Do Basics of survivability and India Yankee and Juliet Yankee Bissotwo stack?

[antenociti]

As per the title:  Do Basics of survivability and India Yankee and Juliet Yankee Bissotwo stack?

Or can one drop the two flags if one chooses BoS?

[Commander_Cornflakes]

They stack, so get them all on your battleships ^^

[rnat]

They stack multiplicatively, as do all the other duration reductions (e.g. Dmg-Con mod. 1)

I.e. The total duration will be 60s x 0.85 (BoS) x 0.8 (Flag) if you run both.

See also here: https://wiki.wargaming.net/en/Ship:Fire

[Nautical_Metaphor]

And that is how you get the "Beijing smog" build on Pan Asian DDs.