I must replace the coach roof hatch in its entirety. Its somewhere around 24X24. I dont know the manufacturer and I dont care at this stage. My only problem right now will be in removing the old hatch. It is definately an offshore type of hatch. I see screws all around the base of the hatch attaching it to the coach roof. Does anyone know what other surprises that I might expect? I have a 1976 Allied 39 Mistress Ketch Im pretty sure it is the original hatch and is 32 years old. Has anyone here ever done this? Im planning on starting this tomorrow. Tony B