Saturday, February 25, 2023

Rock Symbols in ENC

While working on another project, it seemed that it would be nice to have one more example of how rocks show up on an ENC, which is what we provide here.  We have several earlier notes on rock symbols

Chart Symbols: Rock or Coral on ENC

Rock Talk 1, Is it Awash or Not?

Rock Talk 2, RNC to ENC

and this image from the last one, summarizes the situation.

The project that brought back the rock symbol question is the very subtle way that a properly presented ENC (i.e., according to IHO Standard S-52)  decides when to show the isolated danger symbol to replace a standard  rock symbol. 

So the goal here was to show the above samples in an actual charting program, where we can change our choice of safety contour and decide if we want to see these symbols inside of the safety contour, or just outside of it.  That article is forthcoming.  For now we just look at samples of the rock symbols in play and have this addition resource for a quick reference.

Here we see the pick reports for each of the rocks that shows most, not all, of the information needed to decide when the symbol might be replaced with the danger symbol, example 5 above.