①She says the boat would be shaped like a capsule, powered by a small nuclear engine, and ②though there would be no sail, it would have a mast to hold a camera.

and连接的是①和②。其中的②后面也是一个复合句：it would have a mast to hold a camera是主句，though there would be no sail是让步状语从句。第三小句的句首不能再用连接词and。