Raymarine ST290 got a black spot!!

With sun cover on, bimini & speayhood + sun covers for the whole deck.
so not getting any sun at all.
 
It's an age thing! The polarization film on the front of the instrument is failing. You can buy new film and fit it yourself but it's a complicated and fiddly process. Some firms will do it for you (if it's possible), otherwise...…..buy new instruments! I've had instruments and VHF radio do exactly the same, even though they are inside at the chart table.
 
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