Cargoes and ShipPort Interface
Alternative Standard for the Intact Stability of Unmanned Deck Cargo Barges Carrying Oil Tank Trucks
 Application
 Definitions
 Prerequisites
 Procedure to determine barge minimum freeboard
 Minimum Freeboard Tables
Application

The following Minimum Freeboard Tables may be used as an alternative to STAB 8 to evaluate the Intact Stability of Unmanned Deck Cargo Barges carrying oil tank trucks and/or tanks:
 which are existing barges not required by LOAD 2 to be assigned load lines
 which are of typical monohull scow type proportion and form which do not have box walls or ramps
 which do not exceed a Cubic Number (CN) of 4000 m³
 whose Breadth to Depth ratio (B/D) is between 3 and 8 (8 ≥ B/D ≥ 3)

This standard does not apply to:
 Crane, Derrick or Hopper Barges
 Oil Tanker, Chemical Carrier or Railcar Barges
 Multihull Unmanned Deck Cargo Barges and those of unusual proportions and form
 Unmanned Deck Cargo Barges outside the parameters of 1(c) & 1(d)
Definitions
“Breadth (B)” – means moulded breadth of barge at main deck amidships in metres (m).
“Breadth to Depth ratio” – means the ratio of the Breadth divided by the Depth (B/D).
“Cubic Number” – means the product of Length, Breadth and Depth (L x B D) in cubic metres (m³)
“Depth (D)” – means the moulded depth of barge at centerline amidships in metres (m)
“Length (L)” – means the moulded length of barge from the aft side of head log plate to the fore side of transom plate at centerline in metres (m).
“Minimum Freeboard” – means the minimum distance from the loaded waterline to the top of the steel main deck measured at any one corner of the barge in metres (m)
“Vertical Centre of Gravity (VCG)” – means the distance from a given weights center of gravity to a given reference plane in metres (m).
Prerequisites

The barge shall not carry fluid cargos and/or bilge water below main deck.

The trim is to be as close to level trim as possible.

Oil tank trucks and tanks shall not have a VCG exceeding 2.25 metres off the steel main deck.
Procedure to determine barge minimum freeboard
Typical Unmanned Deck Cargo Barge of monohull scow type proportions and form with wood sheathed main deck.
Length (L) = 45.700 metres
Breadth (B) = 13.400 metres
Depth (D) = 3.000 metres
Cubic Number (CN) = L x B x D = 45.700 m x 13.400 m x 3.000 m = 1837.14 metres³
Round off to the nearest ten = 1840 m³
Breadth to Depth Ratio = B/D = 13.400 m / 3.000 m = 4.467
Round off to the nearest 1/100 or second decimal place = 4.47
The CN is less than the 4000 m³ maximum limit and the B/D falls between the three (3) to eight (8) limits, therefore, the chart CAN be referenced to determine the barge Minimum Freeboard.
Refer to the chart and read off the barge Minimum Freeboard where the CN of 1840 intersects with B/D of 4.47.
In this particular example the barge Minimum Freeboard reads as approximately 1.000 metre.
In other words, this barge can be loaded with any number of Oil Tank Trucks and/or Tanks on deck as long as the Minimum Freeboard is NOT LESS THAN 1.000 metre at any one corner of the barge and the Vertical Centre of Gravity (VCG) of the Oil Tank Trucks and/or Tanks does not exceed 2.250 metres above the steel main deck.
Typical Unmanned Deck Cargo Barge of monohull scow type proportions and form with wood sheathed main deck (similar in proportion and form to Empire 46).
Length (L) = 67.056 metres
Breadth (B) = 17.678 metres
Depth (D) = 5.182 metres
Cubic Number (CN) = L x B x D = 67.056 m x 17.678 m x 5.182 m = 6142.49 metres³
Round off to the nearest ten = 6140 m³
Breadth to Depth Ratio = B/D = 117.678 m / 5.182 m = 3.411
Round off to the nearest 1/100 or second decimal place = 3.41
The CN is greater than the 4000 m³ maximum limit, therefore, the chart CAN NOT be referenced to determine the barge Minimum Freeboard and must fully comply with STAB 8.
Actual Unmanned Combination Oil Carrier and Deck Cargo Barge of typical monohull type proportions and form with steel main deck (Dakota Creek 180'0” Combination Oil/Deck Cargo Barge).
Length (L) = 54.964 metres (180'0”)
Breadth (B) = 15.850 metres (52'0”)
Depth (D) = 4.420 metres (14'6”)
Cubic Number (CN) = L x B x D = 54.964 m x 15.850 m x 4.420 m = 3843.16 metres³
Round off to the nearest ten = 3840 m³
Breadth to Depth Ratio = B/D = 15.850 m / 4.420 m = 3.5862
Round off to the nearest 1/100 or second decimal place = 3.59
The CN is less than the 4000 m³ maximum limit and the B/D falls between the three (3) to eight (8) limits, therefore, the chart CAN be referenced to determine the barge Minimum Freeboard.
Refer to the chart and read off the barge Minimum Freeboard where the CN of 3840 intersects with B/D of 3.59.
In this particular example the barge Minimum Freeboard reads as approximately 1.45 metres.
In other words, this barge can be loaded with any number of Oil Tank Trucks and/or Tanks on deck as long as the Minimum Freeboard is NOT LESS THAN 1.45 metres at any one corner of the barge and the Vertical Centre of Gravity (VCG) of the Oil Tank Trucks and/or Tanks does not exceed 2.250 metres above the steel main deck.
The actual data indicates the barge can carry a deadweight of 1712.5 tonnes or 27 Oil Tank Trucks at maximum GVW of 63,500 kgs each to satisfy the 0.16 metre radians criteria. In fact the barge main deck can only accommodate 10 Oil Tank Trucks at the most.
The Minimum Freeboard read from the chart is within 8% of the actual Freeboard at 0.16 metre radians and is 13% greater than that at the required area of 0.08 metre radians.
Actual Unmanned Deck Cargo Barge of typical monohull type proportions and form with steel main deck (Key Lake 56'4” Deck Cargo Barge).
Length (L) = 17.170 metres (56'4”)
Breadth (B) = 6.706 metres (22'0”)
Depth (D) = 0.889 metres (2'11”)
Cubic Number (CN) = L x B x D = 17.170 m x 6.706 m x 0.889 m = 102.36 metres³
Round off to the nearest ten = 100 m³
Breadth to Depth Ratio = B/D = 6.706 m / 0.889 m = 7.5429
Round off to the nearest 1/100 or second decimal place = 7.54
The CN is less than the 4000 m³ maximum limit and the B/D falls between the three (3) to eight (8) limits, therefore, the chart CAN be referenced to determine the barge Minimum Freeboard.
Refer to the chart and read off the barge Minimum Freeboard where the CN of 100 intersects with B/D of 7.54.
In this particular example the barge Minimum Freeboard reads as approximately 0.41 metres.
In other words, this barge can be loaded with any number of Oil Tank Trucks and/or Tanks on deck as long as the Minimum Freeboard is NOT LESS THAN 0.41 metres at any one corner of the barge and the Vertical Centre of Gravity (VCG) of the Oil Tank Trucks and/or Tanks does not exceed 2.250 metres above the steel main deck.
The actual data indicates the barge can carry a deadweight of 16.8 tonnes or one (1) only single axle Oil Tank Truck at maximum GVW of 16,850 kgs to satisfy the 0.16 metre radians criteria.
The Minimum Freeboard read from the chart is within 7% of the actual Freeboard at 0.16 metre radians and is 60% greater than that at the required area of 0.08 metre radians.