keel winch

I recently replaced the keel cable and winch on a 21 San Juan. When I purchased it the window was open and left exposed. Does anyone have experience in repairing this? Hoping to get recommendations of how to properly seal it and what thickness of plexiglass, ect to use. This first time sailboat...

So from other previous posting, you may know that I am replacing the keel cable, brass pivot ball, and keel tunnel hose....excited to get the new parts installed and maybe sailing this weekend...my new question is do I need to upgrade to the large keel winch drum from CD to avoid problems with...