Ninth Voyage in Bass Strait - Argh! Software Bug!

Conditions were good for a 2-day passage commencing from Torquay Fisherman's Beach on the evening of Monday 28/7/2025.

The weather on the course was initially running, and was predicted to back toward a reach, and continue backing to a beat with moderate winds near the end of the main leg to Western Port.

But it didn't get there, and this time the reason was a software bug.

Ready for Launch at Torquay Fisherman's Beach, 28/7/2025.

The software bug was introduced in 2021, but had not shown itself in ocean conditions before.

When beating to windward the software limits the upwind course with a minimum upwind angle, forcing the vessel to tack to reach a windward waypoint.
In early 2021, a similar constraint was added for downwind sailing, forcing the vessel to tack downwind to reach a waypoint within the minimal downwind angle. This was to improve downwind performance by avoiding sailing dead-downwind.

This all appeared to be fine, but there was a latent error, that was not recognised until now.

The error was revealed when sailing a running course that requires tacking downwind, and then the wind changes so that the course requires tacking upwind, without a period in between where the course is directly sailable.

Given this specific scenario, the software had an error where it did not allow the vessel to leave the running course. I've named it the "Stuck Running" bug.

This lead the vessel off the course and it did not recover.

The software has now been updated to handle the direct transitions between upwind and downwind courses that are not directly sailable. 

On a positive note, everything else with the vessel appeared flawless.