Long prop shafts

I am interested as well. I have come across quite a few references where the exposed shaft is in fact turning. But I've also come across quite a few where the shaft proper is in a tube., in which case it gets painted too. maybe the turning ones get painted, I can't think of any reason not to...

I remember quite a few years ago getting a tour of the engine room of a very large steam piston powered ship. There was a spare crankshaft and a spare prop shaft mounted against the hull, reason being that they would have had to cut a big hole in the hull to get new ones in or out.

The shaft was spinning and exposed.  This was because to have the shaft in a tube was prohibitively expensive to construct and also because, since the shaft twisted somewhat against the load, it would flex and the surface of the metal would stretch and contract, especially when switching directions, and encasing it in a tube would invite a jam or some such thing and since the steel alloy was different from the ship's bottom hull (but not yet stainless in Dreadnought's day) and the fact that the shaft was lubricated at the stuffing box and at the support strut, and taking into account the stretching and contracting of the steel, it was rarely painted.  My father's first ship, a Sumner class destroyer had a similar configuration and a paint that would adhere properly to a highly polished piece of steel such as a prop shaft, under the twisting conditions was not yet known so paint was not typically applied and the fact that it was spinning, anything in the water would be unable to attach itself to it so that was not a problem to be addressed by anti-fouling paint.

Hope this helps.

I just had a conversation with a young man who is a friend of my daughter's. He's an engineer and oiler on the Jeremiah O'Brien.

That ship doesn't have an exposed shaft, although the one it has is 150 feet long!.

But he's familiar with the concept, and echoed all that P said. And that such shafts are made from non rusting metals..

His ship originally had ironwood seals, but they've been replaced with plastic.

I like this guy.

Thanks, guys. I guess I'll use one of my mixtures of Testors steel with black, maybe semi-gloss like their Black Chrome.  I'll buff it a bit to shine it a bit, but not a full gloss.

In USN Service at that time the shafts were painted. Can't speak authoritatively about the RN, but you wouldn't want a shaft to become unbalanced and that will happen on a ship that gets growth on the shaft.

I'd paint it the same as the bottom paint. I doubt a shaft spins fast enough to deter marine growth, and anyway, a ship of this period would spend the majority of its time at anchor.