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Old 11-07-2019, 11:21   #301
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Re: Paper Charts or Just Electronic

Exile. I’m in San Diego. Would travels as far North as San Clemente.

Is it the sextant itself you need help with or sight reductions or both?
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Old 11-07-2019, 11:53   #302
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Re: Paper Charts or Just Electronic

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Originally Posted by Pizzazz View Post
You can also use an app called CamSextant, it allows you to use the camera as a sextant (low precision but will do if crossing an ocean).
SV Pizzazz
Cool app, but has anyone tried it at sea? I think I'd need to get one of those gyroscopic camera stabilizers for it! And a third hand
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Old 11-07-2019, 11:57   #303
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Re: Paper Charts or Just Electronic

Doesn’t need a stabiliser as long as the image sensor is fast enough.
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Old 11-07-2019, 12:47   #304
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Re: Paper Charts or Just Electronic

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My boat is e. coast (US) based, presently in the Norfolk, VA area. But I do make it out to S. Cal. on occasion if that's where you are.

I'm nearby and would also be happy to help.
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Old 11-07-2019, 14:32   #305
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Re: Paper Charts or Just Electronic

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Originally Posted by Adelie View Post
Exile. I’m in San Diego. Would travels as far North as San Clemente.

Is it the sextant itself you need help with or sight reductions or both?
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I'm nearby and would also be happy to help.
Many thanks to you both. Truth be told, my ignorance thus far has nothing to do with the sextant or sight reductions, but my own lack of due diligence & study. So in fairness I should probably at least get to a point where I'm sufficiently schooled up to know what questions to ask! I think that the sextant and the SSB are the two remaining systems/skill-sets on my boat that I am not yet on top of. Perhaps when I'm finally able to live aboard and/or do longer passages I'll check these off the list as well. But nice to know there's help to be had along the way.

Btw -- SeanPatrick -- I like your avatar.
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Old 11-07-2019, 14:34   #306
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Re: Paper Charts or Just Electronic

The ammo boxes work because they are mild steel which is a good attenuator of RF energy in the frequency band generated by lightning.

Galileo, GLONAS and Beidou are not “real” global positioning systems with apologies to my European friends. IMO you are wasting your time fiddling with these systems. Nothing is more reliable or accurate day in day out than GPS. It will be thus until all of us discussing here are dead and buried. Don’t believe the fear mongering that US DOD will disable or make GPS inaccurate. They have no reasonable cause to do that. I can safely predict it will never happen. What possible situation would make them want to? GPS is ingrained into all facets of the world economy and the US government will never jeopardize that. They can’t afford the risk. The entire global financial system runs on GPS. As does the global telecom network.

All satellite based navigation systems are susceptible to localized jamming. The non-GPS systems are a bit more susceptible than GPS because the others have much smaller constellations and a fraction of the GPS operational budget. In regions where GNSS jamming is prevalent you need to take special precautions. For example, check your position frequently using radar or paper (radar is the most accurate for this purpose).

If a solar flare or high altitude nuclear burst makes GPS not work globally for an extended period then the other GNSS systems will also have huge problems. But at that point you won’t care, because civilization will begin to crumble.

Bottom line is that it’s a waste of time and resources to worry about GPS. Spend your time and money on having adequate backup devices and a good written log with a written down passage plan including key bailout coordinates. Planning ahead is the best and only practical way to prevent a disaster.

You also need radar in my opinion. It is not optional if you want to run the safest boat possible. The so-called Mark I eyeball can be easily fooled. A radar not so much.
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Old 11-07-2019, 15:59   #307
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Re: Paper Charts or Just Electronic

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Galileo, GLONAS and Beidou are not “real” global positioning systems with apologies to my European friends. IMO you are wasting your time fiddling with these systems. Nothing is more reliable or accurate day in day out than GPS. .
Tell me then, why does my expensive GPS only marine plotter suffer from dropouts and gdop issues even after I brought a new antenna?
Why does it sometimes show me taking a mark on the wrong side on screen to what is actually happening at the time?

My cheap $14 gps/usb puck with opencpn, or tablet with navionics that also picks up the other satellites never has this problem.
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Old 11-07-2019, 16:01   #308
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Re: Paper Charts or Just Electronic

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So to this end, I was much intrigued when transmitterdan posted awhile back his opinion re: the robustness of handheld devices when it comes to lightening strikes. Anecdotal I know, but based on a lot of technical experience in the field so perhaps worth taking some comfort in.

Anyone every heard specifically of an EPIRB being rendered inoperable by a lightning strike?
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Old 11-07-2019, 17:44   #309
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Re: Paper Charts or Just Electronic

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Anyone every heard specifically of an EPIRB being rendered inoperable by a lightning strike?
No, but it's probably a good question for a marine electronics tech/installer or surveyor. Those are the people who likely see more of the aftermath of lightning strikes on boats than anyone else. Perhaps EPIRBs are built to similar standards as consumer devices such as phones & tablets?

