Laytime

Weather working day in laytime

Published 12 October 2026 · updated 13 October 2026

A weather working day (WWD) is a working day on which the weather allows cargo to be loaded or discharged. When weather stops work, some time is taken out of laytime (the time the charterer is allowed for cargo work). How much time depends on the exact words. Three different wordings are in use, and for the same rain they give three different answers.

The three wordings

The Laytime Definitions for Charter Parties 2013 were agreed by BIMCO, CMI, FONASBA and the Baltic Exchange. They define each wording separately, in definitions 15 to 18. An earlier set of rules from 1993 had merged the three into one, and the 2013 text deliberately split them again "in line with English law decisions". The definitions apply only when the charterparty (the charter contract) brings them in, but they are the clearest statement of what each phrase means.

Why the plain wording scales the stoppage up

Under the plain form, a day of laytime is a full 24 hours on the clock, but the port may only work part of it. Rain during working hours therefore costs more than its own length. The definition takes out "a period calculated by reference to the ratio which the duration of the interruption bears to the time which would have or could have been worked".

BIMCO's commentary published with the definitions gives the arithmetic. A two hour stoppage in an eight hour working day is pro-rated to six hours. In a twelve hour working day it is pro-rated to four hours. The sum is the stoppage, divided by the working hours, times 24:

8 hour working day     2 / 8  x 24 = 6 hours taken out
12 hour working day    2 / 12 x 24 = 4 hours taken out
24 hour working day    2 / 24 x 24 = 2 hours taken out

The same commentary states the other half of the rule: no deduction is made for rain that falls outside normal working hours. Rain at 0300 at a port that works 0800 to 1600 stopped nothing.

One port call under all three

Take a fixture that allows four days. Laytime starts on Monday 5 October 2026 at 0800. The port works 0800 to 1600, every day of the week. Two spells of rain are recorded in the statement of facts:

• Tuesday 6 October, 1000 to 1200. Two hours, inside working hours. Work stopped.
• Wednesday 7 October, 0200 to 0500. Three hours, at night. No work was planned.

The first two rows are an hour apart. That is typical: the two common wordings usually land close together, and which one favours the charterer depends on when the rain fell. Daytime rain at a port with short working hours favours the plain wording. Night rain favours the 24 consecutive hours wording.

The third row is eight days later. The commentary calls this wording "an artificial day made up of twenty-four working hours" and notes that an eight hour working day equals three calendar days of laytime. It is rare for that reason. If it appears in a recap (the written summary of the deal), check that both sides mean it.

The free laytime calculator on this site takes the excluded time as a figure you enter. Work out the deduction under your own clause first, then enter it, and the calculator prices the result.

Weather counts even while the ship waits

All three definitions cover a ship that is still waiting for its turn. Laytime can be running at anchor, for example after a notice of readiness given under a WIBON clause (whether in berth or not). If rain would have stopped work had the ship been alongside, the time is taken out in the same way. The definitions say so in terms: "or, if the Vessel is still waiting for her turn, it would be possible to load/discharge the cargo without interruption due to the weather".

The reverse does not follow. Weather that only delays the ship reaching the berth, such as fog that closes the channel, does not stop a cargo being worked. Whether that time counts is a different question, answered by the berth and waiting clauses. Notice of readiness covers those.

What counts as weather depends on the cargo

The test in every wording is whether the weather would interrupt loading or discharging of the cargo. That makes it a test of the cargo as much as of the sky.

• Rain stops grain, fertiliser, cement and steel, because the hatches must close. Cargoes such as coal and iron ore are often worked through rain.
• Wind can stop shore cranes or loaders above their safe working limit while the cargo itself is unharmed.
• Swell at an exposed berth can stop work on a clear day.

So the statement of facts needs two facts for every spell: what the weather did, and whether work actually stopped or would have stopped. "Rain 0210 to 0645, hatches closed, work suspended" can be applied to any wording. "Rain during the night" can be applied to none. The statement of facts shows what a usable record looks like.

Three things the weather clause does not do

• It does not except Sundays. A working day is a day when work is normally done by local law or practice. Whether Sundays and holidays count is settled by SHINC or SHEX, which sit beside the weather wording. See SHINC vs SHEX.
• It does not apply after laytime has run out, unless the charterparty says so. Definition 30 says demurrage "shall not be subject to exceptions which apply to Laytime unless specifically stated in the Charter Party". Rain on a ship already on demurrage is paid for.
• It is not used on tankers. Tanker laytime is normally counted in running hours, which the definitions describe as hours that follow one immediately after the other. Weather stops the clock on a tanker only if a clause says so.

This page explains how the wordings are defined and normally applied. It is not legal advice. Where the charterparty does not bring the 2013 definitions in, the same words are read under the law that governs the contract.

References

• BIMCO, CMI, FONASBA and the Baltic Exchange, Laytime Definitions for Charter Parties 2013, with BIMCO Special Circular No. 8 commentary, 2013, definitions 11, 13, 15 to 18 and 30. fonasba.com
• Baltic Exchange, Shipping Glossary, read 12 October 2026. balticexchange.com
• West of England P&I Club, Interruptions and exceptions to laytime in a nutshell. westpandi.com
• BIMCO, GENCON 2022, 2022. bimco.org

Related