Defence R and D Canada - Atlantic Dartmouth, NS Canada
HMCS FREDERICTON collided with USNS KANAWHA on 18 November 2010 while FREDERICTON was approaching KANAWHA for replenishment at sea. The ships were in calm water of depth greater than 600 m. VENTURE Naval Officers Training Centre NOTC requested that DRDC Atlantic investigate whether hydrodynamic interactions between the two ships contributed to the occurrence of the collision. It is unlikely that hydrodynamic interaction effects were a factor in causing a collision between FREDERICTON and KANAWHA. In the present report, the non-dimensional lateral separation is defined as the lateral separation distance divided by the beam of the larger ship. FREDERICTON and KANAWHA had a non-dimensional lateral separation of 3.0 when FREDERICTON commenced unexpected motion behaviour. Available data suggest that hydrodynamic interaction forces at the onset of unexpected motion behaviour were likely less than 10 percent of hydrodynamic interaction forces that would have been experienced when closer to the alongside refueling position. During replenishment operations, ships typically have forward speed Froude numbers less than 0.2. Under such conditions, wave-making effects will be small, simplifying analysis of flow conditions.