All hatches leak eventually. To fix a leak, you first have to find the source of the leak. You might immediately assume that the gasket around the lid is the source of the problem and very often it is. It might also be a failing oring or gasket on the handle, or aging caulk around the hatch base or the lens.
Before you think about repairing an old hatch, check it thoroughly to make sure that it can be repaired. If it is bent or the frame is too badly damaged, no amount of sealant or gasket material is going to suffice, and you will need to replace the hatch if you want to remain dry below.
If the problem is the lid gasket, we can help you to find the correct gasket if you know the model of the hatch. If you don’t know or can’t identify it with our help, you may need to remove a small piece of it to see what shape the groove is. The gasket material can be round, half round, square, rectangular, or it could be an extruded shape made for only that model of hatch. You will need to clean the groove with either an adhesive remover or acetone before replacing the gasket. The new gasket should be glued in place with contact cement that is made for gasket material. Make sure that you have an adequate length of gasket material. It’s better to have too much than not enough, because you want to end up with only one joint.
If the handles are leaking, you will have to take the handle off and if possible, remove the oring intact. If it doesn’t come out in one piece or you are not able to bring it into the store to match it, you can measure the groove width and inside and outside diameter of the groove to identify the correct size o ring.
If the caulking around the base has deteriorated, you will need to remove the entire hatch, clean off the old caulk, and rebed it. This will be more or less difficult depending on how it was originally fastened and sealed. Choosing the right sealant for rebedding your hatch is very important. Pay very careful attention to the sealant manufacturer’s recommendations for the ideal sealant for the materials being sealed, and always use marine sealants. There are nonmarine sealants that can actually damage the metal on your hatch. Using the appropriate primer for the caulk will help it to bond and increase the life of your repair.
Replacing the lens or recaulking around an old lens is not particularly difficult, but it is time consuming and should be done carefully. Once the lens is removed from the frame, the groove needs to be cleaned. There are a number of products that will break the bond of the sealant without making a big mess. You can also use adhesive cleaners or acetone, but don’t use solvents directly on the lens as they may damage the plastic. You can sand the groove lightly if needed, and use the appropriate caulking primer before you caulk. When bedding the lens, you will also need to be careful to use the correct sealant. Polysulfide sealants will damage the plasticizers in the lens and cause crazing. Masking off the lens and the frame before caulking will save you a lot of aggravation and time cleaning up.