Following the Tay watershed exactly will be possible for the most part, but not always. In the lowland sections, particularly the initial days from Broughty Ferry to the Highland boundary fault, I'll be threading a way through cultivated land, sticking to minor roads and farm tracks, and maybe the odd dismantled railway line. Forestry may get in the way at one or two points as well. The extent to which I have to deviate from the watershed (or not) in these early days will need to be figured out on the ground. Between Forfar and Kirriemuir the A926 follows the watershed almost perfectly for around three miles. I'm not sure I want to be faithful to this section though. Tramping along a pavement-free 'A' road doesn't appeal, especially when there are options to follow minor roads slightly north, and a combination of roads, tracks and a dismantled railway to the south. The success of the venture depends on it being enjoyable, after all.
There's one place where I may well have no choice but to leave the watershed completely. Between Glen Artney and the River Knaik headwaters near Comrie there's a firing range covering several square kilometres of undistinguished peaty hill country - highest point Ben Clach (533m). Accounts exist on t'internet of people walking these hills so it depends whether I get lucky on the day and the red flags aren't flying.
Whether these count as potential obstacles or not is unclear, but there are also two large windfarms right on the watershed: the monster Braes of Doune site, situated next door to the south west of the aforementioned firing range; and on the Ochils hilltops to the north of Glen Devon, roughly a couple of days' walk further on.
Windfarms are a huge source of controversy in Scotland at the moment as they intrude further and further into wild country - arguably Scotland's greatest asset. This picture of the Braes of Doune windfarm taken from Stirling gives an idea of the impact these turbines have on the landscape. It's not just the turbines though: there are also miles of access roads and pylons to be constructed.
The Ochils - hills close to where I grew up and therefore close to my heart - are under great threat from windfarms, as this summary from the Friends of the Ochils describes. Windfarm developers seem to be targeting the humble, unfashionable Ochils. Perhaps the reasoning is that it's easier to get away with there than in the renowned Highlands.
Even a single turbine can dramatically alter the landscape. Near my parent's house in Dunfermline a lone turbine was erected to local controversy, and dominates the view from the south over the town like nothing else.
Returning to the two windfarms en route, I expect I'll be able to walk through them, but I don't relish the prospect. I remember seeing wind turbines for the first time many years ago somewhere near the M6 in Cumbria. They looked fantastical and futuristic then; nowadays the novelty has worn off.