Hi Nigel, I have just finished building a Sparrow from the book and plans, and like you it was my first attempt at building just from plans. I have done some things a bit differently from the plans though. I just have to play around with the keel bulb weight until I am happy with it, 1.3 kg seems a lot to me, the boat sits very low in the water. I have a Robbe Sirius which is a bit bigger and this boat has a lead bulb weighing 1kg, so I am a bit confused at the mo'.
Cheers, Terry