Voyager 3.0 Emerges

Voyager 3.0 Design Goals

Voyager 3.0 is next in the series of the Voyager sailing drones.

The main aim for Voyager 3.0 is to be able to operate at sea for about 14 days or longer.

Voyager 2.0 can only operate for about 4 days on battery. Voyager 3.0 will include solar charging with the aim of allowing continuous operation. An endurance of 14 days at sea should allow for a rounding of King Island from the Victorian coast and back.

Tests of solar charging rigs have suggested that around 20 solar cells as a minimum are needed for reasonable charging levels for a 2S battery powering Voyager.

The dimensions of Voyager 3.0 have been entirely dictated by the compromise of minimum size for ease of handling, versus adequate deck space to accommodate enough half-size solar cells to support reasonable charging levels.

Overall dimensions of 1800mm length and 350mm beam were chosen to allow possibly up to 23 half-size solar cells to be accommodated.

Proposed Deck Layout with 23 Cells 

Proposed Layout for Voyager 3.0 along side Voyager 2.0 for comparison

Commence Construction of Voyager 3.0 with the Stringer, shown partially completed here

Preparing to glue the first foam sheet on the stringer.

Part way through cutting the foam sheets using a hotwire cutter.

Commence shaping the laminated foam hull.

Part way through shaping of the foam core hull

Voyager 3.0 with glassing finished, ready for fit-out, along side Voyager 2.0

Note: This is part of the ongoing development of a low cost autonomous oceangoing sailing drones, utilising a self-trimming wingsail. This is the Voyager series of sailing drones.

Another Port Phillip Crossing Attempt - Post COVID Lockdown

Melbourne, Australia has come out of the second lockdown recently, so on December 10 2020, I commenced another run across Port Phillip.

In the months since the last run we've been in lock down for weeks at a time and not permitted to either leave home or leave our local area without good reason.

During this time Voyager 2.0 has had some hardware and software updates based on lessons learnt during the last crossing attempt.

The main software issue being addressed was the method of correcting the course as the vessel is steering toward a distant waypoint.

Checks done. Ready to go again.

 Steering to a Waypoint

When waypoints are only a few hundred metres away, it is simple to steer a course representing the Bearing to Waypoint (BTW) and you will typically arrive there, having followed closely along the rhumb line.

When the waypoint is many miles away, and the steering method is to steer the BTW, then it is quite likely that the vessel will deviate great distances from the rhumb line over a period of time.

This was one of the problems encountered during the last voyage across Port Phillip in March 2020.

The main software design change since then was to continual measure the Cross Track Error  (CTE) and use this to add a proportional course correction to the BTW to encourage the vessel to return to the rhumb line. The amount of course correction to apply is calculated as the ratio of CTE to CTEMax (where CTEMax is defined in the mission as half width of the corridor to the next waypoint), multiplied by gain constant.

Hence the simple course to be steered is: BTW - CTE/CTEMax x Kc

Note: This is all assuming that a course can be laid directly to the waypoint without tacking. If tacking is required, then a whole set of different rules apply which are beyond the scope of this article.

The first 10 hours were good

The vessel sailed from east to west, and for the first 10 hours was perfectly on course, staying very close to the rhumb line.

Unfortunately, at 6am the next morning, it was once again picked up be a fishing boat. A commercial fishing vessel this time.

This can be seen in satellite tracking plots shown in the image below. It was picked up in the middle of Port Phillip, as it was heading eastward, and carried on the remainder of their fishing trip, before the fishing vessel returned to her home port of Port Arlington.  I arranged to meet them there for the handover.

Satellite Tracking Plot 

Shared View: Voyager 2.0 December 2020 - SPOT Tracking (findmespot.com)

Mission in Yellow and actual course in Green. You can hardly separate them

Conclusions

The new method of steering using CTE combined with BTW appears to work well.

I've tried to sail across Port Phillip twice now, and failed both times due to human intervention.

I'll need to add signage suggesting to "KEEP CLEAR" or head out to the open ocean where there's less chance of meeting other vessels.

Port Arlington - Home Port for the last vessel to "rescue" Voyager

This is part of the ongoing development of a low cost autonomous oceangoing sailing drones, utilising a self-trimming wingsail. This is the Voyager series of sailing drones.