Very different on a RIB to a SIB though - they can be run more like 2.5 for a softer ride as the hull gives the stiffness and strength with the tubes cushioning the ride and lower pressure makes it more supple and forgiving. Another disadvantage of a SIB in this respect!
Fenlander will be along with the keel pressure I'm sure
we're all getting to old to remember these blooming figures...