Mandela is/was well known today as the leader of the ANC who overcame decades of imprisonment to become the head of South Africa and an important world leader. Most know him because of the struggle of all colored people (not my term) and imposed by the Dutch Afrikaaner controled South African government as a result of apartheid.
What's not well known is that he was caught with lots of explosive devices, ordered lots of bombings himself, married a person who did some of the most heinous things committed by the ANC, was a Communist but wouldn't publicly admit it in his written biography though a leaked and authenticated biography admits this, and would never condemn the terrorist actions committed by the ANC. He also purchased enormous amounts of armaments after becoming a leader in his country.
Do some checking as to the state of South Africa today especially regarding the number of murders. It's appalling. Apatheid was horrifically bad and affected folks who were Asian and Indian as well as African or combinations of those things even in the most miniscule amounts. But all of that has to be measured within an honest appraisal of history and seeing Mandela for who he was completely.
There's nothing wrong with your art. It's creative and beautiful. But naming a diplomatic ship the Nelson Mandela is rather like naming a diplomatic ship the Ariel Sharon. It would be as controversial.
Desmond Tutu would be entirely appropriate, an almost saintly man, known for trying valiently to end apartheid, respected by almost everyone, etc.