Eric ferret - the problem is that no one has tried, despite the push for SAR aircraft around the world. It is not rocket science, you just need to start from the concept of a rear crew work place and a stable hover platform - then you add the bells and whistles. A Wessex with modern blades and engines would still give you 140 Kts and a brilliant winching platform - add decent avionics and glass cockpit and you are most of the way there - a modern version of the Sea King would be pretty splendid!
Sadly the model that is currently fashionable (apart from the S-92 which would be great if the MRGB was redesigned) is one of corporate cockpit and cabin design which is 'reimagined' as a SAR aircraft and it doesn't work!