The Turtle Solves The Series Virtual Mark Mystery

The inaugural Tipsy Turtle race occurred on Sunday November 9. The race was being held using a virtual mark due to the wind not cooperating and forecast to be light. The virtual mark location was provided in NOR earlier in the week.

As the captain of Commotion was entering the virtual mark into the chart plotter, he realized that the information given in the NOR may not be the format easily used for use in everyone’s chart plotters. A quick calculation was done, and the virtual mark format was reformatted and shared via Facebook and an email sent from the club email software. At no pointed was the mark location changed, it was just reformatted.

Some participants, prior to the race, saw the post/email and others did not. Some understood what the post was telling them and others did not.

The race occurred and a variety of locations were used as a virtual mark.

The race was meant to be fun, and it was scored based on the assumption that the boats started legally, rounded a mark that was somewhere in the middle and finished legally.

The race chair received a few calls asking “why was the mark changed at the last minute” and chatter was heard about “why did the race chair make last minute mark changes and how thing got messed up, etc. etc. etc.

Based on the phone calls and chatter, the first thing we did upon arriving at home was double check the accuracy of the mark calculation. What we found was that the race committee made no mistake. The real mystery was “what the heck coordinates did boats use as a virtual mark and how did they calculate them?”

After some thought and discussion, the mystery was solved. Solving the Tipsy Turtle mark mystery solved the ongoing virtual mark complaint from the past few years that not all boats were going around the same virtual mark. So, score an extra cruising point for the Turtle!

Below is a clear explanation of what happened during the Tipsy Turtle and has been happening over the past few years when the club has used virtual marks.

And thank you Captain Ken for being honest.

Explanation:

There was some post-race discussion about the announced position of the turning mark used in Sunday's inaugural Tipsy Turtle race.

The position of the mark was provided in the Notice of Race (NOR) using two different formats - Degrees, Minutes and Seconds (DMS) and Decimal Degrees (DD).

Round a virtual mark located at 26° 10′ 24.6″ N 80° 04′ 57.1″ W

(Decimal degrees: 26.1735 N, 80.0825 W)

These two provided formats represent the exact same physical location.

On race day, it was observed that many chart plotters require waypoints to be entered in a separate, third format - Degrees and Decimal minutes (DMM). As a courtesy, that additional format for the same waypoint was provided to competitors in a separate communication. This communication did not constitute any type of change or correction as it merely reiterated previously provided information. Anyone with the DMS position from the NOR could have performed this conversion themselves.

For anyone that needs today's tipsy turtle rounding mark location in degrees minutes and decimal minutes its 26° 10.410′ N, 80° 04.952′ W

All three provided lat/lon formats represent the identical location.

It's important to understand what format your navigation system is using, and what format the position you're entering is provided in. DO NOT take a DMS position like 26° 10′ 24.6″ N 80° 04′ 57.1″ W and enter it directly into your chart plotter as a DMM position by just moving decimal points around, such as 26° 10.246' N 80° 04.571' W - you'll go to the wrong place. In this example, you'd find yourself almost .4NM from the actual correct mark.

To convert a DMS position to a DMM position, it is necessary to divide the "seconds" value by 60 and add that to the minutes (60 seconds in a minute). So in this example, 24.6 seconds divided by 60=.410 minutes. Therefore 26° 10′ 24.6″ = 26° 10.410′

Here's an online calculator to help you with this https://www.calculatorsoup.com/calculators/conversions/convert-decimal-degrees-to-degrees-minutes-seconds.php

As always, please reach out to the race chairperson before the race if there are any questions about the Notice of Race.