Using old charts....

[ean_p]

Just been offered a lot of old charts (various ages ranging from 2 to 18 years old)...what do you think, are they any use, can they be trusted, or not worth the trouble.....ok so the fairly new ones can be corrected, but what of the rest??.

 

[Shanty]

Get hold of a copy of NP109 - the Hydrographic Office NW Europe Catalogue for 2002 (its free). That will give you a fair idea of which charts are still current. Strictly speaking, you should also check Notices to Mariners for new editions of charts since the catalogue was printed.

If a chart is still current, correct it to date as necessary from ANM and its fine to use for navigation.

If its not current, then strictly speaking, its not safe to use for navigation, even if corrected. However, with a bit of caution, I don't see too many problems with using older small scale charts for passage planning, providing you have larger scale charts available to navigate on.

Some of the old fathom charts have views of the land from seaward - can be useful if you don't have a pilot for that particular piece of coast (and providing it hasn't changed too much).

BTW if you have any current charts you don't want, give me a shout - I'm on the lookout for charts of the UK coast at the moment

 

[rich]

i have loads of old charts, the bouys may move, but the rocks don't...

rich

 

[Trevor_swfyc]

Thats the problem rocks do appear to move, the accuracy of old charts is no match for the accuracy of GPS so no good plotting a waypoint on an old chart and expecting 10 metre accuracy.
Chart are being updated to GPS 84 datum, the sooner the better. How much do you pay for insurance compared to charts, if you use 18 yr old charts just use them for practice not for the SAFE navigation of your boat.

See my posting on GPS ACCURACY
All the best
Trevor

 

[bedouin]

If they are UK charts then the almost certainly can't be corrected up to date as UKHO are rapidly replacing the old OSGB datum with WGS 84 - that implies a new edition of the chart.

The official line is therefore that the charts are useless as they are not safe for use for navigation. In practice I have no problem plotting my passage across the channel on an out-of-date charts, but you should use corrected ones if you want to rely on the buoyage (i.e. near the coast).

 

[AndrewB]

All charts are 10 years out of date.

Look at the date at which the survey was done - that's the key. 10 years ago is typical, even round the UK. I've sailed over coral banks, which are constantly changing, for which my freshly purchased Admiralty chart is based on surveys over 100 years old, and highly inaccurate.

Its much more important to have recent charts for sandy coasts rather than rocky. Those of the west-country will last, while the Thames Estuary, Goodwins and the French-Belgian coast need to be renewed very regularly.

It is impractical to update old charts completely. One thing to check is whether any Traffic Separation scheme has been established - if so those should be marked. The buoyage and lights change of course, but an up-to-date almanac will allow them to be checked as needed on passage, though I would double check major lighthouses beforehand.

Whether with an old chart or new, buoyage must never be considered 100% reliable, specially in outlying areas, and with GPS available it would be foolish to put trust in buoys alone. Don't forget with GPS that chart datums change, but more important in some parts of the world is that longitude was not measured accurately enough in the original survey, and the chart may be ½nm out.

At entrances to major harbours the buoyage is generally more trustworthy, it is changed quite frequently, it can be extensive and a mass of lights seen at night is often confusing. If entering port you don't want to be constantly diving down to double check with the almanac whether the GpFl(3) you can see is the one you think it is.

So ... you are OK with 18 year old charts, used with caution, but not in areas of shifting sands or close to big harbours. I would also now reject any pre-IALA chart in a busy area such as around NW Europe, though that should not apply to you.

 

[miket]

Why?

I know charts are relatively expensive, but not in comparison to the boat or my family's wellbeing.

 

[LadyInBed]

Old charts / pilot books, Mk1 eyeball, echo sounder and common sense work quite well together.

Take the common sense out of the equation, and you are in trouble, whatever else you may have on board!

 

[PeterGibbs]

Large charts suitable for pilotage, why not use them even if they are dated.

All others, especially those for difficult and changing areas - eg Thames estuary - potential problems lie ahead, but only a couple of years' corrections normally available to bring them back to fit for purpose condition. Beyond that they're junk.

And then there's the wayward factor: if there were any incident or accident and any kind of inspection were made of the boat, its log and charts etc it would be that much harder to establish right on your side if the charts were deemed inadequate. An insurance claim could be scaled down on the grounds of contributory negligence, especially if you put your boat aground.

Second hand charts are perfectly ok but within reason.

PWG