DSC/GPS - I'm as baffled as Adam and Eve on Mother's Day

[Reptile Smile]

Right, the more I find out, the more confused I become.

 

At Xmas, I took the plunge, and now live on a wonderful old lifeboat. It came set up for coastal work - depth sounder, VHF, etc. My planned Summer jaunt this year is to tootle across the Severn to Cardiff. All very exciting.

 

I bought the RYA map CD, which is £49, and which interfaces with GPS. Whilst they are at pains to point out that it is only for planning and not for primary navigation, it still effectively functions as a plotter.

 

Now - here's the thing. If I used it for navigation, I would use a USB aerial for it (there's also, obviously, the practicality of battery life of the laptop as I have no invertor - I do have a generator, but it seems a bit cack-handed).

 

However, if I did this, how would I manage to interface it to a DSC radio?

 

Or am I barking up the wrong tree? Is there no alternative to getting a plotter and a DSC radio? Do they just share one antenna? And what kind of cable do they use to interface with each other?

 

Cheers all

[Naughty Cal]

I cant tell you much about ours as it was all rigged up and working when we bought the boat. The chart plotter has a small transmitter unit bolted to the cabin roof and the DSC/VHF has an aerial on the roof (big whip type). Other than that i dont know how they communicate to each other.

[carlt]

Get on a course, learn how to navigate the traditional way and use your electronics as a convenience, not a necessity.

 

If you have no VHF licence, by the way, you should not use your radio.

 

Your plotter uses a GPS antenna, your VHF radio uses a VHF antenna.

 

They can be linked, so that your GPS coordinates are transmitted, in case of an emergency and they can also be linked to provide AIS information (and even transmit AIS, these days).

 

Your equipment needs to be NMEA compatible, to talk to each other.

 

I have a DSC/VHF radio linked to my laptop which provides GPS plotting and navigation and AIS monitoring.

 

I also have a portable PC PDA which has my charts uploaded to it and a portable VHF handset in the event of a major electrical meltdown.

 

But, most importantly, I update my position, every 20 minutes, on my paper charts, using old fashioned navigation techniques, to confirm the accuracy of the satellites.

 

If any of the acronyms, abbreviations or jargon need further explanation GET ON A COURSE!

 

Oh and post some photos of your boat!

[Naughty Cal]

All chart plotters carry a warning that they are for planning only and should not be used as the primary source of navigation. As carl says get some paper copies of the correct and up to date charts and check your location on a regular basis.

[carlt]

Edited to add;

 

If the RYA charts you're referring to are these; Clicky then they are perfectly ok for navigating with (are you sure you're not seeing the "unsuitable for navigation" when you are using the zoom facility?).

[GUMPY]

You will need a GPS and a VHF DSC set with its own antenna

 

I have my usb GPS set up to feed NMEA to both the PC and the VHF, using a software interface

http://franson.com/gpsgate/

This enables you to have any number of inputs and outputs, however to send to a VHF DSC set your PC will need a serial port .

 

Easier is to get a Garmin Etrex from Ebay for about £30 and interface that direct to the VHF

[NB Willawaw]

Hi.

 

I tend to do this stuff for a living.

 

DSC only needs a position reference for transmitting an automatic position when you send a distress etc.

 

It normally uses a position sent to it from an external source (i.e. GPS) in NMEA0183 format.

 

Your GPS (be it a black box one or one with a display) needs to be able to provide NMEA to both your RYA software for the plotter

and the DSC part of your VHF radio.

 

The PC will use USB but the DSC modem will need a serial input.

 

I did buy a serial to USB interface from Maplin, so if you have serial coming out of your GPS, it should be possible to feed both.

 

 

Edited to add - having read Idleness' reply, I agree it would be simpler to buy two GPS units - a black box USB one for the plotter and a separate one with serial output for the DSC. As the VHF/DSC is really about safety, it doesn't do to complicate things too much..

 

Right, the more I find out, the more confused I become.

 

At Xmas, I took the plunge, and now live on a wonderful old lifeboat. It came set up for coastal work - depth sounder, VHF, etc. My planned Summer jaunt this year is to tootle across the Severn to Cardiff. All very exciting.

 

I bought the RYA map CD, which is £49, and which interfaces with GPS. Whilst they are at pains to point out that it is only for planning and not for primary navigation, it still effectively functions as a plotter.

