Discussion in 'Stability' started by stlamont, Jan 8, 2017.

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stlamontNew Member

1. Need urgent help in how to calculate total cargo weight a ship carry.

2. A ship is expected to sail a distance of 3,200 n.m. at an average speed of 12

knots. Calculate her expected time of arrival if she departed on December 28,

2014 at 2200 hours.

2. Joined: Dec 2003
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Olavnaval architect

1:

Payload = Total displacement - light ship weight - provisions (fuel, lube oil, food,...) - ballast water

2:

Distance travelled: 3200 nm
Avg. speed: 12 kts = 12 nm/h

--> Time en route: 3200 nm/(12 kts * 24 h) = 11.11111 d.

Since 2014 was no leap year, the time of arrival is on

March 11th, 2014 (Feb 28th + 11 d), at 0.11111 d - 2 h (remaining two hours from Feb. 28th), thus at 0:40 in the morning (assuming the vessel stays within one time zone).

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HeimfriedSenior Member

No, no, the homework is: doublecheck the results of your friendly helper.

4. Joined: Dec 2003
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Olavnaval architect

Oops!

Correction: January 8th, 2015 at 0040.

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Mr EfficiencySenior Member

Question 1 looks tricky to me !

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kilocharlie2Junior Member

Compliments to Olav, who makes the answers seem simple!

Question 1 involves a technique known to mathematicians as subtraction. Question 2 involves a method known as division.

Of course it leaves out choice of route, time of year, winds, current, coriolis effect, and error.

On the ocean, we do not plow through distance, we plow through moving water and wind. It's a blasted good ship design that makes 12 knot in all weather and current, and a phenomenal skipper who stays on course around 1/8th of the planet, although our GPS / computer combo is making solid inroads into this last part.

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