calculation and application of burn off

8/2/2019 Calculation and Application of Burn Off

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Calculation and application of Burn Off

Burn off is defined as the amount of

Fuel, Water, Stores that are consumed fora defined period of time for a particularvessel.

For example a vessel sails loaded fromBrownsville, TX to Oakland, CA a transittime of 17 days. The Departure draft is35-00 arrival draft is 33-04 inches. TheTPI is found in the hydrostatic tables to be109 tons what is the average daily burnoff assuming the speed and weather

conditions remain constant?


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Calculation and application of Burn Off

Calculate the change in draft from arrival todeparture.

Draft = 35- 00- 33-04 = 1-08 or 20.Multiply Draft by TPI for tons consumed. 20 x109 lt/in. =2180 tons

Divide the total tonnage by days enroute; 2180/17=128.23 long tons per day.

After a period of time an average burn off valuefor both light and loaded conditions can be

obtained with a large degree of accuracy.

This value can be used to pre-calculate drafts soas to comply with load line restrictions or draft/trimrestrictions at a particular port.


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Sample Burn off Problem #1

Your vessels Summer draft is 36-08 with aFWA of 10 and a TPI of 103. The MT1 valueat this draft is 1150. You are loading inHouston at a berth with a salinity of 1012.

You are to discharge in Long Beach aftertransiting the Panama Canal where yourdraft is limited to 34-10 fresh water. Burnoff is estimated to be 165 tons per day and

your transit time to the canal is estimated tobe 5 days. What should your sailing draft beupon completion of cargo in Houston


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Sample Burn off Problem

Maximum draft is 34-10 fresh water or34-00 salt water. (10 FWA)

Burn off is 165 tons per day x 5 days or

825 long tons which translates to 8 ofdraft. Therefore you should be at 34-08Salt waterupon completion of cargo inHouston.

Applying FWA for the dock salinity of1012 or 13/25 x 10 = 5.2 inches addedto Salt water draft or 35-01.2 should bethe mean draft upon completion of cargo.


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Sample Burn off Problem # 2

Another example of burn offcalculations applies when your vesselcrosses a load line boundary. Using

the same vessel as before whatshould the final draft be if you areenroute to the Keil Canal and will

cross from Summer to WNA after 8days at sea. Your WNA marks are35- 02.


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Sample Burn off Problem # 2

35-02 Salt water draft for WNA;

burn off is 8 days x 165 tons perday/ 103 (TPI) = 12.8 inches.

35-02 + 13 for burn off = 36-03

Saltwater upon completion of loadingin Houston. Allowing for a salinity of1012 and FWA of 10 the vessel canload to 13/25 x 10=5.2

36-03+5.2 = 36-08 uponcompletion of cargo in Houston

calculation and application of burn off

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