For catamarans and tri-marans what rules or formulas are there about what bridge deck clearance  is needed to prevent pounding?
Are there formulas that give the chances of pounding in some time period, like once per hour or day, in different sea states for different height/width numbers?

Now we are working on a single family seastead design.  So the goals are stability, low cost for the space, and we don't need it to be fast.
Lets imagine a design that has a big triangular platform 80 feet on a side above the water.  Next in each corner their is "leg" that is a NACA wing
shaped thing going down into the water (maybe 19 feet long and half under water).  This is a hydrodynamic column, sort 
of like a column on an oil platform but easier to push through the water as it has a wing shape.  Probably like 10 foot chord and 4 foot thickness
so it fits diagonally in a 40 foot container.  So these legs are sort of rotated 90 degrees from a usual tri-maran type hull to
get a small waterline area and a softer/gentler motion.
This will be used in the Caribbean (outside of hurricane season) and move at about 4 MPH.  We want the chance of pounding to be extremely small,
like in 7 foot waves less than once per day.   Try to figure out what the bridge deck clearance should be.

Note that this design will be solar powered and have lots of batteries that will be located in the bottom of the legs.
We will also have long term canned food stored in the legs and water and waste tanks in the legs.  We will get as much 
weight into the corners to get more rotational innertia and make it harder for the waves to tip the structure.