Ace destroyers in 1939?

[bigboywooly]

Because not every RN vessel has asdic and not all conditions are optimal
Plus with the rapid growth of the navy there wouldnt have been trained personnel for every ship

And 104 uboats sunk in 3 months of 39 and all of 1940 would say not every sub was succesfull
Add that to the fact the RN didnt have enough ships to protect every convoy out into the atlantic