Fix grade conversion for old South African grading system

[Willemfvz]

As per the discussion here, the old South African grade conversion is currently incorrect on the site. The grading system is still being used in some areas. In the link above, Cormac suggested using a conversion table linked here:

In the chart the French grading vs SA grading is off by one compared to The Crag's grade conversion chart, but this probably does not need to change on the website. The focus of this issue is the chart's conversion from SA to Old SA, which is more accurate (especially at higher grades where the current website conversion is significantly off).

[CMAXXTR]

I would not trust my chart above, there is no scientific proof behind it.

[grae22]

The SA / Old SA looks good to me and lines up with published sources like Gavin Raubenheimer's "Drakensberg Select".

I'll post his conversion table here this evening.

[rouletout]

Can you please post pictures of the conversions from these books?

[grae22]

The above is taken from Gavin Raubenheimer's Drakensberg Select (2017) - probably the most recent publication covering this area in which the Old SA system is still mostly used.

The above is from Duncan Souchon's Serpent Spires (2005).

In my experience the Drakensberg Select table is more in line with current interpretations.