A smaller boat was moved to the Washington State Ferries’ Point Defiance/Tahlequah route Sunday, creating back-ups on the nearby Triangle Route as drivers sought an alternate way off Vashon Island.

According to spokeswoman Susan Harris-Huether of the Washington State Department of Transportation’s Ferries Division, the 34-car Hiyu ferry began shuttling passengers between South Vashon and Tacoma June 1, replacing the 60-car Rhododendron.

“I want to thank the Vashon community and regular users of the Point Defiance/Tahlequah route for their patience and resilience during this time,” said David Moseley, the assistant secretary of the Ferries Division. “I am aware of the inconvenience that a smaller vessel will cause.”

The first day the Hiyu was running, riders on the Southworth/Vashon/Fauntleroy route encountered longer waits in the middle of the day as many users decided to use the ferries that leave from the north side of the island rather than the Pt. Defiance route from the south.

At 12:12 p.m., the WSF alerted riders on the Triangle Route that “extremely heavy vehicle traffic has created a two-hour wait departing from the Vashon Island terminal.”

An hour later at 1:26 p.m., an alert was sent out to warn that “heavier than average volumes of vehicle traffic have created slowdowns in the loading and offloading process,” causing the Issaquah to run up to 20 minutes late.

The WSF said that the increase in traffic was “possibly due to the smaller capacity vessel Hiyu operating on the Point Defiance/Tahlequah route.”

To help alleviate traffic, the WSF announced that beginning Monday, it would add an extra midday sailing to the route — a 12:50 p.m. departure from Pt. Defiance and a 1:15 p.m. departure from Tahlequah.

According to the WSF, the Hiyu is expected to be on the South Vashon Route for approximately two weeks while the Rhododendron is “on loan to Pierce County.”

The Rhododendron is needed there because the Pierce County’s ferry, the Christine Anderson, had a “blown shaft seal.”

“I am pleased that we have been able to find a compromise that allows both WSDOT and Pierce County to avoid service disruptions,” said Moseley. “Pierce County has generously helped us out by loaning us the Steilacoom II for the Port Townsend/Keystone route, so I’m glad we are able to return the favor while their other vessel is being repaired.”

While the 34-car Hiyu is on the Pt. Defiance route, WSF advises that “customers can expect longer wait times during busy commute periods,” and advises drivers to “arrive early and to use the Fauntleroy/Vashon/Southworth route, if possible, for travel to Vashon Island.”

In addition, extreme low tides beginning today through Saturday may cause delays for vehicles with less than 14 inches of ground clearance.

Customers are advised to check the Ferries Division website, www.wsdot.wa.gov/ferries/, for wait times and other updated information, or call (888) 808-7977.