Your vessel has a forward draft of 26'-11" and an after draft of 29'-07". How many tons of cargo can be loaded before the vessel reaches a mean draft of 28'-06" if the TPI is 69?
A. 204 tons B. 207 tons C. 210 tons D. 213 tons
A. 204 tons B. 207 tons C. 210 tons D. 213 tons
First let's find the initial mean draft.
ReplyDelete26'-11'' + 29'-07"/ 2 = 55'-18"/2 = 56'6"/2 = 28'-03"
Next find the number of inches to the mean draft of 28'-06"
28'-06" - 28'-03" = 3 inches
So we can load cargo to increase the mean draft 3 inches more.
Given the TPI of 69 tons per inch immersion we can find the answer by multiplying the TPI by 3 or 60 Tons/ inch x 3 inches = 207 tons or Choice B.
Keep in mind this question really assumes that the LCF is at Midships and the trim does not change! In the real world any more that is not true. For example a PANAMAX vessel with a LBP of 229 meters in the light condition can easily be trimmed 4 meters by the stern with the LCF also aft of Midships. With out correcting the displacement for trim because the true draft is at the LCF there will be a difference between the actual mean draft and the calculated mean draft in this type of question.
So what is this question actually trying to test? I assume it is calculating the mean draft, testing to see if you know what TPI is, and seeing if you can work with feet and inches.
Do you agree or disagree?
ANS: BRAVO
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