Do some plotters have a depth alarm?

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

Guest
Playing around with some PC software that accesses my C-Map cartridges, I noticed that, like PC Planner NT (C-Map's own PC charting software) and my plotter (Navman 5500i), it does not seem to have a low depth warning.

In particular, I would have expected the Navman to be able to give an alarm when the depth, a defined distance ahead on the present COG, will fall to a preset limit. Far more useful than depth sounders or even forward-looking sounders. Is it a product liability issue, or what?
 
I use SOB on my laptop:

http://www.digiboat.com.au/

which has a facility for entering minimum safe draught. I presume there is an alarm, but have never heard it <g>

Not sure whether the Lowrance has a depth alarm.. I'll have a look when I get back on board, (25/10... cant wait!!).
 
The ECS I use has around 100 alarms or warnings for various dangers/circumstances when look ahead is enabled, including various depths and contour changes, overhead clearances, etc.

I guess it gets down to what you either know to look for or want when you buy the application - certainly isn't a product liability issue unless the supplier claims it does these things but it turns out that it doesn't.

John
 
Thanks, Richard, I had a look at SOB a couple of years ago but I was so busy doing other things I didn't get my head round it and have dropped it. Now I'm playing around with MaxSea on a trial basis. Since I have C-Map cartridges and the C-Map USB cartridge reader I have the official C-Map offering "PC Planner NT" which, apart from being flaky software, has lots of boxes that you can fill in and which do nothing because they have disabled all the real time stuff. They sell it only for planning before departure and (just to be clear) you can never see a little boat icon on the screen - all you ever see are waypoints and lines. So, just because SOB has the facility to input your draught doesn't necessarily mean... /forums/images/graemlins/smile.gif

Neither my Raymarine radar/plotter nor my Navman provide grounding alarms yet the Navman has a low fuel alarm (if fitted with a fuel sensor) so why not a depth alarm?? Then again, imagine if everyone started using depth alarms and either due to poor cartography, the GPS network per se, the plotter, installation problems, unreliable electronics or even 'finger trouble' the plotter manufacturer started to get claims following groundings. The product liability potential is unthinkable and hard to prove in any given case, putting the plotter manufacturer right in the firing line. Let's face it, with a bill for tens or hundreds of thousands, and in the case of professional crew, peoples' livelihoods, there is good motivation for suing the plotter manufacturer when things go wrong, and allegations of a failure of a vital alarm would make them very exposed.
 
Is that a leisure ECS or a professional unit?

It could be a product liability issue if boats ground with consequential losses and the owners claim that their plotter failed to warn them, or warn them in time. Of course there are traditional depth sounders with alarms and forward-looking ones with alarms, so at first glance it might seem strange that there should be a problem with plotters. However, with plotters you have the added complication of tidal prediction and tidal anomalies as well as old cartography (C-Map cartridges are almost necessarily several months out of date when you first take delivery of them). With old cartography there could be real problems in areas. Anyway, that is the question I am asking by starting this thread. Maybe someone will know.
 
Interesting that about 10 years ago commercial airliners started installing a system called Ground Proximity warning System (a part of the latest version) which does exactly as you describe. ie refers present location and heading and altitude to a map to raise an alarm if a conflict is likely. (a system to be madated in due course) I can't imagine any product liability concerns. olewill
 
That's commercial. I believe that there are grounding alarms for commercial ECS systems for ships but I haven't come across any for the yacht market. Surely it cannot be a cost issue - the processing isn't hard and the software routines for determining the characteristics of a specific point are already written for the cursor. It is only a matter of using the same technique for the boat icon...or there are other ways to do the same thing, I'm only saying that I cannot see a technical problem.
 
C-map ECS has an anti grounding function..with audible alarm, but not a shallow alarm persee.
The depth alarm seems to be the province of fixed depth sounders/fishfinders of which most have a shallow alarm function.

Steve.
 
I didn't know that C-Map made an ECS (other than PC Planner NT software). Is it for yachts? I thought the just did the cartography and media.
 
As Steve says, fishfinders have this option. I have a 5500 but also a Navman 4380 fishfinder, so can set a miminum depth alarm to correspond with the depth I want to "alarm" at from the 5500.

btw, if you get a Navman (I don't know about other makes) fishfinder, the 5500 will allow some of the info from the fishfinder to be displayed on the 5500. I have log speed alongside sog, and also the depth in the top data field.
 
C-Map NT+ provided the facility to warn about approaching shallows (called Guardian) However the Navman 5500 was one of the first to achieve NT+ capability, and they did not implement the Guardian. (one of my first questions to Navman)

I have a habit of comparing echo sounder depth with what is on the chart so not a great loss.
 
I know that fish finders and sounders have low depth alarms, the question is whether anyone makes (for yachts) a plotter that has a low depth alarm in real time from the charted depth, not the depth derived from an external sounder or other kit.
 
