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KVSA Guide > Wiki Pages > Draft Adjustment  

Draft Adjustment

A cubic foot of fresh water weighs, 1,000 ounces, a cubic foot of seawater 1,026 ounces. The increased depth above the centre of the freeboard disc to which a vessel is allowed to be loaded in fresh water, weighing 1,000 ounces per cubic foot, is indicated by a line market F. 

The allowance to the draft for loading in fresh water being known, the allowance, when loading in partly salt water can be easily ascertained from the following table: 

Allowance to the draft in sea-water
Density Draft (inInches)
                     
1.000 1 2 3 4 5 6 7 8 9 10
1.002 0.92 1.85 2.8 3.7 4.6 5.6 6.4 7.4 8.3 9.2
1.004 0.85 1.70 2.55 3.4 4.2 5.1 5.9 6.8 7.6 8.4
1.006 0.79 1.54 2.3 3.1 3.8 4.6 5.4 6.2 6.9 7.7
1.008 0.7 1.38 2.1 2.8 3.45 4.1 4.8 5.5 6.3 6.9
1.010 0.62 1.20 1.9 2.5 3.08 3.7 4.3 4.9 5.6 6.1
1.012 0.54 1.06 1.6 2.2 2.7 3.2 3.8 4.3 4.9 5.3
1.014 0.45 0.95 1.38 1.9 2.3 2.8 3.2 3.7 4.2 4.6
1.016 0.38 0.8 1.15 1.5 1.9 2.3 2.7 3.1 3.5 3.9
1.018 0.3 0.6 0.9 1.2 1.54 1.8 2.2 2.4 2.8 3.1
1.020 0.23 0.4 0.7 0.9 1.15 1.4 1.6 1.8 2.1 2.3
1.022 0.15 0.3 0.5 0.6 0.8 0.9 1.15 1.2 1.4 1.5
1.024 0.07 0.15 0.2 0.3 0.4 0.46 0.54 0.6 0.7 0.8

Example: A  vessel is allowed to load 5 inches deeper in fresh water than in sea-water. What will she be allowed in water of which the density is 1.016?

Fresh water density is  1.000 Loading water density is     1.016 
Sea-water density is    1.026 Sea-water density is 1.026   
  .026    .010

Allowance in loading water density is then 5 inches x 10/26 = 50/26 = 1.9 inches, this being the extent to which she may be loaded over the sea-water mark.

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Last modified at 9/18/2008 12:44 PM  by Jeroen van der Veen