DIY replacing boat windshieldsLeaky boat windows? Cracked glass? It could cost you a chunk of your emergency savings if you bring it to professionals. 

Nowadays, many boat owners choose to deal with their damaged boat windshield by themselves using more affordable materials such as Lexan glass and plexiglass. However, not all DIY-ers could do it excellently. It’s not that they don’t have enough ability but mostly due to unfamiliarity and misinformation. Before going to a tough battle with your damaged boat window, it is important to arm yourself with enough knowledge. Here are some things you should and shouldn’t do in replacing boat windshields


  • Make proper and accurate measurements of your window.  Whether you need a fixed or sliding boat window, knowing the specs of your window is a crucial process. Not just the glass size though, you should also measure the thickness of the window and panel to find a seal with the correct fit.
  • Thoroughly clean old sealant residues. Any old sealant residue may affect the quality of the new seal. Before replacing your boat windows, scrape up the surfaces and rub away the residue with paint thinner. Meanwhile, use abrasives such as sandpaper if the surface has corrosion. 
  • Make the holes substantially over-sized. To prevent the glass surface cracking, the holes should be larger than the normal requirements. For example, when using a 1/4″ size screw or fastener, the hole should be 7/16.”
  • Choose the right seal for the material. Lexan glass and Plexiglas are relatively harder to seal than tempered glass. For example, if you use polyurethane sealants, the outgassing of the plastic will affect the seal, and your windows will not only leak, it would be very difficult to take apart. Sealants containing solvents are also detrimental to Plexiglas. Ask a trusted marine supplies store for the right sealant.


  • Apply new sealant while the surface is wet. As you clean the surfaces on the window frame, make sure all surface dries out completely, or else the sealant won’t hold properly
  • Countersink screws into the holes. Too tight or countersunk screws would cause cracks. The heads of the screws should rest flush on the surface of the plastic or cushion the screws with a rubber washer.  
  • Make the sealant too loose. Apply the sealant generously. Run a continuous bead along the surfaces that make contact with your boat window. It would be better to use too much than inadequate sealant.
  • Squeeze in the excess sealant. While putting a generous layer of sealant in between the surfaces, the excess should be scraped away as you level the sealant. Don’t squeeze it in, or else, your window will crack sooner or later. The seal shouldn’t be too tight to accommodate the material’s expansion and flexing.


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Boat windshield replacement can be a very daunting task, yes. But if you have the proper understanding of how to do it, it can also be a very fun and rewarding experience. Since you have decided to do it—you should at least do it right—or else it would just be a waste of your time and materials.  Interested to know the best boat dock accessories and boat window parts? Visit our blog.