About the boat
Principia is a Beneteau First 25.7 sailing boat. They're built for racing more than cruising. Light and fast. Not ideal for my purposes, but she's all I've got and I'll make the most of her. She has a lift keel and so can take the ground easily as well as navigate shallow waters (down to 1 meter depth). I think this will be a considerable advantage as I will be making relatively short hops and many harbours either dry out or have very shallow depths. She has a 14HP inboard auxiliary engine which pushes her along at a stately 5 knots. She sails very well in light winds and in any kind of favourable wind will cruise comfortably at 6 knots. But for passage planning I have learned that 4 knots average speed is a safe estimate.