What do engineers do when bored. Well, yesterday, two I know decided to go boating with a purpose. They took a set of 20 year old charts, a set of 11 year old charts and a set of charts printed yesterday. They had a Garmin plotter (updated yesterday) on a center console and a depth finder. They went from Fort Lauderdale to West Palm and did some canals and rivers between. Now this is a well maintained area, not like you might find in South Georgia or Central SC.
In advance they marked all major differences in the three charts. They concerned themselves with whether a boat with a 6' draft would run aground.
They checked 79 specific differences. 60 of the differences weren't going to run a 6' draft aground anyway or so they thought. However, interestingly, 4 of those were getting close and 1 that showed 7' on today's printed chart showed shoaling on Garmin and 6' and actually measured 5'.
So, not to the other 19 which showed 6' or less on one of the charts. 2 showed 6' eleven years ago and 8' today and are now 8' or more so clearly dredging and not a problem on any charts. Now, to the final 17. The 11 year old chart was not appreciably better than the 20 year old and appeared to mostly use the same data. Only one instant where it would have protected you and the 20 would not have. 11 cases where the current chart showed 6' and had at least that or more so the difference in charts made no difference as to running aground on a 6' draft but the differences would have been significant to greater drafts.
This left 6 cases of significance to a 6' draft. In five of those today's chart would have protected you and in only one of those would have the 11 year chart while in 5 it would not have and the 20 year old would not have in any. In some cases the older charts has as much as 8 and current chart showed 5' or so. In one case the older charts had 7 and the current showed 3' and that's what it measured. Note that they did find an old notice to mariners but it was just that, old. If you're looking at recent notices, you wouldn't see it. Then there was the 1 remaining spot where the 20 year old chart showed 8', 11 year old showed 8' and current one showed 6' but Garmin showed 4' and they measured 4'.
Now none of these were in the channel of the ICW so stick there through this area and you're safe. However, some were just outside the channel. Others were side rivers or canals. If you were local you likely would have known to exercise care. It's just one small group, but it also clearly shows some shoaling and filling that didn't exist 11 and 20 years ago. It appeared the 11 year old chart had very little work done to improve versus the 20 but today's chart had a lot of improvement. The one where Garmin indicated 4' and the current chart 6', I looked at more carefully and found an Active Captain posting six months ago. I don't know if that accounted for it or not.
If you never leave the channel, it doesn't likely matter. However, if you take side rivers and streams or pull out of the channel occasionally, then with the limited dredging over the last 10 and 20 years, I'd be concerned and have the latest chart I could.
Note this was not about paper vs. electronic, but about old paper vs. current. Oh and just out of interest there was one old location close to the channel that showed 6' twenty years ago and a 3' shoal eleven years ago but 8' in today's chart. They only checked that because they knew the old charts had to be wrong. Actual today was 10'. Clearly much better dredging.