Boston Light beacon change

[DMF Sailing]

Originally Posted by jt11791

That symbol (red square around black dot) is for an always underwater rock, not a rock that uncovers. I don't know why the depths are slightly different, could be different survey data was used, or the data was interpolated differently.

On the soon-to-be discontinued NOAA charts I've relied on in U.S. waters for 50 years, * denotes a rock that uncovers. Rk is a rock that does not. (see attached.)

Obviously, that an experienced mariner such as yourself knows the universal system used by Navionics as the rule means simply that an old fuddy-duddy like me has to put away the NOAA charts and adapt to the new world.

Especially if I ever leave U.S. waters

[EDIT: As for the depths, that was user error, as Requiem pointed out. In my haste to disparage the modern era, I screenshotted two adjacent but different sections of the channel. Other than using different symbols, Navionics and NOAA charts seem to be in sync, at least in New England waters.]

[requiem]

Originally Posted by DMF Sailing

In my haste to disparage the modern era, I screenshotted two adjacent but different sections of the channel. Other than using different symbols, Navionics and NOAA charts seem to be in sync, at least in New England waters.

Oh, you can still disparage those tiny symbols. Here's why...

The first attachment is another view of the area using a different set of charts from my previous ones. I've added arrows pointing to the rocks. The circle indicates the seabed type which is also rock.

Next for the fun bit. Navionic's "rock" symbol indeed looks similar to the "rock awash" symbol for international charts (row 12). It's also re-used for that purpose as well. This doesn't help. I think they do similar for buoys. The paper chart symbols you see are on row 14.2. Note that the screenshot is consistent with the ECDIS presentations for such rocks, which aren't too far off from the international equivalents.

[DMF Sailing]

Originally Posted by requiem

Oh, you can still disparage those tiny symbols. Here's why...

The first attachment is another view of the area using a different set of charts from my previous ones. I've added arrows pointing to the rocks. The circle indicates the seabed type which is also rock.

Next for the fun bit. Navionic's "rock" symbol indeed looks similar to the "rock awash" symbol for international charts (row 12). It's also re-used for that purpose as well. This doesn't help. I think they do similar for buoys. The paper chart symbols you see are on row 14.2. Note that the screenshot is consistent with the ECDIS presentations for such rocks, which aren't too far off from the international equivalents.

What kills me is that the symbols for "rock that does not uncover and sits at a certain depth" and "rock that uncovers and will sink you dead if you don't heed it" are nearly identical. Woe betide the farsighted mariner who depends on this chart! (see attached; Devil's Back uncovers at mid low water; the shoal inside Red 6 is at 14 feet depth. There is a very minute difference between the two symbols.)