I'm on my 13th boat. Have installed from the outside on over half, including the last 5. Use screw type and tighten real good. I have bad wrist's and arthritis in my fingers. I made a little pvc jig to help me tighten the plug. Gonna put on a pic of the type plug I use and a couple pics of the jig I made. Hope this helps. Also carry a spare plug in the boat.