Tuning

J80 Sailing tips

Downwind, Tuning

Jib Trim
The latest Jib design is sensitive to sheeting in light winds but the speed gains are significant if the trimmer is constantly adjusting the trim. You will find that you need to set the leech line tighter as the wind increases, to stop the leech vibrating or ‘motoring’. Always pull it on the minimum amount that stops the vibration because excessive tension will distort and hook the leech. As the sail gets older you will eventually find it impossible to
stop the motoring without tightening the leech line to the point where it distorts the leech shape – this is the time to start thinking about ordering a new sail!

Mainsail Trim
What you are aiming for is to power the main up sufficiently that you have a decent amount of weather helm, but not so much that the boat cannot accelerate when a gust hits. The principle tools you will use to do this are the mainsheet, traveller, backstay, vang and outhaul; The outhaul should be set in light winds with a 100mm gap between the foot of the sail and the boom and gradually tightened so that in a breeze it should be so tight that there is distortion in the foot of the sail. 

The Cunningham should be left slack until you are intermittently overpowered, then it should be progressively tightened to remove the wrinkles from the luff, but not pulled so hard that it distorts the sail.
In light airs, the backstay and vang will be loose and you have complete control of the sail shape with the mainsheet and traveller. In this case you should trim the main until the top tell-tale is flying about 50 – 70 percent of the time with the boom held in the middle by pulling the traveller up to windward. Once the breeze is up to the point where the boat is fully powered up and it is necessary to ease the traveller, then you must also
use the backstay and vang to help control the mainsail shape. From this point on it is impossible to stop all the  tell-tales flying, so we must use the balance and feel of the helm to help us trim the mainsail instead.
The principle of sailing the J80 in fully powered conditions is to have the mainsheet locked off and play the traveller through the gusts. You then use the vang and backstay to control the drive and power in the main to balance the helm properly. When everything is set up perfectly the boat will have a reasonable amount of  weather helm. When a gust hits and you ease the traveller the boat should accelerate easily and smoothly and the helm will feel light and sensitive almost to the point where it is neutral – with neither weather nor lee helm.

If you have pulled on the backstay and vang too tight, then you will have neutral helm before any gust hits and the boat will not point. Apart from feeling wrong so that you will have to push the rudder around a lot to make the boat steer, you will notice your lack of pointing ability very quickly compared to the boats around you.
If you have not pulled on the backstay and vang enough to de-power the mainsail, then the helm will not go neutral before the mainsail starts flogging in a gust.
So you must learn to judge from the feel of the helm, and the way the boat accelerates in a gust, whether or not the mainsail needs more or less power. Remember that you pull the vang and backstay on to de-power, and ease them to power up

This leaves us with the crucial question of how much of each you should pull on to de-power the mainsail efficiently. Generally the vang will de-power the lower third of the mainsail and the backstay the top two thirds. You shouldn’t pull the vang on so much that you create luff starvation creases. This distortion will consist of vertical creases running from the mast towards the clew, and it will be particularly severe around the track feed on the mast three or four feet above the gooseneck. If you see these luff starvation creases, ease the vang and pull on more backstay. If you have too much backstay and not enough vang, then you will find that the sail starts to backwind low down the moment you ease the traveller in a gust. This is because with not enough vang, the bottom of the mainsail is too full, and when you ease it, it falls straight into the jib exhaust and backwinds.

Downwind Sailing
The mainsail trim is straightforward for downwind sailing. Ease the vang and the backstay as you round the mark, not before – otherwise you will power the mainsail up at exactly the moment you don’t want to, when you are trying to bear away. The cunningham should go off completely and the outhaul be eased until there is about a hand’s width gap between the foot of the sail and the boom. Once you are sailing downwind with the asymmetric hoisted, trim the vang so that the back of the top batten is parallel to the boom. Keep an eye on the top batten which has a tendency to invert which is slow!. Ease the backstay again until it has just got some load on it. Ensure that there is sufficient backstay tension to keep the mast straight and stop it inverting.

Always fully hoist the spinnaker halyard. The tack line should also be pulled on hard except when running very low in medium conditions where it can be eased up to 30cm, which allows the sail to rotate further around to windward.

Downwind sailing in the J80 is all about sailing the right angles with good spinnaker trim. This requires the maximum concentration from everyone on the boat. The tactician needs to watch the opposition closely to see how you are doing. He gives this information to the spinnaker trimmer and helmsman, who then use it to help to balance the pressure in the spinnaker sheet with the angle that the boat sails downwind to optimise your performance against the opposition. This focus on what is going on around you is the critical point to
sailing well downwind. You will never find the fastest angle and trim on your own, it is only by constant direct comparison with the boats around you that you can judge your VMG.

