Setting up your Dragon
When setting up a Petticrows Dragon there are some basic steps to follow, so you can be sure the boat is set up in a "standard" way. Use these settings as a base reference, then experiment to find exactly what suits your sailing.
Find your settings
The lower shroud tensions are a guide only, for any chosen upper shroud tension. They can only be set correctly by sailing upwind, sighting up the mast and adjusting the lowers until the mast is straight sideways.
| Light | Medium | Strong | |
|---|---|---|---|
| Upper | 12 | 15 | 20–25 |
| Lower | 0 | 5–10 | 15 |
| Light | Medium | Strong | |
|---|---|---|---|
| Upper | 10 | 14–15 | 16–20 |
| Lower | 0 | 5–8 | 10–12 |
| Light | Medium | Strong | |
|---|---|---|---|
| Upper | 14 | 18 | 20–25 |
| Lower | 0 | 5–10 | 15 |
Loos PT-2M readings for boats built after 2008. Mast ram upwind: forward from max aft by 1–1.5 cm in light and strong winds, max aft in medium. Older hulls are less stiff and need up to 30% more tension.
Measuring from station 4
All fore-and-aft positions are measured from a taped line joining the station 4 marks on each side of the boat. Bow to the left, distances in centimetres, drawn to scale.
Rig set-up guide
Set the jumper tension
With fixed jumpers, set the tension before stepping the mast. An average setting is 8 on a Loos tension gauge. Check the mast is straight sideways.
On adjustable jumper systems, mark the overall tension control rope at 6, 8 and 10. This can only be measured with the mast up, from a ladder.
Mark the forestay
Put the mast up so it stands vertically, all the way forward. Measure 81 cm up the mast from the deck and mark it (class rule: min 79 cm, max 81 cm). This will probably be at the top of your black band.
Pull the forestay down the mast and mark it at the 81 cm mark. The mark on the forestay is your reference.
Establish the mast rake
Connect the forestay but not the mast ram bottle screw or shrouds. Get some tension on with a little runner or backstay, then measure from the forestay mark to the deck. This is your mast rake.
122 cm average 121 cm heavy wind 123 cm light wind
Alter rake by changing the forestay attachment point. Tape above and below the most commonly used holes.
Rake is measured along the forestay, from the mark down to the deck. Not to scale. Find the station 4 line
Small spots on the topsides, just below the deck edge, show the measurement stations. Station 4 is about 120 cm in front of the mast. Join the station 4 marks across the deck with a straight edge and tape. This line is your reference for mast, forestay and shroud positions.
Find the shroud positions
Measure perpendicular from the station 4 line to the front face of the upper shroud: 82 cm and the lower shroud: 85 cm.
- Normally the shrouds are in line with the front of the mast when sailing upwind.
- Moving them aft makes the mast bend less.
- Forward of in-line, the mast bends more.
Shroud position relative to the front face of the mast, seen from above. Find the forestay plate
Station 4 line to the front of the forestay measurement plate: 104 cm. The plate can be 75 mm long and the forestay must be within it. We always put the forestay at the front of the plate.
Find the mast plate
Station 4 line to the aft end of the mast measurement plate: 82 cm. The plate is 50 mm long.
Check the "J" measurement
The distance from the front of the forestay plate to the aft of the mast plate must be a maximum of 186 cm under class rules. With the plates at 104 cm and 82 cm from station 4, that is exactly 186 cm; see the deck plan above.
Mast step position and pre-bend
Without the bottle screw or shrouds, and with rake at 122 cm, push the mast aft so the forestay has some tension (a little runner helps). Do not bend the mast.
The front face of the mast should be level with, or aft of, the aft end of the mast plate. Level gives no pre-bend; 5 mm behind gives 5 mm of pre-bend once the bottle screw is set. Normal is 0–10 mm.
- More than 10 mm behind the plate: move the mast step pin forward.
- In front of the plate: move the mast step pin aft.
Front face of the mast against the aft end of the mast plate, seen from above. Each mm aft of the plate becomes 1 mm of pre-bend. Connect shrouds, set the mast ram
Connect the uppers and wind to 15 on the Loos gauge. Connect the lowers in the next hole aft and wind to 10. Keep the calibration marks equal port and starboard.
Connect the mast ram bottle screw and pull on the runners. Adjust it so that with the lever fully aft, the front of the mast is level with the aft of the mast plate, then lock it. The mast should be straight fore and aft, or have up to 10 mm forward bend.
To check forward travel, release runners and backstay and uncleat the lever rope. The front of the mast must not go past the front of the mast plate; if it does, restrict it to the class maximum movement of 50 mm.
Measure the shroud tension
Use a Loos PT-2M tension meter directly on the wire and set tensions for the conditions with the tension finder above. Figures are for boats built after 2008; older hulls are less stiff, so up to 30% more tension is needed.
Mark maximum runner tension
Attach a Loos gauge to the forestay and pull on the runner until it reads 32. Mark the runner wire where it enters the deck as your guide while sailing. 32 is the absolute maximum, for strong winds.
Pull on the runner until the forestay reads 32, then mark the runner wire at the deck. Not to scale.
Please note
The shroud and forestay positions shown are the current measurements used on new boats for best balance. On older Petticrows boats the mast and forestay measurement plates were fitted in the optimum position for that age of boat. Check these plate positions and adjust the shroud and forestay positions using the same principles.
Petticrows trim tips, October 2026 update. Tension figures are Loos gauge readings.