505 TUNING GUIDE - North Sails, Ethan Bixby

How to get the most from your new North 505 Sails.

INTRODUCTION - The following tuning guide is meant to be a good starting point in setting up your boat. Depending on your crew weight, strength, sailing style and local conditions, you may have to alter your rig slightly. As you read this, write down any questions you may have, and we will be happy to discuss them with you in more detail.

We are trying to achieve a rig set-up that is fast in all conditions; upwind, reaching and running, and is very easy to adjust or change gears. Your new North Sails are designed around this all-purpose philosophy.

INITIAL SETTINGS - The first thing that should be checked is the heel of your mast. It should be filed, cut, or somehow angled so that the mast heel sits on the aft end of the step, and the forward end of the mast heel will be just clear of the step until the mast bends forward. This angle keeps the step from limiting or stiffening the mast down low.

Before calibrating your mast rake, check that the mast is even in the boat athwartships. You can do this by tensioning the rig and measuring with a tape down to the gunwales, even with the chainplates. Next sight up the back edge of the mast to ensure that it's straight athwartships. If the measurement to the gunwales is even, and the mast isn't straight side to side, then either the spreaders are uneven in length or the mast partners at deck level are uneven and pushing the mast to one side. It is important that the mast is straight in the boat and tight in the partners. Any side to side play in the partners depowers the rig, which is especially bad for reaching.

MAST RAKE - Mast rake and rig tension are the two most significant tuning variables. To measure your rake, tension your rig to your standard sailing tension, and hoist a tape measure to the top band on the main halyard. This should be hooked on the halyard lock.

Ensuring that the mast is straight with the mast ram, the tape measure should be read at the hull/transom intersection, passing the tape through the cutouts in the transom. Heavy air settings will show some compression bend. A good range of settings would be:

25'9" with 300 lbs. shroud tension - light air

25'8" with 500 lbs. shroud tension - moderate air, full power

25'7" with 600 lbs. shroud tension - beginning to depower

25'6" with 800 lbs. shroud tension - heavy air

25'? max depowering with large waves and footing

In light air, the looser tension makes the jib luff sag and become slightly fuller. The leeward shroud should be just tight. As the windspeed increases, increase rake to prevent the boat from getting "bound". If you are pointing too much and going too slow, increase rake and loosen the helm up. If you are fast but not pointing, decrease your aft rake. Remember that an increase in tension flattens the main with more mast bend.

In light air and flat water, some mast pre-bend should be used to flatten the main, open the slot and ease the leech. It is a good idea to mark the partners for normal mast bend range.

HULL - The mast step should be close to the maximum aft position which is 10' from the transom.

The Centerboard pin should be at 8'4" from the transom for launcher boats, and 8'6" to 8'7" for bag boats. This assumes that the pin is 2" from the leading edge of the board. Most builders will put the pin in an appropriate location. It is important that the board fit tightly in the trunk. To check this, flip the boat on it's side, extend the board, hold it over onto one gybe, and wiggle the tip to check for slop. The head of a gybing board is a parallelogram, and all of the surfaces must be flat and parallel with their respective opposite side, and as tight as possible.

MAST RIGGING - Shroud pin location effects the amount of fore and aft bend due to compression loading with rig tension, and the athwartship stiffness of the mast above the headstay. We recommend the hounds about half way between the spinnaker halyard sheave and the jib halyard sheave. The highest position would be at the spinnaker halyard sheave.

The pole ring should be at about 48" above deck black band. Topping lift sheave at about 11.8' above deck level. This should support the pole at boom level when stored on the boom. A good height for spreaders is between 10' and 10'4" above deck-level black band.

Spreaders should be pinned to deflect the shrouds about 2.5" to 3' outboard to restrict side bend and 1.5" to 2" forward to restrict fore and aft bend. You can use your trapeze wires as a rough guide, held next to the shroud. When measured from a straight line between the shrouds, the distance to the aft edge of the mast should be between 4.5" and 5". Spreader length of about 17.5", although this will vary depending upon the location of the shroud base, hounds, and spreader bracket. Also you should have nicopress stops under the spreaders so the spreaders don't drop in angle.

BOOM VANG - In light to medium conditions, trim your vang so the top batten is about parallel to the boom. If you are sailing in very smooth water, trim hard enough to hook the top batten 5 degrees to windward. When overpowered sailing upwind, if you have speed with no pointing, try straightening the mast, or vanging harder. If you have pointing with not enough speed through the water, try bending more or checking to see that you are not vanged too hand.

MAIN CUNNINGHAM - The main cunningham should be slack up to 10 knots. Above 10 knots, tighten enough to remove wrinkles along the luff. Always be aware that the cunningham pulls the draft forward and depowers the leech, which is not always good.

OUTHAUL - This sail is sensitive to outhaul control. Ease 2-3 inches for power in a chop. Tight in heavy air.

JIB LEAD POSITION - Your fore and aft jib leads should be set so that the jib sheet lines up with the trim line on the clew of the jib. In choppy conditions it may be faster to move the lead forward from this point. At this setting, the jib sheet will be angled down from the trim line on the jib clew. [The trim line is a line drawn on the clew, defined by the center of the clew and intersecting the luff exactly midway between the tack and the head.] Move the jib lead aft as the wind increases, and/or more rake, to accomplish the same end result of twisting off the top of the sail. If you have speed with no pointing, try moving the leads forward. If you have pointing with not enough speed through the water, try moving the leads aft. Experiment with different lead positions, especially in stronger breezes, as changes are readily felt. For rough numbers, launcher boats should have the lead at about 8'7" aft of the tack, and about 12" up from the floor.

JIB LUFF TENSION - Tighten just enough to remove wrinkles.

Good luck and sail fast! If you have any questions or suggestions call Ethan Bixby of North Sails Florida, (813) 898-1123, Fax (813) 898-0211.