Hole saw size for bulkheads.

1/2" bulkhead needs a 1 1/8" hole using a 30mm diamond coated hole saw

3/4" bulkhead needs a 1 1/2" hole using a 40mm diamond coated hole saw

1" bulkhead needs a 1 3/4" hole using a 45mm diamond coated hole saw

1.5" bulkhead needs a 2 1/2" hole using a 65mm diamond coated hole saw

2" bulkhead needs a 3" hole using a 75mm diamond coated hole saw