Canadian Coast Guard: Manoeuvring in challenging conditions.

The Canadian Coast Guard needed to modify the design of two of its in-service river vessels, the Dumit and Eckaloo, improving manoeuvrability in fast flowing, shallow waters. Before acting further, we were asked to investigate the proposal. 

Both vessels are shallow draft designs, based in Canada’s Northwest Territories. They operate on the MacKenzie River, with challenging navigation conditions at certain times of the year. Shaft tunnels house the propellers, directing the flow to the rudders, mounted to the vessels’ transoms. In particular, the manoeuvrability of Eckaloo had been less than ideal since commissioning.

We teamed up with Lengkeek Vessel Engineering Inc. and HydroComp Inc. to perform engineering studies, evaluating the impact of the proposed changes. 

Our support comprised:

• developing computational fluid dynamic (CFD) models of the vessels and river conditions
• using these models to generate baseline results of the current vessel configurations' manoeuvrability at various water depths
• testing the vessels by systematically changing and analysing different manoeuvres. Analyses included time and distance required to make a 180 degree turn when reversing course and diameter of a full 360 degree turn.

The Canadian Coast Guard provided estimates of relative manoeuvrability improvements that could be achieved with alterations to the vessels’ hulls, propulsion systems and rudders. The model was created with Star-CCM+ software, one of the commercial tools we use. 

The results provided a clear understanding of the issues, enabling design alterations to improve the manoeuvrability of both vessels, without impacting other performance criteria. In particular, the Eckaloo benefited significantly.

To operate safely in difficult environments, CFD analysis offers a cost-effective, detailed solution. The approach can assess both initial design and proposed retrofit modifications that may affect a vessel meeting its performance objectives.