New York harbor

[U-84]

hello, I have been playing Silent Hunter III recently, and from a short amount of time i started as a really nooby U-boat commander to a decent beginner..anyways, long story short, im in may 1941 in career mode, and was wondering if i go into New York harbor will there be any ships to sink, and is it worth sneaking into, cause i tried once to sneak in portsmouth, only to sneak past 3 destroyers, and 2 trawlers, and finding only 1 merchant in the harbor... which sucked, lol, then began a long trech out of there, sinking 1 destroyer...anyways, just wanted to know if it were worth sneaking into New York harbor and if there will be any ships there, as it seems sometimes there are alot of ships in a harbor and sometimes there are none, any advice would be great, thanks. also any other places to sink many ships on the map would be appreciated thanks.