Upwind Speed - Centring the Boom Upwind

The race has started, and it’s early on the first beat. The wind is a pleasant 5-8 knots and you’re sailing near one of the class hot-shots, keen to match yourself against one of the best. To your dismay, you find he is going just as fast as you, but pointing about 3 degrees higher. By the first windward mark the champ is already miles in front. How does he do it?

Probably the biggest influence on how high you can point in lighter winds is where you sheet your boom relative to the centre-line of the boat.  This is essential because the Pacer has relatively small sails and is therefore well under powered in light winds.  Maximum height and power is therefore obtained by make sure the boom is centred or even up to 2 cm to windward of centre.  The key, however, is to pull the boom into the centre without using sheet tension to do so.

Until this year, my boat had centre boom main sheeting using a fixed length bridal. This allows you to centre your boom in light winds, but only by using a significant amount of mainsheet tension.  Here there is a quandary.   If you use a lot of sheet tension it results in a hooked mainsail leech, which is slow in light winds.  If you don’t use the sheet tension, you can’t get the boom in the centre so you can’t point as high as you would like!  What you need is a method of pulling the boom in to the centre without tensioning the mainsheet.

This can be done using end boom sheeting and an adjustable bridal system such as that on 2 time national champion Phil Chadwick’s boat (shown below).

Note how Phil has a mark showing when the traveller is centred. He also has two knots about 2 cm either side of the centre mark. These allow him to confidently pull the boom slightly to windward without accidentally pulling it too far.

The traveller rope is then led forward to some cleats near the thwart to allow for easy adjustment.

If you prefer centre boom sheeting, you can still rig up a simple adjustable bridal system such as that on my boat shown in the picture below. Note that the system uses a continuous piece of rope such that the act of pulling the traveller to windward on the new windward side will automatically uncleat the rope from the leeward cleat.  The blue plastic stoppers are essential to stop the traveller running out too far.  To centre the traveller, simply uncleat on both sides so that the blue plastic stoppers are resting against the top of the pulley on the side tank.

I find that I pull the traveller to windward in light and medium conditions up until I can no longer hold full power in the lulls.  Once you are over powered even in the lulls it’s easier to centre the traveller and use the vang to control mainsail leech tension.

A word of warning. I find that with the centred or pulled to windward it is very easy to over tension the mainsheet and still the main sail. In tense situations such as getting away from the start line, or a close port and starboard crossing I often find I’ve oversheeted and have to remind myself to relax and let things “flow” a little more.

Don’t forget, boom position is important but like any other small boat, in light winds you need to set you boat up correctly to get good speed and height.  Don’t forget to make sure:

  1. The downhaul is off on both the main and jib
  2. You have little to no boom vang tension on
  3. The jib is sheeted in to the inside edge of the buoyancy tank, with enough tension to keep the jib leach almost straight, but not so much the leach ribbon at the top of the jib is stalled (note where the jib is sheeted in the picture above)
  4. The mainsail is sheeted on tight enough so that the top leach ribbon is stalled about 50% of the time
  5. The mast is standing straight both fore and aft and sideways
  6. The outhaul on the main sail is not on too tight

Setting yourself up with a traveller or bridal system that allows you to pull the boom slightly to windward is a relatively simple and inexpensive thing to do, whether you like end boom or centre boom sheeting.  So go to it! And tell the champ to watch out next time!