Rusty
Why not take that yacht somewhere else? A sailing adventure to Cape Town might be fun!
Always remember that the UK rules don't always apply elsewhere. For example, so far I believe the UK is the only country in the world that overtakes on the left while taxying! (There is a separate thread on this in 'Private Flying', unfortunately without many contributors).
In good old South Africa they have a nice sensible low flying rule of not less than 500' above ground or water "....unless the flight can be made without hazard or nuisance to persons or property on the ground or water."