Opening portlight in perspex window

Sea Change

Active member
13 Feb 2014
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In an effort to improve ventilation, I'd like to add an opening portlight in our large perspex saloon windows.
Is there any particular type of hatch I should be looking for? The perspex is about 5mm thick.
The window is only 23cm high and I will need to leave enough perspex around the opening for strength, so I suppose the hatch will need a fairly neat surround in order to leave a meaningful opening.