I'm planning to visit Dalian , shanghai ,Beijing between 5 jun and 15 jun

I'm afraid the boat across the sea would be impossible. As I know, the boat between SH city and Dalian has stopped operating. Anyway, as for your trip, here is my suggestion about the transport and direction:
From Dalian to Beijing, it is suggested to take a direct plane, whose price varies from time to time. During your travel duration, the airtickets may have some discounts. By air, you can reach Beijing in about 1 hour and 20min.

Then from Beijing to SH city, the high-speed train between can take you to reach within around 5h.