Page 35 - Race

RYA GUIDANCE

Speed Charts - Using and Customising

On the Resources/Data Reference area for Race Officials on the RYA website are a number
of spreadsheets to aid Race Officers and Mark Layers in Setting course size to achieve an
agreed race "Target Time". Initially created to cover the Olympic Classes during the lead in
to the 2012 Olympics, these have been regularly updated over the years to revise the data
and more recently expanded include the Current Olympic Classes. Although the speeds for
a number of the classes have been updated over the years based upon user feedback,
additional feedback is always welcome. Details on who to send feedback to is included
within the header page on the spreadsheet.

More recently, additional spreadsheets have been added to the website that cover the
prevalent UK Junior and Youth Classes and the likely course configurations used at major
regattas. These include the standard Windward/Leeward and Trapezoid courses. For the
Trapezoid configuration, there are both the traditional (Olympic) form using a separate finish
vessel and an IX/OX form (which uses a Mark 5 and committee vessel finish). If an OX/IX
course configuration is used and an internal angle less than 80⁰, the outer loop will become
shorter than the inner one. Allowance has been made within the IX/OX spreadsheets for
classes where an internal angle different to 80⁰ has been assumed. This is provided as an
additional item of mark laying data, where the leeward mark on the inner loop is offset to
windward of the reference point. For full details, refer to the individual charts, where a short
explanation is provided. If required, a user may always adjust the offset by choosing a
different scaling factor to account for the required internal angle.

One thing to remember when using the charts is that they are only a guide. Local conditions
can have an impact on the actual race duration. The main factors that can affect race
duration are tide and wave action, especially for shorter and slower boats. For example the
upwind VMG in light winds is relatively low and so a tidal current of 1 knot and greater can
stop a slow boat such as an Optimist from sailing upwind in 5 knots and less. Even when
the wind speed is up to 8 knots, the VMG upwind is considerably slowed and the course
size would have to be reduced to compensate. Again, this can be modelled within a
spreadsheet, but is outside of the scope of this guidance note. In inland waters and confined
estuaries, wave action will have less of an effect than on the open sea and so course sizes
may need to be increased at higher wind speeds (>15 knots) compared to the charts as the
VMG is higher due to a shorter distance sailed (especially true for classes such as the
Optimist).

Using the charts for different classes
Although the published Speed Charts are for a limited number of classes charts for other classes
may be easily created using an adjustment based upon published RYA Portsmouth Yardsticks or
PY's. Any such chart should be able to provide an indication of course size to within 5% under most
wind conditions.

One potential method of using the PY is to choose a documented class of boat similar to that required
for course setting at a specific regatta. For example:

(a) Una Rigged boat (like Optimist, Topper or Laser)
(b) Two sailed monohull (no documented example but decide if it similar to say a Laser or 420)

Version March 2018 33