Slideshow

2016 Spring – IWN

CSIG CHARTS SAVE THE DAY

The once in a 100 year flooding event has happened again after only 6 years, and brought with it all the devastation for property, animals, homes, businesses, boats and people. However, this time round at least we had the CSIG charts to assist, and they certainly did that.

One of the CSIG lead surveyors, namely Pat McManus, is also both the coxswain and the PRO for the Athlone Sub-Aqua Club, and he tells me about the many incidents that the Club was tasked with during the disaster. Some of these were funny, some had a brilliant result and unfortunately, some were too distressing to mention here. Pat tells me that in a lot of cases the Athlone Subaqua Club took on rescues south of the weir and lock in Athlone, whereas the RNLI targeted mostly Lough Ree. Whereas the markers in Lough Ree were either floating or mostly above water level, those markers south of Athlone were mostly under water completely and navigation to stay in the official channel became almost impossible. It was like travelling on a lake except most of the area was in fact fields.

Enter the CSIG charts. The navigation channel is fully marked and has been surveyed by a number of CSIG members, so the crews knew they had accurate charts and could actually travel very quickly and safely to wherever the event was. The charts proved invaluable and boats, animals and people were all saved in record time.

Therefore, who would attempt to travel during this time you would think, but some did and ended up stuck on land or hedgerows. The photo shows a boat nicely stuck in a field being rescued by the crew of the Club. It was safely retrieved and returned to a very grateful owner. There were many incidents of boats breaking loose and most of these were rescued and returned.

However, one of the more interesting rescues was on Ballymacegan Island, near Esker Riada south of Meelick Lock. The crew received a call to rescue a number of horses who were trapped on the island, and they despatched a RIB and a jet ski to the location. So, how do you rescue horses with a RIB. The trick was to make them swim across to the mainland, and to do this a rope was placed downstream of the proposed crossing, a jet ski was posted upstream and then divers entered the water and herded the horses across. The owner was delighted since these horses represented his business. Here is a video on YouTube rescue of horses

I believe the efforts of the Athlone SubAqua Club deserve a huge thanks and the CSIG was delighted to be able to assist in those efforts.

SURVEYING THE NORTHERN WATERS

When the CSIG was formed about four years ago, the focus for surveying were the two main lakes, Lough Derg and Lough Ree. We still have loads of areas yet in those lakes to survey and we do have teams in both lakes continuously doing that. But the Shannon Erne Waterway (SEW) and both the Upper and Lower Lough Erne were very sparsely covered. I am delighted to say that for the last year the teams in the North have addressed that and are very actively surveying not only the SEW, Upper Lough Erne and Lower Lough Erne, but also the River Bann and the Newry Ship Canal, and have plans to cover the start of the Ulster canal from where it enters Lough Neagh. For example, they have proven a perfectly good navigable channel from the River Bann is available into Lough Neagh, something no one thought existed. This makes the River Bann a viable navigation out of Lough Neagh for many miles. Peter Maxwell, Robert Navan and Pat Shanks are surveying this area in their RIB, and they do this during the winter months. Well done guys.

The CSIG has some data for the North Shannon including Lough Key, but would like a lot more data for this area. So, if anyone wants to help us out, please contact me, Les Saunders at barge41m@yahoo.co.uk and we will get you started. All you need is a chartplotter (almost any type) with a depth transducer attached, and an old laptop. We can set you up with this kit to record your tracklogs and then you send them to us for processing. If you want to see a system working, any of the surveyors would be delighted to take you out and show you how to do it.

TECHI BIT – BRIAN’S DATA LOGGER

When the CSIG started surveying, all of the tracklogs were coming from Garmin 451s chartplotters, which have a limit of 9999 soundings. We sample every second, so this meant each 451s had a limit of about 2.5 hours surveying before the data would start to be overwritten. Furthermore, there was no way of telling if the data being recorded was any good until a mapper interrogated every single sounding manually, a really tedious job. You might ask why would a sounding be bad, well there could be many reasons including, sun spot activity, height differences, weed, and deliberate GPS errors. Unlike in your car, where a satnav will jump to a road, this does not happen on a chartplotter and GPS is notorious for jumping around.

