Not sure where it would dock in ishinomaki. It is a fair walk from the port area to the train station so a bus / taxi would be best. It would be a good 1.5 hours to train into Sendai, so I think matsushima would be a better option and faster to get to. Good temple / sightseeing cruises and food there. Lived in Sendai for a few years and was there a few months ago, as much as I would love to recommend a day trip to Sendai, it would be too rushed