 

Now - here's the thing. If I used it for navigation, I would use a USB aerial for it (there's also, obviously, the practicality of battery life of the laptop as I have no invertor - I do have a generator, but it seems a bit cack-handed).

 

However, if I did this, how would I manage to interface it to a DSC radio?

 

Or am I barking up the wrong tree? Is there no alternative to getting a plotter and a DSC radio? Do they just share one antenna? And what kind of cable do they use to interface with each other?

 

Cheers all

Edited April 7, 2009 by NB Willawaw

[NB Willawaw]

The Admiralty Leisure Electronic Chart Plotter products say "This product is intended to be used for navigation only when used in conjunction with Admiralty paper charts that are kept fully up to date"

 

I suspect that is because the electronic charts cannot be updated with the weekly corrections issued by the UKHO whereas paper charts can be corrected using the Notice-To-Mariners which can be downloaded from their website.

 

 

Edited to add;

 

If the RYA charts you're referring to are these; Clicky then they are perfectly ok for navigating with (are you sure you're not seeing the "unsuitable for navigation" when you are using the zoom facility?).

[carlt]

The Admiralty Leisure Electronic Chart Plotter products say "This product is intended to be used for navigation only when used in conjunction with Admiralty paper charts that are kept fully up to date"

 

I suspect that is because the electronic charts cannot be updated with the weekly corrections issued by the UKHO whereas paper charts can be corrected using the Notice-To-Mariners which can be downloaded from their website.

According to the link they can be.

 

I use Imray Digital which are updatable but have an expiry date, when they wiilno longer be supported, so you have to buy them all over again, so I will be switching systems, soon.

 

personally I think it is outrageous that I have to pay for my charts over and over again, especially when we paid for them, out of our taxes, in the first place (off-topic rant over).

[GUMPY]

Edited to add - having read Idleness' reply, I agree it would be simpler to buy two GPS units - a black box USB one for the plotter and a separate one with serial output for the DSC. As the VHF/DSC is really about safety, it doesn't do to complicate things too much..

 

Because I like redundancy I actually carry the following:

2 GPS puck

2 laptop

1 hand-held GPS

Charts and compass, dividers etc

DSC VHF set

VHF hand-held with own external antenna

 

So I have a backup even if I loose all power on the boat.

 

Did get caught out last April when coming up the Thames just past Coryton and it started snowing, visibility down to 100m and the layer of snow on the GPS and wheelhouse roof meant no signal. Could have done with radar at that point........ ended up calling London VTS to ask if it was OK to cross the shipping channel as I just couldn't see what was about.

[NB Willawaw]

Carl,

 

You definitely cant update the UKHO RYA electronic charts in the accepted mariners way.

The charts are re-issued yearly.

 

They say that you can add NTM's but this is actually an edit/graphic function that allows you to highlight a geographic

point or area and write free text next to it.

 

To me, a chart correction means, for example, if a new buoy appears, you should be able to draw that buoy in the new

position with the correct shape/top mark and show its light flash characteristics next to it.

 

With this product, you have to write all those things in text.

 

This is maybe one of the reasons why it is not intended for primary navigation.

 

Personally, the chart plotter is ideal for seeing your position in real time, especially, if you are being set by wind or tide

and are not conscious of it. However, I prefer to also have a single paper chart (£20.80) of the area that I buy from a good chart

agent so I know its up to date at point of sale. I then just keep it updated from the NTM's.

 

Concerning your point about paying twice, I don't believe you do. The primary function of the UKHO is to make charts for the Royal Navy.

This is probably what we pay for in our taxes.

They then use this chart data to supply charting information to commercial ships worldwide. Its now been spun off into a highly lucrative leisure series of chart products like this and waterproof cockpit charts and its this production and distribution that you pay for.

 

Charting, paper or electronic is big business.

 

Just out of interest, a typical initial supply of charts and navigational books for a new deep sea ship is around £30,000.

Edited April 7, 2009 by NB Willawaw

[carlt]

Fair point but i imagine the tax burden will increase, somewhat, if we all went to sea with our Collins Road Atlas.

[NB Willawaw]

We don't make regular crossings as we are a narrowboat, but we have done the Severn, Thames, etc and I do the occasional coastal delivery voyage.

 

The laptop and chart plotter software is just for additional situation awareness.

 

I normally have my own hand held GPS, hand held VHF, paper charts for the area and chart tools.

