I am crew aboard a private vessel and my usa b1/b2 visa expires in 1 month. Where can I get this renewed without going back to my country of residence?

Holders of B1/B2 cannot work in US. If you work for company as crew, your employer must apply for C, D or C-1/D.

You should check the US consulate in the countries for you next port of call and see if they accept third country national (TCN) applications.