With a potentially generous state grant on the line, the West Tisbury Library trustees are gearing up for a grant application this winter to help underwrite an ambitious plan that would see doors to a dramatically expanded library open early in 2014.

For years the library, which boasts the highest circulation on the Island but the second-smallest facility, has been functioning with spatial shortcomings. In 2007 the library space needs committee estimated that the 6,031-square-foot building would need to double in size by 2020 to accommodate projected growth. Several possible design plans unveiled at a public forum last month by Boston architects Matthew Oudens and Conrad Ello called for a facility of over 13,000 square feet.

In January library trustees hope to file an application for grant money made available by the Massachusetts Board of Library Commissioners that would cover up to 50 per cent of the library expansion’s cost. Edgartown also is planning to apply for the grant money for its proposed expansion.

The space needs committee report in 2007 estimated the project would cost between $5.1 and $5.3 million, though library trustee Dan Waters expects to have firmer numbers in late December when the committee has a specific design in hand.

“We’ve been making a lot of great progress,” he said at the public forum. “We’re very much on schedule to apply for this grant in a proper way.”

The remaining cost would be paid by the town and by private contributions, planned at 25 per cent each. The Massachusetts Board of Library Commissioners requires that the library meet its private fund-raising goals by the end of 2011. Mr. Waters estimates that the recently established West Tisbury Library Foundation, honorarily chaired by David McCullough, along with the friends of the library have already raised over $200,000.

“The momentum is just incredible,” library director Beth Kramer told the Gazette on Tuesday. “The staff is excited; we’ve got dedicated volunteers. It’s been a really positive experience.” Ms. Kramer said that although state library commissioners have a stated goal of distributing the grant money geographically within the state, there is enough room for both Edgartown and West Tisbury at the table if both towns put forward compelling projects.

As part of the grant application process, the town was also required to consider an alternate site for the library, in this case a block of town property at the intersection of upper Lambert’s Cove and State Road near the business district. That property has proven undesirable for a number of reasons including its proximity to a well, the resultant clear-cutting of trees and its contribution to sprawl in the area. Library trustees and members have expressed their preference for the library’s current site and architects from Oudens Ello of Boston presented mock-ups of three possible designs for the expanded library at the forum.

At that meeting, and in subsequent feedback the library has received, the most popular design is one that retains the library’s street-facing façade while expanding back through a corridor that connects to another parallel wing in the back, essentially making an H-shaped building. The design would incorporate a north and south reading garden on either side of the middle corridor and an excavated lower level. The building committee has also been considering an O-shaped proposal that was presented at last month’s meeting, and Mr. Waters said the committee has been working with architects to incorporate the most successful elements of each design. The architects said they would aim for a platinum LEED certification. Another public forum to further discuss design is scheduled for Dec. 6 at the library.

The grants will be awarded some time in the early summer followed by a six-month period for towns to accept the grant money. Following that, Mr. Ello estimated an eight to 10-month period of more rigorous design and engineering work, during which town comment would continue to be incorporated in tweaking the ultimate plan. He said if all goes well, the new library could open early in 2014.