Groton — A tiny seam running down the side of the Research Vessel Connecticut is all that's visible of the months-long, $2.5 million project to cut the boat in half and expand it by 14 feet.

But the extra space inside the UConn vessel's cabin will mean more students and researchers will be able to use the R/V Connecticut for long research trips, and will make the vessel an even more popular tool for scientists to rent, researchers said Monday, hours before the boat set off on its first major research trip since work on the boat began.

Nine researchers from UConn, the University of New Haven and the U.S. Geological Survey will set off for a week on Long Island Sound early Tuesday morning, collecting detailed data for a National Oceanic and Atmospheric Administration project to map the floor of the Sound.

That number of people would never have fit on the R/V Connecticut before the boat was expanded, said Turner Cabaniss, marine and waterfront operations manager at UConn Avery Point.

"The space has probably tripled," Cabaniss said.

The vessel, which usually is docked at the University of Connecticut's Avery Point campus, has been out of commission since February while workers at Blount Boats in Warren, R.I., severed the boat, creating a large gap in the middle and adding room for additional bunks and labs in the cabin and steel on sides. They then welded the boat back together, leaving only a small, painted-over seam on the outside and enough space for six additional scientists on the inside.

Delays in construction and acquiring equipment meant the original finish date was pushed back several months from July to this fall.

The vessel was finally put back in the water and used for a one-day research trip into the Sound earlier this month, which went smoothly, Cabaniss said.

"There were a lot of little bugs to work out, but everything is fine," he said.

It will set off again Tuesday morning on its first major expedition since the repairs, taking Ivar Babb, the director of the Northeast Underwater Research, Technology & Education Center, with it, along with eight researchers from three institutions.

They will use high-definition cameras and tools to collect sediment from 90 sites on the bottom of the Sound, data that will contribute to the NOAA mapping project. The work is being funded with a $1.38 million settlement between the two states that share the Sound — Connecticut and New York — and the Long Island Power Authority, Northeast Utilities and the Cross Sound Cable Co. over adverse impacts caused by an underwater utility cable.

Graduate students will use the new onboard labs to sift through the sediment and analyze it, then send it to Columbia University for further testing, Babb said Monday.

The trip comes not a minute too soon for Babb, who said he and the other researchers are eager to start work while the weather is still good enough.

"We really wanted to be out in August," he said. "We need to get out now."

The vessel will also now be available to other research institutions that may rent it for thousands of dollars a day, and it is already booked by organizations such as the Woods Hole Oceanographic Institution.

m.shanahan@theday.com