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 grew up in the business by serving in a variety of roles including Marine Environmental Supervisor, Environmental Division Manager and General Manager. He was appointed President in 2009 and added the title of Chief Executive Officer in 2013. He also serves on Global’s Board of Directors. Mr. Grennan’s primary role is to implement Global’s strategic plan, including development of partners along the West Coast and abroad, and the expansion and growth of Global’s core strategic service lines. His passion is looking for ways to introduce younger generations to the maritime industry, and he is proud to continue his family’s history of working on the water. He holds a Bachelors of Science degree from the University of Washington, and admits to being a law school dropout.

Industry Associations:
Spill Control Association of America, President
Vistage, Seattle
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 joined Global in 2013 as head of the Quality Assurance Group, which encompasses Human Resources (HR), Health, Safety and Environmental (HSE), Compliance, Certifications, Contracts, and Professional Development. She ensures these groups are responsive to the needs of our clients, our operations and our employees. Ms. Jensen holds a BA in Business Administration from Eastern Michigan University; she also holds SHRM-CP and PHR certifications. Prior to working at Global, she gained experience in the airline, higher education and retail industries, holding a number of management positions including Director of Human Resources.

Industry Associations:
Society for Human Resource Management
Association for Talent Development
The Risk Management Society
Lake Washington Human Resources Association
World At Work

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 has over 30 years of experience in the industry as a diver, engineer and manager. After several years working as a commercial diver he returned to school and earned a Bachelors of Science in Ocean Engineering. After graduating, Mr. Langen worked as a design engineer and project manager developing ROVs and other underwater systems and tools. In 1998, Mr. Langen rejoined Global Diving & Salvage, Inc. to organize and market the company’s growing inland marine construction business, developing it into a competitive and nationally sought after business line. As Vice President of Marine Construction, Engineering and Technology, Mr. Langen is responsible for project management, engineering support, bid evaluations, cost estimating and field operations of the marine construction service line, as well as operation of the ROV Division. He also oversees a full time support services group focusing on in-house engineering and design.

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 started in the industry in 1991, and has worked 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 as the Secretary/Treasurer 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.

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

Industry Associations:
American Salvage Association, Secretary/Treasurer
Alaska Marine Response Network, Board Member