Waiting for a narrowboat at Parkend swing bridge

I've been trying to establish when the traditional Thames sailing barge 'Gladys' will sail down this canal from Gloucester en route for the open sea in the Bristol channel. Now I know it will be tomorrow afternoon, I thought I'd drive around looking for good vantage points to film it.

The boat has spent nearly a year being renovated in the dry dock at T. Neilsen's, the renowned ship builders in the Gloucester docks. The journey along this canal from there to the sea at Sharpness will take about four hours, and it is likely to moor up overnight at Purton, beside the Severn estuary before entering the sea lock on Wednesday morning at the high tide. 

I'm hoping to photograph it but I'm not yet exactly sure where or when. I'd love to see it with its sails up heading out to sea, as I watched very similar Thames sailing barges when I was a young child on the Thames estuary. Here's hoping.