VESSEL REVIEW | Enetai – Fast and stable 255-pax catamaran for Kitsap Transit’s Seattle-to-Kingston service

Bremerton, Washington-based ferry operator Kitsap Transit recently took delivery of the first of two new 255-passenger catamaran vessels in a series from Nichols Brothers Boat Builders (NBBB) in nearby Freeland.

Designed by UK naval architects BMT, Enetai was completed by NBBB in fulfilment of a design and construction contract for two new high-speed ferries for Puget Sound awarded by Kitsap Transit in December 2018. Sister vessel Commander is under construction and scheduled to be launched later this year.

Named after a Seattle suburb, Enetai was designed and built to satisfy a unique set of criteria: the ability to perform passenger loading and unloading via the bow and utilising Washington State Ferries' (WSF) existing Coleman dock in downtown Seattle, a minimum cruising speed of 35 knots to allow for efficient route scheduling so as not to interfere with WSF's existing schedule, and improved passenger comfort and amenities.

The all-aluminium vessel measures 140 by 37 by 12 feet (42.6 by 11.2 by 3.6 metres) and was built to both DNV and US Coast Guard Subchapter K regulations. In addition to being able to transport up to 255 passengers on each sailing, the ferry has onboard space for 26 bicycles.

Amenities include an advanced heating and air conditioning system to keep passengers as comfortable as possible in the winter and summer, a USB outlet and charging station installed on each of the passenger seats, and wi-fi connectivity.

Although Enetai was also designed for compatibility with the WSF Coleman dock at Pier 50 in downtown Seattle with regards to bow loading/unloading, side loading/unloading is also possible to allow the vessel to easily serve the many other ferry terminals along its intended route, which also covers other Puget Sound cities such as Southworth and Kingston in Kitsap County. BMT added that mooring and passenger loading arrangements have been optimised to improve turnaround times – an important attribute as the operators expect the ferry to complete up to nine trips per day.

The ferry is powered by a pair of MTU 16V400M65L main diesel engines, each with an output of 3,435 hp (2,560 kW) at 1,800 rpm. The engines drive two Kongsberg Kamewa S71-4 waterjets via ZF 9050 gearboxes to deliver a cruising speed of 35 knots at full load. During trials, the vessel's waterjet propulsion and lightweight construction enabled it to easily reach speeds in excess of 38 knots.

High-speed cruising is made more comfortable thanks to an active ride control system supplied by Naiad. Further, due in part to Enetai's low displacement, minimal wake wash is generated, ensuring that the marine ecosystem within Puget Sound suffers no major adverse impact as a result of the ferry's sailings.

Even with its significant propulsive power, Enetai was also designed with the goal of keeping emissions to a minimum regardless of its regular operating profile. Among the features that help the vessel achieve this objective is a selective catalytic reduction (SCR) exhaust aftertreatment system. Further, the MTU engines were built in compliance with US EPA Tier IV standards, thus ensuring NOx, SOx, and particulate emissions of as much as 90 per cent compared to the traditional powerplants that have been fitted on vessels of similar size and performance. Power for all onboard electrical systems is drawn from a 132hp (99kW) MER Equipment Bollard MG99 generator.

BMT added that the ferry has also been designed to reduce cabin noise by minimising the overlap of the passenger and engine compartments and by using specially-made noise attenuation materials.

Enetai has already begun operating on Kitsap Transit's Seattle–Southworth–Kingston service. The ferry's daily schedule includes four round trips out of Southworth beginning in the morning and five round trips out of Seattle in the evening.

Click here for the other news, features and reviews comprising this month's Passenger Vessel Week.