Commercial Marine / Loss Control Services

WHEN HURRICANE SEASON HITS, ARE YOU PREPARED TO KEEP YOUR VESSELS SAFE?

WELL-INFORMED IS WELL-PREPARED.Be ready for hurricane season, which runs from June 1 through November 30. Hurricanes have been the cause of many maritime disasters and unfortunately, there is no single rule of thumb to ensure safety. However, constant monitoring of a hurricane’s potential is critical to minimize its impact to vessels at sea or in port. The strength of a hurricane is measured and categorized on the Saffir-Simpson Scale:

CATEGORY SUSTAINED WINDS STORM SURGE ABOVE NORMAL DAMAGE

I 74-95 MPH 4-5 feetMinor pier damage, some

small craft in exposed anchorages break moorings

II 96-110 MPH 6-8 feet Considerable pier damage & marina flooding

III 111-130 MPH 9-12 feetSerious coastal flooding with smaller structures

destroyed

IV 131-150 MPH 13-18 feet

Major damage to lower floors of coastal structures

from flooding and battering action

V 150+ MPH 18+ feetSome complete building failures, small buildings

overturned and swept away

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Commercial Marine / Loss Control Services

BEST DEFENSE – FOLLOW A HURRICANE AVOIDANCE PLANFollow these guidelines to limit the potential of a close encounter between ship and storm:

FOLLOW THE 34 KT RULEFor vessels at sea, avoiding the 34 KT wind field of a hurricane is paramount. 34 KT is chosen as the critical value because as wind speed increases to this speed, sea state development approaches critical levels resulting in rapidly decreasing limits to ship maneuverability. The state of the sea outside of the radius of 34 KT winds can also be significant enough to limit course and speed options available to the mariner and must also be considered when avoiding hurricanes.

APPLY THE 1-2-3 RULEThis is the single most important aid in accounting for hurricane forecast track errors (FTE). Understanding and use of this technique should be mandatory for any vessel operating near a hurricane. The Mariners 1-2-3 rule establishes a minimum recommended distance to maintain from a hurricane in the Atlantic. Specifically, it refers to the rounded long-term National Hurricane Center (NHC) forecast errors of 100-200-300 nautical miles at 24-48-72 hours, respectively. The danger area to avoid takes account of weather forecasting errors and then is broadened to reflect the maximum tropical storm force (34 knot) wind radius at each of those times by the National Hurricane Center.

Mariners operating in the vicinity of these systems are advised to continually monitor the latest forecasts from the NHC and proceed at their own risk. Larger buffer zones should be established in situations with higher forecast uncertainty, limited crew experience, decreased vessel handling, or other factors set by the vessel master. The rule does not account for sudden and rapid intensification of hurricanes that could result in an outward expansion of the 34 KT wind field.

COMPARE SHIP VERSUS HURRICANE TRACKSIn the dynamic state of moving ships and hurricanes, recurring comparison of hurricane forecast track versus planned ship movement is mandatory. The continual monitoring of the latest official NHC forecasts compared to current or planned evasion options can greatly increase a mariner’s confidence regarding vessel safety.

NEVER CROSS THE “T”Never plan to cross the track (cross the “T”) of a hurricane. The negative effects that heavy weather places on a vessel’s speed and handling combined with sudden accelerations in hurricane motion can place a vessel in unexpected conditions that could result in disaster. Adjustments to course and speed in order to remain clear of the danger area in a hurricane are the most prudent navigation decisions a mariner can make.

WATCH THE FORECAST TRACK TRENDSComparison of the most recent NHC forecast track with forecast tracks from the past 24 hours can sometimes reveal a trend in the forecast motion of a hurricane, such as a noticeable shift right or left (with respect to storm motion). This information may provide an indication as to how the forecast and actual hurricane track are trending and provide more guidance in navigation planning for avoidance, particularly in the 2-3 day forecast range and beyond.

CALCULATE CLOSEST POINT OF APPROACHThe last item to complete in the at-sea risk analysis is comparison of CPA between current and possible evasion options. Over time, increases in CPA between vessel and hurricane based on current navigation decisions should increase the mariner’s confidence in current avoidance plans. However, decreases in CPA should be dealt with immediately. Conduct an immediate review of all evasion options against the latest official forecasts/discussions to determine a new evasion course/speed option to increase CPA from the hurricane.

ASSESS OPTIONS EARLYMariners must be cautioned never to leave themselves with only a single navigation option when attempting to avoid a hurricane. Sea room to maneuver is not a significant factor when operating in the open waters of the North Atlantic, but becomes extremelyimportant in the confined waters of the Western Caribbean Sea/Gulf of Mexico. Early decisions to leave restricted maneuver areas are the most sensible choice.

MAKE TIMELY DECISIONS TO LEAVE PORTThe decision to leave port for hurricane avoidance must be made very early. The most important factor to be taken into account when considering the latest safe departure time and likely avoidance routes is time versus distance. The risk of damage to a vessel at sea increases as the motion of the hurricane increases towards the maximum safe speed of the vessel attempting to leave port. When reviewing these time/distance considerations, mariners should also include the effects “squally weather” associated with the rain bands will have on preparations and movement from port. Similarly, building wind and sea conditions ahead of the hurricane, can also hamper vessel speed and maneuverability. Recognizing these time/distance problems, early decisions to leave port in attempt to avoid hurricanes are crucial.

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Commercial Marine / Loss Control Services