By Dan Perruzzi and Cyndy Gibson Murphy. Perhaps one of the most interesting (and certainly challenging) aspects of building on a floating barge is creating a level work surface. The first step in beginning framing on any project is making certain that you have a level foundation, especially since concrete has a much higher amount of tolerance than most other building materials. The problem with the barge, however, would prove to be the lack of level. This is yet another way that the Tea Party in unique. While level is a basic assumption on any land-based project, on the Tea Party, getting to level required lots of work.
The barge uses ballast in its hulls to control the amount of freeboard (how much of the barge floats above the waterline) it will have. The freeboard has to be carefully controlled to a predetermined dimension due to the constant access that must be had by all from the ships docked around the barge.
In order to transport the barge from the Quincy shipyard (where it was built) to the Fort Point Channel in Boston, enough ballast had to be installed to keep the barge level. Once the barge was in place, work to complete the barge building began. In the process of continuing construction, weight was added in the form of additional wood framing, mechanical equipment, roofing and siding. That additional weight could never be evenly distributed, and as a result, the barge began to list, or tilt, with the front (fore) of the barge lower than the rear (aft).
Many of us noticed this as we watched the project from our office windows. Someone said: “Hey, that barge is out of level! Isn’t that a problem?” Everyone directly involved in the project was well aware: walks up and down the barge told the story. To their credit, Suffolk had already anticipated this. The question became when to correct for level. Suffolk wanted to install additional ballast in the form of concrete, pumped into the barge hold. Suffolk wanted to do this as soon as possible since the longer they waited, the more difficult it became. Pumping concrete is a messy business.
We questioned the structural engineer: how much will be the building weigh when complete? We soon realized that structural engineering does consider weight when designing a foundation, but only with healthy safety factors. Those safety factors would create too great a building weight and not enough ballast. The answer came from the marine designer: wait until the building is mostly complete, with most of the components installed, then place ballast.
This meant that, for a short period of time, the barge would remain out of level. Because they were building on an unlevel plane (the barge deck), Suffolk devised a way for the trade workers to establish “plumb” and “level” without benefit of normal layout tools such as a level or a laser. As a work- around, it was decided that the barge deck would act as a reference plane. Anything intended to be plumb had to be built perpendicular to the deck. Anything level had to be built on a line exactly parallel to the deck.
The framers constructing the second floor wood frame on the barge built large-scale squares (a square is actually a right-angle triangles used to confirm 90-degree alignment) that they could use to ensure their walls were perpendicular to the finish deck. The framers finished the roof structure having used only squares, tape measures and a bit of trigonometry to confirm the building is, in fact, square. Following behind them are several other trades that will, in short time, realize that their tried and true levels and reliance on lasers won’t be of use while they build on “uneven ground.”
The Pier Building
The Boston Tea Party Ships and Museum will commemorate an amazing historical event with the use of exhibits and a very sophisticated audio/visual system. Exhibit cases and merchandise racks are all to be fabricated so that they look antique. HTA had, from the beginning, planned to design and build many of the exhibits and display cases. There was no question they could do it. They had done this many times at several of their other museum sites across the country. HTA wanted MPA to design a building that was essentially a white interior box. After that was complete, HTA would come in to complete the project by installing exhibit cases, moving electrical components to fit the layout and installing projection screens, video components, finishes and other fittings. The original design drawings, inherited by MPA, are consistent with this.
The problem was: Boston is different. The local building inspector from the City of Boston Inspectional Services Department would expect to see everything in place before they would issue an occupancy permit. Exhibit cases can define, or block, the egress path. Added elements, such as screens or fabric wallcoverings, had to comply with stringent local fire codes for flammability. While other locales across the country might allow someone without a license to install electrical wiring and place architectural moldings, local unions in Boston would not be happy.
BP knew this better than anyone. Early in the process of reactivating the project, BP argued for a more complete interior design. This meant that MPA had to work with HTA to accelerate the design of the components that would be fabricated. We also transferred some of the work in their scope of services to MPA’s. For example, instead of wainscoting panels to be installed later by HTA, they were included in the project millwork scope.
Three ships will be docked around the barge. They will be replicas of the three ships involved with the original Tea Party: the Beaver, the Dartmouth, and the Eleanor. Two of the ships, the Beaver and the Eleanor, are under construction at the Gloucester Marine Railway, the oldest, continuously operating shipyard in the United States. They are being built under the direction of Leon Poindexter, who is a master shipbuilder with a specialization in the reproduction of period ships and boats. He built the ships that were used in the film “Master and Commander”, as well as many other films. We visited the shipyard in Fall 2011 to see the ships’ progress and found they were using traditional techniques that would have been used by shipbuilders in the 18th century to construct the original ships. The hulls were being planked by hand, with each plank carefully cut and fitted by hand. Seams were waterproofed with traditional materials and tools.
When the two ships are ready, they will be towed by tug from Gloucester to Boston, with masts waiting for them on a flatbed truck in Boston. Once the ships are moored, their masts will be placed by crane into the mounts. Leon and his team will then begin to set the rigging on the ships, which should be an interesting process to watch. Once complete, the ships will be a big part of the Tea Party site. They will help to educate about what conditions were like aboard those ships. They will also be an important visual part of the experience, as lighting installed on the ships will illuminate the masts and rigging at night, adding a new attraction to the Boston waterfront skyline.
The third ship, the Dartmouth, is planned to go under construction in Gloucester sometime in 2013.
Tags: Boston Architects, Boston Interior Designers, Boston Tea Party, Boston Tea Party & Ships Museum, Fort Point South Boston, Historic Tours of America, Leon Poindexter, Margulies Perruzzi Architects, MPA Boston