Problem Solving with Michael McNamara:
Changing Gears

You are going well. The boat is flying and you are with the pack. Then, quite horribly suddenly, and often without your apparently altering anything, it all changes. To leeward, boats point higher and go faster, and the windward boats start to roll over you.

So, what has happened? Why are things going wrong and what can you do about it?

Firstly, don’t panic. You were going well and can do so again, providing that you are logical.
So, identify whether it's a pointing problem or a speed deficiency and then apply a check list
of cures.

Don't forget to alter one thing at a time only, and to give the change time to work.

You need to point higher...

Q: Is the mainsail leech too open?

Answer: Try tightening it by

  • increasing main sheet tension
  • increasing kicking strap tension
  • bringing the boom closer to the centreline
Use the angle of the top batten to the boom as your guide. Ideally, it should be parallel to the boom. The top windtuft should, in fact, be streaming aft most of the time. But stalling it, up to 40% of the time, should give the best pointing ability, although at the expense of speed.

Q: Is the mainsail too flat?
If the mainsail is too flat, the leech is likely to be too open and the slot between the foresail leech and the front of the main too wide. A good guide here is: If the main luff does not backwind in medium conditions from time to time, then the mast is too bent. Also, the sail can have large diagonal creases which in extreme cases will flutter.


  • straighten mast
  • ease clew outhaul
Q. Is the foresail too full at the luff?
Identify this problem by luffing up rather more than usual to see if the whole luff length collapses at the same time. Increasing the rig tension (Al’s note: = jib halyard tension) straightens out the angle of attack, it is possible to go too far and make the sail difficult to "read". (Al’s note: at this point, windtufts on both sides of the jib would become very ‘jumpy’ and you would have trouble settling into a groove where the jib is neither luffing nor stalling)


  • increase rig tension
  • ease luff cunningham until luff has minute wrinkles
  • move fairlead closer to the centreline

Q: Is the foresail leech too open?
This problem shows itself when lufling up more than is usual. If the top windward windtuft collapses first, tensioning the foresail halliard reduces rake, raises the clew and so tensions the leech.


  • sheet foresail harder
  • move fairlead forward
  • reduce mask rake
  • increase jib halliard tension

Q: Is the Helm too neutral? Has it no "feel”?
Some "feel" is necessary to the helm in order to keep the boat on track when the helm is looking elsewhere. Up to 70% of windward concentration is spent in anticipating what changes in the environment are about to affect the boat.


  • increase mast rake
  • sit further forward
  • angle centreboard forward

Remember, try one adjustment at a time, waiting a while to see if it makes an improvement.

You want to go faster...

Q: Is the mainsail too full?
In a breeze the very best speed seems to come when the top quarter of the sail has very little curve and will seem almost straight when viewed from below. The top telltale will stream all the time.


  • bend the mast more
  • tighten the clew outhaul
Aim to make the sail inert in the gusts, so that it gathers rather than flaps.

Q: Is the mainsail leech too tight?
Signs that the leech is too tight are excessive and uncontrollable heeling in gusts, associated with sail being too full and so there could also be massive backwinding.


  • increase mast bend
  • ease boom away from centreline on the main sheet/bridle/traveller
Q: Is there excessive weather helm?
This problem shows itself particularly in gusty conditions when the out of balance boat tries to luff into the wind as the gust hits. Keeping the boat flat and moving aft not only keeps the hull shape symmetrical but also makes best use of the fatter flatter aft sections.


  • keep boat level and do not allow it to heel
  • reduce rake
  • move crew weight aft
  • raise centreboard a fraction
Q: Is the foresail angle of attack too shallow?
If the angle of attack is too shallow, the sail is not only difficult to read but the centre of effort goes aft. When this happens the bottom windtufts become unstable as first the windward one and then the leeward one stall out as the airflow rapidly fluctuates from one side of the leading edge to the other.


  • reduce halliard tension and/or
  • reduce rig tension overall
  • tension foresail cunningham
  • move fairlead outboard
Q: Is the foresail leech too tight?
This shows as excessive mainsail backwinding and the lower windward windtuft collapses before the top one. Aim to keep the middle leech parallel to the centreline with the leech at 3/4 height being 5% - 10% open and the leech at 1/4 height being 5% - 10% closed. Tiny movements of sheet and fairlead adjustment have massive effect on the leech so don't overdo them.


  • ease sheet slightly
  • move fairlead aft slightly
  • increase mast rake

As a general rule flatter is faster, while a tighter leech improves pointing.

By working through these adjustments, it is possible to bring the boat's performance back on track. Don't forget to wait a moment after each adjustment to see if it helps.

Michael McNamara      UKWA News 1995