A not very techy needs advice

[JohnGC]

I've asked this before and I'll ask it again with the certainty of being boring. Why do peeps prefer ipads / tablets to phones? Yes, a big display but at the cost of portability and one handed use. To try and simulate a plotter at the helm by putting a tablet in a plastic bag makes things worse. I have a 10" tablet and never, ever use it to navigate.
Plus 2 or 3 or whatever for the Garmin 128. I have its successor, the 158 and much prefer the numbers to a picture for nav.

Either way, I don't want to hold it or have it sliding around. Waterproof, daylight readable mounted at the helm. Mounted at the chart table.

I have used Navionics on my phone and a 10in tablet in a bag. Much prefer what I have now.

 

[JumbleDuck]

What have you not found. You can install them on two devices.

Is a "device" the storage or the processor? Ie can we test on one Pi and then move the SD card to another one for use? And is a movable USB stick a "device"? It's not clear to me. And can you uninstall from one device to install on another? And do you need a web connection to install? to start up? during use?

I expect it works, but it's all a typical FOSS bodge.

 

[scottie]

Digressing slightly on a fully crewed sailing boat with the chart plotter mounted directly in front of the helmsman it is very useful to have a navigator with a tablet in the cockpit calling the shots without the stress of steering.
Personally I have actually switched the chart plotter off when a novice helmsman would not look at anything else but a enlarged screen whilst oblivious to his surroundings.

 

[garvellachs]

We have:

an Eagle/Lowrance plotter with a small but bright high def screen at the chart table,
a had-held plotter,
a cheap tablet with Memory Map with an admiralty chart set,
leisure folio charts,
an garmin 72 handheld gps,
a NASA AIS screen,
and a small radar set.

We found our way down from Conwy to Plymouth last week without stopping, so two nights at sea. Our style is to to plan waypoints beforehand at the chart table using paper charts and put them into the log and the garmin 72. The rest is back-up really. A couple of examples:

My wife is on watch at night and we're crossing Cardigan Bay heading for the islands off St Davids in pitch black, no moon but very clear. I'm asleep. She wakes me saying sorry but a bright yellow flashing light has appeared dead ahead and it looks really close! I wake up quickly and get upstairs for a look: she's right on all counts. So a quick 30 deg to starboard while we sort out what exactly we're looking at. Nothing close on the AIS screen, nothing close on the radar - both are running and available at the chart table. Nothing close on the plotter either. So we calm down and look more closely at this threatening UFO/buoy/hovercraft. It takes a few seconds to note that it has begun to flash regularly in a pattern - in fact it's just the lighthouse on the Small Islands, 18 miles away, coming up over the horizon exactly where we would expect it to be. But at night it's hard to judge distance. My point is that the radar, AIS and plotter are great back-up tools when extra info is needed fast.

Later in Mounts Bay, pitch black again, I'm on watch and there's something really faint ahead, so faint you can only see it by not looking at it (if you know what I mean). There are plenty of other lights around so easy to miss this one. But I go and check the AIS - nothing where I'm seeing it - then the radar, which shows an echo ahead less than a mile away. Back up top, the light is a little brighter now so 20 deg to stbd we go and back to the radar. Closer. Visually the bearing is beginning to change and I reckon now that we're looking at a yacht sailing the other way on a reciprocal course with a really dim tricolour, dangerously dim, probably been sailing a while and their battery is declining? We sweep past and all is well, but again the radar is looking useful when something small is not transmitting AIS (we don't either but we do have bright lights).

So I would rank radar and AIS ahead of a plotter; I think a tablet with charts is nice for planning and occasionally for rock-hopping with Antares in Scotland, but a small plotter is more useful because it is on all the time and always visible. Integrating radar and AIS on a big-screen plotter must be wonderful I guess, but expensive - as much as our annual boating budget probably - and not justifiable for us and cumbersome when racing too.

 

[AntarcticPilot]

Liquid helium is fun too, but you can't rally slosh it around by the bucketful.

Getting it to stay in the bucket would be fun!

 

[mjcoon]

Getting it [Liquid helium] to stay in the bucket would be fun!

