If you google images LCVP you should come up with some line drawings of LCVPs.
There are also some in this book on LCVP and LCM handling at the USNHC Online Library
http://history.navy.mil/library/online/surfskill.htm
Your best bet for pictured of the davits on APDs will be in the Warship Perspectives book on the Flush Deck destroyers. There are several full-page photos taken of the length of an APD conversion (Mare Island kept wonderful photo records of their work). The gravity-type davits show well.
There is another line drawing of the davits in a Naval Systems Technical Manual (NTSM) on small boats. It is in a huge PDF document which I snatched off a naval site a while back. Try googling NSTM Small Boat and see what you get