I could not rest easy with the roof. In fact I am getting a bit anal about the sides being the same angle (lean in) to each other. I had to put quite a bit of pressure on with ratchet straps to get it on square. This resulted in the sides going out AGAIN! Eventually I had to put so much tension on the inside to try and bring them true to each other with the 8 ratchet straps that one of the 1" tack welds on the rear sheet tore away. I was inside at the time and the bang was horrendous.
So today I cut all the tack welds off and repositioned the roof sheets again this time with the sides trued and held in place with the ratchet straps so there was no tension needed in the roof sheets.
Out came my small portable arc set for this job as the big MIG set is now inside the shell. This little set cost me £35 on an Aldi special and has come in handy so many times on my other NB. It hasn't got a very good duty cycle so is only good for "little jobs".
I am much happier now :-) I'd like to think we'll have the straightest, truest boat on the cut.