It does need to be well insulated to stop it vanishing... The dewars we had it delivered in (this was in the 1960s) had an outer shell of liquid nitrogen to assist. And we got some money back by collecting the gas we pumped off in getting down to superfluid temperatures in radiosonde balloons. It is in limited supply and party balloons should be more expensive in favour of MRI scanners and the like...

Mike.

 

[AntarcticPilot]

It does need to be well insulated to stop it vanishing... The dewars we had it delivered in (this was in the 1960s) had an outer shell of liquid nitrogen to assist. And we got some money back by collecting the gas we pumped off in getting down to superfluid temperatures in radiosonde balloons. It is in limited supply and party balloons should be more expensive in favour of MRI scanners and the like...

Mike.

I was thinking of its superfluid properties!

 

[mjcoon]

I was thinking of its superfluid properties!

I wondered! But that does take extra work. I remember looking through the observation bare stripe in the glass dewar's silvering and being unable to see the liquid level unless I gave the dewar a careful shake! But the superfluidity was not the topic of our research, just a side-effect...

Mike.

 

[JumbleDuck]

Getting it to stay in the bucket would be fun!

Oh, it stays in buckets fine, although not for long. Unless you pump it down and get the temperature under 2K or so, at which point serious weirdness (technical term) sets in.

 

[JumbleDuck]

It does need to be well insulated to stop it vanishing... The dewars we had it delivered in (this was in the 1960s) had an outer shell of liquid nitrogen to assist. And we got some money back by collecting the gas we pumped off in getting down to superfluid temperatures in radiosonde balloons. It is in limited supply and party balloons should be more expensive in favour of MRI scanners and the like...

The dewars we had for delivery omitted the LN2 layer for simplicity. We had a liquifier on site, so didn't have to store it wrong. The magnets we stuck it into, on the other had, typically had kapton superinsulation, vacuum, LN2, kapton, LN2, vacuum, LHe.

Sorry to ramble. I've noticed that most people who have done cryogenic work remember it with great fondness, as I do. It's something about the inversion of normal physics and trying to stop coolth leaking out ...

And yes, using it in toy balloons is a bloody disgrace.

 

[ShinyShoe]

Is a "device" the storage or the processor? Ie can we test on one Pi and then move the SD card to another one for use? And is a movable USB stick a "device"?

No. A device is based on some wierd key hash from a motherboard, processor and possibly 'hard drive' combo that identifies an individual 'pc'. MS uses something similar to check licencing of systems... Unplugging your hard disk and putting it in a new motherboard / processor combo is likely to annoy a windows licence check. Same applies to this - specifically they say changing OS will upset it.

They (oocharts) have a solution for true portability. See below.

It's not clear to me. And can you uninstall from one device to install on another? And do you need a web connection to install? to start up? during use?

https://manuals.o-charts.org/oesenc_en_US.html

Uninstall - no (unless using the dongle). You allocate the device's fingerprint and can not unallocate it once you downloaded the charts.

Web connection - yes & no. You need the fingerprint from the device you are allocating to. If that is a pi on a boat with no WiFi you can copy the fingerprint to a usb stick, go to a web enabled pc, use the fingerprint to download the charts to the stick then take them back to the boat and copy them to the pi (or use them from the stick)

No need for internet when on the boat.

In short:

OpenCPN creates fingerprint of computer
OoChart download comes encrypted to only work with the fingerprint you told it
OpenCPN recreates fingerprint when opening so it will know if it moved pc, otherwise it will open the OoChart.

If you have the dongle, OoChart uses the fingerprint on the dongle, as long as the dongle is present the chart will work.

Internet only needed to get the charts.

I expect it works, but it's all a typical FOSS bodge.

I don't think it is a FOSS thing. The issue is it's not free. If it was free you'd type sudo apt install ukchart and be done! I think they've done quite a lot to get cheap delivery of charts with a licencing arrangement rather than charge a fortune to compensate for the black market copies.

Portability:
You can have a portable solution using a USB key. The maps still get installed on the device but you transport the key with you.

https://o-charts.org/shop/index.php?id_product=38&controller=product&id_lang=4

You can install the maps on as many machines as you want but only access them with the key plugged in. You can have your maps linked to two keys or 1key and 1device.