Hi Barry,

I would not worry too much about the size difference. Do make sure you are looking at the medium size profile series as opposed to the Ocean series and the low-profile series.

Word of advice; also order new hinge pins as you are likely forced to break the existing ones out when removing the hatch. Lewmar did not put anti-seize paste on the hinge-pins (stainless pin in alloy hole). Also the small grub-screws holding the two halves of the frame together may prove a pig to remove. When replacing the lens most definitely also replace the seal that holds the lens, you will get leaks otherwise.
I had all the hatches done last year, but did not require new lenses. Only the seals were replace because of leakage.

Regards,

Arno Luijten
SV Luna,
A54-121