I had 3 narrowboats, did that for 12 yrs or so. Then a gap of some years, house kids etc. Then 15 years ago fitted out a 10metre x 3.4 metre tug and have kept it on the European canals, (Also travelled the Thames, Severn, GU to nearly Braunston, Warks. Avon,bristol Avon and River Wey) Have since travelled many miles in Europe and i reckon that is probably the best way to do it - Not the only way by any means, I did wonder about a small fishing boat at one time with rudimentary accomodation and also a Wilderness Beaver or similar but the compromises between narrowboat and sea going are very difficult. Also looked out of the window of my narrowboat near Warwick once to see Shane Acton and Shrimpy going by (look it up on Google) - buy the book if you can find it, it is inspirational.