I actually strongly disagree on this. I think that ability would be pretty fun and pair well with England's industrial focus.
The +1 movement is already granted by the Dockyard. The +10 CS is a copy of Frederick. If you meant only against coastal city states, it's too situational.
Edit: so if you had both that and a Venetian Arsenal, does that mean you'd get 4 naval units every time you build one?
(probably three, or maybe the ability doesn't stack)
New Achievement: occupy every water tile with a naval unit.