Language selection

Marine Safety Advisory Letter No. 01/21

February 1, 2021

Director – Transportation, McKeil Marine Limited
1001 Champlain Avenue, Suite 401
Burlington ON L7L 5Z4

Re :

Marine Safety Advisory Letter No. 01/21
Rudder effectiveness angle on the Florence Spirit (IMO 9314600)
TSB reference M20C0188

On 11 July 2020 at 1606 Eastern Daylight Time there was a collision between the Canadian-flagged general cargo vessel Florence Spirit (IMO 9314600) and the Antigua and Barbuda-flagged general cargo vessel Alanis (IMO 9468085) in the Welland Canal, Ontario near mile 16. While both vessels sustained major damage to their hull structures, there were no injuries or pollution reported. The Transportation Safety Board (TSB) investigation into this occurrence (M20C0188) is ongoing.

The Florence Spirit (formerly named the Arklow Willow) was built by the Kyokuyo Shipyard Corporation in Japan in 2004 (Hull No. 460) to Bureau Veritas rules. It is the third vessel in a series of 3 that were constructed between 2003 and 2004. The other 2 vessels are the Longwave (IMO 9287314) and the NACC Argonaut (IMO 9287302). The Florence Spirit, now classed with Lloyd’s Register, is equipped with a high-efficiency fish tail rudder and is paired with a steering gear capable of turning the rudder up to 70° to both port and starboard. Vaage Ship Management is the technical manager of the Longwave, which has a similar rudder arrangement to that of the Florence Spirit.

Information from the Florence Spirit’s rudder manufacturer (Annex A) indicates that that lift force created by the rudder is varied by both the rudder angle applied and the speed of the vessel. For most operating speeds and all speed above 4 knots, rudder angles above 35° do not increase the lift force created by the rudder.  In fact, the effective lift force decreases by approximately the same rate as it increases up to and including 35°. The TSB obtained rudder position information for the Florence Spirit for the time leading up to the collision which indicated that the rudder was applied at angles of up to 68° to starboard while the vessel’s speed was approximately 9 knots.

The investigation determined that there was no information available to the bridge team regarding the performance of the rudder, including the effective lift force created at various speeds and rudder angles. The steering stand on the Florence Spirit does not contain any notices about the vessel’s speed in relation to the angle at which the rudder is most effective, nor does the steering gear contain a system to limit the rudder angle at speeds where a rudder angle above 35° was less effective.

McKeil Marine Limited may wish to review on-board notices, training, equipment and/or procedures to ensure that rudder angles are applied in a manner that yields the desired lift force. The TSB would appreciate being advised of any action taken by your company in this regard and an investigator may follow up with you at a later date.

Upon completion of investigation M20C0188, the Board will release its investigation report into this occurrence.

Yours sincerely,

Original signed by

Clifford Harvey
Director, Marine Investigations
Transportation Safety Board of Canada