1) All the measurement shown are in MM.

2) First set up de forestay lenght by adding toggels or use the bottlescrew ( if fitted ) to a lenght as specified ( 15.850 mm) Be aware that when you hoist the measurement tape up you will have some distance between the point where the halyard locks and the point where the measurement tape starts. ( in our case this was 180 mm ) If your schackle lenght is different please change the measurement accordingly.

3) Change the mast foot to the position were you measure 714 mm between the bulkhead and front face of mast. Then position the mast in the middle of the mastcollar at deck level. ( this should give a prebend of about 55 mm )

4) Now tension up de V1 mainshrouds equally ( after measuring it to the center ) untill the mast has a prebend of about a full mast diameter. Then start tensioning de D's shrouds. Go sailing and keep tensioning the V1 untill the leeward V1 at about 25 degrees of heel ( but fully pressured at 20 knots) just does not come slack any more. The main shroud tension should now be hard enough. Keep calibrating the D's untill mast is straight or rather sacking to leeward a touch in the middle.

5) Adjust the pressure relief valve at the haydraulic backstay to a setting were it allows a pressure of 5000 psi before it starts releasing pressure ( there is a pressure relief valve positioned under one of the big screws on the unit. For full details read the instruction manual with the Navtec hydraulic backstay unit. This 5000 psi will be your max backstay setting.

6) Your ready to win races !!!!

Please be aware that the V1 shroud tension is vital to give the mast enough stability and prebend. especially when the mainsail is reefed this prebend will avoid the mast inverting.

On the chart you will see some settings we used on our calibarated O&S spanners ( 5.1 m for instance) These settings are no use to you but gives an idea how we keep track of our changes. On general % I have given a guideline to what relation the tension is of all the D's in comparison to the main shrouds in percentages.

If you have anymore questions or when I can assist you on the water please let me know.
Jochem Jachtservice "the boatspeed doctor"

Dutch address: Th. de Bockstraat 17/3, 1058 TW Amsterdam, Netherlands.
Tel. 020-6177033 Mob. 06-51429737 Mob.fax. 06-51491953

UK address: 2 South Drive, Stanbridge Earls, Romsey, Hampshire, SO51 0HE, England.
Tel: +44-1794-521672 Fax +44-1794-830610