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 stiffing the mast down low.
Before calibrating your mast rake, check that the mast is even in the boat athwartship. 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 athwartship. 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 and upwind pointing.
At your light air rake setting of 258 or 34 measured forward, and about 200 lbs. of shroud tension, set the mast bend to about 1.5 to 2 of bend. You can use the halyard to measure this visually. Mark your mast ram at this position. This is your neutral position. Your ram can need only to vary about 3/8 above or below this setting, except in light air when you need lots of pre-bend and the car will be well above this neutral point. As the breeze builds, and you need to depower, you rake the mast aft and the ram stays essentially in the same place, and the mast bend increases around this point. A calibration scheme can be found at: http://www.int505.org/200108Calibration.htm, and the table at: http://www.int505.org/200108NorthTuningMatrix.htm.
MAST RAKE - Mast rake and rig tension are the two most significant tuning variables. We are now using a different method of measuring rake.
Without the jib hoisted, attach a tape measure to your jib halyard and hoist it until the zero mark is at the top of the boom black band. Cleat the halyard and swing it forward to the extreme upper forward corner of the bow, where stem, gunwales and deck all meet. Essentially the top forward point on the centerline of the bow. Rig tension does change this measurement slightly, but mast bend does not. Therefore it is much easier to check and relate rakes over a wide range of hulls and rigs. I record the 34 datum point as a reference to the tack fitting, then just mark the system from there. I often mark the jib at the fork to eye junction.
Measurement range should be as follows:
34 200 lbs. (leeward shroud just slack in marginal trap), apx 258 measured aft.
35 200 +/- lbs. Moderate air, full power, apx 256 measured aft.
36 350-400 lbs. 18 kts, apx 255 measured aft.
37 350+ lbs. depowering and planning upwind.
38 450 lbs. apx 250 measuring aft.
38 max for your boat. Max depowering w/ large waves and footing, board raised.
In light air, the looser tension makes the jib luff sag and become slightly fuller. The leeward shroud should be just loose, unless you are pre-bending against the shrouds. 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. As a rough guideline, once you are trapezing upwind, keep the leeward shroud just tight.
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 or your ram for normal mast bend range.
HULL - The mast step should be close to the maximum aft position, which is 10' from the transom. When using standard boards, 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. If you are using a High Aspect centerboard with a pin bracket extension, you will probably need to have the pin right forward, but you should check with the designer of the board.
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 that the shrouds terminate about 10 above the forestay.
The pole ring or Spiro fitting should be at about 20" above the boom band. The topping lift sheave should be immediately below the jib halyard sheave. For more info, contact us for our comprehensive guide on setting up the rigging for the 6 meter spinnaker.
A good height for the spreaders is 10' 4" above deck-level black band. Spreaders should be pinned to deflect the shrouds about 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. Another detail to check is that the mast heel plug be well rounded aft. The mast can get too stiff low if the heel point loads on the back of the casting.
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 moving bending more or checking to see that you are not vanged too hard.
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 upper trim line on the clew of the jib with the rake at 34 (or 258 measured aft.) In choppy conditions it may be faster to move the lead forward from this point. As you rake as the breeze picks up, you should end up at the lower trim line on the jib. Rake usually does this perfectly, but if increasing the rake is not an easy option, move the jib leads aft to line up with the lower trim line, which will twist off the top of the sail. Moving the lead outboard is an excellent way to depower, and preferred. If you have speed with no pointing, try moving the leads forward or inboard. If you have pointing with not enough speed through the water, try moving the leads aft or outboard. Experiment with different lead positions, especially in stronger breezes, as changes are readily felt. You should move the leads outboard for heavy conditions whenever you are over powered, footing, or backwinding the mainsail. For rough numbers, launcher boats should have the lead at about 8'7" to 8'11" aft of the tack, and about 12" up from the floor for a full hoist jib.
JIB LUFF TENSION - Tighten just enough to remove wrinkles, but soft in light air.
Good Luck and sail fast! If you have any questions or suggestions call Ethan Bixby of North Sails Gulf Coast, 727-898-1123, Fax 727-898-0211, or email@example.com
Scot Ikles 10 Step Checklist for Speed in the 505.
1. A 505 likes to be sailed with a little weather helm in light conditions and a neutral helm in windy conditions. If you have too much helm: sail the boat flatter, flatten the sails, decrease the rake, or raise the centerboard.
2. A 505 likes to be balanced in the speed/point groove upwind. If you have speed to burn, but cannot point with the pack, stand the rig up.
3. If the rig is too loose: the jib is too full, and the boat cannot point. If the rig is too tight: it is hard to keep the boat in the groove.
4. Sail the boat on its lines. Keep the knuckle from digging in, and keep the stern from dragging.
5. When the breeze is on, the bow must be able to float freely through the upwind groove without the boat healing over when driving off. The centerboard controls this feeling.
6. Set up the rig and main so that the luff curve matches mast bend. Do not sail with overbend wrinkles.
7. Start the luff of the jib breaking evenly, if overpowered, twist off so the top telltale breaks first. Use a jib leech telltale to judge jib sheet tension. Keep it flying and ease if its stalled.
8. In light to medium conditions, both sails should have small horizontal wrinkles along the luff.
9. The main and jib leeches should be parallel. Be careful not to close the slot. As the wind builds and the main is twisted off, with the sheet eased, twisted off the jib, and or open the slot.
10. Keep the top batten parallel to the boom for most conditions. If you need to point, the batten could be hooked to windward. If you need to foot, the main should be more twisted, and the top batten should be falling off to leeward.
+ Once you are set up, find the sweet spot for the given conditions, and keep it rolling.