I can tell you that a loader made a world of difference to my launch and helped all around, especially in the chop.
It is true that the older blocker styles do cause cavitation out of the hole and actually all around. Blocker loaders work by depriving the impeller of water and inducing cavitation. The blocker design closes off the opening in the center of the intake. Because the blocker loader is partially blocking the intake opening, water is deflected out of the pump. This deflection has some benefits: 1.) it generates more lift in the rear of the boat to reduce drag, 2.) it allows the engine to RPM up into its power band with a pump that has an impeller that is too large. Depriving the impeller of water causes pseudo cavitation by reducing impeller inlet pressure. The impeller slips more and the engine thinks that it is attached to a smaller impeller.
Current thinking on loader design leans towards evenly loading the impeller inlet top to bottom combined with an impeller that is matched to the engine’s output. Minimize drag while maximizing thrust.
Rock grates are a leftover relic from when driving a jet boat over sand bars was actually an advertised benefit over owning a jet over a prop boat. Rock grates do nothing to help load the pump and will actually restrict pump inlet pressure. You are better off not running anything than running the stock rock grate but, IMHO, you will be very happy with addition of a modern design loader.
Cheers,
Joe
