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Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation
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Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


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  #31  
Old 02-22-2007
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Quote:
Originally Posted by btrayfors
Capt Hand,

Yeah, easy, but I believe confusing on several counts.

First, the friends boat (Vessel #1) is on a COURSE of 036T, not a BEARING.
Oops, my bad, thanks for catching that. I've edited the post to correct it.

As for the question of the initial bearing from one boat to the other, I responded to the post the way it was asked. This was explained several posts back and a link to a diagram of the vectors was included.

If the bearing of the intial positions is interpreted in the conventional way, from your boat to the friend's boat, then the internal angle between the initial bearing to the friends boat and his course will be 120 deg. The solution is to head on a course of 57.8 deg. The boats will intercept in 28 hours.

Is this horse dead?
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Last edited by CapnHand; 02-22-2007 at 11:09 PM.
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  #32  
Old 02-23-2007
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Okay guys, I have a really easy fix to this problem with the least amount of errors that could occur.

One guy heaves-to and reports their position

the other guy sails to his position.

Done!


Take drift and current into account of the other boat, and it's flawless!
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  #33  
Old 02-25-2007
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sailaway21 is just really nice sailaway21 is just really nice sailaway21 is just really nice sailaway21 is just really nice
To the best of my knowledge, you are allowed to use manoeuvering board sheets in the USCG exam and, as previously mentioned, they come complete with the directions on them. It really is the easiest, most fool-proof way to do the problem. They can also be used for small area plotting sheet construction used in celestial navigation. A word to the wise on USCG exam questions (I've passed four, not counting renewals). The multiple choice answers have accounted for the, "oh good, it's multiple choice if I'm close the answer will be right there" factor. The incorrect answers are the result of the most common errors made in answering the question and, as such, will be exactly wrong. Clever people those CGs. Good luck and remember to read the question. I taught the navigation portion of the license prep course at the USMMA and one of the most common complaints was, "oh, I thought they meant something different". The wording must be read and interpreted exactly as written and not as to what you "think" it's trying to say. (I know that doesn't make sense to those who haven't been there-just think in terms of a double trick question!) If you are in doubt about the accuracy of the wording of the question, you can protest it in writing, but the protest writing comes out of your exam time. Don't waste time asking the proctor for an explanation of the question, he is generally a petty officer with little or no knowledge of the exam itself-he's just there to pass out the papers and monitor.

Just nit-picking, but relative bearings are not marked True, Magnetic, Compass or otherwise. Relative bearings are only related to where the bow is and the bow doesn't change regardless of what choose to call the course you are on.

As btrayfors said, it is of utmost importance to use these navigational terms with rigorous exactitude. Mis-speaking can lead to mis-construing, and that can ruin your day at sea. As Robert Ganier, who has also taught navigation, will tell you-the devil is in the details. Small math mistakes ruin the other 99% done correctly. A "passing" grade on the navigation portion of the exam is 90% on the principle that the correct answer is right where the ship is located and an incorrect answer is, well.....aground.

Allowing for set and drift does not detract from the relevance of the question. We always have to factor that in, usually as we go, and it doesn't change the fact that we do have to set an initial course. I suppose one could intercept Bishop Rock starting with even a westerly heading, but something in the northeastern quadrant might be less time consuming.

Last edited by sailaway21; 02-25-2007 at 06:07 AM.
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  #34  
Old 02-25-2007
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how about this one?

two guys want to meet at sea soon as possible.
what course they have to set respectively to minimize intercept time?

Last edited by Tea-Rex; 02-25-2007 at 08:35 AM.
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  #35  
Old 02-25-2007
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One bit of information is missing, the bearing of the friends boat to yours. With this info you can figure it out in a minute on a manuvering board
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  #36  
Old 02-27-2007
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camaraderie: CapnHand's solution is indeed assuming that my friend's boat is to the west of my boat.

Given that interpretation of the problem, CapnHand's solution is correct.

Kind of a fun little algebra problem!
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  #37  
Old 02-27-2007
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camaraderie is a jewel in the rough camaraderie is a jewel in the rough camaraderie is a jewel in the rough
Yep..Epic, That WAS fun...now my brain is full...may I be excused?
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  #38  
Old 02-27-2007
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Did anyone suggest that the two vessels sail reciprocal courses based on their relative positions? (i.e. toward each other.) It would be the quickest way to close on each other.
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  #39  
Old 02-28-2007
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Quote:
Originally Posted by Goodnewsboy
Did anyone suggest that the two vessels sail reciprocal courses based on their relative positions? (i.e. toward each other.) It would be the quickest way to close on each other.
Looks like the wind is about 10 deg to the reciprocal course. The optimal courses will depend on how well the boat sailing upwind will point.
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  #40  
Old 02-28-2007
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How many blondes are on boat "a" and how many brunettes are on boat "b".
pigslo
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