[Driftwood]

Early in the war most sub skippers ( a lot of whom got relieved) followed standard peacetime doctrine for US Subs, meaning you submerged all day and only surfaced at night to recharge batteries. All attacks were conducted submerged and even sound attacks (IIRC) were in the peacetime "tool kit" of sub commanders althought they were HIGHLY ineffective. Prior to hostilities breaking out Naval doctrine for submarine employment was primarily scouting for the surface fleet. It wasn't until the Silent Service became the only offensive naval capability available (post Pearl Harbor) that their role as a major offensive weapon began to be explored. And even then the different views of the major Sub Commands (Adm's Lockwood at Pearl and Christie in Australia) varied greatly on how best to employ our submarine force. So, in answer to your question, as the war progressed your more famous sub skippers (Morton, Dealey, O'Kane, Fluckey, Street, etc.) stayed on the surface (both day and night) to find their targets and then dove (during daylight) once in postion to attack. They stayed on the surface at night for attacks. As always tactics are driven by the situation at hand.