Pretty much.

If you can't uber-armor the deck, then in order of importance you want...

0.2 belt (reduces torpedo damage)
3 bulkhead (maintain speed further into yellow damage)
1+ bulge (absorbs torpedo damage that has been reduced by belt above)

Keep adding bulge until you slow down, then back it off slightly til you speed up again.

If you can't armor enough to bounce most of the shells that are going to hit you, then
don't bother to armor at all. It's all-or-nothing. With only a very few exceptions, if you
aren't in a UK ship (and in truth only certain UK ships) then don't even consider armor as
being viable.

With a PBB, no armor. It's plenty durable enough as it is, and you'll want the speed.

--Helms