I'll be replacing one of my port lights and would like some advice on the best way to seal it. The instructions just say to use a sealant but doesn't specify anything in particular. I've read a number of bloggers who are quite vocal about not using any silicone sealant. 4200 gets a lot of votes. I'm a big fan of using butyl tape for deck fittings and was wondering if it's just as applicable for doing the port light. Thoughts?