Hi Brian. Have you read the article linked to this thread? (Top left). Basically, if your charts are more than a few years old, it is very difficult to correct them, because you don't know how far to go back to find all the corrections they are missing!

Here is the key bit of Richard Thomas’ article (above):“Admiralty NMs (Notices to Mariners) contain all the corrections, alterations and amendments for Admiralty Charts and Publications and are published weekly as booklets. They are also available online, but if you have got behind and need to work back over a number of months, or even years, you can find them all, dating back to 2000, at www.ukho.gov.uk/amd/weeklyNms

“NMs are fine if you do corrections every week - as most professional navigators are required to do - but they can potentially apply corrections to every chart published by the UK Hydrographic Office, and many of the notices are temporary in nature - a new wreck being marked before clearance, for example, or the temporary removal of a buoy.

“So if you haven't corrected your small collection of charts for a while you have to discard a huge amount of information in order to spot the few corrections that apply to you. The UK Hydrographic Office website provides a more focussed service where you can enter the identification number of your specific chart (provided they are Admiralty charts) to find the corrections that apply to that chart.

“You can find it at www.nmwebsearch.com . Trinity House, the authority responsible for the UK's major lights and buoyage, provides a very useful website which gives the latest NMs in specific sea areas around the UK coast. www.trinityhouse.co.uk "

However, NMs only go so far. If there has been a major change in an area, too big to be dealt with by corrections, a new edition of a chart is published. Corrections only therefore apply to the latest edition of a chart.So if you are behind with your corrections, the best advice is to buy new editions, and start keeping up to date with corrections from now on!

It’s not to be recommended, but lots of people sail happily with very out of date charts, by applying a bit of common sense, and paying close attention to the GPS. But if you are doing this you must be aware that things can change. Sandbanks shift, and buoys are moved. And then you are faced with the question: which do you believe? The GPS that says you are safe, or the buoy that says you aren’t? 

Does depend where you sail-up here in NW Highlands little changes-BUT worth remembering if you do sail in tidal waters that a river chanel if not a main navigation can change overnight-certainly true of Morecambe Bay where I used to sail where local knowledge then becomes very important-in Morecambe Bay you can have great sailing in places where all you have at low tide is mud and sand.

Phil

Worth marking the number of the correction along the bottom edeg of the chart when its been done.

W.

".....It’s not to be recommended, but lots of people sail happily with very out of date charts, by applying a bit of common sense, and paying close attention to the GPS......."

I suspect that Cathy's comment above probably applies to the majority of boaters - let's face it many small boats are out and about without any charts or even a compass! I myself have found that occasional bits of pertinent nautical information are missing from my old British Isles Road Atlas so have reluctantly had to glance at a chart in the chandlery and try to memorise what's missing - just to be sure!!!

The only (potentially) sensible comments I would add are that REEDs Nautical Almanac with it's regular updates is a first class source for changes and if you use that with a reasonably up to date chart you should have a rough idea of what a true chart should be indicating.   BUT as always - the best policy is to actually get your head up from the chart table/GPS/Chart Plotter regularly and look at what is around you and under you. The echo sounder and visual appreciation are absolutely key to safe pilotage. Charts often lie, buoys go out of position and lights fail without notice. If, despite what the paper and screen indicate, you can see hear, smell and see breaking surf and the echo sounder is running low on big numbers it might be time to re-appreciate your situation. 

Having spent many years doing this mind-numbing exercise as a Ships Navigator - I can say that I am not inclined to start again !! Latter years depending on how good the shipping co. was - we would be sent tracings to use to draw on the item, NtM's of course when significant changes would have a paste cut-out to fix.

As to working back corrections - the standard accepted method of recording correction was 2fold. a) Chart record cards and b) year underlined and then correction number after .... each correction added to the line of numbers till change of year ....

NtM's had a list of charts affected so it was not necessary to read all corrections through the books.

Rotrings ... KEEP the nib damp ... if you don't you'll soon find out why ! Traditional ink used was Indian Ink Magenta. I still have my Chart Correction set somewhere !

Tips :

Cables - the zig-zag lines .... get old hacksaw blade and run nib along making sure the teeth are "with" direction of nib - NOT to cut the nib !! This gives perfect cable line and also acts as straight line between the plotted points.

Light circles - old desert spoon handle cut away from spoon and drilled in the wide end, then bend handle up slightly to allow you to hold it.

Old Hypodermic syringe for filling Rotring if old style pen.

Generally the Chart Correction Templates - the items were usually too big and crude so most ship-board 2nd Mates became adept at free-hand correction or using items as above.

Oh nearly forgot ........ Adm publication 5011 .... blimey it's years since I used that term and still remember it !!