Spotting Mistakes

The visual feedback of the chart display can help course designers avoid unintended, and sometimes embarrassing, mistakes.

Certain errors will get highlighted with a red frame around the edit box and an insulting red circle around the mark

"Buttonhooks:" these are a common problem arising when a mark's incoming boats' paths cross the outgoing. There's a risk of collision at worst, and pointless yelling at best. These are easily detected by noticing when the lines cross. You can correct these by changing the rounding direction or adding an offset, of course. Note that in some cases tactical considerations based on current or other factors may create or eliminate buttonhooks differently than straight-line sailing would suggest.

"String Rule" The RRS definition of Sailing the Course calls for the boat's course, if represented by a string drawn tight, to touch each rounding mark on its correct side. This means that a course which merely passes a mark designated as a "rounding mark" will require the boat to sail a circle around the mark. Needless to say, this tends to anger the 90% of racers who do not notice this and get protested.

You can spot a string rule problem by the course loop around a mark and the red error circle, as these will always count as "buttonhooks." Repair the problem by designating the mark as a "Passing" mark, or changing the rounding direction, or removing the mark altogether from your course, as appropriate.

Land. This is the most obvious. If the course crosses land the boats must sail around it. In some cases, this may lead to confusion as to which way to cross the finishing line. In most cases, the course deviation caused by the land will affect course distances and wind direction. You can address this in several ways:

• Define a point of land as a mark of the course, eliminating all confusion.
• Insert a "land/obstruction" into the course and leave it on the correct side. This will correct the course display and calculations but will not change SI course definitions.

• Move the finishing line. Note that you CANNOT redefine the direction of finishing under the RRS.