Technical question on tactical computers and racing tasks

[jfitch]

I am collecting information on tactical computers, and need some help with the ones I don't own. Particularly SN10, ClearNav, LX9000 and any others than may be popular. The scenario is this: a racing task (not AAT) with a start and finish line, and at least two large radius turn points. I would like to know how the computer sets the start line in these computers. Does it set them square with the course to the turn points proper, or to the ideal course which reflects off of the cylinder?

On iGlide for example, the starting line is depicted at right angles to the course from the proper start point to the proper 1st turn point (their centers). The ideal (shortest) course will reflect off the first turn point cylinder towards the second turn point and will not be at right angles to the starting line, but will tilt towards the direction of the 2nd turn point, making that end of the line favored. I would like to know if other tactical computers do the same thing, or do they adjust the start line so it is square with the ideal course. Same issue for the finish line.

This effect is more pronounced with long start/finish lines and large turn point radii.

Thanks for helping. This affects a scoring program and am attempting to develop.

[Tony[_5_]]

Most default to perpendicular to the first leg which would go to the turnpoint. But you can program in a different angle if something different is called for.

At the 13.5m WGC the finish line was aligned with the edge of the airfield, not the final leg, for example.

[jfitch]

On Monday, January 16, 2017 at 6:33:47 PM UTC-8, Tony wrote:
> Most default to perpendicular to the first leg which would go to the turnpoint. But you can program in a different angle if something different is called for.
>
> At the 13.5m WGC the finish line was aligned with the edge of the airfield, not the final leg, for example.

Thanks. Yes I am aware you can set the angle, but wondering what happens in most of these programs if you don't. And secondarily, what is the typical practice of racing rules worldwide.

[Tim Taylor]

On Monday, January 16, 2017 at 8:49:41 PM UTC-7, jfitch wrote:
> On Monday, January 16, 2017 at 6:33:47 PM UTC-8, Tony wrote:
> > Most default to perpendicular to the first leg which would go to the turnpoint. But you can program in a different angle if something different is called for.
> >
> > At the 13.5m WGC the finish line was aligned with the edge of the airfield, not the final leg, for example.
>
> Thanks. Yes I am aware you can set the angle, but wondering what happens in most of these programs if you don't. And secondarily, what is the typical practice of racing rules worldwide.

Most are perpendicular to the path line from the last turnpoint to the finish or start to fist turnpoint and 1 km wide (for those not handicapped by an outdated measurement system).