A word about replacing hatch lenses on Lewmar hatches. I did this last year on my Tartan, two Lewmar Ocean hatches. I got a quote for new lenses from Hatchmasters: $439 and $347, plus shipping two ways. That includes the lens, seal, gasket, and o-rings. What you would do is take the hatch lids off, cover the openings with plastic and tape, send the lids to Hatchmasters and wait a few weeks.
Next I checked to see if I could just buy new hatch lids. I found Defender had them. $425 and $324, plus shipping one way ($22.50). This is an entire new hatch lid: frame, lens, latch assemblies, etc. What you do here is swap your hatch lids - took me about 20 minutes to do both. And then get rid of your old hatch lids - sell them, throw them away, whatever.
New hatch lids are cheaper, and infinitely more convenient.