Fastener Question

[JonRiley56]

Hi All,

I am ready to install my stuffing box. It is cast bronze. Can I use stainless steel bolts or is there potential for galvanic reaction ? The boat will be trailered so it wont be "living" in the water.

thanks

jon

[Lopez Mike]

Any particular reason not use bronze fasteners? They are commonly available. That way, if you need to leave the boat in the water for a while some time, you won't have that to worry about.

Stainless is a great material when you want something to look sweet when left out in the weather. It has a lot of drawbacks, though. For one, it is only 'stainless' on the very surface. A layer of chromium oxide forms and is fairly resistant to various sorts of corrosion. But if anything breaks that layer and there is any shortage of oxygen to reform it, it is no different than mild steel. It goes away rapidly. In a crack with relative movement or in oxygen starved water, look out!

I make a habit of keeping stainless steel out of situations where I might worry about it. If I want the look of stainless without worry, I use one of the nickle based alloys like Monel. I would stay with the old standards like bronze. A do make sure some feather merchant doesn't try to sell you brass. The zinc leaves and leaves a cheesy copper lump with no strength. Keep brass out where you can look at it and polish it.

The bottom rudder bearing on my 1971 sailboat looked odd a couple of years ago when I was hauling the boat for new bottom paint. I gave it a whack with a hammer and it flew into fragments! Brass. Everyone in the boatyard got to hear some new words. I have been across oceans with this boat. It could have failed at any time.

I'd stick with bronze. They dig up statues and cannon from hundreds and thousands of years ago made out of bronze and it is still hanging in there.

Mike

[JonRiley56]

Thanks Mike !

Will do. I also need to hang the keel. I am hanging a big piece of mahogany. It is three inches thick and eleven feet long. It will be 10 inches deep at the widest point (at the stern). Threaded bronze rod is very expensive. Can I use galvanized ?

jon

[Lopez Mike]

I have used galvanized fasteners without disaster but I have kept them out of contact with incompatible metals and I have sealed them off from contact with the water.

Can you get bronze rod and thread the ends? How many do you need and how long?

[JonRiley56]

Hey Mike,

I am going to have 5 rods supporting the keel. The longest one will be about 12 to 14 inches long and they will get progressively shorter. I was planning on countersinking the rods up into the keel and paving over the openings with something, maybe 5200. I was going to put a "liberal amount" of 5200 on the keel itself and suckitup against the hull with the threaded rod. I am then going to run a line of glass tape down each side and coat it with West System.
Inside the hull I will have the rods running up through 2x6 pieces that are bedded down in
5200. I will use big fender washers to spread the load out a bit.

Jon


P.s. the bronze bolts for the stuffing box are on order.

[Lopez Mike]

I keep forgetting that this is not a sailboat keel with all of the serious side forces involved. You will get by just fine with hot dipped galvanized rods and nuts.

Fender washers are pretty thin. I think you might be able to find some thicker washers in hot dipped. They are called structural washers. Sometimes they will try to sell you square wedge shaped ones for fitting inside steel channels. You want the thick round ones. Any good fastener supply house will have a source for them. Harder to find them in small though.

Probably the 5200 alone would hold the keel on just fine all by itself! That stuff is death to get loose. I have made the mistake of bedding some deck fittings with it when a simple caulk would have been more than enough. When I went to remove a cleat, it took the jell coat and some of the fiberglass layup with it. Brutal.