How close is close

May I butt in and Congratulate you Adrian, on a very fine posting,

Your Topic has reached the 100mark

And its all been a very interesting read for someone who knows very little about GPS.

Congratulations.

Alistair..



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Petrol Rules..
 
Re: Plain English

"there are some very good safety reasons to not have a boat overshoot its waypoint when in track mode"

I cant see how this is avoidable unless we're going to make matters worse, and cross link the plotter/route to the throttles. All we need then is a web interface, and at long last we really will be able to go to sea without going down to the boat. Mind you - should make predicted log events easier!

At a practical level, I think there is an issue with the alarms on pilots - even under sail they are way too quiet. If we could use the DSC alarm, you would never miss a 'track advance' event, or waypoint overshoot!

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Agreed

There used to be a facility on some units for an external alarm, which was great because you could hook it up to a cheap and cheeful but very loud little alarm sounder from the likes of RS and Maplins. I'm not sure it is the case on most modern units...certainly on the last batch I looked at.

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Still no answer to the original question

As has been pointed out we have over 100 posts and NO-ONE has got even close to explain how my GPS moves onto the next waypoint.

My question was - what is "CLOSE ENUF" and how do I tell my GPS that if I have pased within 6 feet or 60 feet away from the turn point that I have passed THROUGH the waypoint (and where do I set the/my definition of close enuf). In open sea 60 may be fine - in a narrow channel it may be 6 foot.

We have all this about being "off course" cus you missed the Waypoint. I want the GPS to say "Ok 20 foot away" so we'll tick that waypoint off and go onto the next one.

We have established that it does not have the 90 rule built in, so what rule does it use, if any ??
My gut feeling is that it continues to point to a way point until you pass within some form of adjustable distance. And is it thrown into confusion if the same waypoint is used later on in the route on the return leg.

Simple question ?

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Re: Agreed

All Raymarine systems can drive a very loud external alarm through the Raymarine NMEA/SeaTalk/RS232 Interface box but it does not qualify as a cheap option. All (most? but certainly including the waypoint arrival) alarms on the SeaTalk bus will be repeated by it with the non critical ones (eg waypoint arrival) delaying a period after the instrument's own alarm going off to give you the chance to cancel before getting blasted.

That was how one got a loud alarm with the old 100/300 Course Computers and I understand the same applies for their new Corepacks too, certainly the smaller ones.

Cannot say for any of the other pleasure vessel systems but the Raymarine Interface Box claims to pick up a number of NMEA alarm sentences (again including the waypoint arrival) so I assume it could possibly be used with any NMEA system.

John

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Re: Still no answer to the original question

Well, I have not read much of this twaddle, but just looked in amazad at 100 posts on a subject that I've never found a need to know about in umpteen years of using GPS/Deca.

You stick some way points in. Press auto button. Boat goes to waypoint, bleeps, press track, boat goes to next way point. If owt goes wrong, for what ever reason. You put the boat back on track, by any available method and carry on.

<hr width=100% size=1> <font color=blue>No one can force me to come here.<font color=red> I'm a volunteer!!.<font color=blue>

Haydn
 
Re: Still no answer to the original question

Sandra! This is starting to annoy me. Why is every bugger so lazy these days. I don't know the unit that you have, but a 0.26 second search on Goggle cam up wiv this <A target="_blank" HREF=http://www.garmin.com/products/gps72/>http://www.garmin.com/products/gps72/</A>.

Its all there in black and white, well colour on my screen, It says what you unit can and can't do. I think the error here is not the units fault, but the operater! It quite clearly states that it has a waypoint proxsimity alarm. Read the blimmin' manual. That is of course if you can understand a manual thats been translated from yank english into japanese then into Tiwanesse then into English English.

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Re: Still no answer to the original question

Adrian, after you sending us all down this adventurous trail I thought the least I could do is read the manual, especially as it is obvious from the thread drift that no one can answer your question and so are avoiding looking silly by getting onto other things which make them look clever instead!

The manual certainly does not say how you advance it to the next waypoint once you get to a waypoint in a route.

You may have fathomed the following out and tried it already, in which case sorry for boring you, but I think it works something like this (referring to Revision A of the manual):

Page 35 - you set up "proximity" waypoints and when doing so you are prompted for a radius. You use these in your route, not ordinary waypoints, and the proximity alarm shows when you get inside the circle of the radius set.

The manual explains how you start off down a route, which gets you to the first waypoint and the proximity alarm is displayed when you get into the arrival circle. You say it does not automatically advance to the next waypoint when one gets to a waypoint - maybe it does though if you use proximity waypoints - if so, that is how it works.

If not - what happens when the proximity alarm is displayed when you get into the circle of the proximity waypoint and you push the GOTO Button? It may advance you to the next waypoint, in which case THAT is how it works - this is what one would expect if you were using a route.

If does not advance to the next waypoint with the GOTO button, then I suspect you are stuck with having to use the GOTO button and select it from the list of Nearest Waypoints as described on page 36. If it advanced to the next waypoint when you pushed the GOTO button as described in the paragraph immediately above, or if it advances automatically as described in the paragraph before that one, then if you happen to miss a waypoint ie arrive outside of the arrival circle, then the Nearest Waypoint list is what you use to select where you want to go next.

