470 Tuning Guide

The M7 Section has proven to be the most popular mast at all major championships around the World. This, linked with the correct sail choice has offered a real performance advantage for 470 sailors.

SPREADER SETTING

Measure the spreader length from the side wall to the centre of the shroud. This should be 475mm. To measure the deflection, place a batten across the shrouds at spreader height and measure from the centre of the batten to the back wall of the mast. This should be 147mm.

MAST HEEL POSITION

Measure from the inside of the transom (on the centreline) to the back wall of the mast heel. This should be 3185mm.

PRE - BEND

Secure the main halyard at Gooseneck and measure pre-bend at spreader height. This should be 55mm.

SHROUD TENSION

Using a Super Spar Tension meter measure the shroud tension at approx. shoulder height. This should read 36-38.

MAST PULLER

This can be fitted to pre bend the mast and change the sailshape for differing conditions. Consult your sailmaker for best effect.

MAST RAKE

Secure a long tape at the lower edge of the upper black band at the top of the mast. This can be done by securing the tape to the halyard but you must be sure that the tape is in the right position. Measure to the top of the transom when there are no chocks in front of the mast, and you have full tension. It should be:- 6720mm (for winds 0 -12 knots) 6675mm (for winds 12 - 15 knots) 6660mm (for winds 15 knots +).

RUDDER POSITION

Make sure that the rudder s in the maximum down position at all times to give you a finely balanced helm. If in any doubt contact your fleet captain or builder for advice.

CENTREBOARD

Angle the leading edge forward in light winds. Position it approx. vertical in medium conditions and as the wind increases it needs to be raked slightly aft.