I was recently involved in a race in which keel boats were required to round a coordinate a number of times. Not an actual physical Mark. This has me wondering. Given the definition of room and the meaning of touch. Is rule 18 applicable or enforceable in any practical way?
This is an interesting question as there is no mark on the water. I would be keen to know how the scenario pans out in such a case wrt rule 18.
www.sailing.org/inside-world-sailing/rules-regulations/racingrules/
https://www.sailing.org/tools/documents/OC13bRacingAroundWaypoints-%5B19446%5D.pdf
It would be great if the OP could provide a copy of the regatta documents (NoR/SI) which could be quite helpful, or not.
The Appx does not define a min decimal-depth (sig-fig) for WGS84 location. Therefore, the size of the location, depends upon the resolution.
Since we have a relative measure in the zone of 3 BL's, the zone's location needs to be specified to something substantially less than 1 BL for it to be usefully determined.
My point is that people should add the trailing zeros in the description to 5 places and IMO the Appx should state or at least guide to that location-resolution.
Describing 5-places is not that onerous of a step (adding trailing 0's if required) to remove the ambiguity implied by their absence.
The Mark 3 will be the coordinate....
APP WP was not invoked. I am happy that at least this sorts out the issue of wether it is possible to touch a coordinate. There is still the matter of given that GPS location is accurate to between 2-8 m 95% of the time ( according to WS Judges Manual). How can one decide if room was given or when the zone was reached.
If I say something is 1 km away ... I'm describing something that has a less than 1/2km location resolution.
Add a decimal .. 1.0km ... now it's a 0.05 location resolution.
If a location wants to be resolved for a 3 BL zone ... and 1 BL is 10-20m ... then the location should be located signicantly less than 10m. 1-2m should be fine ... so 5 decimal places.
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
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.
Ok ... so why bother defining "zone" in Appx WP? 2 boats meet in the middle of the ocean .. why not let them work it out without 18?
The issue is that we have a 3BL zone defined in the Appx and 18 is still there ... locating both the WP and the zone in a functional way is a worthy topic driven by Appx WP's contents.
That describes and resolves to a location that is approximately the size of a physical mark.
I also think we should not get too side tracked about the accuracy of the GPS system. We often have races going around waypoints (using WS Appendix WP). If any GPX track carried on the boat shows the boat went around the mark, the boat gets the benefit of the doubt and the boat is scored as sailing the course.
Is see there are three separate issues:
1. Whether rule 31 is broken (no, it cannot, as there is no physical mark to touch).
2. How rule 18 applies to waypoints.
3. Whether a boat has sailed the course (whether the boat rounded the waypoint).
Recently I was close to a waypoint. The chart plotter could not zoom in any further at the time. I though we passed it on the correct side. I downloaded the track after the race, and checked the GPX track and ascertained that the track was 4 m the wrong side of the mark, so I retired from the race.
For the purposes of rule 18 it will be difficult to decide a protest, but that would be up to the protest committee to decide after hearing all the evidence. I would be inclined (as a protest committee) to accept the evidence of a track showing how close a boat was to a waypoint and whether the boat was in “the corridor” (in umpire speak) or not.
To digress: In our short handed series we also start races without a RC, where, if there is a question we ask a boat for a GPX track, to ascertain whether the boat is OCS or not. We have found that at times, where a rounding or finishing mark is a physical mark and a boat sailed the course correctly, the GPX track sometimes shows differently (by as much as 20m). For this reason one should be give a boat the benefit of the doubt regarding whether she sailed the course instead of relying on a GPX track. It is different where it is a waypoint as opposed to a physical mark: There the boat must show, using its own GPS, that it has sailed the course. Our sailing instructions requires every boat to record its own track (which can be done on a smartphone) with a frequency of 0.2 Hz (at least one data point every 5 seconds) and send the GPX track to the RC on request. The requirement to record the track is a marked DP.
In short, I think it is not really practical to make decisions about rule 18 on the water watching a chart plotter. However, if a protest committee is faced with a protest, it will have to do its best with the evidence presented to it, presumably in the form of GPS tracks (which I refer to above as a GPX track, as it is a common format).
The NoR and SI can be found here: https://www.sssa.africa/racing/.
Lance
"In my view, a waypoint defined by coordinates is mathematically a zero dimensional point. It is a location with no physical size. I don’t think it should matter whether it is defined in the SIs as 38 00.00000N 122 00.00000W, or 38N 122W. Either way the location is defined exactly and the point has no dimensions and no uncertainty. Although if folks writing the SIs want to specify the trailing zeros it does no harm but it doesn’t change the location or characteristics of the waypoint. It still has zero dimensions and is mathematically a point."
What you and Stan are doing is assuming the zeros are there ... without writing them or acknowledging them. That's ok as long as everyone agrees that's what's happening (unsaid).
If I say the cost overrun by the govt was $6B ... I think most people understand that doesn't mean the cost overrun was exactly $6,000,000,000.00.
One value has an sig-fig of 1 place with units of $B and the other of 12 places with units $1 resolved down to $1/100. $6B can have a large variation. Say it was a $6.1B overrun ... you narrow the variation (a higher resolution of the value) as you know it down to a $100M.
The value $6B actually represents 100's of millions of possible exact amounts when resolved down to the penny. Like the dollar amount above, a location represented without decimals represents a large swath of possible locations within an area of ~50km along its side .. unless we all agree to assume the trailing-zeros are there without being actually described.
Anyway ...I don't know how to say it any better than that.
The guidance document, 2.4 says:
(a) A waypoint is not a physical object, and
(d) RRS 18 and RRS 28.2 cannot apply unchanged because a mark is defined as an object.
Does anyone have any insights about the apparent philosophical change?