FAQs - Sure-Path GPS Boat Lane Tracking

Boat Lane Tracking
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Multiple Rovers
I have more than one lake at my site, can I run two or more boats at the same time from one Base?

A Base station can provide RTK error data to any number of Rovers concurrently. Therefore additional boats just need their own Rover setup to work. A Rover setup consists of an antenna, receiver and phone (unfortunately the expensive bits).

There is one limitation however, Rovers should be within 10km (6 miles) of the Base. Beyond that, the system works but accuracy starts to degrade.

8 Buoy Course
Does Sure-Path work with an 8 buoy course?

Yes, when mapping the course, mark the entrance gates as usual but use the reverse direction entrance gate buoys for your exit gates. This gives a "short" course length of 177m. However, in each direction, Sure-Path only needs a start point (the centre point of the entrance gates) and a bearing to be able to create the centre line of the course and hence to calculate deviations from that centre line. Thus the mapped length of the course is irrelevant.

Note that if you are surveying for homologation in preparation for R or L class tournament, then the courses in each direction should be surveyed separately and homologated as separate items.

Pregate and Gate Deviation Values
When Sure-Path displays a deviation at the pregates/gates, is the boat left or right of the centre line?

As per the World Rules, when displaying deviations at each buoy, Sure-Path uses the convention that a deviation towards the skier is positive and a deviation away from the skier is negative. Thus at buoy 1, a positive deviation is to the right of centre; at buoy 2, a positive deviation is to the left of centre...etc. This convention is based on the assumption that being towards the skier is an advantage and away from the skier is a disadvantage.

Although not specified (or even required) in the Rules, Sure-Path applies the same convention to the pregates and gates. Therefore a positive deviation is left of centre and negative is to the right of centre.

Buoys used for mapping the Jump course
When you survey a jump course in preparation for boat lane tracking, which buoys are required to be mapped?

Sure-Path looks for combinations of buoys in the following order of preference:

  • ST15 + ST19 + ET15 + ET19    (this calculates the mid point of each pair of buoys and draws a line between them. This relies on the 19s being set accurately but is the easiest for the driver to follow)
  • ST15 + ST19 + MT15 + MT19   (as above but using the MTs)
  • ST15 + MT15 (draws a line from ST15 to MT15 and calculates a line offset by 2 metres in the direction away from the jump ramp. This is arguably the "purest" method since all homologated positions are referenced to this line. However, if the 19s are not placed correctly then the driver may find it difficult to follow)
  • ST15 + ET15 (as above but uses the ET15). This has the slight advantage over using the MT15, in that any error in the ET has less impact on the line's bearing.
  • ST19 + ET19 (draws a line from ST19 to ET19 and calculates a line offset by 2 metres towards the jump ramp)
  • ST19 + MT19 (as above but uses the MT19)

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