It depends on many details of the vehicle - not just its size and the parts that hit the water, but also how it moves (e.g. wheels, legs, something else).
For humans, this study is interesting. It doesn't work on Earth, but it should work on Moon.
There are a huge number of variable involved here. The most important one is the shape of the hull. Even given that, there are problems with the "roughness" of the hull. This is an extremely difficult, complicated problem.