Safe Speed

While travelling recently as a passenger on a fast ferry the Master announced vessel would be entering fog and the fog signal would be heard (do not be alarmed, etc…).  I observed from the numerous GPS displays of position, course and speed throughout the vessel, no reduction in speed was made.  Vessel maintained approx 42 kts.  Small vessels would have had no chance to avoid catastrophic collision.  We were lucky that night – I think!




CHIRP’s Maritime Advisory Board considered this report and a full response from the high speed ferry operator; a “disidentified” extract of which is reproduced below:

“…..following investigation into the circumstances of the sailing concerned we are happy to make the following response.

Unfortunately the white box of the vessels Voyage Data Recorder only maintains records for 21 days so a full examination of the data from this equipment was not possible, other records including the logbook and electronic chart system were however consulted.

The vessel sailed with the company’s most senior Master in command. The Chief Officer was also very experienced with significant command experience prior to joining the company. The bridge team was completed by the Chief Engineer and initially one and then two lookouts providing back up to the Master.

Two ARPA equipped radars operating on the 3cm and 10 cm bands and specifically designed for operation of High Speed Craft with increased scanner rotation speed were continually in use and monitored by the Master and the Chief Officer. In the conditions encountered on the night concerned these radars can track small craft (without radar reflectors) at over 4 nautical miles and can easily pick up fishing floats and seabirds. Compared to this the vessels stopping distance from 42 knots is 480m and turning radius at full speed is 495m.

The weather conditions had been fine with wind light and negligible swell and when the vessel left port there was little cloud and good visibility, during the voyage however patches of reduced visibility were observed and then encountered from 2230 onwards interspersed with periods of good visibility, a suitable warning for passengers was made when it was assessed that sound signals would therefore be required.

Vessel procedures [Extract below: Ed] in accordance with detailed Risk Assessments and in compliance with guidance recommended by MCA and MAIB were implemented. ….. It has been verified by questioning that the procedures were implemented in full….

Speed: An assessment of the appropriate “Safe Speed”.

The nature of the vessel her manoeuvrability and the radar AIS and electronic chart systems fitted to the vessel may be taken into account when assessing the requirements of Rule 6 with respect to safe speed.

As the visibility reduces so the advantages enjoyed by HSC in this respect to an extent reduce and the likelihood of needing to reduce speed increases reflecting the requirement for the vessel to be able to take proper and effective action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances.

The vessels can be crash stopped from 42 knots in 480m (2.6 cables) in under a minute and can turn through 90 degrees in 495m (2.7 cables) in a similar period of time. It is considered therefore that in normal circumstances it is appropriate to proceed at normal operational speed in visibility down to 5 cables.

With respect to visibility less than 5 cables a reduction in speed would normally be necessary unless ALL the following aspects are satisfactory.

(In considering the extent and appropriateness of any speed reduction the need to avoid the generation of excessive wash/wake in sensitive areas (and consequently speeds between 12 and 30 knots) must also to be considered):

1) Bridge team properly closed up and briefed.

2) Both radars working to maximum efficiency (such that small contacts being tracked at appropriate range)

3) Traffic situation carefully assessed, especially concentration of small craft and whether appropriate CPAs are achievable.

4) Navigational situation reassessed and appropriate iaw Operational Manual.

I am satisfied that in the circumstances pertaining on the night in question the decisions made by the Master and his bridge team were appropriate in that all the above situations were duly considered.

The adequacy of procedures is a matter for individual companies based on their own assessments; however the Maritime Advisory Board does make the following observations:

  1. The UK’s MAIB continues to investigate accidents where incorrect assessments of safe speed have been made in restricted visibility and has made recommendations to the UK Maritime and Coastguard Agency to produce additional guidance on the subject (The MAIB does not produce guidance itself).
  2. The Maritime and Coastguard Agency guidance is expected in the near future, however in the interim Masters are reminded of their responsibility to make full assessments based on the prevailing circumstances and conditions.
  3. Whilst full use should be made of the capabilities of electronic systems; Bridge Teams should be aware of the risks of over confidence in the equipment

Bridge Teams are also reminded to consider how much time they require to assess situations and decide upon appropriate actions when considering a safe speed.  This may be particularly relevant in the case of High Speed Craft (HSC).