If you measure across the outside of the acrylic from the inside edge of the metal frame on one side to the inside edge of the frame opposite, if you have a Bavaria/Lewmar standard hatch for that year, your measurement should be 500mm x 500mm for length and width. If yours is exactly that size, then the Lewmar part number will be A300819002582 (not too sure if that last 8 is a 6 or a G).
Ocean Chandlery in the UK are advertising replacement acrylic for their Bavaria Large hatch which corresponds to the one I’ve referred to above and their article number is 361248990 which further confuses the matter. However if you buy from them, you will get a new replacement seal rubber included, but you have to re-use your existing handles and hinges. (Note, don’t get confused in regard to the catches and hinges used on the portlights where those are glued on).
In the USA there are yacht chandlers who do sell Bavaria sized Lewmar hatch and portlight acrylics, because I did check them out before writing the article referred to in my earlier posting, but unfortunately I didn’t make a note of who they were. Sorry, to those of you on that side of the pond, but you’ll have to do that research yourselves. The Lewmar replacements were significantly cheaper in the USA than they are over here where a hatch replacement acrylic is currently for sale at around £206, and then there would be postage and import taxes, though you might be able to buy it without paying our 20% VAT.
Using your existing hatch acrylic as a template I’m sure you could at least halve that price by taking it to a plastics manufacturing firm as I did. But you would have to cover the gaping hole in your cabin top while they made it !!