The tapered steps are my solution to getting stepped hull boats to handle better throughout the speed range and also in turns etc. Basically the depth of the step is greater at the centreline and becomes less towards the chine. It does not get all of the efficiency of soem racing steps - but the gains in handling more than make up for this in my opinion. Bit more to it - but can't give all my secrets away
On the 999 the keel has slightly more angle of attcak over the step areas. This is more so on the 888. Both boats have exceeded their expectations for speed and really pleased with them from a design point of view. However must also say a lot of credit goes to the build from Technohull and really good hull finish and fairness of lines.