Types of Roller Coaster Systems
The Amazing Water Brake
The water splash brake system used by B&M roller coasters is a unique design to use the force of water through a tube to slow a roller coaster train. The water brake is a funnel shaped device added to the back of a roller coaster car that dips down into a pond of water forcing water through the funnel creating drag. The water splash element on some of the coasters can achieve up to about a 30% drop in speed by varying the design and shape of the water cone. Here are some graphics of the basic idea of how the water splash works and the overall design of the water trough and funnels.
Griffon also uses the water brake and they have a different design funnel as well. With each different shape they can achieve various amounts of brake and over all splash effect in the splash pool. Diamondback a hyper coaster design which has there own design due to train length and the amount of brake they want to apply. These funnels are a much smaller design and do not apply as much brake force to the train but do produce a large splash effect.
They have another design using a type of paddle that just sticks down into the water. This seems to not have as much of a brake effect as it does a water splash effect. The paddle is used more to displace the water into a splash effect. There are several designs of the paddle some with a hook on them to produce various amounts of the splash effect. Here is one of the paddle designs.
There have been many designs used on the water brake system each utilizing different water volumes and pressures to vary the amount of brake and speed reduction that is applied to each roller coaster installation. In the beginning Sheikra tested several different designs of the water scoops. From round ones, to tall ones and even had a set that were more of a paddle instead of a scoop. Each design produces a different splash effect from sideways, to fan shaped and tall or wide. Sheikra over the years has had several shapes and designs to get the correct amount of brake. These photos show the various funnel shapes and  splash patterns as a result all to control the brake effect of the trains.