Our simple repair kit includes a dozen O rings to fit your Bomar hatch. That is enough to refit all of the Bomar hatches on Catalinas up to and including the Catalina 42. It also includes a re-sealable tube of a silicone grease suitable for your tool kit. The O rings seal better, last longer, and the dog will turn more freely with the application of a bit of the grease. The O rings should be cleaned, and re-greased every season. The re-sealable container of silicone grease will be handy for other projects aboard as well. Kit is sufficient to rebuild 6 ports.
We offer a similar kit for Lewmar hatches (see below). Be careful! some boats have both Lewmar and Bomar hatches. You may need both kits. We also carry both Lewmar hatch dogs and Bomar hatch dogs if a broken part leaves no other alternative.