100 days on a Beach and a broken leg - 6th Bass Strait Voyage

100 days on a Beach and one broken leg - 6th Bass Strait Voyage

The 6th voyage on Bass strait for Voyager 2.7, commenced from Torquay Fishermen's Beach at around 4:45pm April 19th  2024.

Conditions were good.

Pre-launch at Torquay Fishermen's Beach 

But, the next day after around 28 hours sailing, Voyager appeared to suddenly deviate from course and drift to coast under the influence of the South-Westerly  wind, and eventually washed up in an isolated cove near Cape Schank, Victoria.

Track reported by the Satellite tracking showing the apparent time of failure.

The coast near Cape Schank is difficult to access so recovery will be difficult.

The coast line is mostly cliffs around 30metres high. It is mostly private rural residential land or farm land.

I attempted to gain access by following a gully down to the coast, but during the hike, I fell and broke my leg. This put me out of action for around 10 weeks.

Coast near Cape Schanck where Voyage come ashore.

The Satellite locator beacon continued to function for several weeks until the batteries finally ran down. the last signal was received at 9pm 22/5/2024, after 35 days. 

While recovering from my broken leg, I formed plans to recover Voyager by water, using my kayak.

The nearest practical location to commence the recovery trip was from Flinders Ocean Beach. This beach had easy access by car, and is protected by offshore reefs.

This would result in a journey 4 miles WSW toward Cape Schank, to the location of  Voyager.

Planned recovery journey in a kayak from Flinders Ocean Beach.

Then on 6th July 2024, after 80 days, a friend flew his light aircraft over the location of Voyager, took photographs, that showed the boat was still in the cove.

It is visible in the image below as the white dot on the beach above the high water mark.

View of Voyager from the air.

I planned my recovery trip using the kayak. I practiced paddling an equivalent distance in the Yarra River near to home to ensure that I could complete the journey in Bass Strait.

I needed calm conditions in Bass Strait, with out too much wind or swell, and not too much rain.

I made two trips to launch location, 1.5 hours drive away, but did not proceed because I was not happy about the conditions. 

The third time the conditions were good to proceed, and on 30th July 2024 at around 10am I started paddling.

The trip in the kayak was around 2 hours, and timed for low tide at the destination.

Voyager was found high up on the pebble beach as expected.

The beach consisted of wave washed rocks around 6 inches across. it was difficult to walk on.

Voyager was found in good condition, considering it had been on the rocky beach for over 100 days by now.

The electronic housing was intact, and the electronics were in good condition.

 

She had been on the beach for 100 days, or 3 1/2 months.

Voyager 2.7 as found after 100 days

Voyager was strapped on to the kayak, and I headed home as quickly as possible, retracing the 4 miles back to Flinders Ocean Beach, another 2 hours.

After recovery, heading home.

What caused the failure ?

At first I thought the failure was due to a mechanical problem with the Wing Sail. 

The Tail section was completely missing, including the stainless steel screws, leaving clean 2mm threaded holes in the carbon fibre tail booms.

The electronics appeared to be in good. 

I powered up the electronics while preparing to rebuild and relaunch Voyager.

But I was surprised to find the main steering servo was not operating, despite appearing to be in good condition.

The servo was disassembled and revealed an obviously burnt-out FET driver transistor.

This is one of the four FET driver transistors that form the H-bridge DC motor driver.

Steering Servo showing the burnt FET Motor Driver.

Further disassembly revealed that the brushes on the DC servo motor had failed.

The brushes each consist of around 4 fingers of brass or bronze.

The image below shows one of the fingers has been displaced and was on the wrong side of the commutator.

This would have shorted-out the motor causing the failure of the FET driver transistor.

Servo Motor with failed brush

I had previously studied the log files on the SD Card, but had not looked carefully at the current consumption.

After reviewing the current consumption, the time of failure of the servo become clear, and is shown in the image below.

the servo failed at around 80,000 seconds into the voyage, or around 22 hours.

Plot of Current versus time showing failure near 80,000seconds.

The failure time was reviewed against the track taken by Voyager, and is shown in the image below.

More detailed review of the logs around this time showed, the vessel lost steerage and its heading appeared uncontrolled from the time onwards. 
It was quite a coincidence that the wind was running almost directly down the desired course.

This continued for around 4 hours, until the wind changed direction and blew the vessel toward land.

Actual steering servo failure time 

The servo had failed prematurely. 

It was a Hitec HS-322HD.

Previous servo endurance testing had yielded around 4 million operations before failure, due to the failure of  the motor brushes.

This servo failed at around 280,000 operations. well below expectations.

Typical servo usage seems to be around 50,000 movements per day.

Servos will be covered in more detail in a future article.

The plan is to investigate brushless servos that should have a much greater lifespan.