I have a canvass hatch canopy and sail cover that are fading to a very light blue however the material is still in good nick. Has anyone any experience in redying canvass or is it a replacement job?
Depends what type of fabric it is, Canvas to the purist will be made from natural cotton. The fabrics of today that are called "canvas" are more likely to be acrylic. That said you can get brushable dyes that incorperate a waterproofer from some outlets. Probably easiest to do this off the boat wearing rubber gloves as once the stuff gets on something it stays!
Theres a company that makes a dye for car hoods, made of "canvas" very good it is aswell, used it on my e type, try a classic car mag, or car accesory type place.