Reliability for March was 99.9 per cent, compared to 100 per cent in February.
Punctuality was 99.9 per cent in both months, the company - a CalMac offshoot - said.
A spokesman said: "The performance figures for the Gourock-Dunoon service for March demonstrate that technical reliability of both vessels, along with punctuality, remains very good.
"Passenger traffic is in line with projections and we had a busy Easter weekend despite the disappointing weather.
"The number of day trippers using the service is starting to increase and we also expect to see more people taking advantage of our later sailings as the days grow longer."