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- Feb 1, 2015
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If brass will work, https://www.mcmaster.com/#brass-coupling-nuts/=1bp5r39
The shaft is tapered: it's 1" stock, which has a slight taper onto which the mating taper of the prop fits (with a key as well); then there are two nuts, the first of which snugs up the prop on the taper, and the second of which pushes on the first, and is typically either castellated or has a through-hole, and gets a cotter pin into a small hole on the very end of the shaft (which is turned down to about 1/2". So there's not really any shaft left behind that second nut. (Sigh), and it's certainly not 1" material.Okay, I see.
Is there any reason you could not connect the sacrificial zinc right to the stainless threaded shaft?
https://www.thechandleryonline.com/product_info.php?products_id=8201
That one woulnd't tighten onto a 3/4 inch shaft, but zinc is soft so taking a little off the mating faces to make the thru hole smaller is easy.
Just don't breathe it if you sand/grind it off!
I guess you still want a second nut to jamb the first one.....maybe the shaft isn't long enough?
-brino
If brass will work, https://www.mcmaster.com/#brass-coupling-nuts/=1bp5r39
I don't know exactly what "naval brass" is, but if it's the stuff that's used for naval clocks and other such things, then the answer is "yes." On deck, it rapidly develops verdigris. It's the sort of thing that used to keep sailors in the British Royal Navy very busy with their polishing rags. Fortunately, stuff on deck may sometimes get sprayed, but rarely suffered prolonged immersion of the kind that leads to serious corrosion. If it does, your ship's upside down, and you've got bigger problems to worry about.Does even naval brass have this problem? I know silicon bronze is expensive
Mark
Silicone bronze works pretty well in salt water; the zinc is meant to reduce the already-fairly-low-corrosion-rate of the propeller (which is slightly raised by it sitting on a stainless rather than a bronze shaft). Brass, on the other hand, in most alloys tends to act like a battery, and first gets pink spots as the zinc in it disappears, and then begins to look like Meunster cheese. Not at all the right material to use in any critical application underwater. It's a pity, because that'd be a great starting place to work from.
If you only need the threads at the hex end, why not just use a single nut with a longer cylindrical bushing (1" OD, 3/4+" ID)?