Don't know if this helps or not, but consider: every leviathan has multiple boilers & steam engines, both for the sake of redundancy, and because the engines need to power two separate systems - the ducted fans that generate propulsion, and the generators that run the Tesla coils that make electroid generate lift.
Warships have enough engine capacity to run both systems under full military loads, plus a bit more. The reasoning is simple: there's no point in moving if you can't stay up, and vice versa. During battle, however, damage can reduce this capacity. In that case, there's one simple rule - "power to the coils". If you can't fly, you die. Now this doesn't mean that a captain of a failing Lev might not divert power to the fans to get over land at the expense of dropping faster, but this isn't what you might call a long-term survival tactic, and as they got lower he'd probably divert energy back to the coils to soften the crash.
So in game terms, damaging engines slows down the leviathan. It could be boiler or steam plant damage, or smashed ducted fans, but the coils come first. And the ducted fan systems can only take so much power before they fail, so if you did have a waterproof Leviathan floating on the water, it couldn't go twice as fast by turning off the coils.
Interestingly, the reverse need not hold. One could - in theory - divert all power to the coils. However, the ceiling of "modern" leviathans isn't dictated by electroid, or by the power available - it's dictated by the voltages and currents that 1910 electrical engineering can deal with. Put too much power into the Tesla Coils, and you get arcing, melting metal, and flashover in short order. Enough theoretical scientists have killed enough airman for even the slowest Sky Fleet to get the point.
(And yes, every major power is engaged in finding better conductors, stronger insulators, more efficient generator windings, etcetera etcetera. Perfect excuse for an adventure!)