The interesting thing is that nobody else has done it either. No, it's no big problem for me but I have a plotter and a conventional depth sounder. Lots of folks fit forward-looking sounders and they are expensive. A plotter-derived signal would be interesting.

My interest is simply the question 'why is nobody doing this' not 'how do I avoid going aground' /forums/images/graemlins/smile.gif

Incidentally, there are quite a few areas with uncharted depths on the NT+ cartridges so I cannot see how the Guardian would work. The first one that comes to mind is an area of shallows between a small island and the mainland on Majorca.
 
At one time C-map ECS was the leading commercial shipping program...way ahead of anything else on the market...still is in some ways.
You cannot buy it anymore and the charts for it are horrendously expensive anyway.
It is possible to find old versions around on the net, but the cartography will be out of date...from about 2001.
C-map has just been aquired by the boeing group (Nobeltec).
We shall have to see if they bring back their ECS type stuff.

Steve.
 
Simrad have it on their CX units - but I'm not convinced of the usefulness. I don't believe it takes your boat's draft into account, or the tide height. It will alarm for objects though.

Rick
 
That makes sense to me - a sort of long-stop to warn you if you are doing something daft rather than a technique for ensuring adequate bottom clearance. The usefulness would depend on it's ability to look forward. The Navman has a programmable heading marker that shows the extrapolated COG based on current conditions, over a range of times (e.g. 10 mins, 20 mins, etc.). You can also specify a corridor width, of course, as you can with any GPS so if you could have a depth alarm covering the 'stub' from your boat outwards, in the direction of travel, for, say, 10 or 20 mins it could be nice to have. I would set it as a matter of routine unless I was approaching a pilotage situation that would take me very close to such things, deliberately.
 
Is that a leisure ECS or a professional unit?

It is targeted at pleasure and small commercial/naval.

Is not something I have specifically looked into with common ECS's available in Europe (MaxSea, Euronav, etc) but I would be surprised if many of them did not do the same.

John
 
Which make and model is it? As for MaxSea, etc., that is software for laptops, to turn a laptop into an ECS. By 'plotter' I mean a piece of marine hardware whose only function is the navigation of the vessel, by design.

At the present stage of product evolution it is important to differentiate between dedicated hardware and software-only products.
 
I was just following your first post where you were talking about PC software you were playing around with and also had said that did not have the capability so wasn't aware that you meant plotters only.

In any event it is Endeavour Navigator produced by HSA Systems - is based on their ECDIS code. Is targeted at straight navigation tasks (and at competent navigators as market is small commercial/naval as well as pleasure, so only does official charts too) and has its own GUI so doesn't have all the gimmicks those targeted mainly just at pleasure users do and no MSWindows GUI (although windows applications can run concurrently with it eg for weather fax, word processing, whathaveyou).

Some pleasure users would be unhappy with it not using HDM NMEA sentences, just HDT (heading true) so only handles magnetic compass if nav computer/instruments/sensors are able to add variation to give the true HDT sentence (which mine do), or one has a sensor that inputs variation (eg many GPS's) or one has a gyro (a real one that is /forums/images/graemlins/smile.gif). However, regardless one can work in magnetic within it for plotting magnetic bearings for manual fixes, clearing, etc from a hand held compass or whatever no problem even if variation ends up having to be manualy entered.

As I say, I would be surprised if other ECS applications were not often the same with respect to warnings and alarms for look ahead dangers but I have not specifically checked. Maybe only those which do the official charts (of which many pleasure targeted ones do) do the warnings?

Regarding your liability question, perhaps one way of considering it is that ECS's (using them as the example case) that do have look ahead warnings obviously can't do the look ahead for dangers if currently using raster charts - so have the situation that if on a raster chart there is no look ahead warnings but if then go onto a vector one then there are. Really left to the common sense of the navigator I would have thought.

John
 
Ok - lets look at the problem ...

A Depth sounder has a regular sounding happening that is feeding info ..... it doesn't rely on outside data as a chart etc. It uses real info coming in. You set on many the offset of transducer depth if you want.

Charting programs can only work on the number shown on the chart at that specific point .... inbetween is ?????? Even in Vector charting sounding data is not a separate layer to work with - so how will program extract that info ? to be able to set an alarm off ... and anyway even with CMapECS - which had grounding alarm - there was notes in ops that it was unreliable and wouldn't work in between where no soundings available.

Add another dimension - the Raster Chart has no way to give info to an alarm system - as all info is embedded into one graphic ... it doesn't have the layer possibilities of Vector ....

That's my view without even having to delve into it too deep ... it's flawed before it starts and probably why no-one seriously goes for it .... cause How ?
 
You must log in or register to reply here.

Share this page

Top