DASS Project



Toptech participated in the Dynamic Analysis Support System (DASS) Project, a 5-year cooperative project between US Naval Sea System Command (NAVSEA), Royal Norwegian Navy (SFK), Norwegian and US research institutes and universities, and Norwegian industry. The project developed improved computational methods for the response of high-speed vessels in a seaway. The focus was on commercial monohulls and catamarans built of aluminium, and military monohulls of steel.


Toptech was invited to join the project as a result of the company's experience with global structural analysis of large high-speed vessels, and with ship classification requirements.


Results, computer programs and information from the project were exchanged between participants in Norway and USA. The DASS project had a total budget of USD 8 million, contributed by participants in the form of direct financial support and project work.


Principal areas investigated were:


Loads-and-motion computer codes

Prediction of hydroelastic response of materials and structure

Establishment of dynamic stability criteria for surface ships


In simpler terms, this amounted to developing reliable methods of first-principles design, ie. being able to estimate loads, motions, stability and structural response of fast ships in given sea conditions.


The Scope of Work included:


Developing engineering descriptions of time series wave data

Developing fully non-linear 3-D loads and motion computer codes for predicting local and global hull structural response

Enhancing interface capabilities between the hydrodynamic load prediction program and existing ship structural analysis (finite-element) programs

Developing methodologies for determining allowable-stress values, including also statistical analysis techniques

Developing methodologies for predicting hydroelastic response of materials and structures due to local and global loads

Establishing dynamic stability criteria in intact and damaged condition for monohulls, multihulls, and surface-effect ships

Developing procedures for defining the capabilities and limitations of high-speed craft

Validating and verifying the computer codes and statistical procedures described above

Developing integrated software and methodologies for predicting dynamic response of surface ships to all sea conditions

Conducting training, and developing plans for maintenance and further improvements.

Producing final reports and documentation


Main deliverables from the project were:




Seakeeping Performance

Wave Load Calculations

Slamming Analyses Structural

Design Fatigue Analysis

Wave Load Calculation

Design by Direct Calculations


Computer Programs






LAMP (3-D non-linear loads and motions)


Test Reports


Verification & Validation Reports


The project was completed in 2000. Developmental work has continued at Marintek in Trondheim, Norway, in the form of preliminary ship design tools.