As you pass under the Vicksburg Bridges, you estimate the current as 3.0 mph. What is the speed over the ground, if your vessel is making turns for 10.5 mph?
β’ Difference between speed through the water and speed over the ground β’ How current in the same direction as the vessel affects speed over the ground β’ Basic formula: effective speed = boat speed Β± current
β’ Is the current helping you (going the same way) or opposing you (going the opposite way) as you pass under the bridges? β’ If your engines are making turns for 10.5 mph in still water, how would a 3.0 mph following current change your speed over the ground? β’ Try calculating both possibilities: boat speed PLUS current and boat speed MINUS current, then compare your results to the answer choices.
β’ Be clear whether 10.5 mph is through the water (engine/turns) or already over the ground β’ Check your sign: use "+" when current is with you and "β" when current is against you β’ After calculating, confirm that your final speed is reasonable given that the current is helping your vessel.
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