Sorry, but I am not going to go out and buy one to practice on. But so everyone knows that you really are clever and it is the manual that is hard going, I can at least confirm that the manual is very hard going and the GPS is more complicated than a Boeing 747.

John

Edit {BarryH - Adrian is correct, the manual does not say how you do the things he has asked}

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by MainlySteam on 15/10/2003 11:39 (server time).</FONT></P>
 
Re: Still no answer to the original question

According to Dale, a guy who tests and writes books on all common handhelds on the market, the 76 calculates the bisecting line

<A target="_blank" HREF=http://www.gpsinformation.org/dale/routes.htm>http://www.gpsinformation.org/dale/routes.htm</A>

relevant info is just over halfway down. Also stuff about alarms

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Re: Agreed

Yes - you could get an external 'Watch Alarm' - but as it was SOLAS compliant it was pricey. When I need a watch alarm I 'wear' a clockwork kitchen pinger on a lanyard. Even I cant doze through that! I set to 15 minute intervals when I know I'm in danger of dozing, but havent got time for a sleep.

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Re: Plain English

"At a practical level, I think there is an issue with the alarms on pilots - even under sail they are way too quiet. If we could use the DSC alarm, you would never miss a 'track advance' event, or waypoint overshoot! "

I am in total agreement - in fact there should also be a system for how alarm sound so that iy easier to know what a beep is coming from and why. I reckon I have at l;east 100 potential things capable of beeping at me on my boat - sometimes it takes a while to foind out what it is!

<hr width=100% size=1>Paul
 
Re: Still no answer to the original question

Yoyr GPS will work on a proximity alarm, speed alarm etc.
You set the waypijnt proximity alarm and activate it - then when you are within that distance of the waypoint it offers the next (assuming you have a route set).
Do you have the manual - if not you can download it.
Paul

<hr width=100% size=1>Paul
 
Re: Still no answer to the original question

"According to Dale, a guy who tests and writes books on all common handhelds on the market, the 76 calculates the bisecting line "

Excellent - now the flippin manual does not state it - I could not find it but it moves onto the next leg as you pass the first regardless of being within the proximity zone - it seems to do this without a warning which is dangerous and confusing.


So it seems that GARMIN do have something like the 90 degree rule and some unhelpful manuals to really complicate things.

After learning this bit of news, I suspect that most GPS units have something similiar. So my ealier conclusions based on manual reading were wrong.

I frankly think that any GPS units that switches to a new waypoint on a route without seeking permission with the option under the control of the user is a dangerous beast.



<hr width=100% size=1>Paul
 
Re: Still no answer to the original question

Exactly why I made the orignal post !!

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Re: Still no answer to the original question

Which Garmin model do you have. Originally you said you had the 72, now everyone is talking about the 76. The 76 may or may not work the same as the 72, but have you bought a 76 now?

Seems confused now as to whether people are saying yours automatically moves to the next waypoint or it doesn't.

If it doesn't, and I suspect it doesn't then I suspect you will find that if you set "proximity waypoints" as described in the manual and put them into a route, when you arrive in the circle you set when you create a proximity waypoint, as long as you have a route defined, pressing the GOTO button will start it using the next waypoint.

In case it is not clear to the others, the manual makes no reference to an audible alarm, just to a visual one.

John

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by MainlySteam on 15/10/2003 20:29 (server time).</FONT></P>
 
Re: Plain English

Ok, so what we need is a centralised siren, and a remote (Bluetooth?) LCD display you carry with you that tells you what the alarm is, and allows you to cancel it?

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Re: Still no answer to the original question

I have a Garmin 176c which works exactly like this, and I love it, and not dangerous, because it's a plotter, and you can see exactly where you are and what your course is going to take you over, without having to worry about proximity alarms and pressing buttons to accept next leg etc. If I want to, I can set a proximity alarm round a waypoint to chosen radius, but never use it. Don't see this as dangerous, it's in my opinion a rather nice feature.

Having said that, my previous (and still back up) is a Garmin III, which also has basic map function, so still a useful tool. If I was using a pure handheld, I'd want to check rolling road display against a paper chart if I was off track anyway.

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Re: Still no answer to the original question

My mistake, mentioned 76 as I BarryH mentioned it and I didn't scroll back up to check - the original post was about a 72.

Doesn't really matter in the context of the link I posted about generic Garmin handhelds, and in my experience of several Garmin units, they all seem to work the same way, including some plotters.

Can't speak for the 72 though, as it seems this may work on a different system. It's worth noting though, that the manuals for 176c nor III that I currently own mention the bisection method of calculation, though they do both mention proximity alarms. The proximity alarm is purely that, and has nothing to do with actually transferring the unit to the next leg

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Re: Kim?

It's apparent that the manuals for many units does not describe how the legs are transferred from one waypoint to another. How about asking the major manufacturers to comment on their various units: eg Garmin, Magellan, Raytheon etc

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Re: Still no answer to the original question

I personally do think that an automatic change of target without alarm etc is dangerous. I think the skipper should always have to accept a change in status. So we will have toi just agree to differ on this as we both lnow the facts.



<hr width=100% size=1>Paul
 
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