After endless hours of testing, measurements and observations I can safely say that, among other things, the propeller we will finally choose for our boat must absolutely meet the following 4 preconditions at the same time:

1… to match with the characteristics of both our engine and hull at the same time.

This is one of the most critical requirements that our propeller has to meet. It has to match with the hull and the engine at the same time too, because otherwise, it is certain that either the boat’s performance will be poor or the good functioning of our engine will be undermined.

To make it clearer, our propeller must match with our engine’s horsepower in relation to its gear ratio and at the same time with the type, length and width of our hull.

We can not install any propeller on any engine but neither any propeller can push any hull.
There are restrictions defined by the horsepower and gear ratio of each engine as well as our own hull.

For example, in a low-horsepower engine or on a very fast propshaft, we can not install a «large» propeller, because the load on the propshaft and the gear will definitely be enormous. The larger (numerically) the gear ratio is, the bigger the propeller can be installed.
On the other hand, each hull requires a certain amount of thrust i.e. a minimum of propeller’s diameter to run efficiently. If our propeller’s diameter is smaller than the minimum required, then, even if we have the best propeller in the world, the performance will be disapointing and the slip’s values very high.