Normal wet winching height for the Whirlwind was 15ft (interesting in a heavy swell!), whilst for the Wessex 25ft, although that crept up a bit in later years, whilst for the Sea King I think they needed oxygen. Fot the Chinook we started at 50ft, but even then the downwash on the water was quite horrendous so we ended up higher still.
In FEAF they developed a type of double cable (I can't remember the name but I'm sure someone else will) to extend the usable cable length so as to get survivors out from under the jungle canopy. If you can find the original (c 1970) RAF Jungle Survival film it can be seen in use with yours truly being 'rescued' - which I believe was one of the very few times it was used for live winching.