Swimming Rules

I'm collecting ideas for creating a Quest that takes place under a city/town, in a sewer system that's flooding.  In several areas the Warrior might need to swim, so I'm trying to flesh out some quick and dirty (literally) house rules that will allow them to swim through the filth.

Fatigue Points

At the start of the adventure each Warrior will roll 1D6 for every point of Toughness they have.  The total will be the Warrior's "Fatigue Points" for the adventure.  Dwarfs must halve their total after the roll, due to their natural disaffinity for water.

Swimming

A Warrior can swim through a square containing water at a cost of 2 Movement Points, and 1 Fatigue Point.  If a Warrior stays put treading water for an entire turn it costs 1 Fatigue Point. Whenever a Warrior is required to lose a Fatigue Point when they have none left, they begin to drown and lose 1D3 Wounds.

Swimming and Armor

I watched a historical TV show that once said that swimming in plate mail was actually not as difficult as is believed.  There's also this link that supports my memory.  Still, it will tire you out pretty quickly!  For every point of Armor worn that reduces your Movement rate, deduct 1 additional Fatigue Point for each Swim Move made.

Swimming and Combat

Figures Swimming suffer -1 Attacks (1 minimum), and each attack is made at -1.  For obvious reasons, missile fire is not possible.  Exceptions to this rule are Monsters tagged with the Swimmer or Fly Special Rules.

Regaining Fatigue Points

Once out of the water, the Warrior regains 1 Fatigue Point per turn.  If they do nothing but stay in the same square, rest, and catch their breath, they regain 1D6 Fatigue Points.