Once all reasonably practical measures have been taken with the ship’s equipment to give generous supply air flows, if the open deck risk is still not acceptable by closed deck
assessments, the ‘reasonably practical’ benchmark is different again. Having exhausted equipment options, we look to the reasonably practical operating
measures. There are opportunities for operating ships to avoid still air and to use crosswind beneficially. The practical avoidance of still air requires knowledge of the port weather
patterns. We give below general descriptions of the discharge port wind patterns, followed by ‘reasonably practical’ guidelines for when not to dock. The generality of the information
on which these criteria are based and their simplistic nature mean that they are likely to be inaccurate in some circumstances. The criteria are intended to be separable from this
report, to be updated and maintained by the industry as further data come to hand. In summary, we propose that the risk management of open decks be addressed in three
ways: i
Build new ships with ‘full’ ventilation of open decks and assess risk on those vessels as for closed decks. Over many years, with fleet renewal, this will make other
approaches redundant. ii
Improve the ventilation of existing open decks as far as is reasonably practical. iii
Require that open decks not meeting closed deck criteria be operated to a set of guidelines which minimise the risk due to low crosswind.
7.2 Discharge Port Wind Behaviour
7.2.1 General comments
In port, there is a higher likelihood of persistently calm conditions a few hours after dark through until mid morning, due to the formation of nocturnal temperature patterns. Also, if it
is calm offshore, there is a very good chance that nearby ports will also have light winds. At the very low wind speeds we are looking at here, there may be a significant variation in the
number of calms experienced from one part of the port to another assuming there are large warehouses, piles of shipping containers, etc near by. The orientation of the ship relative to
the prevailing wind direction is also important, as wind along the ship generates no effective crosswind. Also, the superstructure of the bridge can act as a wind break for the decks on
its lee side.
There are a number of rules of thumb that can be applied as follows: In general, if it is nearly calm over the open waters outside the port, conditions inside the
port are likely to be worse. If winds are light, in the mid afternoon in particular, expect a very calm night unless a
significant weather system is approaching. If there is a uniform deck of cloud overhead, prolonged calm weather is more likely,
particularly if winds are light as the cloud deck approaches. This rule has fewer exceptions in the summer months.
With approaching cumuliform cloud, especially cumulonimbus thunderstorm clouds, there is a good chance the light wind period is about to end.
Outside of the coldest months of the year November to March, in sunny conditions all Middle East ports can be expected to have a sea breeze in before noon.
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If there is a breeze from the north at sunrise except at Kuwait and Aqaba, expect an early fresh sea breeze.
If there is a breeze from the south at sunrise apart from Aqaba, Kuwait, Fujairah and Muscat there could either be an approaching dust storm or several hours of calm
conditions are possible. Wait until the sea breeze arrives before entering port. For Fujairah and Muscat, a moderate southerly or south easterly often means the winds will
not drop to calm quickly.
7.2.2 Red Sea Ports
