Plotters & Compasses, how does that work then?

Re: Plotters & Compasses, how does that work then?

I remember throwing a hissy fit in work the day they took my AVO 8 away and left me with a Fluke 25 digital multimeter. Then, sacrilege, they did me a favour by removing my analogue vector network analyser and gave me a all singing all dancing digital heap of crud. Trying to set up RADAR receiver phase with a digital meter probably added x4 the time it used to take me. Not all modernisation is good!

Here is the thing. It is the same with compasses, wind anemometers etc etc. With an analogue readout you can follow trend, it makes sense. You will never for instance find those pathetic LED bars on a professional mixing desk.

With digital I found I always tended to set over with a greater error. Lets say I was trying to set up a figure of 10v on something. The two results I could obtain were for example, 9.98v and 10.05v. Instinct makes you set at 10.05v as it has a 10 and a .0 but in fact the first figure is closer. With a good analogue you set the needle closest to 10v.

I wonder how many sailors who rely on digital are always sailing to stbd of their course slightly? Maybe just me?

This does not even touch on the other fine points made here.

I can see the headline now, sailor rescued from rocks found not to have compass on board says representative from MCA........


I was not going to get involved in this.......
 
Re: Plotters & Compasses, how does that work then?

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I'm intrigued, how do you sail a compass course without a compass?

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I have ST60 instruments. Autopilot has fluxgate compass, this is set to true. The autopilot display reads heading when in standby and desired heading in auto.

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Do you find every time you are on passage of any distance the wind always changes in the last few hours and you luff up?
 
rather enjoying this thread. When i did my YM theory, of course lots was on M vs T, and although most of the course was raggies used to moving at quite an exciting pace of 3 knots, I couldnt quite see why we didnt work on True,assuming you had any electronics. Bcz in fact, there was only one thing that did have no option but to work on M-the compass.
Ok, it was an educational course, so fair enough to have an understanding of the issues of T vs M in case you do have to make a lengthy slow passage with a compass alone. Still, for all other situations, surely T makes life simpler?
 
General reply to all...

I prefer true, it's horses for courses.
I have posted this link before. You can see that in many parts of the world using magnetic is a pain in the bum!
 
Re: Plotters & Compasses, how does that work then?

Blimey, you were lucky, if the electrics had gone down you might have been stuck up there all day!
(The old ones are the best!)
Oh, and one final point about using true or magnetic. I use true on the charts so that I can use my Captain Fields Pattern parallel rule. It's not rocket salad to make a mental variation calculation.
 
Re: Compasses, etc? You haven\'t got one?

Another True ( ouch! ) story:

This may be pertinent to the Chentlemen's Cruise. Some years ago I was a 'jest' on a friend's new and exotic £300k sailboat, and we wandered for a few days up and down the Sound of Mull. Coming back down the Sound, aiming to pass through between Lismore Light and Lady's Rock, I was steering in showery weather while my host was fiddling about below, trying to get various instruments to work.

I was enjoying the multi-paged features on his top model Raytheon plotter, mounted on the companionway sliding hatch - the track and heading vectors expanding and shifting with every little windshift - when I noted a big rain squall coming up fast behind. As it does thereabouts! "Where's your compass?" I asked, thinking he hadn't got round to fitting one on the binnacle and had a wee HBC on a bracket somewhere. "Don't need one with this," he replied smugly, patting his multi-colour chart plotter miracle-of-technology, "Does everything I need on its own."

No problem. I had a good look around, identified where the hazards were and that we were in clear water, then pulled my oilies hood up real tight - as one does thereabouts! Seconds later, the downpour hit, and visibility dropped to about 10 feet - as it does thereabouts! I held our course.....

The racket brought my friend up, just in time to see a solid 'grey wall' advance across the plotter's screen - just like the rain. Perplexed, we both stared at this coincidental break in service, then realised that we were sailing off the edge of the installed chart cartridge. Matey panicked, for he hadn't been following where we were, and now hadn't a ( visual ) clue! He dove below, and foul curses rent the air as a stream of books, tools, torch batteries, keys and other missiles flew up from his crowded chart-table drawer.

He couldn't find the other wee chart cartridges! He had no compass on the boat! And he knew only that there were some some big sticky-up rocks nearby, and he couldn't see them!

He was panicking, and I had a fit of the giggles. The more he shouted, waved his arms, and rushed about, the more hysterical with laughter I got..... He was not amused.

The boat, needless to say, was unscathed - 'cos I'd ensured plenty of sea room and knew exactly where we and the hazards were. We also had the sounder.... But we didn't have the plotter contributing when it was most needed. Nor the owner....

I don't think he ever forgave me for his loss of face!


Digital good; analogue better!

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Re: Compasses, etc? You haven\'t got one?

true but this 'modern' world brings many new hazards to that analogue device too - Ipods, mobile phones, blackberries, beard trimers.........all can give you 20 degrees of deviation.

Funilly enough they coexist with a plotter so much more easily! Personally I like the on/off aspect of these digital wonders - you know when it's misleading you as your post so clearly sets out.

Would I be without a fixed 'steering' compass at the helm? No - daft not to have one permenantly there when required. Do I steer by it - equally no - I have 3 plotter screens at the helm too with so much more information.
 
Re: Compasses, etc? You haven\'t got one?

All my experience past and current - and there's a fair amount of that - emphasises that one needs to check that each bit of kit, on which one intends to rely to keep one's a** in one piece, is behaving as it should. That usually means cross-referencing its output to some other, wholly independent source of similar output.
e.g. compass comparisons, echo sounder function crossing 'drop-offs', electronic position indications agreeing with a visual reality.....

Our job remains to evaluate the quality of info coming in, before trusting our boats and our people to decions based on it. That's easier now than it has ever been - but that's no excuse for abdicating.

To those techies who write that 'one should put trust in the electronics', I say I'll trust nothing - neither 'leckie nor analogue - until I have satisfied myself that it is performing properly.

So there....

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Re: Compasses, etc? You haven\'t got one?

certainly wouldn't disagree with the principle - not sure what the 'so there' is all about though I was simply suggesting that it was easier for a significant error to be inadvertantly introduced in to a magnetic compass nowadays than (1) 100 years ago and (2) than a GPS plotter.

To not constantly cross check the available information from all source would simply be bad seamanship - so everyone here would do it all the time!
 
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But also shocked that big boats like that are thundering up the harbour

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Yes. Lots of use for a compass when 'thundering up the harbour' /forums/images/graemlins/laugh.gif
 
Re: Compasses, etc? You haven\'t got one?

In answer to one or two points:

no, i am not inexperienced, nor untrained, there are just questions to which i don't know the answer. I thought it was wise to ask for advice as i respect the accumulated experience on the forum

yes, i am less likely to ask questions in future and yes, i was disappointed in dogwatch's intemperate response. The debate between other forumites as to whether it is best to set the electronics to true or magnetic shows it is not a foolish question to have asked.
 
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