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  #1  
Old 06-03-2009
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Stupid racing question - Navigation

This question is going to reveal just how little I know about racing big boats, so apologies in advance.

I have been reading about interesting instruments systems that provide target boat speed data to the crew. As a software guy I find this intriguing, and I understand how the computer combines all the data to produce target boat speed data and the best course to sail to a downwind mark.

What I don't see is how it knows where you are going. Of course if the crew knows this then they can tell the machines. And I suppose if the race uses well known navigation aids as marks that's easy to do.

But, in the case of a race where the marks have been dropped in place for that race, how does the crew get the mark location information into their computers?

More to the point, someone mentioned that I won't be able to see the marks, so I should "just follow all the other boats." Well we all know the flaws in that strategy! So then, how does the crew know where the marks are, just to get to them?

Thanks...
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Old 06-03-2009
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They'll usually give you a bearing and distance from the previous mark or starting line if its a drop mark course. Check your SI's.
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Old 06-03-2009
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zzrgta is correct

There are at least two methods that are used to define a course. The method that zzrgta has stated where the committee boat has at or very near the start line and on the boat the post the wind/course bearing from the committee boat and the distance.

The other method that is sometimes used is to use two government marks as the course. Mark 1 is one half of the start line (the committee boat or a drop mark is the other) and the turning mark another gov mark. If your sailing in the same waters each week (weekly race), they sometimes print a chart and label each mark with a letter or or some other designation that distinguishes it from the other nearby marks. On the committee boat, the post the mark labels on a panel before the start of the race You pull out your chart with the mark labels and determine the course.

If there is a course change during the race, and it is a multleg race, they put up flag and post the new course.

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Old 06-03-2009
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Quote:
Originally Posted by zz4gta View Post
They'll usually give you a bearing and distance from the previous mark or starting line if its a drop mark course. Check your SI's.
Ah, so they just tell you. Makes sense, thanks!
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Old 06-03-2009
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Quote:
Originally Posted by DrB View Post
If your sailing in the same waters each week (weekly race), they sometimes print a chart and label each mark with a letter or or some other designation that distinguishes it from the other nearby marks. On the committee boat, the post the mark labels on a panel before the start of the race You pull out your chart with the mark labels and determine the course.
Yeah this is how we did it years ago for dinghy club racing, thanks!
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Old 06-03-2009
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Around here there are two yacht clubs that use the same set of marks. Two of them are permanent government marks, the other four are dropped by the race committee in more or less standard locations; the sailing instructions contain lat/lon coordinates of these locations, and they are depicted on a little photocopied chart. Also, you get used to the locations pretty quickly. However I would agree that it's still difficult to see the next mark right away, but with a couple of crew members looking out for it we usually spot it quickly.
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Old 06-04-2009
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If the course is a combination of govt and club marks, set them as waypoints in your GPS prior to race day. I do this with a handheld Garmin and make it somebody's responsibility to navigate to the next mark/waypoint after rounding each mark. Using the "compass" view on the GPS, we have a clear bearing and distance indication to each mark to help keep us on track, regardless of weather or conditions. Chances are the club marks are set at approximately the same coords (probably checked by GPS).

Good luck and have fun.
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Old 06-04-2009
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Well its sure NOT anything new as Flyer had the first full systems allmost 30 years ago in the Whitbread (Now Volvo race)

Many basic handhelds give a VMG readout if you know were your going

We have and Ockam system and you dont want to know thats it worth about 25k BUT it does not really matter were you need to get it takes wind speed ,dirrection ,boat dirrection ect and if you want to add another module give a % of what you should be doing


We pretty much wing it and use the knotmeter as the Ockam cant really figure out the current and other boats
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25k? wow!
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Old 06-04-2009
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Quote:
Originally Posted by tommays View Post
Well its sure NOT anything new as Flyer had the first full systems allmost 30 years ago in the Whitbread (Now Volvo race)

Many basic handhelds give a VMG readout if you know were your going

We have and Ockam system and you dont want to know thats it worth about 25k BUT it does not really matter were you need to get it takes wind speed ,dirrection ,boat dirrection ect and if you want to add another module give a % of what you should be doing

We pretty much wing it and use the knotmeter as the Ockam cant really figure out the current and other boats
So you have $25,000 worth of instruments in the best system available and all you use is the boatspeed indicator? I'll offer a favor; I'll be happy to take the rest of the system off your hands. I'll come and collect the stuff, and only charge a small, discounted rate for my time

I am building up a Nexus system which is quite nice. I selected it because I already had a server and log and depth transducers that came with the boat, and I am adding compass and wind transducers. I am more interested in getting true wind direction then VMG.

But I was wondering how to find the marks, regardless of the instrument package. If the RC provides distance and bearing for set marks or otherwise tells us ahead of time what the marks are it's easy.

I mostly raced dinghys so you could generally see the marks.
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