Grounding Aftermath

There has been some progress in chart issue raised by my recent grounding.  The following was the response to my request for the coordinates of the grounding.  Having that information enabled the sending of the subsequent message to DOT (WA Department of Transport). 

And the following message has been sent to the DOT by one of the members of the FSC Cruising Section.  (An NtM is a Notice to Mariners.)  (Also, note that "a depth of 1.9m some distance to the west of the grounding location" in the text would still have been OK for my boat, given that the water level was at 0.7m above, datum - yielding an actual depth at that time of 2.6m.)

Dear Sir/Madam,

I wish to draw to your attention a  region that has been reported as significantly shallower than charted. On Sunday 14^th June the yacht Pachuca went aground on Parmelia Bank between Carnac and the channel at 32 07.3S, 115 40.7E. The details of the incident are reported in the yacht blog at http://pachucaroundtheworld.blogspot.com.au/2015/06/grounding.html

The yacht draws between 2.3m and 2.4m so the depth at the grounding location, after account for tide height and storm surge, was less than about 1.7m. The chart sounding nearest  the location appears to be 4.6 m, with a depth of 1.9m some distance to the west of the grounding location.

Many locals know that both Parmelia and Success Banks often change bathymetry after storms, usually during winter. It is therefore perhaps unreasonable to expect these areas to be surveyed after every winter with the severe budget constraints currently being experienced by government agencies. However, in the interests of safety may I suggest two (inexpensive) actions:

1.       When the next edition of chart 001 is printed, include an additional caution to the effect that those two banks often end up shallower after storms, so extra caution should be exercised if travelling over them.
2.       Given that the next edition could be some time away, issue a NtM with the same cautionary note.

Cockburn Volunteer Sea Rescue have already issued a similar warning on their Facebook page: “NAVIGATION WARNING: Please note the charted depth in the area of 32 07.300S, 115 40.700E is inaccurate and can be less than one meter deep depending upon tide. Mariners are advised to navigate with caution in the area.”  source: https://www.facebook.com/CVSSR/photos/a.568131439874686.1073741825.524373530917144/981368245217668/?type=1

On a related matter, I note that none of the listed corrections to chart 001   http://161.152.28.103:10003/pls/lweb/notice_info?p_chart_id=WA%20001  includes reference to the shallow patch of 1.8m reported to DoT in 2012 and 2013, for which an AHS NtM (119 for chart 754) was issued in January 2014. It behoves DoT to issue a parallel chart correction notice, as that shallow spot causes winter swell to break on it, making it a very serious hazard when the swell is up and from the westerly quadrant.

NOTICES TO MARINERS for Aus754

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119* WESTERN AUSTRALIA - Success Bank - Depth.

Fremantle Ports (DHDB 2566728) ( )

 Aus754 [1052/2013]

Insert    depth, 1.8m, enclosed by contour            32° 04.997 S  115° 42.917 E

Delete  depth, 4.1m       32° 04.900 S  115° 42.900 E