how do you change the oil on a 1977 carver santa cruz

making the assumption gas engines and you cannot get to the drain plug on the oil pan then most people use a vacuum pump and suck it out through the oil dipstick. many different kinds of pumps but heres one for your knowledge, they all work the same so it doenst matter what you get just suck out as much as you can. some you have to insert a small tube down the dipstick tube and others you can attach to the top of the dipstick tube and suck it from there to get most of the oil out. you wont get it all but get the most out you can. move tube around etc.
on my vacuum pump tank (its larger than the one shown) when i got it and before i used it i marked the outside with a line at each quart (by filling it up with quart of water and then making a mark) on the outside so i would know how much oil i did get out of the engine, you dont have to do this i liked knowing, once you use yours you can decide on that. anyways heres a link to what i am talking about

http://www.pbsboatstore.com/Attwood...ntEqfCfVsDKr4pkXcYZ961pvyvv01SxJnjBoCWzXw_wcB