I am an Indian Citizen. Planning to travel to Gibraltar using visa for UK with 6 months validity and multiple entry visa.
After reaching Gibraltar since I love sailing in boat planning to travel in a cargo ship as passenger to South Africa. I will also have the South African visa. From there I would travel back to India.

In the above case I would like to clarify the following:

1. Will I be given exit stamp in UK gibraltar?
2. If not whether I can get the UK exit stamp through some UK Embassy since I travel to South Africa in cargo ship.
3. While entering into South Africa is it enough if I get the immigration entry stamp of South Africa. Does it mean it will be automatically informed to UK immigration?