National 125 Sailing Association

Sail your 125 Faster

Mast rake
Probably the most important thing to get right before you leave the beach. Your mast rake should be set for an almost neutral helm. To establish where this is, take the boat out on a 5kn day and sail it flat upwind. Let go the tiller. If the boat rounds up, the mast is too far back, if the boat bears off, the mast is too far forward.

Another indicator you can use is that if you find yourself going slowly upwind, but going fast on reaches and runs (compared to other boats), then your mast is probably too far forward.

Once you have your mast rake set well, and are sailing fairly fast, you can adapt your rake to the wind conditions. As the wind gets stronger, rake your mast back further. It will take a lot of experimentation and sailing to find the right settings, so don't start this the week before a big event.

 

As a general guide, National Champion Jamie Thompson recommends that from the upper black band on the mast to the point where transom meets the floor of the hull, should measure 6140mm. This is a good starting point, but may vary in relation to mast step position, sail shape, and variations in hull shape.

 

 

Jib settings
There are three important things in to consider setting the jib. The position of the draft in the jib, the angle of the jib, and the amount of twist in the leach.

The draft of the jib should be about 40-45% of the way back from the forestay. To adjust the draft, use the jib cunningham, pulling it tighter will move the draft forward, looser will move the draft back. As the wind increases, it will change the shape of the sail and move the draft back, therefore you should use a tighter cunningham in stronger winds.

The jib angle should be small (ie the jib close to the center of the boat) in light to moderate wind, and move further out as you become overpowered (ie you're easing the main a lot to keep the boat flat) The twist in the leach of the jib affects the performance of the mainsail. Too closed up (hooked) and you will backwind the main, too open and you are not getting full power. The twist should be set, so that neither of these things are happening, to tell this, your jib leach ribbon should be flowing straight back.

If you have fore-aft fairleads
With fore-aft fairleads you use the sheet to control the position of the jib, and the fairlead to control the amount of twist. To adjust the twist move the fairlead forward to close up the leach, move it back to open it up. Be aware that changes in sheet tension have effect as well.
If you have transverse fairleads
With transverse fairleads, you use the fairlead to control the angle of the jib, and the height of the jib on the forestay to control the twist (the sheet should always be firm, tightening slightly with the wind). To adjust the twist move the jib up the forestay to close the leach, down to open the leach. You will only need to move the jib a small amount (in the order of 5mm) to achieve a large effect.

 

Mainsail settings
There are four important things to consider in setting the main. The position of the draft, the amount of draft, the amount of twist in the leach and the angle of the sail. These things are controlled using the cunningham, outhaul, boom vang, mainsheet and traveller or bridle (depending on whether you have mid-boom or end-boom sheeting).
Position of draft
As on the jib, the cunningham controls the position of the draft in the sail. The draft should be about 40-45% of the way back from the mast. To move the draft forward, pull the cunningham tighter, to move the draft back, let the cunningham off. As the wind increases, it will change the shape of the sail and move the draft back, therefore you should use a tighter cunningham in stronger winds.
Amount of draft
The amount of draft is controlled via the outhaul and the vang. The outhaul controls the amount of draft in the lower part of the sail, while the vang controls the amount of mast bend, which gives a more general control on the amount of draft. For both of these, pulling tighter reduces the amount of draft, looser increases the draft. The amount of draft should be set for the wind speed. In light wind you shouldn't have much draft as this will detach the wind from the sail and stall it (but avoid using the vang as it also induces twist). In moderate wind, you want to power the boat up, therefore you should have more draft. As the wind becomes strong, you will have too much power and should reduce the amount of draft again.
Twist in the leach and angle of sail
The amount of twist in the leach, and the angle of the sail are controlled together in different ways depending on the set up of your boat. With both systems you want to get the boom close to the centre of the boat with the right amount of twist. The amount of twist affects the power of the mainsail, too tight and the wind detaches from the sail, causing it to stall, too loose and power is lost. As a guide, the top batten should be roughly in line with the boom, and the leech telltale should be flowing (and occaisonally backwinding when on a beat).

In light wind the sail should have roughly the right amount of twist without needing to be pulled down tighter, as the wind increases it will open the leach up, inducing more twist. To counteract this you set the boat up so that the mainsheet is pulling the boom down as well as into the centre of the boat.

Mid-boom sheeting
With mid-boom sheeting and a traveller, the position of the traveller determines how much the mainsheet pulls down. The further to windward the traveller is, the less the mainsheet pulls down, and the more it pulls across. As such, in light winds you should set it to windward, so that it pulls across the boat. As the wind gets stronger, move it into the centre of the boat so that it pulls more down. The mainsheet should be adjusted so that the boom is close to the centre of the boat (when beating).
End-boom sheeting
With end-boom sheeting the height of the bridle determines how much the mainsheet pulls down. The heigher the bridle, the less the mainsheet pulls down, and the more it pulls across. As such, in light winds you should set it high, so that it pulls across the boat. As the wind gets stronger, move it down so that the mainsheet pulls more down. The mainsheet should be adjusted so that the boom is close to the centre of the boat (when beating).

 

Spinnaker Settings
When Reaching
Firstly, note that this advice applies when reaching, but, for whatever reason, you may be reaching while on the run of a course.

When reaching the spinnaker needs to work as a wing. To get it working at it's best, you need to create a good aerodynamic profile, and let the air flow across it, rather than capturing it.

A good profile is one that looks roughly like a shallow dish. To create this, you should have the pole angle roughly in line with the boom, and at a height so that the luff is curved nicely. Have a look at the photo of Buzz Bomb II to get an idea of this.

To let the air flow across the sail, rather than capturing it, the crew must constantly be working the sheet. If the sheet is too tight, the wind will be captured, too loose, and the kite will collapse. To find the point in between, let off the sheet until the luff of the kite begins to collapse, then pull the sheet on just a touch.

When Running
When running your sails no longer work as aerofoils, but rather you are literally pushed along by the wind. As such, it is important to get as much sail area exposed to the wind as possible. Your spinnaker should therefore be set out very wide (a tight brace), and your pole should be quite low. The head of the spinnaker should also be a bit away from the mast (let the halyard off about 15cm).

For more advice on rigging see Racing basics - Rigging

For a good collection of racing information see The Winning Formula


This file may be freely copied and distributed, provided the information within it is not altered, and due credit is given to the National 125 Association. It's URL is http://www.125assoc.com/rigging.asp
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