There was also the problem of which boat did the recording, where was the location of the GPS aerial in relation to the sounder, what was the date of the recording and what datum was being used. Amongst many other refinements, it needed to be easy to use, flag instantly for a bad string, eliminate the 9999 limit, identify the boat for later processing and standardise the tracklog. Brian has also automated the output from the Logger so further processing of the data has removed huge amounts of manual interaction. For the Techis, the Logger is written in Visual Basic, and runs under Microsoft Windows, hence the need for a laptop. It cannot be stressed enough what a huge step forward this Logger has been to the CSIG. Many, many, thanks Brian.

I include below Brian’s own write-up to me about his Logger.

BACKGROUND

“When I first started surveying for the CSIG, I was a little frustrated with the inbuilt recording facilities of the Garmin units we were using to capture the survey data.  It was all too easy to lose data or overwrite it as it had a limit of 9999 data points per recording. Whilst this may seem a lot, you are capturing one data point per second and this only equates to a little over 2.5 hours – at which point you needed to start a new recording or you start to lose data.

As a data analyst, I was also interested in the captured data and how it could be processed automatically.  This exposed another issue in that the data was not easy to extract from the recorded file and was also missing useful information.

As NMEA data captured by GPS devices is simply a series of text strings that can be de-coded to reveal the contents it occurred to me that a simple application could be used to get the more detailed data directly from the GPS output of the unit.  Unfortunately there was little available commercially that fitted the bill exactly so I set out to write an application so that it could be moulded to my own requirements.  What started as a simple application soon became much more sophisticated as other surveyors started to use the app and I became responsible for processing all the data. I had to accommodate different GPS units and I also added functionality to make the app more user-friendly.

FUNCTIONALITY

The basic function is to capture the NMEA data strings.  There are many different types of strings but the ones we are most interested in record position and depth. I also use various quality values so that the data can be validated as “good”.

One of my first challenges was synchronising the depth data with the position data.  Whilst the position data has a time stamp, the depth data does not. This required careful programming to ensure I recorded the correct depth at the correct position.  I later added visual indicators to show instantly if the data being recorded was both complete and accurate.
As the data for any survey needs to be corrected for both the vessel being used and the depth of water on the day, I also included the requirement to capture this information as well – this makes the automated processing of the data possible when I receive them from the other surveyors.

Another addition was the ability to capture events. Some events were already captured automatically but I introduced the ability to enter manually something as simply and quickly as possible. If, for example, you want to capture the position of a new or misplaced object you can add a note to the recording, which is automatically, logged with the time, position and depth. 

It can also be used to make recording data in your ships log easier by capturing the distance covered along with time spent both stationary and moving.  There is also one facility that is not used for surveying depths – the ability to geo-tag digital pictures.

Whilst this is “old hat” for many modern cameras and digital phones, there are members of our team (including me) that have older equipment that does not record the position that the photograph was taken at. Using the timestamp of the cameras image and the matching timestamp from a file recorded with my app, I am able to add the GPS position to the exif [1] data of a series of photographs and they can then be viewed on a map in relation to their original location.”

© Brian Willson 2016

SUMMARY

So we head into another year with the CSIG growing in numbers of Beta Testers and Surveyors, new areas are being surveyed, better and better charts are being produced and used, and we are still having fun doing it.  If you would like to become a Tester or a Surveyor, or indeed, if you have IT skills and would like to contribute to this great project, please contact me at barge41m@yahoo.co.uk.

Finally, the CSIG is planning a date to meet in April 2016, which will most probably be held in Athlone, and is for the Beta Testers as well as the core CSIG members. We would like to get feedback on the charts, obtain ideas for the future, acquire some more surveyors, and generally meet up to put faces to the group. I will be announcing this date to the beta testers and CSIG groups shortly, but if you are not on this list please contact me and I will advise details. The event will also be announced on the IWAI Forum.

That’s all for now, have a great start to the season and safe boating.

© Les Saunders 2016