It has switched places with the Leif Ericson, which usually takes commercial traffic on the Port aux Basques-North Sydney, N.S., run.
Tara Laing, spokeswoman for Marine Atlantic, said the Smallwood developed mechanical problems Friday night, increasing the Argentia run crossing time to 17 hours from 14.
As of Monday night, Marine Atlantic was expected to substitute the Ericson, which will have a longer crossing time on the Argentia run as well.
Some repairs on the Smallwood's broken engine can be done en route and because it's doing a commercial run, there is extra port time, Laing said.
The Smallwood can cross from Port aux Basques in the same time as the Ericson would, because it only needs three engines to keep that pace.
However it would require all four to make the usual schedule on the Argentia run.
Marine Atlantic is hoping it will take less than 10 days to return the Smallwood to the Argentia run.
Because the Ericson is a smaller vessel, passengers who had prebooked will sail as usual on the Argentia run, but passengers who haven't made a reservation likely won't be accommodated in the next 10 days.
Reservations may be affected
As well, everyone with reservations might not get the accommodations they booked due to the reduced capacity, Laing said.
Meanwhile, on the Port aux Basques run, travellers will have access to fewer of the popular overnight crossings on the Gulf run (Port aux Basques/North Sydney) this summer.
The 11:30 p.m. sailings - allowing a full day's daylight driving time after docking - are not available on all days in either direction.
That's due to a 10 per cent increase in crossings, Laing said.
She said the increase was meant to accommodate the province's growing economy.
However, because of the way the schedule worked out and due to regulatory hours of rest, some of the crossing times are "less friendly in terms of departures and arrivals," Laing said.
With new additions to the fleet next year, the schedule will change again.