Just realized I've been spelling lightening lightning wrong, probably for a long while now. Thanks Stu!
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Old 11-07-2019, 18:47   #310
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Re: Paper Charts or Just Electronic

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Tell me then, why does my expensive GPS only marine plotter suffer from dropouts and gdop issues even after I brought a new antenna?

Why does it sometimes show me taking a mark on the wrong side on screen to what is actually happening at the time?



My cheap $14 gps/usb puck with opencpn, or tablet with navionics that also picks up the other satellites never has this problem.
Is it made by Navico or one of its many brands?

Anyway, GPS in my message means the GPS system built and operated by the US government as compared to similar systems operated by the EU, Russia and China.

The only way to have super high availability in GPS receivers is to carry more than one and always have 2 or 3 made by completely different GNSS module suppliers. That last part is sometimes hard to figure out. You don’t want the same software bug in all your devices.
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Old 11-07-2019, 20:03   #311
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Re: Paper Charts or Just Electronic

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Is it made by Navico or one of its many brands?
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Old 11-07-2019, 20:15   #312
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Re: Paper Charts or Just Electronic

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Originally Posted by Exile View Post
Many thanks to you both. Truth be told, my ignorance thus far has nothing to do with the sextant or sight reductions, but my own lack of due diligence & study. So in fairness I should probably at least get to a point where I'm sufficiently schooled up to know what questions to ask! [...] But nice to know there's help to be had along the way.
You're welcome. If you ever do come up with some questions, do not hesitate to ask. Also, you can find a lot of useful info by searching the archives of NavList.

BTW, I recently wrote a postscript program to generate plotting sheets in pdf format. I was inspired by John F. Hughes' ps plotting sheets.

The program I wrote can be found here. Each element (compass, latitude lines, longitude lines, scales, etc.) can be "turned on or off", and the sheet will automatically scale itself for the latitude you specify. (I recommend using Notepad++ to edit the program and Rampant Logic's Postscript Viewer to view/print the results. Both are free.)

Here is an example of the output:





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Btw -- SeanPatrick -- I like your avatar.
Thanks! It's an Astra IIIb from Celestaire. IMHO, the best bang for your buck when it comes to sextants. Of course, you already have two so you don't need another ... unless you become as fascinated with celnav as I have and end up wanting every sextant you see.
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Old 11-07-2019, 20:19   #313
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Re: Paper Charts or Just Electronic

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Tell me then, why does my expensive GPS only marine plotter suffer from dropouts and gdop issues even after I brought a new antenna?
Precisely because it is a USA GPS only device.

If, like a relatively inexpensive USB GNSS puck, it polled a greater number and variety of satellites (e.g. GLONASS, BeiDou, and QZSS) it would be more accurate.

Anyone telling you differently is just unaware of your location (i.e. longitudes that benefit from coverage from the PRC BeiDou satellites and the Nippon QZSS) and the accuracy thus gained.
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Old 11-07-2019, 23:58   #314
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Re: Paper Charts or Just Electronic

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. . . . Sometimes you can see a ship going in and can record his track ,once again adding clarity and confidence to your picture.. . .

I'm not proud of this story, and I think I know who is going to jump in to heap derision on it, but I'll tell it anyway. Due to an error in preparation, which I shall never ever repeat, I did not have any chart of any kind of a harbour I needed unexpectedly to get into on a dark moonless night, namely Gedser in Denmark, through a difficult winding channel marked with unlit buoys, in a building onshore wind.


Weather was coming in and I could not just stand off until dawn. I stood off just long ago to watch on AIS another vessel getting through the channel and dropped waypoints every time it turned.



Using those waypoints I was able to find the buoys one by one and stayed off the shoals and got into the little anchorage behind the yacht harbor.




I don't understand why this discussion is so polarizing. The main issue is the SKILL. Not the choice of tools. The tools by themselves won't do the job. Electronic charting is a great boon but is not a magic bullet which suddenly means you don't need any skill. Nor is satellite imaging nor is a dumb paper chart. Even the "art of pilotage" as described by Ping -- that particular, powerful method which good sailors know -- may not be enough if you neglect to collect other data by other means when it's necessary, and use other tools, whatever they are, when they can increase your awareness and orientation.
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Old 12-07-2019, 00:17   #315
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Re: Paper Charts or Just Electronic

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. . . You also need radar in my opinion. It is not optional if you want to run the safest boat possible. The so-called Mark I eyeball can be easily fooled. A radar not so much.

I spent the whole summer last year navigating with radar in an area which has never been properly surveyed.


The problem with radar, and with satellite imagery, is that it only shows you what is ABOVE the water (sometimes you can see shoals or mud plumes in a satellite image, but rarely underwater rocks). Radar is a killer app IF you have some kind of cartography based on some kind of survey you can fix your position on. Otherwise it's just a greatly improved pair of eyes.
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