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RC400 – listen up all you “diehards”

By Russ, on August 14th, 2009

RC400 on helmFollowing correspondence with one of the readers here I thought I would highlight this item in case you are one of the diehards who keep on using the ill fated RC400 handheld GPS/ Chartplotter abandoned by Raymarine….

The reader was having trouble getting his RC400 to boot past the usual globe picture and the warning message.

So I advised :
1. The usual reset procedure
2. Using the uprated NiMH batteries … Click here for the full description…

But what the reader found was that the Raychart 400 Software UpgrRC400ade v01.03.00 was what he was missing…once downloaded and installed the unit jumped into life.

So above are the 3 definitive thing to do if your unit is playing up…or are they?!…:-)

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1 comment to RC400 – listen up all you “diehards”

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Your chartplotter doesn’t know Course to Steer

By Russ, on August 9th, 2008

I use a Raymarine C120, it can display tidal flow and even “animate” the flow over time, it is fully interfaced to my instruments for wind, and speed – but alas what it doesn’t do is:

a. Tell me precisely what time it is using – yes I know I should know – but why can’t it tell me it is set to UTC or GMT or BST or whatever at the point when I need it i.e. when I am calculating a route! This is critical to working out the time of HW at your reference port of departure, and then the tidal flow for each hour of the passage.

b. The tidal flow is not connected to any sort of calculation of course to steer – so you have to leave your 3,000 dollar technology and get your pencil and notepad out to calculate CTS.

Track CTS3On a recent trip from Dieppe to Brighton, this is a representation of the scribble I had to do to calculate CTS. This is after adding all the tides West and then East along the English Channel for the exact time of day and the duration in hours of the planned passage. Since the passage is at least 12 hours for a normal yacht averaging 5/6kts there will be two tides almost cancelling each other out at this part of the Channel. According to my calculations the net effect was in fact an easterly tide of about 1.5Kts.

There was – luckily – a steady W wind leaving me to hold a close reach all the way (except when avoiding cargo vessel in the Traffic Separation Zone!). But this increased leeway on my rather heavily built 32ft sloop so I used 7 degrees leeway in my calculations.

Giving a final Course to Steer of 310 degrees M.

 

 

 

The other issues is that since the predicted track is not displayed on the C120 screen, you don’t get an easy time estimating whether there are any Track CTSdangers to avoid if you stick with your course to steer. Crossing the English Channel that is not normally such a problem – but there could easily be an island, a rock, an oil rig or even a wind farm in the way…

Naturally the CTS of 310 degrees M that I steered gave me the banana shape course over the ground rather than the red line that the C120 shows as the course between the beginning and end of this journey. (Click on the adjoining screen shot for a larger image.)

So, a plea to Raymarine – please update the C and E series software to do what programs such as Neptune and SeaPro can do !

That would be far more useful than an aerial photo of Dieppe!

 

 

 

 

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August 9th, 2008| 3 comments - be the next!|Tags: - .

Using MARPA instead of AIS…

By Russ, on August 9th, 2008

Returning to Brighton from Dieppe recently I realised that the AIS was not working, but had not time to fault trace or fix it so I thought I would revisit using the radar in earnest.

This is crucial given that the Traffic Separation Scheme that separates the Channel into two one way traffic streams for large vessels adds to the excitement for a yacht – as they say a “tortoise crossing the motorway” – gives you some idea of the experience.

DSC01864The rather shaky photo here – sorry but we were bouncing up and down a bit! – and I didn’t want to leave the helm too long just to take a photo! – shows the MARPA targets acquired on the Raymarine (C120 + Raymarine Radome 2kw) – click on the image for a larger view.

 

Just like the AIS you must take the heading, speed, and collision DSC01865avoidance data with a pinch of salt. I have seen a moored cross channel ferry registering 17kts on the AIS – and so it is here – this screen shot shows variable quality of data eg. was the second vessel in this MARPA list really doing 33kts ! – also the vessels were all clearly on a heading of about 250 degrees magnetic, but the heading data on the display shows the vessels going in all sorts of directions…

The bottom line is that standing in the cockpit with a pair of binoculars and taking bearings was my chosen primary source of data…and although we had bowled long from Dieppe for some 8 hours on a close reach doing 6.5 to 9kts with only the occasional sail trim adjustments… I was forced to reel in the genoa and come to a standstill to let an imposing cargo vessel from Iran thunder past.

Good decision as it turned out since it took a good 10 minutes to cross the wake after it had passed by!.

Track MARPAThis screen shot shows our track as we took avoiding action and then tried to get underway again before the next charging container vessel came barreling down the track.

 

 

 

 

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“No Ais” – on Raymarine C and E Series

By Russ, on August 9th, 2008

DSC01879It is annoying that the Raymarine C and E series which have an AIS interface have no displays to show whether AIS is actually working but has no data to display.

Both these displays simply say “No AIS” in the top right hand status corners of the screen. From the software developers point of view they probably would say indignantly that this language is consistent with the message displayed before the GPS Fix is obtained – in other words “No Fix”.

But the difference is this:

1. “No Fix” means the GPS is still obtaining satellite and the chartplotter is calculating the position of the boat. After few minutes if no fix is still displayed you know the GPS is not working and you need to fault trace. So the passage of time adds another piece of vital data that helps you decide that something is wrong (assuming the USA has not declared war and switched off the whole GPS system!)…whereas…

2. “No AIS” means two different things -
a. the AIS is fully functional, is receiving transmissions, but there are none to display, or
b. the AIS is NOT fully functional, is NOT receiving transmissions, and you need to due some fault tracing…straight away

This means you can set sail unaware that the AIS is faulty – but you would be totally aware if the GPS was faulty.

Please Raymarine, do something about AIS error detection – a suitable button could live nicely on the MARPA/AIS settings toolbar.

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GPS Terminology – nanu nanu :-)

By Russ, on June 16th, 2008

After the last post I had a few emails asking me what PRN 32 means so I thought I would list a few terms that you may come across if you start looking into the GPS system..

SV – Space Vehicle
PRN – Pseudo Random Noise
NANU – Notice Advisory to Navstar Users – there is a free mail list service run by the US Coast Guard to send GPS watchers an automatic status report.

For the latest nanus see the US Coast guard site here.

BTW its called Navstar because that is the correct title of the US military GPS system

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