Re: Drilling A 5/8" Hole In The Hull?
Use a spade bit. You only need one hole, they are cheap. They don't self feed like a twist drill, so it won't tear a big ugly hole. The point comes through well ahead of the cutting edge, so you can finish from the other side if you want and get an absolutely clean hole.
If you HAVE to use a twist drill. Do NOT drill a smaller pilot hole, that will guarantee a rip out when it grabs. Remove the rake from the drill bit, using a diamond file or stone. Hold the bit horizontal with your right hand and the point away from you. Rotate until the cutting edge on the left is also horizontal. Hold the stone or diamond file horizontal and stroke it towards you on the cutting edge until you create a small flat. Rotate the bit to the other edge and repeat. Now you have drill bit that works excellent in all plastics, copper, and soft aluminum.
Gary H. Lucas