"Under federal law, there is currently a 100-yard exclusion zone around any large passenger vessel that is underway or at anchor in Puget Sound. This exclusion zone is reduced to 25 yards when the vessel is moored. The United States Coast Guard, federal law enforcement officers, and Washington law enforcement officers are all empowered to enforce this exclusion zone. The Coast Guard Captain of the Port of Puget Sound can waive these restrictions for a vessel or class vessel."

In addition if a vessel comes within 500 yards of a ferry they are required by law to reduce speed to the minimum required to maintain steerage and a safe course.

So the powerboat was clearly in violation of federal law (33 CFR 165.1317) and had no right to navigate within 100 yards of the ferry unless the ferry captain specifically allowed it.

Consequently I think the powerboat was 100% at fault.