ITS ok im quite accustomed to craft in all shapes and sizes from planes to boats i know my threshold and that of the craft ill be flying ,plus the 3 litre cylinders and regulators which will be stored in the cockpit will give me a extra safety margin in case i flip it which will probably happen at some time !!! from hovercraft to submersible in one foul swoop cant be bad !! dont worry ill learn the hard way or no way . they say there are still fish in the thames maybe ill see one ?