STABILITY AND LOADING · FOR OFFICERS AND CADETS
Load line zones and seasonal areas
The Load Line Convention divides the oceans into 17 zones and seasonal areas. 15 of them change with the date, between Winter, Summer and Tropical periods. The table shows each one's periods and the one in force on 8 November 2026.
Seasonal zones and areas, and their periods
| Zone or area | Type | Periods | On 8 November 2026 |
|---|---|---|---|
| North Atlantic Winter Seasonal Zone I | Winter seasonal zone | Winter: 16 Oct to 15 Apr Summer: 16 Apr to 15 Oct | Winter |
| North Atlantic Winter Seasonal Area | Winter seasonal area | Winter (ships >100 m): 16 Dec to 15 Feb Summer (ships >100 m): 16 Feb to 15 Dec Winter (ships ≤100 m): 1 Nov to 31 Mar Summer (ships ≤100 m): 1 Apr to 31 Oct | Summer (ships >100 m) Winter (ships ≤100 m) |
| North Atlantic Winter Seasonal Zone II | Winter seasonal zone | Winter: 1 Nov to 31 Mar Summer: 1 Apr to 31 Oct | Winter |
| North Pacific Winter Seasonal Zone | Winter seasonal zone | Winter: 16 Oct to 15 Apr Summer: 16 Apr to 15 Oct | Winter |
| Southern Winter Seasonal Zone | Winter seasonal zone | Winter: 16 Apr to 15 Oct Summer: 16 Oct to 15 Apr | Summer |
| Seasonal Tropical Area — North Atlantic | Seasonal tropical area | Tropical: 1 Nov to 15 Jul Summer: 16 Jul to 31 Oct | Tropical |
| Seasonal Tropical Area — Arabian Sea | Seasonal tropical area | Tropical: 1 Sep to 31 May Summer: 1 Jun to 31 Aug | Tropical |
| Seasonal Tropical Area — Bay of Bengal | Seasonal tropical area | Tropical: 1 Dec to 30 Apr Summer: 1 May to 30 Nov | Summer |
| Seasonal Tropical Area — South Indian Ocean (Madagascar) | Seasonal tropical area | Tropical: 1 Apr to 30 Nov Summer: 1 Dec to 31 Mar | Tropical |
| Seasonal Tropical Area — South Indian Ocean (Australia) | Seasonal tropical area | Tropical: 1 May to 30 Nov Summer: 1 Dec to 30 Apr | Tropical |
| Seasonal Tropical Area — China Sea | Seasonal tropical area | Tropical: 21 Jan to 30 Apr Summer: 1 May to 20 Jan | Summer |
| Seasonal Tropical Area — North Pacific (western) | Seasonal tropical area | Tropical: 1 Apr to 31 Oct Summer: 1 Nov to 31 Mar | Summer |
| Seasonal Tropical Area — North Pacific (American) | Seasonal tropical area | Tropical: 1 Mar to 30 Jun Tropical: 1 Nov to 30 Nov Summer: 1 Jul to 31 Oct Summer: 1 Dec to 28 Feb | Tropical |
| Seasonal Tropical Area — Gulf of Carpentaria | Seasonal tropical area | Tropical: 1 Apr to 30 Nov Summer: 1 Dec to 31 Mar | Tropical |
| Seasonal Tropical Area — South Pacific (Coral Sea) | Seasonal tropical area | Tropical: 1 Apr to 30 Nov Summer: 1 Dec to 31 Mar | Tropical |
All-year zones
Tropical zone (all year): the deepest load line. Summer zone: everywhere not in another zone or area.
Questions officers and cadets ask
What are load line zones?
The Load Line Convention divides the sea into zones and seasonal areas: Summer, Winter and Tropical, some all year and some by season. The zone a ship is in, at the date it is there, decides which load line mark it may load to: Tropical allows the deepest draught, Winter North Atlantic the least.
Which load line applies today?
It depends on the zone. On 8 November 2026, the date this page was built, the seasonal areas are in the periods shown in the table. All-year Tropical and Summer zones do not change.
How do I plan a voyage across load line zones?
Load so that the ship is never deeper than the mark allowed in each zone on the date she is there, including fuel and water burnt on the way. The draught at departure may therefore exceed the next zone's mark only by what will be consumed before entering it.
When is the North Atlantic Winter Seasonal Zone I in winter?
From 16 Oct to 15 Apr; summer from 16 Apr to 15 Oct.
Where is the official chart of load line zones?
Annex II of the International Convention on Load Lines, 1966 (and its 1988 Protocol), with its map of zones and seasonal areas. Your flag state and class society can confirm a case.
More guides
Load line zones on your route
Turn on Layers › Load line in the planner to see the zones under your route, with the dates you will cross them. Free with an account.
Open the route planner →About our guides
NaviBoss guides are written and checked by maritime industry experts, masters and deck officers. Each one is built from the same data the planner uses, dated, and rebuilt when that data changes. Spotted something wrong? Tell us on the feedback board.
A planning aid, not for navigation or loading decisions. The Load Line Convention, the ship's load line certificate and the stability booklet always come first.