When they crack open the rear doors of the historical Rossie Mill, where Mystic Seaport has much of its watercraft collection in deep storage, you can almost hear the roar of crashing waves or the slap of loose canvas in a stiff wind, ghosts of many thousands of long-ago jaunts and voyages.

A lot of marine history is tucked in here — hundreds of boats of all sorts and sizes, a part of what the Seaport calls the largest collection of classic watercraft in the country.

From Vireo, a 1912 sloop used by Franklin Delano Roosevelt to teach his children to sail, to a boat that carried refugees from Cuba on their flight for American freedom, the collection covers an amazingly broad swath of boating, from commercial to recreational, and time periods. There are dinghies, sailboats, power cruisers, canoes, Navy launches, lifesaving boats, even one of the first windsurfers.

Much of the collection has come from donations, and it continues to grow.

I sought out a fresh peek at the Rossie Mill part of the collection recently because the mill is suddenly at center stage of that part of Stonington, with the town's imminent creation of the new Boathouse Park across the street.

Also, many of the boats in storage now are more likely than in the past to rotate into the exhibit sections of the Seaport, with the completion of the museum's big new Thompson Exhibition Building.

The building's inaugural exhibit, SeaChange, is scheduled to open Dec. 10 and will feature objects drawn from the Seaport's rich collection, some never displayed before, like a historic vessel that will hang upside down from the soaring ceiling of the vast exhibit hall.

The Rossie Mill is itself a big piece of Mystic history, once the largest employer in town, when it was making velvet for the first part of the 20th century. It is now part of an entire neighborhood that is listed on the National Register of Historic Places.

The sprawling mill, covering 147,000 square feet, was first commissioned in 1897 and designed by New York architect Robert D. Kohn, who also designed the R.H. Macy department store and managed the design of the 1939 New York World's Fair.

The front section of the mill has been rebuilt by the Seaport to house its archives, with climate-controlled storage, libraries and offices.

The back, eastern side of the building remains much as it was when it housed the 150 looms run by hundreds of employees, many of them German immigrants.

Even then there was a marine connection, since coal to power the factory arrived by water and was trucked into the mill by way of a tunnel running under Greenmanville Avenue.

Dana Hewson, vice president for Seaport watercraft preservation and programs, told me on a tour of the mill that there is a long-term goal of eventually rebuilding the older part of the mill used for boat storage and making it accessible to the public.

It is a daunting project, not just because of the size of the building and what would be needed to turn it into exhibit space, but also the logistics of separately storing the boats while the work is done.

In the short term, the building is serving its role well — a giant attic, if you were, safely holding the Seaport's impressive collection of boats in a dry and largely stable environment.

The boats are in various stages of repair. While some were donated completely restored, many are "as found," sometimes with peeling paint and bubbling varnish.

A decision would be made, on a case-by-case basis, on what measures to take before putting a boat on display, but they most likely would be shown in natural condition, with the effects of time and use being part of the story told.

The museum has a committee that considers each proffered donation to determine whether it tells an important part of the maritime history the Seaport wants to tell.

That criteria is always changing, too, Hewson said, especially as, over time, even some fiberglass vessels — like the first Laser, which is in the collection — become representative and classics in their own right.

There is a team of volunteers who work on the boats and tend the collection. Each vessel has a tag with a description and a catalogue number.

The part of the watercraft collection in the mill is rarely open to the public, although tours are sometimes offered to groups. It also opens each summer when the Seaport hosts the WoodenBoat Show. I strongly suggest a visit then.

With the exception of the large ships, what you see on display at the Seaport is really only the tip of the iceberg of its remarkable collection of boats.

The boats and the mill itself together tell an awful lot of history — local, national and international, as well as industrial, maritime and architectural.

This is the opinion of David Collins.

d.collins@theday.com