Opinions on sealant for through hulls

thanks for all the help folks. I borrowed a angle drill with a 40 or 60 grit sandpaper attachment. It was a bitty little thing but I felt more confident that I wouildn't grind away more than I wanted to with it. I think I have cleaned up the areas for the backing blocks, but I'm going back for round two to make sure all is dewaxed and properly sanded (including backing blocks).

In going over all this I had a few (hopefully the last) very basic questions. Just making sure that I "get it" and hoping that some future newb can be spared of asking such questions lol.

1. When you dry fit are you putting things together as tight as they would be when you put them in for good? As with the seacock to pipe fitting. I'm guessing the answer is yes so you know where handles and fittings are pointed. I've one one T-H set up that is a flange to a 45 elbow to a ball joint to a 90.
2. Related to the first question, once the backing block is in and cured, I'm assuming you install the seacock and any fittings assembled as one unit otherwise you risk damaging the seal that will be at the through hull to outside of the hull interface. Right?
3. I understand that the T-H to seacock flange is gooped up with ones adhesive of choice. But did you use teflon tape or pipe dope for the NPS threads? And which do you prefer?

Thanks.

is this really a bronze fitting?

An update and a question. I've got the 4 through hulls dry-fitted and ready to install tomorrow if the weather holds. I must say that in my case at least the term "dry-fitting" belies the actual pain in the rear the process can be. Took me several hours up and down the ladder, dremeling the hole ever so carefully. But I think I have it ready to go.

I seem to recall somewhere on this site a discussion about some products being pitched as bronze when they really weren't. I have two pipe to hose fittings for my raw water intake. The apollo brand bronze fitting says bronze but looks more brass like, shiny and smooth. BUT the fitting looks to be full flow given the aperture, which makes a difference since it's a 1/2" fitting. The groco 1/2" fitting is definitely bronze like all my other new fittings, but the aperture is not a wide open (standard flow?).

Question, is the apollo bronze fitting worth trusting and getting that wider opening? Could they really be selling a brass fitting as bronze? (selling me a 6 for a 9 as they say )
Thanks, Jay

Jay,

Apollo makes brass fittings as well as bronze. The one you have looks/sounds like mis-labeled brass. There are a lot of alloys of brass. Red brass is considered a bronze and I have used red brass fittings in my raw water feed to the engine. Since you have gone to the trouble of using all bronze seacocks, thru hulls, etc., I would NOT use the brass fitting. My reading (Goggle: alloys of brass) tells me that "bad" brass alloys (for seawater) have more zinc (Yellow brass = 35% zinc, Red brass = 5% zinc). Since bronze can suffer from de-zincification, brass is probably worse because it has more zinc.

Generally, people are going to 3/4 inch seawater intakes which avoids the fitting ID problem. If your engine ran cool enough before with the current 1/2 inch intake it should be fine with the slightly reduced fitting.

Mark