Tracing the Tribe discovered the blog of the Jewish Maritime Historical Society, billed as being
"dedicated to Jewish captains, pirates, sailors and all seafaring people."
Unfortunately, it now seems defunct with the most recent post in November 2009. Its posts covered personalities, historical events, maritime instruments like astrolabes, archaeological evidence and more. The articles come from major and minor websites and publications.
Posts that Tracing the Tribe found interesting: Jews and Navigation, First Hero of the Portuguese Discoveries and Jewish Traders of the Diaspora. In these days, when immigration issues are part of the conversation, read Aaron Lopez's Struggle for Citizenship. For parts farther afield, there's an article on the Jews of Cochin.
If this area of Jewish history interests you, or if you had ancestors who sailed the seven seas, take a look.