Originally Posted by ericoh88
FWIW, a very good friend who did RTW said the commercial C-MAP and cm93 is exactly same.
RTW sailors are not famous for working along coasts, working through narrow channels with coral
reef all around, looking for anchorages
, or spending time in glorious out of the way places.
Here're two quick screen
grabs to show the difference between:
1. CMAP 93 v 2, the most recent version that can be viewed using OpenCPN (meaning that the chart data is from 2010 or earlier); and
2. CMAP 93 v 3, the current commercial product.
The location I've chosen is the Jomard Entrance aka Jomard Channel, in Milne Bay Province of PNG. The Louisiade Archipelago is to the E; New Guinea to the W.
In late April or early May 1942, the Imperial Japanese Navy
steamed south through the Jomard Entrance, aiming to support the efforts of Imperial Japan
to take Port Moresby (PNG) and Tulagi (in Solomon Islands).
So real soon we'll be celebrating the 77th anniversary of one of the most significant sea battles of the Pacific theatre of WW2. The Battle of the Coral Sea
. No winners. But IJN support for the capture of Port Moresby did not go ahead. And the industrial economy of Imperial Japan
could not recover from its losses of capital ships. The US economy and the USN could.
The IJN did not have charts
as good as CMAP 93 v 2 (see: Jomard Channel CM93 v2 1:119000.jpg). But the IJN clearly had better charts than their enemies, so they steamed through.
At a scale of 1:119,000, the E side of the chartlet is on the brink of being overzoom. The W side (see that strip of deep blue?) is at maximum zoom.
Of what benefit are the latest charts?
Look at Jomard Channel 93 v 3.jpg. It's not yet close to overzoom. I've another few zoom steps to go, each revealing new detail.
These days a surprisingly big number of commercial ships steam through the Jomard Channel. And the reason they do is the quality of large scale charting. As shown on the CMAP 93 v 3 chart - see the indication of the shipping channel.
You have choices ... in parts
of the planet, the charts have not changed significantly. In other parts
, you'd be advantaged to have the latest. And the latest are not on paper.
At the end of the day, you have to ask yourself the Dirty Harry question: just how lucky do you feel, punk?