Keep it Simple Stupid has pride of place on any boat, IMHO. It might not always seem so from some of my projects but I do try.
The lenses of most deck hatches will eventually craze in the tropical sun. In an effort to slow the process we tend to cover them with canvas covers. I have never found these to be long lasting (even with sunbrella) or particularly user friendly. Then along came the Outland Brothers;
The little black dots on the top of each are twist lock fasteners which allow easy removal of the covers.
I have no link with the company but I like stuff that does what it says on the tin.