Another plotter assisted grounding?

[Cadence]

Originally Posted by zstine

I exclusively use raster charts. I don't understand why people are saying raster charts are useless. IMO they are better / safer than vector charts because of the Zoom issue.. things don't magically appear at different zoom with raster and I still do my weather routing, overlay AIS and Grib, etc.. I agree that the technology exists to warn navigators that your route goes into shallow water and even alarm if you are sailing into shallows. This was discussed extensively when team Vestas wind ran aground last Volvo race. The chart plotter makers say they won't add the safety feature due to liability and the expectation that the software will always tell them 'danger ahead'. It is a great example of how individuals suing companies hurts the general consumer and has gotten out of hand, especially in America IMO.

You think we need torte reform? You are not alone but in the minority I suspect.

[donradcliffe]

While chartplotters are way better than paper charts, its still critical to use ALL navigational tools available and make sure that there are no discrepancies between them before you charge ahead.

The US navy ship (USS Guardian) that hit the reef had one layer in its vector charts that had an 8 mile error across the chart. Unfortunately for the navigator, it was the most detailed layer and it was what he used to check for hazards along his route. The other layers all had him hitting the reef. The unforgivable error was when the lookout reported a white flashing light (a lighthouse marking the reef) on the wrong side of the ship, they trusted the plotter and steamed ahead.

I had a raster chart of Bermuda which was exactly 10 miles off in latitude. It was pretty easy to pick up the error when I compared my chart position to my radar returns, even at night.

Coming into Las Palmas on a delivery, I couldn't get the chartplotter to agree with my mark one eyeballs. I used eyeballs and relative bearings to marks and landmarks to get into the harbor and tied up. Working out the problem, I found out the owner had told the chartplotter to use the Croation datum instead of WGS84.

[Otia]

Originally Posted by kentobin

Chartplotters typically show different chart details at different magnifications (resolutions). Good navigators will keep varying the chart resolution to see what may not even be showing up at a different magnification level of that chart.

So true...
Even the best pros get tricked sometimes:

Telefónica Blue completes Volvo Ocean Race leg 9