Penetrometer v GoingStick: how to read the official ground reports from Longchamp this Arc weekend

All week the talk from Paris has been of sunny weather continuing to dry out Longchamp, with Sunday’s Qatar Prix de l’Arc de Triomphe set to be run on the soundest surface since Enable defeated Sea Of Class in 2018, yet the official going descriptions issued by France Galop continue to indicate conditions are much easier.

On Monday the going was described as very soft, while on Tuesday, Wednesday and Thursday it has been given as soft, although trending slightly drier each day at 3.7, then 3.6 and 3.5 on the descending scale of the penetrometer.

Clerk of the course Charles de Cordon forecasts no rain between now and Sunday afternoon, and predicts a reading of 3.3, or good to soft, so why all the talk of a fast-ground Arc?

Two years ago France Galop began using the TurfTrax GoingStick as a second measure of the amount of moisture in the ground; not to replace the penetrometer, but to augment it with a going scale and description which would be recognisable to British and Irish trainers and punters.

The two instruments measure the amount of juice in the ground in a different way but the real confusion is that the two sets of going descriptions do not exactly map on to one another.

France Galop's Lucien de Colbert with the Turftrax GoingStick at DeauvilleCredit: Racing Post/Scott Burton

At its simplest, one way is to slide the GoingStick scale one along from the penetrometer, so that French soft becomes good to soft in Britain and Ireland, while good to soft in Paris would ride more like good, maybe even with some elements of good to firm. That is an oversimplification but it might give race readers familiar with the GoingStick a better feel for conditions in France.

As an example, take a look at the historical times of the Arc when the ground has been officially soft or very soft, against those run on good to soft.

Lammtarra ran only 1.30secs outside the Racing Post standard time on very soft ground in 1995, while Treve was only 1.54secs slow in 2013 on soft. On ground termed good to soft in the mid-2000s, Hurricane Run, Dylan Thomas and Zarkava all ran comfortably under standard.

Fortunately the forecast for Arc weekend is stable. The GoingStick reading is already good, good to soft in places, so we will know that conditions will be quite quick by Sunday.

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