[LukeFF]

Originally Posted by elanaiba

Some boats had propeller guards as built, some had them added (welded) after the war. During the war it was customary for the boats that didn't have the guards to receive temporary ones.

Gino can shed more light on this.

Here's some photos of the USS Barb, without welded prop guards and with the add-on ones, late in the war:

http://www.navsource.org/archives/08/0822012.jpg

http://www.navsource.org/archives/08/0822014.jpg

(big photos so I just linked them instead of posting them)

Thanks for the info!