• Virtual Mark rounding
  17 Comments
  David Dalli Today 15:29
• RYA Appeals
  3 Comments
  Jim Champ Today 12:17
• Rules Situation Diagram Software
  8 Comments
  John Beavis Wed 21:17
• Hitting a mark but not rounding it
  13 Comments
  Phil Macwhirter 26-Mar-06 12:07
• Zone and RRS 18 in a HC fleet with boats of different lengths
  22 Comments
  Andrew Lesslie 26-Mar-04 01:37

• Virtual Mark rounding
  
  Mr. Hubbll raises a good point.
  
  In direct response to the original post by Mr. Dalli: Yes, I do believe Rule 18 can be applied successfully. Let's assume there is an overlap as the two boats enter the zone around a GPS waypoint. The inside boat, using their GPS, asks for Room. The outside boat shall then provide Room, and if she feels that the inside boat was not entitled to Room she will Protest. If there is a debate, it gets sorted out in a protest hearing.
  
  However, during that hearing various key facts need to be discovered. An important one will be: there are two types of GPS available today. The relevant points are covered in the quote below from this source: https://rtkdata.com/blog/rtk-vs-gps-accuracy-2026/
  
  "RTK vs GPS Key differences
  
  

  • Accuracy: RTK provides centimeter-level precision (1-2 cm), while standard GPS provides meter level-accuracy (3-10m)
  • Correction Method: RTK uses a base station to transmit real-time correction data to a rover, correcting for atmospheric and satellite errors instantaneously. Standard GPS relies on direct satellite signals without real-time corrections.
  • Application: RTK is ideal for high-precision tasks like drone surveying, autonomous vehicle guidance, and construction. Standard GPS is used for consumer navigation (smartphones, cars).
  • Cost & Complexity: RTK systems are more complex and expensive ($8,000–$80,000). Standard GPS is inexpensive and found in common devices."

  
  At this time both "RTK GPS" and "standard GPS" are in use aboard various competing boats. As is stated above, the RTK GPS supports accuracy of 1-2 centimeters, while the standard GPS accuracy is 3-10 meters. During any hearing, it would be wise to discover exactly which sorts of GPS was being used and consider this when trying to determine the Room to which the inside boat was entitled.
  
  At this time both GPS and RTK GPS are being used within the commercial starting systems of Vakaros and Velocitek respectively, to provide a more accurate method of determining OCS at the start of a race. That has brought up the obvious question, is the position accurate enough. Extensive testing over the last three years has shown that the 1-2 centimeter accuracy of RTK GPS is better than human visual line sighting, while the regular GPS is not.
  
  As a result, Rule 18 will work just fine at the 1-2 centimeter accuracy of RTK GPS, at least as well as humans rounding a visible mark. It will be more difficult to resolve the 3-10 meter accuracy during a mark rounding for regular GPS. The most difficult situation will be if the two boats have different types of GPSs.
  Beau Vrolyk Today 20:18
• RYA Appeals
  RYA's Casebook is at https://www.rya.org.uk/racing/rules/rya-case-book/
  Peter Glick Today 20:08
• Portsmouth Yardstick
  Thanks everyone for your contributions. There is a clarity in my mind now with all the inputs given here. Now I will close this thread here.
  Satish Kumar Kanwar Today 19:17
• Rules Situation Diagram Software
  Boats Scenario is one good option.
  Satish Kumar Kanwar Yesterday 06:55
• Zone and RRS 18 in a HC fleet with boats of different lengths
  I was being a bit lazy about RRS 14.
  
  Here are some more facts and conclusions
  
  Assuming there was no injury or damage.
  
  Facts
  
  3A.  There was ample space to windward of Y.
  
  
  Conclusions
  
  C1.  Y did not avoid contact with B when it was reasonably possible for her, acting no sooner than it was clear that B was not giving mark-room, to do so. Y broke RRS 14.
  C2.  Y, sailing within the mark-room to which she was entitled, and contact not causing any damage or injury, is exonerated for breaking RRS 14 by RRS 43.1(c).
  C3.  B did not avoid contact with Y when it was reasonably possible for her, acting no sooner than it was clear that Y was not keeping clear, to do so. Y broke RRS 14.
  C4.  B, a right of way boat, and contact not causing any damage or injury, is exonerated for breaking RRS 14 by RRS 43.1(c).
  
  F1.  It was not reasonably possible for B acting no sooner than it was clear that G was not giving mark-room, to avoid contact with G.  B did not break RRS 14 with respect to G.
  F2.  G did not avoid contact with B when it was reasonably possible for her, acting no sooner than it was clear that B was not keeping clear, to do so. Y broke RRS 14.
  F3.  G, a right of way boat, and contact not causing any damage or injury, is exonerated for breaking RRS 14 with respect to G by RRS 43.1(c).
  
  J1.   It was not reasonably possible for G acting no sooner than it was clear that R was not giving mark-room, to avoid contact with R.  G did not break RRS 14 with respect to R.
  F2.  R did not avoid contact with G when it was reasonably possible for her, acting no sooner than it was clear that G was not keeping clear, to do so. R broke RRS 14.
  C4.  R, a right of way boat, and contact not causing any damage or injury, is exonerated for breaking RRS 14 with respect to G by RRS 43.1(c).
  
  Summary
  
  Boats Y and B.
  
  Both boats broke RRS 14 but both boats are exonerated because there was no injury or damage and each one was either a right of way boat or sailing within the mark-room to which she was entitled.
  
  Boats B and G
  
  B did not break RRS 14 with respect to G.
  
  G broke RRS 14 but is exonerated because there was no injury or damage and she was a right of way boat.
  
  Boats G and R
  
  G did not break RRS 14 with respect to R.
  
  R broke RRS 14  but is exonerated because there was no injury or damage and she was a right of way boat. 
  John Allan Wed 01:27

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