This launch failed.
Primarily because, the weather conditions did not provide enough of an off-shore breeze for the boat sail away from shore.
The boat was damaged by breaking waves.
This provided guidance on changes in the design and construction of the boat.
The damage incurred was that the Aluminium Fin bent 90 degrees when the boat was caught in a breaking wave.
What was Learnt ?
The Fin bent so easily, that is fortunate that the launch failed. If the boat had successfully sailed offshore, the fin would have bent in the first storm, leaving the boat lying on its side in the water. In this condition, the SOPT GPS satellite tracking facility would not have worked very well, the boat would have been effectively lost.
The Wind Vane rotated on the shaft when the boat was engulfed by the breaking wave. This is equivalent to changing the course setting of the Vane Steering gear. Hence if a reliable sailing course is to be maintained, steps must be taken to prevent the Wind Vane from rotating on the shaft.
What changes were made ?
The fin was strong enough to support a static load, but bent easily under the dynamic load of a breaking wave.
The fin was reduced in length to about half the original length.
The Wind Vane mounting arrangements were initially fabricated in 3D printed ABS plastic.
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| Version 1 - Almost Fully 3D Printed Vane Steering Gear |
The 3D printed plastic bosses had threads cut for the 5/32" set screws that were intended to lock the bosses on to the brass shaft.
These worked ok, and could resist quite high static torque loads, but in the conditions experienced with a breaking wave, they easily slipped from the set position.
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| Version 2 - More Metal Components added |
The second version, included threaded metal components. This allowed much torques to be applied to the set screws to resist slipping.
Second Launch Attempt February 15 2016 - Woodside Beach, VIC
This launch was partly successful.
The boat sailed well in a light offshore breeze, and launch appeared successful.
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| An Apparently Successful Launch at Woodside Beach |
The first satellite signal was received after about 20 minutes when the boat was about 1 kilometre offshore. But 4 hours later the next signal showed the boat was on the beach several miles up the coast.
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| Satellite Position Signals showing the Launch from Woodside Beach and then running ashore several miles up the Beach. |
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| Washed up on the Beach like a dead Sea Gull |
The boat was retrieved for reworking in preparation for the next attempt.
What Went Wrong ?
My assessment of the weather was wrong. I had assumed the offshore breeze would continue for a much longer period and get the boat further offshore into the prevailing breeze.
But instead, it end up back on the beach.
What was Learnt ?
The weather predictions must not be marginal in any way. If there is any uncertainty, then its best not to launch.
There was some damage when boat came ashore. The polycarbonate Wind Vane was broken, the brass Wind Vane shaft was slightly bent, and the Wind Vane bronze bearing was dislodged from its housing.
What changes were made ?
The vertical shaft for Vane was changed from brass to stainless steel. This was done because of concerns about the brass shaft bending. Stainless steel is almost double the hardness of brass. Hence the replacement stainless steel shaft is much more resistant to bending.
The Wind Vane was made using 2mm polycarbonate sheet. This was broken during the beaching. It was replaced with 1mm carbon fibre sheet. This is considerably stronger and also about 60% of the mass of the polycarbonate sheet.
The weight reduction of the Wind Vane required a rebalancing of the vane assembly, and hence their was a corresponding reduction in the lead counterweight.
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