My Dad filled up in Guernsey a few weeks back at about 60p/L for marine diesel... He was balking at the price as in 2003 he was paying 20 something pence... not funny when your capacity is 3,800 litres!
They have blue marine unleaded in Guernsey now too. Since they have scrapped road tax they have put the tax on fuel instead which makes more sense as what you pay is directly proportional to what you use... unlike over here where (if the government have their way) I will be paying £400 per year road tax for a car that only does 2,000 miles per year and hence produces less annual CO2 than most of the cars on the road!
Anyway... this extra tax obviously wasn't fair for boat users, so they now have concessionary petrol for marine use which is dyed blue!