Final answer:
The question does not provide enough detail to give a precise answer, however in general, gasoline-powered powerboats require a flame arrestor on each carburetor for safety. More context is needed to provide a definitive component or characteristic.
Step-by-step explanation:
The question seems to refer to a component that all gasoline-powered powerboats must have on each of their carburetors. However, there's a lack of specifics in the question that prevent a straightforward answer. Typically, gasoline engines with carburetors will have certain features that contribute to their operation, such as a throttle valve to control air intake, mixture screws to adjust fuel/air mixture, and a method for vaporizing fuel for proper combustion. If this is in regard to safety or environmental regulations, they are usually required to have some kind of flame arrestor to prevent engine fires by extinguishing sparks coming from the engine that might ignite fuel vapors. In high-performance powerboat racing engines, different fuel mixtures may be used, but this is quite a specialized field and goes beyond general safety requirements. For a more precise answer, additional context regarding the regulation or specific aspect of powerboat operation should be provided.