 

Compasses can be more trouble than they are worth on narrowboats as they are often completely wrong due to the

steel and the fact that there is no compensation.

 

If you get it wrong and the fog/viz comes down at the same time as the GPS dies, a handheld compass is better

than nothing and at least stops you going the wrong way.

 

Because I like redundancy I actually carry the following:

2 GPS puck

2 laptop

1 hand-held GPS

Charts and compass, dividers etc

DSC VHF set

VHF hand-held with own external antenna

 

So I have a backup even if I loose all power on the boat.

 

Did get caught out last April when coming up the Thames just past Coryton and it started snowing, visibility down to 100m and the layer of snow on the GPS and wheelhouse roof meant no signal. Could have done with radar at that point........ ended up calling London VTS to ask if it was OK to cross the shipping channel as I just couldn't see what was about.

[carlt]

Did get caught out last April when coming up the Thames just past Coryton and it started snowing, visibility down to 100m and the layer of snow on the GPS and wheelhouse roof meant no signal. Could have done with radar at that point........ ended up calling London VTS to ask if it was OK to cross the shipping channel as I just couldn't see what was about.

An AIS receiver is a useful, affordable, alternative, to radar.

[NB Willawaw]

Bear in mind that many small boats do not carry AIS and so will be invisible and AIS won't show you the jetties that you can run in to in poor viz etc.

On the other hand, small boat radars with radomes have a very wide beamwidth and are pretty poor at showing

detail. If you really want radar, don't settle for something with less than a 4ft open scanner.

[Reptile Smile]

Get on a course, learn how to navigate the traditional way and use your electronics as a convenience, not a necessity.

 

If you have no VHF licence, by the way, you should not use your radio.

 

Your plotter uses a GPS antenna, your VHF radio uses a VHF antenna.

 

They can be linked, so that your GPS coordinates are transmitted, in case of an emergency and they can also be linked to provide AIS information (and even transmit AIS, these days).

 

Your equipment needs to be NMEA compatible, to talk to each other.

 

I have a DSC/VHF radio linked to my laptop which provides GPS plotting and navigation and AIS monitoring.

 

I also have a portable PC PDA which has my charts uploaded to it and a portable VHF handset in the event of a major electrical meltdown.

 

But, most importantly, I update my position, every 20 minutes, on my paper charts, using old fashioned navigation techniques, to confirm the accuracy of the satellites.

 

If any of the acronyms, abbreviations or jargon need further explanation GET ON A COURSE!

 

Oh and post some photos of your boat!

 

Carl, I was hoping you'd respond, as I know you have a lot of experience in this field, and I was delighted to note that it was in typically combative mode. To address the above - yeah, I've been navigating the traditional way since I was 14 (that's 20 years).

 

I am fully aware that it is illegal to currently use my VHF until I have my SRC course, but thanks for the advice.

 

Thanks for all the input from everyone. I can very much see the sense of the separate GPS for the laptop and the VHF. A little bit of redundancy in this area is probably no bad thing (having said that, I'm currently scouring Ebay for Etrexs, and haven't quite seen one as low as £30 yet!)

 

That was precisely the software, Carl, and no - it's not related to the zoom function, but to the fact that they don't support adequate NTM updates.

 

Pics to follow of the lifeboat this evening, BTW )

 

Thanks to all again.

[carlt]

Carl, I was hoping you'd respond, as I know you have a lot of experience in this field, and I was delighted to note that it was in typically combative mode. To address the above - yeah, I've been navigating the traditional way since I was 14 (that's 20 years).

 

I am fully aware that it is illegal to currently use my VHF until I have my SRC course, but thanks for the advice.

 

Thanks for all the input from everyone. I can very much see the sense of the separate GPS for the laptop and the VHF. A little bit of redundancy in this area is probably no bad thing (having said that, I'm currently scouring Ebay for Etrexs, and haven't quite seen one as low as £30 yet!)

 

That was precisely the software, Carl, and no - it's not related to the zoom function, but to the fact that they don't support adequate NTM updates.

 

Pics to follow of the lifeboat this evening, BTW )

 

Thanks to all again.

I didn't mean to be combative, sorry.

 

I have one of these, on my wheelhouse and plugged into my laptop and am very pleased with how it's performed, over the past 13 months (that is, it works and it wipes clean);

 

Clicky

 

The VHF is plugged into a GPS receiver up the mast, so I don't know what type it is (it was there when I got the boat).