To tape or not to tape, a variation on a theme.
Loren and all, I too have that same fitting and would advise not to try to loosen or remove it if you ever plan to use it again. Once that nut below the bottom of the box is loosened, I see no way short of cutting a 4" or so hole in the adjacent plywood bulkhead of ever getting it retightened. After finally winning the battle with refrigeration aboard our boat for the last 16 years, we now have an extremely reliable system that draws close to half or a third of the amperage of the old one, 6 amps vs. 2 to 3 amps, but we still want to have the capability of using block ice in the future if needed. I fashioned an insulated plug out of a combination of vinyl tubing and other available materials that fits snuggly into the drain. The tube is filled with cork and topped off with a 5/16" stainless bolt with fender washer. It's a press fit with the washer acting as a knob of sorts for something substantial to grab on to when/if removing the insulating plug. It all sounds complicated but was simple to make, the most time taken up in shaping the cork and enough of it to fit into the vinyl tube which is about 4" to 5" as I recall. Glyn Judson, E31 hull #55, Marina del Rey, CA