Why fusion propulsion would reach patrol vessels late

How would compact fusion power affect naval design, especially offshore patrol vessels?

It is too early to know, and patrol vessels would probably receive it only after fusion became mature and cheaper than conventional alternatives.

The answer separates the ability to miniaturize a power source from the case for installing it in an offshore patrol vessel. Fusion's practical weak points cannot be assessed until dependable net-positive commercial plants exist, so claims about safety, maintenance, and shipboard integration remain premature. Offshore patrol vessels are normally built to a low price and have limited service lives, making an expensive novel plant especially difficult to justify. They would adopt fusion only after it became an ordinary, economical default rather than as an early prestige application.