When using a hole saw, you drill from one side and the pilot drill penetrates the other side. Then switch sides, and drill from the. opposite side. That way you won't splinter the fibreglass. -----Original Message----- From: montgomery_boats@mailman.xmission.com To: montgomery_boats <montgomery_boats@mailman.xmission.com> Sent: Sun, Jun 15, 2014 4:54 pm Subject: M_Boats: Thru-Hull drilling Hi, I need to add another through hull fitting to my M17 for a new bilge pump hose exit. I need to drill a 1" hole for my 3/4" fitting. I have a 1" wood drill bit but I'm afraid it will not make a clean cut. I looked in Home Depot and seen a 1" bit similar to a bit that you would use to drill out a door handle but the teeth were not close together so again I think it will cause some chipping. Can anyone confirm my doubts or suggest a type of bit to use.. Thanks, Ron McNeil M17/Jackpot/#675