Portsmouth Naval Shipyard, Kittery, ME
Dry Dock No. 1 Expansion

See More Caisson Gate Design

In 2020 HEGER was part of the design team tasked with designing a major expansion project at Portsmouth Naval Shipyard’s Dry Dock No 1. The project objective was to expand the facility by building two new deeper basin dry dock’s at the entrance of the existing Dry Dock No 1. Such a facility would meet the future needs for maintaining and modernizing the US Navy’s submarine fleet.

HEGER was tasked by STANTEC, the prime contractor, to provide the designs two(2) caissons with identical size and capabilities to be used interchangeably at the new facility. HEGER was responsible for the structural design of the hull and the naval architecture aspects of the floating gate including stability and draft requirements. HEGER also coordinated the arrangement of mechanical process components with STANTEC, who’s engineers were responsible for the design of those systems.

As part of the hull design, HEGER created a comprehensive 3D computer model of the gate structure for Finite Element Analysis (FEA). The computer model was utilized to verify adequacy of the structural system in support of all design load combinations and evaluate the performance of various perimeter gaskets to ensure the highest quality product was developed prior to construction.

Caisson Gate #1 Replacement - FEA evaluation of Hull Structure
Figure 1 – FEA Evaluation of Hull Structure
Caisson Gate #1 Replacement - FEA evaluation of permitter gasket
Figure 2 – FEA Evaluation of Permitter Gasket

In 2021, the project was awarded to CIANBRO CORPERATION; however, the caisson gates have not yet been constructed.

Charlestown Navy Yard, Boston, MA
Dry Dock No. 1