Term
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Definition
| Wind Driven Current (0.5), current generated by the wind (0.5) which acts upon the surface of the water for a period of time (generally a minimum of 48 hours) (0.5) in open water (0.5). |
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Term
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Definition
| A sideways drifting tendency (0.5) which manifests itself in anything which moves on the earth’s surface (0.5). caused by the earth’s rotation and gravity (0.5). In the Northern hemisphere drift is to the right (0.5). |
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Term
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Definition
| An expanse of open water (1) over which the wind travels causing the sea to build (1) . |
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Term
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Definition
| The movement of a target through the water (1) caused by winds acting against the exposed vertical surfaces above the water line (1) . |
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Term
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Definition
| A mathematically expressed measure of detection capability (1) due to target characteristics, weather and other limitations (1) . |
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Term
Using SAR Graphs and Tables as a guide, select an appropriate leeway drift value for the following target and briefly explain the reasoning for your choice.
Loaded VLCC? |
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Definition
| Generally a low profile with a deep draught (1), accommodation aft could cause the vessel to ‘sail’ before the wind : A value of 3-4% of wind speed should be applied |
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Term
Using SAR Graphs and Tables as a guide, select an appropriate leeway drift value for the following target and briefly explain the reasoning for your choice.
Man overboard wearing a life jacket? |
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Definition
| Only a relatively small area for the wind to act against will be showing above water (1) however a life jacket will cause the target to sit more upright and higher than a target without and therefore : A value of 2% of the wind speed would be reasonable (1) . |
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Term
Using SAR Graphs and Tables as a guide, select an appropriate leeway drift value for the following target and briefly explain the reasoning for your choice.
24m Fishing Vessel? |
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Definition
| Generally a value of 4% would be appropriate for a target of this kind (1). Consideration should be given to varying profiles and whether or not the vessel has its gear deployed (1). |
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Term
Using SAR Graphs and Tables as a guide, select an appropriate leeway drift value for the following target and briefly explain the reasoning for your choice.
Inflatable Dinghy? |
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Definition
| Very light with little or nothing below the water presents a larger surface area when cresting waves (1) : a value of 7-8% should be applied consider reducing if person in water but clinging to craft or dinghy fills with water (1) |
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Term
Using SAR Graphs and Tables as a guide, select an appropriate leeway drift value for the following target and briefly explain the reasoning for your choice.
Passenger Ferry? |
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Definition
| High sided, relatively shallow draught therefore a large area for the wind to act against with little drag below the water line (1): 4-5% of wind speed could be reduced to 3% for loaded vessels (1) |
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Term
Explain your understanding of the following mathematical equation?
De = D x Def? |
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Definition
| De = D x Def : Drift error = Drift Distance x Drift error factor Mathematical equation to determine drift error(0.5) total distance measured from LKP/DSP (0.5) to datum position (0.5) multiplied by drift error factor, normally 0.3 or 30% (0.5) A value of 30% is usually applied but this value could be modified depending on the accuracy of the data used. (0.5) |
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Term
Explain your understanding of the following mathematical equation?
R = X + De? |
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Definition
| R = X + De : Total Probable error (1)= Initial Position Error added to Drift error (1) The way in which the De element is calculated can give rise to inaccurate search areas In rotary tidal or veering wind (0.5) conditions |
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Term
| With the aid of a diagram, explain fully Sector Search. |
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Definition
| This pattern is used when a datum is established with a high degree of confidence (0.5). The search unit passes through the datum several times (0.5) increasing the POD at the Datum, diminishing the POD at the extremities of the search area (1). Each leg is equal to the radius of the search area (0.5). The maximum track spacing is the length of the search leg (0.5). The datum must be marked (0.5). All turns are 120 degrees to the right (1). Further searches are offset 30 Degrees to the right of the final search leg (0.5). |
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Term
| Advantages and Disadvantages of a Rapid Responce? What are the Advantages? |
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Definition
Advantages
● QUICK to calculate
● DATA readily available
● DATUM estabilished with high degree of confidence
● SMALL search area – generally good coverage and POD
● ALLOWS initial good quality search
● SMC retains control |
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Term
| Advantages and Disadvantages of a Rapid Responce? What are the Disadvantages? |
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Definition
Disadvantages
● WDC not considered
● DIVERGENCE not considered
● NOT appropriate for long drift elapse times |
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