My sailors have heard me say that you can win a race at the start, by the same token, you can loose a race on the downwind leg as it is often the boats behind that have a tactical advantage. Racing downwind on a run and getting to the leeward mark as quickly as you can is dependent on three related factors, boat speed, strategy & tactics.

The dominant factor will be boat speed, sailing as fast as you can regardless of other influences. Circumstance will dictate which takes priority between strategy and tactics.

Boat Speed – put your sailing technique to the test

Your boom should be eased out as far as possible to give maximum presented sail area, until it is touching the shroud.
Just enough kicker to keep the leach mobile with up to 75mm forwards movement in the gusts.
To get maximum projected area, the foot panel of the mainsail should be just tight with a horizontal ridge along the boom.
Your spinnaker should be pulled as far around to windward as possible. Bear in mind that in addition to working in wind from behind it is also working in the accelerating breeze coming off your mainsail.
Crew needs to tell the helm how much pressure there is on the spinnaker sheet & guy. As the pressure eases the helm will have to luff up, if the sail is pulling well, the helm can bear away and sail deep.
To check that the hull is creating as little resistance as possible:
a. Relax your grip on the tiller, if the tiller moves one way or the other, the flow across your rudder is not equal – heel the boat one way or the other until the tiller stays centralized.
b. Look at the wash your boat is creating & change your position in the boat, boat trim and balance) to minimize turbulence off the transom.

Strategy – using the weather and water positively

There is no point in tacking downwind in a dinghy that is in displacement mode, you won’t be able to go fast enough to make up for the extra distance sailed. A dead run is also not ideal, the most advantageous angle to sail is with the breeze coming over the windward corner of the transom.
It is important to minimize the distance sailed, to do this you need to regularily look at where your bow is pointing in relation to the leeward mark and consider if it would be pointing closer to the mark on the opposite gybe.
The windward leg, just completed will give you information on what the wind is doing, speed, gusts, variations in direction, etc. Use this information as you sail downwind – if you spent most of the windward leg on a port tack, then on the downwind leg, you should be on starboard tack most of the time.
In shifty conditions stay well clear of the lay lines, as they limit your options.
When the bottom mark is not directly downwind, there is less chance of overstanding the mark if you sail the longest leg first.
Which gybe to go on first is often determined by your approach to the windward mark. If you are being headed into the mark you should start the run on the same gybe. If the boat is being freed into the mark, you should start the run by gybing.

Tactics – boat on boat action

With boat on boat tactics the objective is to minimize the detrimental effect of your opponents boats on yourself and to maximize the detrimental effect of your boat on your opponents.
On the downwind leg, boat behind can cover boats ahead. To check whether you are being covered, look at the wind indicator on boats behind but within 10 boat lengths of you, if they are pointing at you, you are being covered.
If you are being covered, you need to break the cover as soon as possible by moving one way or the other.
A group of boats together form a barrier to the wind, which lifts off the water before it gets to them and therefore, they will always sail slower than a boat on its own.
Use the last quarter of your downwind leg to ensure that you are on the inside at the leeward mark.