GPS. Or is it GNSS?

One of the Coastal Skipper candidates muttered something about GPS satellites being in geosynchronous  orbits.   Another muttered something in reply about them being confined to equatorial orbits.

This arose from the realization that the variation of a magnetic compass would increase dramatically as one approached the Poles.   Unless,  of course,  one approached along a meridian which passed through the magnetic poles.   Even so,  the dip of a magnetic compass close to the poles would make it very inaccurate.

This led to a discussion that the use of Global Navigation Satellite Systems would be a better way to navigate close to the Poles (or indeed,  anywhere else!).

The LG (in this context,  a Lazy Sailor) was reminded of the time when he attended a five-day Astronavigation class which showed him that for the price of a decent sextant he could buy between 5 and 10 GPS instruments and that for the annual cost of tables he could buy all the batteries those instruments would ever need.

GNSS satellites are,  of course,  in geosynchronous orbits:  they pass over the same spot on the surface once every day or once every half day.   To do this they orbit at a precisely predetermined height at a predetermined speed.   Each has a different orbital angle to the Equator so that a constellation of satellites covers most of the Earth's surface most of the time.

Because the satellites are moving with respect to the receiving instrument the latter must constantly search for other,  more appropriately positioned,  satellites.

By contrast,  communications satellites are placed in geostationary orbits:  they 'hover' above the same point on the surface all the time so that directional antennae (TV dishes!) can remain fixed pointing in one direction.   These satellites orbit at the same speed that the Earth rotates,  and they do so above the Equator.

The LS has always been an advocate for paper charts.

Yes,  they get damp in the well of a small boat,  especially a dinghy,  but they can be enclosed in a waterproof case.

On a recent visit to Imray's offices Amy showed him their new-ish electronic charts on an iPad,  and they were a revelation.   They were,  in appearance,  scanned copies of the paper charts.   No more disappearing detail that is so annoying with vector charts.   Straightforward zoom by 'pinching' and tapping in the classic iPad way.  And when you need the detail charts,  simply zoom in to the detail charts.

The LS has always sailed away from teaching electronic navigation.   He's used the old mantra "better to practice with the machine on the boat",  which doesn't convince even he.

But now he has something sensible to teach.

As soon as he can persuade his iPad to communicate with his monitor and projector he'll use Imray Navigator.

He might even use it on the boat.

Fido's companion

Fido had become unwell;  he had been working too hard.

Fido

Over several years he had done so well that his patch had been enlarged incrementally and he had found himself working all available hours.

"Available hours" is limited;  Husqvarna require that he rest for 7 or 8 hours every day,  so they built it into his firm-ware.   They suggest that he rest for at least one day every week,  but he wasn't able to patrol his entire turf in the available hours.   So,  no rest days.

So he broke down.

The saga of his workshopisation is a sad one,  told elsewhere.   He was lucky to survive,  and he will never go back to that workshop.

Another was found,  and Martin proved to be an able and intelligent technician:  Fido survived and thrived.   But Martin did point out that Fido was not built for the amount of work he was expected to do.

Rover

A replacement?

With Fido working again it seemed harsh to sell him and buy a bigger machine.
A better solution was for Fido to enter semi-retirement and another machine be found to patrol the larger area.
The new machine is a Husqvarna 430X:  Rover.

This was also an opportunity for the LG to ease his workload,  especially as his Sea Cadet duties needed more and more time.
So the vegetable beds were levelled and seeded with grass.   Some of the overgrown shrubs were trimmed back and the slope to the river was smoothed and grassed.
He couldn't bring himself to grass over the asparagus bed,  despite its short season and the beetle.
New cable was laid,  and Rover was activated and released.
Rover's programming turned out to be far more complex than Fido's,  and the LG still isn't sure,  months later,  that he's mastered it.

Decapitated snowdrops

But Rover works,  and he works well.   He copes well with roughish ground and very well with narrow passageways.   He worked,  with reduced hours,  through the winter rain and cold,  but not,  of course,  with the snow.   He coped not so well with the bottom of the slope to the landing stage:  something will need to be rearranged there before the growing season begins again.
The expanded area included some wild flowers under bushes which were removed:  February showed that Rover had no respect for snowdrops.

And Fido?

He was asked to look after the front lawn:  the one that visitors,  students and candidates see first.
He cuts it short,  down to 2cm,  for about 10 minutes every day.
The grass has become thicker and stronger,  and some of the perennial weeds have died down.   But the better grass shows up the patches of moss.

The LG has a new quandary.

He spends no time mowing the lawns,  but the time saved is not spent in a deck chair,  admiring the grass.   He's spending it on lawn maintenance.