrouds
It’s now time to begin tensioning the rigging properly. Take the slack out of the lowers at this stage, but don’t tighten them fully yet. Then, using your tension gauge and making sure you keep the number of turns on each side equal, tension the cap shrouds to their working tension. Most tension gauges are calibrated to show a percentage of the breaking strength of the wire: with my boat, I find that around 15% is sufficient to keep the rig taut in the conditions in which we sail; on Ben Meakins’ Impala Polly he will tension the caps to 17% for a windy race.
If you have a keel-stepped fractional rig with swept spreaders you should carry out this stage with the backstay fully tensioned, as it will initiate a bend in the mast which is fixed by tightening the caps. If you do this, be careful that the mast does not go out of column side to side – if it does, ease the backstay slightly.
Once the caps are tensioned, sight up