Practising your spinnaker trim and steering is only half of the job downwind. For those new to asymmetric spinnakers there are many new skills to learn. The downwind angles of the J80 give you a lot more tactical options than do conventional boats and symmetrical spinnakers. If you see a gust – gybe over to it, run deep, or come high to stay in it. The J80 is so responsive to just a little bit of extra pressure, that it is vitally important to be in it if you can. And if you are not looking around for the gusts, and working the boat into them, other boats will just sail past.
In light and medium airs you must concentrate on trying to get deep. Again, make sure the tack line is eased 30cm and heel the boat to windward which allows the sail to rotate further around to windward into clear air.
Keep trying to work the boat deep as the gains always seem to be made by working the boat low and getting to leeward of other boats. You will never be steering a steady course in these conditions and there must be the same continual dialogue between the trimmer, the helm and the tactician.

Wait till you have the speed built before you bear away in a gust or a wave. Once it is breezy enough that the spinnaker is really loading up you must sail higher and try to get the Boat planing. Keep watching the gusts and remember – pressure is everything, if you’re in it, you’ll win it. Only practice will enable you to master the art of  sailing fast downwind in the J80.

J/80 Mast Tuning Guide

Tuning

 Mast Rake

Mast rake is very critical for getting the best all around performance from your J/80. Because of the  differences in the measurement from the black band to the mainsail halyard sheave box, combined with  slight variances in the total length of masts, we have determined that mast rake should be measured from  the bottom of the black band at the top of the spar to the closest point at the middle of the stern.

1. Hoist someone to the top of the mast on the main halyard. Have them hold the end of the tape measure at the bottom of the black band.
2. Measure to the center of the stern, wrapping the tape measure around the outside of the stern directly under the tiller.
3. Where the tape measure first hits fiberglass on the top outside edge of the stern cutout, the  measurement should be 37′ 4 ½ “.
4) Adjust your headstay accordingly to get this measurement.

Mast Butt Position/Prebend

Once your headstay is set for the correct mast rake, it is time to adjust the mast butt position in order to get 2 ¼” of prebend, which best suits your Ullman mainsail for a wider range of conditions.
1. Make sure your mast is in the standard factory position, well chocked side-to-side, and for-and-aft so the spar can’t move at the deck.
2. Position the aft side of the mast step at 8 ¼” from the bulkhead. This position will get you close to the correct prebend. Due to inconsistencies in bulkhead positions, you may need to move the position slightly forward or aft of this position.
Check to see if the 8 ¼” position is giving you the correct prebend.
1. Attach the main halyard to the gooseneck as close to the back of the spar as possible and tension the halyard hard.
2. Hoist someone up the mast just above the bottom spreader.
3. While someone standing on deck pushes the main halyard against the back of the mast at the goose neck, have the person up the mast measure the maximum distance from the back of the spar to the closest part or forward edge of the main halyard. Again, the maximum distance or prebend should be a couple of feet above the bottom spreader. Have the person up the mast move the tape measure up and down in that area to determine max prebend.
4. This prebend measurement should be very close to 2 ¼”. If your prebend is less, then move your mast back to increase prebend. If your prebend is more, move your mast butt forward to reduce prebend.
5. Once your mast butt is in the correct position, scribe a permanent line on the beam that the butt sits on so you will never have to go through this process again.Pre-bend is very critical in allowing your mainsail to react correctly with back stay adjustments and
ensures the correct slot between the luff of the mainsail and the leech of the jib.

TAKE THE TIME TO ADJUST YOUR MAST BUTT FOR THE REQUIRED 2 ¼” PREBEND FOR MAXIMUM PERFORMANCE  WITH YOUR ULLMAN SAILS!

Centering the Spar

1. Measure back from the stem fitting on the mast 9′ 7″ to each rail. Mark with a permanent marker.
2. Attach a tape measure to the jib halyard and raise a couple of feet.
3. Measure to each side and adjust the upper shrouds so the measurement is the same on both sides.

Shroud Tensions

1. Once the mast is centered, tighten the uppers so that they read (30) on your Loos tension gauge.
2. Tighten the intermediates so they read (8) on the Loos gauge.
3. Sight the rig by looking up the mast track and adjust the intermediates in ¼” increments so the rig is straight. If you tighten one side a ¼ turn, ease the other side a ¼ turn to insure you keep the same approximate tension on each intermediate.
4. Tighten the lowers to (15) on the Loos gauge.
5. Again, repeat step 3 until the spar is straight side-to-side.
NOTE: If you find that it requires much more tension on the lowers or intermediates on one side than the other to keep the spar in column, the mast may need to be re-chalked from side-to-side at the deck. If not corrected, you will be sailing with different headstay sag from tack to tack, which will make it impossible to duplicate jib lead position and jib sheet tensions from tack to tack.
PLEASE CALL US IF YOU THINK YOU HAVE THIS PROBLEM AND WE CAN TALK YOU THROUGH
RE-CHALKING THE MAST AT THE DECK!
Your rig is now tuned for our base setting at 10-15 knots.

J/80 Rig Tension Chart
J80-tuning-guide-2

The thread size of your turnbuckles will determine the amount of turns it will take to get from one setting
to another. We recommend making a chart with the amount of turns so that you can change settings
easily and accurately on the water between races.
Good sailing,