The Steam Packet says Manannan will run on three engines until the end of the fast craft season in October.
It means sailings will take around 30 minutes longer than scheduled, but the alternative would be to take the vessel out of service for a prolonged period, which would result in some cancellations.
Manannan is covering Snaefell's mid-week sailings on the Liverpool route and will continue to operate the Dublin and Belfast services, also on three engines, until early September.
Crankshafts failed on both vessels earlier this month.