I've talked to some of the best hovercraft competitors in my state about their designs - almost all of them used a basic bag skirt, the same blower fan described in this forum, NiMH batteries which most teams use, yada yada yada. Barring major changes, the most important thing seems to be practice. There are certainly a few design issues which can decrease consistency - for example, if the skirt expands out beyond the sides of the hovercraft, it can run and cause inconsistent friction. However, once those are mitigated, teams just need to get a lot of times on a lot of surfaces, as LittyWap can attest. I hope that the rules for next year still reward teams for practicing and testing a lot, but I hope hovercraft will not turn into one of those meta events where every single top team has the same design. I would also love to see some points for making graphs of time scores on different surfaces - this seems to be a perfect event for that type of information, seeing as AFAIK it replaced Air Trajectory.
2017 Hover: 2|2|2|2|3
One off of the greatest streak ever
2018 events: Chem, Hover, Matsci, Thermo, Optics, Mission, Towers, Fermi