fast speed : knots ?

[qmuddy2]

12 or 15 ? thanks

[hauangua]

Depending :
Ship?... type?
Uboot? ...type?
:03:

[UKönig]

Not quite sure what the question is, but...

Slow is from 1-7 knots
Medium is from 8-12
Fast is 13+

Uboats can make up to 8 knots underwater (17 for the type XXI), and up to 21 knots on the surface, but only with engine upgrades and/or a skilled engineer who can 'sit on the pots' to squeeze more HP out of the engines. (Which risks damaging them the longer it continues).

Most warships can make 35 knots or faster, at full flank.
You might be able to outrun a corvette on the surface, but pretty much all other warships will run you down with little to no trouble.

Most aircraft can go 200 knots or faster...