A milestone reached today. The last ribs in place and the last deck plank nailed down.
I thought this last section would be plain sailing - rectangular area, and 8' long so most of the planks wouldn't even need cutting to length - but I should know better than to be too cocky. This last bit of decking put up a fight and took me all afternoon.
It started off hopefully enough. Once I'd cut the middle planks around the masts and nailed them in place, I measured the remaining gap across the width. It looked like I'd struck lucky and ended up with an exact multiple of plank widths. Once I started laying them out, though, I realised I had to chisel out notches along the sides to allow the side planks to snug into the ribs, and then I still had to plane 1/8" off two planks (one each side) to squeeze them in.
Planing a strip off an 8' plank isn't difficult, but it is time consuming. Anyway, I finished with a tight fit, which is good because I know from experience that they are likely to shrink a bit over time.