What are the torpedo-looking things stowed on deck of BB?

It sounds like you're talking about the paravanes. A paravane is a gadget used for detecting mines. The ship "streams" the paravane (this blasted phone is having a terrible time with that word) from its bow on a long, tough cable. The cable snags the anchoring cable of the mine. The mine then comes to the surface, where it can be detonated by gunfire.

Thank you!  I just wiki'd "paravane" and that is definitely the critter I was asking about.

The Professor got you sorted far more eloquently than I could.  But, that probably goes back to being taught how to stream paravanes as a "just in case" (despite not having stream gear, chain shoes, or even the paravanes aboard USN vessles of the time).  Such is life.

Esp in this case where the para vane streams behind the ship

Abaft streaming is nearly exclusive territory of dedicated minesweepers.  That, because those vessels have the needful otters and such to keep the sweep gear out of the screws.  Which would be a difficult task on a DD or the like.  Which is why the BBs, and cruisers all had either  a fixed shoe or sliding she rigged to the forefoot.

Of course, the real problem with a paravane sweep is that it can only affect floating moored mines.  Magnetic, sound sensing, command detonated, and the like will not be bothered i nthe slightest (barring grounding the sweep wire, but that is bad, very bad).

Now, paravanes bow shoe mounts do have an appeal to thos officers convinced that EM morale requires whitewashing rocks and similar endeavors.  This, as the chained to and through the shoe need hoisting out and being cleaned of weeds and the like, with chipping, priming, and repainting those chains.

It wasn't just the combatant ships that were rigged to deploy paravanes. The amphibious ships had them as well. The APA I was on had a plate extension of the forefoot for the chain/cable and small cranes port and starboard on #2 hatch to hoist them out. The rest of the gear was long gone when I was aboard. The accommodation ladders had been repositioned so they could be raised with the paravane cranes.

I think the use of paravane sweeps originated in WWI before mine designers got creative and deployed magnetic and other types of non floating mines.

BTW We had a Navy manual aboard left over from WWII, but never cancelled, that advised that ships in convoy should lower an anchor to discourage U-boats from hiding under the convoy.

Putting, say, 50 fathoms of anchor rode over the side could cause a scary bit of racket; but, I'd not want the man the helm, though.