When the day came that the roof was weatherproof enough, and the paint cured sufficiently, the usual self doubts arose about the difficulty of moving the roof, of whether it would fit- having been built remotely from the boat, whether it would make a difference to the comfort and shelter on the boat, and whether it would make the boat look worse rather than better.
Julia and I and a great pair of friends carried the roof from the ute, along the bush track to the jetty and lifted it on just as I had hoped we would. It slipped straight onto the notches provided and the temporary posts clamped to the coaming made it pretty level at their prepared height.
Despite drawing various positions and angles for the posts, it has been easy to find the preferred alternatives by clamping timber as below. It remains now to fix everything down, and harmonise the edges and transitions so that the structure looks to be part of the boat, not just an afterthought. This will also involve re-forming the cabin rear side edges (to an angle that echoes the angle of the windscreen).
In the hot afternoon sun it was pleasant to sit under the new roof, the four of us having a quiet beer.