I seem to have come to a sticking point with my latest novel. The central character is from West Africa in the 19th century who has learned to speak English over a number of years from a visiting trader. In the story he embarks on a voyage that takes him to the Mediterranean and Morocco and he also meets a Spanish and a Greek person. My problem is that the dialogue, for obvious reasons, is in English, so that the reader understands what's being said. My problem is credibility, that is it would be very unlikely that everyone he meets can speak English. Obviously my character can't just have a translator pop up at the right time any more than he could drag one around with him. Writing in the foreign language and translating after would not be an option either as the character isn't going to understand it anyway and the reader would just skip through anything they can't decipher.
So, do I just completely ignore this and write the whole thing in English? To me this just makes the story implausible. My book is finished but I still need to address this little conundrum of plausibility. Anyone else had this problem? Any help or advice gratefully received.