Critical errors by both the captain and pilot and an operations manual that was out of date and out of compliance were all factors in the crash of the Steamship Authority ferry Iyanough the night it struck a jetty in Hyannis two years ago, a Coast Guard investigation has found.

The 156-foot high-speed catamaran was inbound from Nantucket on the night of June 16, 2017, with 48 people and nine crew members on board when it missed the turn into Lewis Bay and ran up on the rocks of the Hyannisport jetty. Fifteen people were transported to the Cape Cod Hospital for treatment. The allision (a martime term used for a crash that is not a collision) caused severe damage to the catamaran’s three hulls beneath the waterline. Damages were later estimated at $450,000.

Capt. Karl Riddar was at the helm along with pilot Thomas Manley. Both cleared drug and alcohol testing later.

But a 50-page report released last week by the Coast Guard said among other things that the pilot had not been on board the vessel in 10 months and was unfamiliar with its operating systems.

Weather conditions were poor with high winds, fog and rain the report noted. When the captain asked the pilot to turn on the spotlights, he was unable to locate the controls due to his unfamiliarity with the vessel, the report said. The captain became distracted with helping the pilot find the spotlight controls, and mistook a pole and two sailboats for the buoys, which were arranged in a similar structure. Consequently, the captain never turned into the channel as he should have, the report said.

The investigation also cited problems related to the vessel’s radar, reduced visibility due to weather conditions and time of day, and the speed of the vessel — which “was at the high end of the Iyanough’s safe limit.”

The report found further that the operations manual for the Iyanough had not been updated in 10 years and lacked suggested provisions for crew refresher training.

“The operations manual was missing suggested content . . . in particular crew training and refresher training,” the report said in part. “. . . the first officer . . . had not been aboard the vessel in 10 months and could not operate vital shipboard systems. Annual verification and five-year plan approval could have caught this gap . . .,” it also said.

Pilot is the term used by the SSA for what the Coast Guard calls first officer, whose responsibilities include navigating and landing the vessel under direct supervision of the captain.

Formally called Findings of Concern, the report recommends that the SSA adopt new protocols to update its operation manuals every five years, among other things.

“The investigation identified several causal factors that contributed to the marine casualty, including the first officer’s lack of familiarity and training with the vessel,” Coast Guard spokesman Barry Lane told the Gazette.

Citing ongoing litigation, Steamship Authority spokesman Sean Driscoll said he could not comment specifically on what steps the boat line plans to take in response to the report.

“The Steamship Authority uses any incident, large or small, as an opportunity to learn and improve its operations,” Mr. Driscoll said.