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Old 06-02-2013, 01:20   #76
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Re: True or Magnetic for Electronic Nav

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Originally Posted by Kiwi399 View Post
........ They are not all going to fail, surely.
Being sailing long Kiwi????
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Old 06-02-2013, 01:44   #77
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Re: True or Magnetic for Electronic Nav

Aww, come on Geoff...

Right there in the glossy brochure it said that this stuff was REALLY reliable, so if you have several REALLY reliable backups, what could POSSIBLY go wrong???

Hee, hee...

Cheers,

Jim
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Old 06-02-2013, 01:51   #78
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Re: True or Magnetic for Electronic Nav

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Originally Posted by Jim Cate View Post
Aww, come on Geoff...

Right there in the glossy brochure it said that this stuff was REALLY reliable, so if you have several REALLY reliable backups, what could POSSIBLY go wrong???

Hee, hee...

Cheers,

Jim
My bad, I forgot that the glossy brochure is the higher (highest?) authority.

But it does raise the question that if you have two reliable units rather than one, does the chance of failure go double or halve?
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Old 06-02-2013, 01:59   #79
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Re: True or Magnetic for Electronic Nav

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Originally Posted by Wotname View Post
My bad, I forgot that the glossy brochure is the higher (highest?) authority.

But it does raise the question that if you have two reliable units rather than one, does the chance of failure go double or halve?
That depends entirely upon how badly you need the unit to be working!

Jim
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Old 06-02-2013, 02:25   #80
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Re: True or Magnetic for Electronic Nav

"The chances of a bomb on a plane are small. But the chances of two bombs on the same plane are infinitesimal. Therefore, I always carry a bomb when I fly."
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Old 06-02-2013, 02:26   #81
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Re: True or Magnetic for Electronic Nav.

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In John Rousmaniere's book, The Annapolis Book of Seamanship, he recommends doing everything in magnetic unless you're using celestial methods of determining position.

Fair winds and calm seas.
That didn't sound right to me, so I pulled the book off the shelf and I don't think that is his recommendation at all. While he implies that he prefers to work in magnetic and he did give celestial as one reason to use true, his answer is far more nuanced. I think the key quote is "There are good arguments on both sides, with all authorities agreeing that once you chose a style, you should stick with it". (P249 if anybody wants to read it).

I always preferred working in true and since the advent of GPS, I like it even more. And JR says I can as long as I stick with it.

Sorry to backtrack but I just bumped into this conversation.
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Old 06-02-2013, 21:37   #82
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Re: True or Magnetic for Electronic Nav

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Being sailing long Kiwi????
Question one: 3 handhelp GPS units powered by batteries of which you take plenty of spares, one normal Ipad, an Ipad mini, and a cheapo oboard laptop with enough memory for a basic nav programme and storage of some electronic charts in it.

You think they may all fail -- at the same time?

I suppose they could but that would have to be some catastrophic bad luck. No? I mean, if you are storing your spare GPS handhelds in waterproof ziplocs and stowing them along with the batteries - how is it that they could all fail at the same time? By the way - the cost of all the above would be less than a decent metal sextant.

Question two: Pre-electronics when there were only paper charts, there was no backup then of course. So what happened then if you lost your needed chart/s through either bad luck, bad weather (soaked in a storm or whatever disaster scenario this could happen), or even just not having the particular one on board as someone stole it from your boat in the West Indies to chop it up for cigarrette papers?
You are not saying paper charts are infallible?

I am not saying paper charts are to be done away with -- indeed I will have some onboard -- and I bow to your experience -- but just asking these questions because I am truly interested in yours and anyone elses answers.

And If I have a small boat where space and budget is at a premium am I that far off in wanting to do away with most paper charts? Have you seen the cost of them lately?

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Old 06-02-2013, 21:40   #83
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Re: True or Magnetic for Electronic Nav

I know 2 people who have lost all their electronics on their way to the mainland from Hawaii. It does happen. Not often but it does happen. You can follow the airplanes to Hawaii and go north for 10 days and turn right on the return.
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Old 06-02-2013, 21:51   #84
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Re: True or Magnetic for Electronic Nav

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I know 2 people who have lost all their electronics on their way to the mainland from Hawaii. It does happen. Not often but it does happen. You can follow the airplanes to Hawaii and go north for 10 days and turn right on the return.
Yes, but what are the details? I hear and read this all the time "I know someone that lost all their electronics" ..........

