While walking to my work and thinking of building the boat, I suddenly realised I forgot to put the compression strut into float no. 2. Pffff glad I thought of it in time (before laminating the exterior). I'd rather not think about what could have happened if I'd never noticed my mistake.
It was not much work to set my failure right: make a hole, put in the strut, glue a flange and put back the cut-away deck.
Lesson Learned: don't rush things. I try to keep pace building while having a full time job and a family with two small children. That means I can only build small periods of time in between all sorts of other work and household things. It makes it a bit more difficult to keep track. In the future I'll have to stay more focussed.