Yeah that's what I thought because it blistered after being taken from a cold outdoor workshop and put into a warm car. We will just have to sand it and paint again.
On second thoughts I think it looks OK and I'll leave it; after all I'm not trying to win the America's Cup. Thanks everyone for your comments and advice; you have been very helpful. I hope this thread will be helpful to anyone else thinking about making a rudder for a small boat.
You're right, it doesn't look that bad and in a few years when the need arises you can give the blade a quick sand and repaint it for a mirror finish.
I notice that the bolts going through the fittings are too short to engage the nylon on the nyloc nuts, I suggest either using longer bolts or a couple of drops of threadlock. Otherwise you could find yourself in a situation where all your good work will come to naught.
Hadn't noticed that. They are the original bolts but I'll put some lock tight on them or buy longer bolts.