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Loadline Zones

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Loadline Zones

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International Loadline Zones

In the 1966 Load Lines convention, adopted by IMO, provisions are made determining the freeboard of ships by subdivision and damage stability calculations.

The regulations take into account the potential hazards present in different zones and different seasons. The current zones are displayed on a map below:-

 

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International Loadline zones

 

 

When the scanner reports entering and leaving zones it does so by a series of short codes these are cross-referenced to the full zones names in the table below.

 

Code

Zone Description

ASSTZ

Arabian Sea Seasonal Tropical - Tropical: 1 Sep to 31 May, Summer: 1 Jun to 31 Aug

BBSTZ

Bay Of Bengal Seasonal Tropical - Tropical: 1 Dec to 30 Apr, Summer: 1 May to 31 Nov

BLSSZ

Black Sea Summer Seasonal - Summer for ships over 100m in length, Winter Seasonal Area for ships of 100m or less = Winter: 16 Dec to 15 Mar, Summer: 16 Mar to 15 Dec

BSSZ

Baltic Summer Seasonal - Summer for ships over 100m in length, Winter Seasonal Area for ships of 100m or less = Winter: 1 Nov to 31 Mar, Summer: 1 Apr to 31 Oct

CSSTZ

China Sea Seasonal Tropical - Tropical: 21 Jan to 30 Apr, Summer: 1 May to 20 Jan

MSSZ

Mediterranean Summer Seasonal - Summer for ships over 100m in length, Winter Seasonal Area for ships of 100m or less = Winter: 1 Dec to 28/29 Feb, Summer: 1 Mar to 30 Nov

MSTZ

Madagascar Seasonal Tropical Zone - Tropical: 1 Apr to 30 Nov, Summer: 1 Dec to 31 Mar

NAGLZ

North American Great Lakes Zone - Winter: 1 Nov to 31 Mar, Summer: 1 Apr to 30 Apr and 1 Oct to 31 Oct, Tropical: 1 May to 30 Sept

NASSZ

North Atlantic Summer Seasonal - Summer: For ships over 100m in length, Winter Seasonal for ships of 100m or less Winter: 1 Nov to 31 Mar, Summer: 1 Apr to 31 Oct

NASTZ

North Atlantic Seasonal Tropical - Tropical: 1 Nov to 15 Jul, Summer: 16 Jul to 31 Oct

NAWSZ

North Atlantic Winter Seasonal Zone - For ships over 100m in length = Winter: 16 Dec to 15 Feb, Summer: 16 Feb to 15 Dec  For ships of 100m or less in length = Winter: 1 Nov to 31 Mar, Summer: 1 Apr to 31 Oct

NAWSZI

North Atlantic Winter Seasonal Zone I - Winter: 16 Oct to 15 Apr, Summer: 16 Apr to 15 Oct

NAWSZII

North Atlantic Winter Seasonal Zone II - Winter: 1 Nov to 31 Mar, Summer: 1 Apr to 31 Oct

NEPSTZ

North East Pacific Seasonal Tropical - Tropical: 1 Mar to 30 Jun, 1 Nov to 30 Nov Summer: 1 Jul to 31 Oct, 1 Dec to 28/29 Feb

NPSTZ

North Pacific Seasonal Tropical - Tropical: 1 Nov to 15 Jul, Summer: 16 Jul to 31 Oct

NPSZ

North Pacific Winter Seasonal Zone - Winter: 16 Oct to 15 Apr, Summer: 16 Apr to 15 Oct

PSSZ

Pacific Summer Seasonal - Summer for ships over 120m in length, Winter Seasonal Area for ships of 100m or less = Winter: 1 Dec to 28/29 Feb, Summer: 1 Mar to 30 Nov

SIOSTZ

Southern Indian Ocean Seasonal Tropical - Tropical: 1 May to 30 Nov, Summer: 1 Dec to 30 Apr

SLRWSZ

St. Lawrence River Winter Seasonal - Winter: 1 Nov to 31 Mar Summer: 1 Apr to 31 Oct

SPSTZ

South Pacific Seasonal Tropical - Tropical: 1 Apr to 30 Nov, Summer: 1 Dec to 31 Mar

SUMMER

Summer Zone

SWSZ

Southern Winter Seasonal Zone - Winter: 16 Apr to 15 Oct, Summer: 16 Oct to 15 Apr

TROPICAL

Tropical Zone