Did they only have electronics available that were reliant on their onboard power generating system? Did they not have 3 or 4 handheld GPS backups? I mean, you could buy 10 GPS handheld backups if you were going to be that worried, and probably pay less than a $1000 bucks for the lot if you got them off ebay or whatever.

So, what were the details in this case? It is all too easy to blow off my genuine questions by saying you know someone that lost all their electronics, therefore you must have paper charts as a backup. (Edit: and I am not saying that you were saying that EVM1024 as I appreciate all answers).

Again, I am not saying that you should do away with all charts as I will have a few onboard, and each to their own - but having oodles of expensive charts onboard? I am struggling with that one -- but am open to being convinced I am going down the wrong path.
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Old 06-02-2013, 22:22   #85
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Re: True or Magnetic for Electronic Nav

The details are really not important. We can quibble (not you and I but others) about the details but that misses the point. The point was summed up long ago - The best laid plans of mice and men....

They had 3 handheld GPS as well as a chartplotter. The problem was batteries. They ran out. Could they have had more batteries? Yes. Could they only have turned it on for a short while each day? Yes (actually they did) Could they have had more GPS? yes (none failed it was the power) Could they have had a solar panel? Yes. But they did not. and they are prudent sailors.

Snafu, Foobar, Tarfu Things go bad every once in a while.

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Old 06-02-2013, 23:00   #86
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3 GPS units will fail 3 times as often. Just like twin engine aircraft experience twice as many engine failures as single engine aircraft. But maybe all won't fail at the same time. Maybe.
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Old 06-02-2013, 23:02   #87
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Re: True or Magnetic for Electronic Nav

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3 GPS units will fail 3 times as often. Just like twin engine aircraft experience twice as many engine failures as single engine aircraft. But maybe all won't fail at the same time. Maybe.
The problem was batteries. They ran out.
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Old 06-02-2013, 23:21   #88
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Re: True or Magnetic for Electronic Nav

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The problem was batteries. They ran out.
You see - this is human error. This is their failing not some unforseen act of god that caused their electronics to fail. Excellent looooong lasting AA & AAA batteries like eneloops and the like, are widely available. You should never ever run out.

You said they did not have solar power. Again - that is human error. I would say you are nigh on close to being an idiot if you are off the grid and only reliant upon an engine to power your batteries onboard.

If you have a casual approach to powering your various electronic systems, you would probably have been as likely to be just as casual in the pre-electronic age in having all the charts, up to date almanac, sight reduction tables etc etc. Heck - I bet their were even people whom didn't have or lost their last pen and pencil when all coastal and offshore navigation was calculated onto paper. That's not the fault of the nav method its the fault of the person. The same with electronics.
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Old 06-02-2013, 23:27   #89
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Re: True or Magnetic for Electronic Nav

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3 GPS units will fail 3 times as often. Just like twin engine aircraft experience twice as many engine failures as single engine aircraft. But maybe all won't fail at the same time. Maybe.
That is non-sensical. If I own three cars, and one fails I infinitely improve my odds of getting to work that morning If can turn the key on the next car in my garage. Now if i had forgotten where I put the key/s for my spare car/s - just like I had forgotten to ensure I have loads of spare, cheap, long lasting AA batteries for my spare GPS units- then I truly am a dufus.

And the twin engine aircraft analogy makes even less sense. Sorry. But appreciate your input.
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Old 06-02-2013, 23:37   #90
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Re: True or Magnetic for Electronic Nav

One pack of 8 eneloop long life AA batteries for 14.30 a pack. http://www.amazon.co.uk/1x8-Sanyo-En...0218731&sr=8-1

143 quid buys you 80 long life AA batteries - which is an over-the-top number of backup batteries, but serves to illustrate my point. Even I can afford 143 to make sure I never ever never run out of battery power before embarking on a coastal or offshore passage.
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