John Graham

Director, Co-Founder

John began diving commercially in 1973. With more than four decades of experience, he has extensive expertise in ship repair, salvage, marine construction, and pipeline installation utilizing air and mixed gas diving techniques. He has worked in the North Sea, Gulf of Mexico, and throughout the United States. He continues his active involvement in operations through client and staff engagement.

Commercial Diver, Divers Institute of Technology, 1973

Industry Associations:
• Propeller Club
• Puget Sound Maritime Historical Society, Contributor
• Society of Petroleum Engineers
• Society of Port Engineers

Timothy Beaver


Tim began diving commercially in 1977 and has continued to dive regularly ever since. His experience includes ship repair, salvage, marine construction, pipeline installation, and other services utilizing air, mixed gas, and saturation diving techniques.

• Commercial Diver, Divers Institute of Technology, 1977
• Bachelors of Arts, University of Utah

Industry Associations:
• Association of Diving Contractors International – Board of Directors
• American Salvage Association
• Historical Diving Society – Board of Directors
• Propeller Club
• Puget Sound Maritime Historical Society – Contributor

Executive Leadership

Devon Grennan


Mr. Grennan joined Global in 1995 and learned the business by serving in a variety of roles; including Marine Environmental Supervisor, Environmental Division Manager, and General Manager.

He now oversees the day-to-day operational and administrative needs of the company and facilitates relationships with Global’s partners in the banking, insurance, bonding, and legal industries.

Seattle Business – Grennan Speaking about Global

Bachelors of Science, University of Washington
Safety & Health Construction Specialist, OSHA Region X Education Center, 2006

Industry Associations:
Spill Control Association of America, Board of Directors
Puget Sound Maritime Historical Society
Propeller Club
The Beavers

Dan Pierson

VP of Operations

Mr. Pierson began his career at Global in 1992 as a diver and has steadily worked his way up, serving as saturation diver, Dive Supervisor, Dive Superintendent, and most recently in management roles. Mr. Pierson has an extensive background in all diving mediums, from shallow water to saturation diving in projects ranging from heavy construction to marine casualty response. In his current role, he is responsible for leading and managing all regional offices and operations, as well as corporate asset management and personnel coordination support groups.

Commercial Diver, Divers Institute of Technology, 1991

Industry Associations:
ADCI Board of Directors
DIT Program Advisory Committee Member
The Beavers

Jennifer Jensen

VP of Quality Assurance

Ms. Jensen heads the Quality Assurance Group, directing the efforts of the Human Resources (HR), Health, Safety and Environmental (HSE), Claims and Compliance, and Professional Development groups. She ensures that these support groups are responsive to our employees, clients, and operational needs. Ms. Jensen has held management positions in the airline, higher education, and retail industries. Prior to her work at Global, she was Director of Human Resources and has extensive experience in talent management, leadership development, organizational development, and employee relations.

Bachelors of Arts in Business Administration, Eastern Michigan University
Professional Human Resources Certification

Industry Associations:
SHRM, Society for Human Resource Management
Association for Talent Development
The Risk Management Society
LWHRA, Lake Washington Human Resources Association

Trinity Ng-Yeung

VP of Finance & Administration

Ms. Ng-Yeung began her tenure at Global in 2004, quickly rising as the company Controller and in 2009 being named Vice President of Finance & Administration. She heads the accounting team and leads the administrative support staff. Her direct responsibilities include audits, budgets, financial forecasts, and the ongoing development of Global’s accounting systems.

She has more than 10 years of extensive professional experience in the public and private accounting sectors; performing various tax reporting functions, auditing assignments, and preparing financial statements. Ms. Ng-Yeung’s previous employment in the industrial sector includes working at a CPA firm, a private electrical business, and a crane company.

Bachelors of Arts in Accounting, Portland State University

Industry Associations:
AICPA, American Institute of Certified Public Accountants
WISTA, Women’s International Shipping & Trade Association

Mike Langen

VP of Marine Construction, Engineering, & Technology

Mr. Langen is responsible for project management, engineering support, bid evaluations, cost estimating, field operations, and ROV work. During his tenure with Global, Mr. Langen has had direct oversight over notable projects in Montana, Colorado, Arizona, and New York. Mr. Langen has been responsible for initiating many of the corporate programs currently in place.

Bachelors of Science in Ocean Engineering, University of Washington
A.A.S. in Diving Technology, Highline Community College

Industry Associations:
The Beavers

David DeVilbiss

VP of Casualty & Emergency Response

Mr. DeVilbiss has spent more than 18 years working as a diver, supervisor, salvage master, and project manager on marine casualty response projects around the world, working with the majority of large international salvage companies. He currently serves on the Executive Committee of the American Salvage Association and as Vice President of Marine Casualty Response for Global. His duties include client maintenance, strategic positioning within the salvage and emergency response market, maintaining leading edge technology within the field, and oversight for all of Global’s Marine Casualty Response projects.

Pacific Maritime Article – DeVilbiss Speaking on Salvage

Mechanical Engineering Study, LeTourneau University
Commercial Diver, Divers Institute of Technology, 1997
American Welding Society Certificate

Industry Associations:
American Salvage Association, Executive Committee
Alaska Marine Response Network, Vice Chair