I am hoping to finish the work I want to do to the roof before I lift it onto the boat. Part of what I want to do is to add another layer of core to the cockpit overhang to stiffen it so that it wont flex much if I walk out onto it. The added thickness will also help with the fitting of the sunroofs, the roof is curved but the sunroofs must be mounted flat so the extra thickness will help to bury the flat roof into the roof minimising the amount I have to build the sides back to flat.
I also intend to fit a rim around the roof edge made of pvc pipe. When glassed on it will also help to stiffen the roof but it has 2 other purposes. The round edge makes for a better grip and the raised rim will stop water dripping into the cockpit randomly when it rains, it will pool at the low points each side and then overflow more predicably (makes it easier to avoid it dripping where I don’t want it to) or I may decide to actually drain the roof through a deliberate drain point (unlikely).
I have experimented with a piece of pvc pipe. I have one very tight radius curve (the outside back corners) the rest of the curves are very gentle and not too difficult to get the pipe around. At the tight radius curves I will have trouble getting the pipe not to bulge at the bends (kerfs) but this is not too big a problem. Once glued on and a layer of glass on I can grind down the bulges and re-glass the section before bogging it all and fairing the curve. There is only the 2 curves (meaning 4 bulges) and only about 400mm of nearly 6000mm of roof edge. I will have to be more careful cutting the slot in the pipe over long lengths, it is difficult not to get twist in the pipe. I will also cut the pipe just before the corners and only kerf small sections as it goes around the corners and just join the pipe 100mm or so either side of the corners.
I have also marked out the roof shaping and will cut it tomorrow. I will be gluing the extra core layer on Saturday and perhaps also gluing the pvc pipe on. Just inside the pvc pipe on the underside of the roof will be an LED rope light and I will need to fit that at some point or at least make provision for the wiring and fitting. I have also marked the position of the sunroofs, but I am not sure I will cut them into the roof before lifting it onto the boat.