What are these?

They are for small boat boarding, and jumping off of during swimming breaks.

The proper term: "Schmallbootgefunkeneingang".

I've heard them called "booms and ladders".

Modeling them extended only really works on a waterline model, IMO.

Dumb ass move to blow that beautiful little ship up.

And including Sara and Nevada in the bunch.....But with the war over, they figured no need for all the hardware, and were cutting everything back. 

But Sara was always kind of a hard luck kind of gal, catching fish twice before she ever lanched a strike, and Nevada, the only BB to get underway at Pearl, but both were at "life's end" for ships in those days.

Boat booms, to moor the ship's small boats to when the ship is at anchor or in port. They usually have ladders extending from them, as shown in your photos, for the crew to climb up from the boat onto the ship. I have modeled them using plastic rod, stretched sprue or thin wire for the ropes to hold the booms out from the hull, and scrap PE ladder sections.

Adding the booms, some boats and the people using them can add a little life to a waterline model, as another point of interest. That's one reason I included one in my diorama of a Haskell-class attack transport:

Thanks guys, I'll do a serch to get a good look at them. My dio will be of the Eugen as it is shown in the pictures I posted. It will have small boats and some crew. This will display the Eugen a day before test Able.
I'll start a WIP of it when I start.

Steve

Well, I am a real advocate for working from pictures. Seeing USN units around her is very interesting. It looks like she wasn't too highly modified from wartime fit.

Hi ;

     Having your question answered and quite well I only have to add that in the Navy of the late fifties they were indeed referred to as " Boat Booms " .

  All ships had them and the bigger ships more of them . I felt sorry for the " Deck Apes " when it was really nasty weather and I could see them from my engineering office Porthole , scuttling out to get the Captains Gig and bring it around so the Occifers could stay mostly dry when it was raining Goats and Dogs .  T.B.

Taken from the port side elevator aboard ESSEX CVS-9 in 1962, St Thomas VI when I was aboard. The Captain's gig and the Admiral's barge.

K & S brass rod is nice for booms. It is stiff enough that it will not dip or bend.  Just be sure to prime it with a proper metal primer before painting.  Depending on the scale and diameter, the 1/16 tube may work too.

The US Naval Historical Center's caption for your first picture in the original post identifies a 'radar van' parked atop of the bridge.   There is a detail you need to catch.  

The USNHC's photos are all waterline views and will not answer the question about the barrels.

I know it's hard to see, but looking closer, I do believe the Anton guns are missing for the test.

I really wish the Government saved that ship as a museum. Can you imagine going to something like that.

I see the “radar van” you’re talking about now Ed. I could do that, no prob. It also looks like the port anchor is missing.

Well well well, look at this wealth of info I found. I couldn't ask for more.

https://wwiiafterwwii.wordpress.com/2015/06/23/uss-prinz-eugen/