Mac....I hesitate here as I've no wish to offend anybody...
There's been a fair whack of discussion on "ports, portholes, scuttles" , or whatever your preferred term for them is.
A simple search (on this forum) should bring it all up.
But (always a "but"...if, when fitted, they are meant to represent opening ports please put the flange on the inside of the hull/bulkhead. That's because the various hinges etc. are part of the flange...and ports tend not to open outwards. If they are to be fitted to a wooden structure then having an exterior flange is acceptable.....that's because the outer (visible) flange is, in all probability a "false" flange, fitted to prevent the mounting studs digging into the wooden structure. If they are non-openable (as on a RN Picket boat) they can be fitted with the flange "outboard.
Sorry if I'm teaching you to "suck eggs"1 BY.