Tuning Guide

The mast step should be set at 9’-4 1/2" measured from the inside of the transom along the floor of the boat to the back of the mast. Usually this places is the first pin hole from the front.


MAST RAKE and RIGG TENSION

Hoist a tape measure to the top of the mast with the main halyard. Lead the tape measure over the top of the transom, down the aft face of the transom to where the transom meets the bottom of the boat. For club/junior sailing the rake should be adjusted to fall between 21’-6 1/2" for light winds and 20’-9 1/2" for heavy air. Note that the shrouds and, therefore, the rig tension should be adjusted as well for diferent wind conditions.

With heavier winds and as you become overpowered, rake the mast farther aft which will twist open the leech of the jib and depower the sail. This has the same effect as moving the jib lead aft. Raking the mast aft also moves the center of effort aft, which makes the boat naturally head up into the puffs instead of being blown over sideways.
Heavy crews will want to rake aft in higher wind conditions because they can use the extra power. Lighter crews will tend to be overpowered sooner and should rake farther aft with less wind intensity. If the boom is consistently out beyond the corner of the boat to maintain the boat balance when sailing upwind, you should rake the mast farther aft.
With the vang more eased the mainsheet will control the amount of twist (the angle of the top batten to the boom). You can depower quickly by easing the sheet and twisting the main more open. This makes it easier to quickly balance the boat and pop it up on a plane when sailing upwind in a breeze.

The tension of the rig is effected through shroud position and channel adjusters and tension of the jib halyard. The rig tension should be varied from 200 lb. in light winds, to a maximum tension of 360 lb. in near survival conditions. When the rig is tensioned properly for upwind sailing, the leeward shroud just starts to go slack
For the collegiate sailors, since you are not able to adjust your shrouds, go ahead and read on.
The best method to change your rig tension while on the water between races is to ease the jib halyard until the forestay is just taking all the load. This will allow the mast to fall back enough that it should be fairly easy to adjust the position on the leeward shroud. When completed, tack and do the other side.
To pull the rig back forward, use the 3 to 1 purchase on the jib halyard, "bowstringing" the halyard above the purchase, then taking up the slack created with the 3 to 1 purchase.


MAINSHEET TENSION

Trimming the mainsheet harder will hook the top batten in relation to the boom which will proved the boat with short bursts of pointing ability at the expense of power and acceleration. Easing the sheets so that the top batten twists open (falls away) from parallel to the boom will compromise top end speed and pointing ability, but greatly increase the boat’s power to punch through waves and ability to accelerate out of a tack. The mainsheet will never just be cleated and left alone. It is one of the more critical adjustments on the boat. Play it constantly to allow the boat to point and power up and to sail with a balanced helm


TOP BATTEN

The tension on the upper batten is not critical, it is important that the batten is neither too loose or too tight. Overtensioning the batten will make the sail too full and the leech will be too closed. Undertensioning the batten in heavy winds will allow the batten to slide aft in the pocket and the leading edge will poke through the front of the pocket.


MAIN HALYARD and CUNNINGHAM

Tension on the luff of the main affect the draft position. A looser luff with wrinkles all the way from tack to head is necessary in lighter winds to allow the draft to move aft and flatten the entry of the main. In heavy winds tension the luff until the wrinkles are almost completely gone. This will help maintain the proper draft position. You can adjust the luff tension with either your main halyard or cunningham.
If you expect to be sailing in a constant, relatively unchanging condition, then use the main halyard to tension the luff of the main. If the conditions are puffy set your main halyard so there are slight wrinkles all the way up and down. Then use your cunningham tension to fine tune the luff tension for the proper wrinkle and draft position.


OUTHAUL

For light winds only tension the outhaul until vertical wrinkles just disappear . As the breeze picks up and the boat becomes more overpowered progressively tension the outhaul. The foot tape on the bottom of the sail should be standing straight up from the boom in very windy, near survival conditions.
.

BOOMVANG

Downwind the boomvang is tensioned just enough so that the last part of the top batten is nearly parallel to the boom. Be careful of overvanging in light winds and undervanging in heavy winds.

Upwind in light winds, the vang needs to be loose enough so that the leech will twist open (upper batten angled outboard) to help the boat drive through waves and accelerate out of a tack. The vang should not be totally loose as this will compromise the boat’s speed and acceleration out of tacks. The vang should be set loose enough so that when the mainsheet is eased out the upper batten a good 15 to 20 degrees open from parallel to the boom, but no looser.

JIB SHEET TENSION

On the Club 420 the jib leads are fairly far outboard which makes it necessary to use windward sheeting in light to medium winds to bring the lead closer to the centerline. The leeward sheet is trimmed in tight until there are slight creases from the tack to the clew. Trim the windward sheet hard enough so that the creases just barely disappear. In light to medium winds when trying to accelerate ease the leeward sheet and not the windward sheet. In breezy conditions do not use the windward sheet.

CENTERBOARD POSITION

When sailing upwind the centerboard is usually in its maximum down position. In the near survival conditions when the boat is greatly overpowered, it is helpful to pull the board up as much as 2 or 3 inches to balance the helm and make the boat easier to steer. Downwind and on a reach with or without the spinnaker, the board should be positioned high enough so that the helm is neutral. If the board is down too far and there is too much windward helm, the boat will tend to "trip" over the board and will not plane as fast.

CREW WEIGHT

Upwind in very light winds the helmsman should sit just in front of the traveler with the crew placed just forward of the centerboard thwart. In medium winds the helmsman will move aft slightly just straddling the traveler. The crew will be anywhere from just behind the thwart to just forward of the helmsman. In a breeze the helmsman will move aft of the traveler. When on the trapeze, the crew will have his/her aft foot just forward of the helmsman’s body. When hiking the crew will be just forward of the helmsman and hopefully leaning aft and angled behind the helmsman. Remember to keep the weight centered so the boat maintains proper balance through chop.