Hi- I am adding a vang to my 1976 Mariner. It does not have one nor any accomidations to attach one. Therefore, I am drilling (hacking?) away from stratch. I would like some help on placement. How many inches from the mast base is yours? How many inches from the mast along the boom is the other? Is there are certain angle I should try to make? What is your purchase? I am looking at a 3:1 with 3/8" line from WM. About $170. Ouch! Thanks for your response in advance. Regards, Craig