Diamond Bit size for 1.5" bulkhead

[Reefhawk1]

Hi all

Just wondering what size of diamond bit I would need for a 1.5" Bulkhead. With a measuring tape it is pretty close to 2.25 inches but I would like to be exact. Unfortunatly I dont have a measuring caliper at home

Also If I drilled this hole a little bigger than 2.25" or 57.15mm for you metric folks would a 60mm 2.36" hole work?


Thanks

[vanreefer]

just drilled.. a 2 3/8" hole is required... but I don't think there is a 2 3/8" holesaw... so I got 2 1/2"