Melbourne Dive Maps Database

Keep up-to-date about what's happening with the Scuba Doctor's Melbourne and Victorian dive maps and dive site information.
User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:32 am

G'day,

Added two marks the other day.
The Ledges - source Alan Beckhurst
Chimney Rock - source Black Rock

Hopefully they are okay. Could someone please confirm the Chimney Rock one?
See https://www.scubadoctor.com.au/melbourn ... imney-Rock
Any more information about the dive site would be helpful.

Before I work on adding any more dive sites I'm going to focus on making some changes to the database application I use to manage the information and display it.

Things to do to the database application include:

Being able to easily add, edit, and update the URL of the page where more information about the dive site can be found. Then make sure I have a URL for every dive site.

Add a date_updated column to the database. Currently there is a date_add column, but the date gets changed when the marker information is updated. I want to be able to show both the date added, and the date updated. Then reset the date_add columns to an appropriate date.

Have a source column in the database. Currently the source information is put into the short description. I want to move it out and be able to maintain the information easier.

Taking the GPS location in Degrees and Decimal Minutes out of the short description. Instead generate that information from the Decimal Degrees location stored in the database. Generate and show the Degrees and Decimal Minutes version in the pop-up box displayed when users click on a site marker when looking at a map.

Include a 'Read more' link to the extra information about a dive site in the pop-up box displayed when users click on a site marker when looking at a map.

Be able to add, edit and update the marker location in Decimal Degrees or Degrees and Decimal Minutes. Currently only D.D is accepted. I'm usually given marks in D M.M and have to convert them myself. Errors creep in. Being able to properly handle both formats will make things easier and improve accuracy.

I've been trying to categorise the dive sites and display the categories as icons. The set I'm using so far is:
Advanced Open Water Rated, Crayfish Dive Site, Deep Rated, Drift Dive Site, Ideal For Snorkelling, Inside Port Phillip Bay, Marine Park - No Fishing, Night Dive Site, Open Water Rated, Outside Port Phillip Bay, Reef Dive Site, Scallops Dive Site, Subject to Shipping, Slack Water, Technical Rated, Wreck Dive Site. I've been adding the details as HTML in the long description. To better manage and display them, the details need to be stored in the database differently.

I'm still thinking about better ways to handle the min, average and/or max depth for dive sites. Take a site like the Canberra which is 8m to 32m. But it can be a dive site for Open Water, Advanced Open Water, Wreck and Tech rated divers depending on how the dive is planned.

Then the real work begins.

For wreck dive sites I've added links to the Heritage Council Victoria page and MAAV page for each shipwreck that has them. Now I want to finish adding links to the Australian National Shipwreck Database for each shipwreck.

If wrecks or dive sites have an entry in Wikipedia, then I want to have links to them. I have some, but there are bound to be more.

Michael Mallis has provided me with more information about a number of shore dives. So the information needs to be added.

The Australian National Shipwreck Database has entries with crude location marks for many shipwrecks and plane wrecks I've not seen anywhere else. I'm thinking of adding a new dive type, e.g. Exploration Required, and add them to the database. Then these locations become a challenge for wreck hunters.

Improve the information available to make it easier to locate dive sites. For example, how a wreck lies on the bottom and the best direction to approach it from. Maybe add the equivalent of Packo's GPS plotting sheets to the long description, where available. Encourage people to get out there and create them.

Seek out and get permission to use more videos and images of dive sites.

Encourage people to create new, or provide existing, dive site drawings, or the modern equivalent.

Seek out and get the locations for more dive sites. It would be great to improve what we have for other areas in Victoria, e.g. Wilsons Prom.

Any help with any of the above would be most appreciated.

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:36 am

packo wrote: Regarding the "Chimney Rock" coords mentioned in your post above. I haven't dived it yet, but did scrape this off the web some time ago:-


That's where I got the mark from. But I now plan to update it with the details provided by Alan. It's possible the reason BRUDG had trouble finding the place was that they had a mark like AB's one, but not the information on how to use it. It's this sort of extra information that makes what AB has provided so valuable.

packo wrote: "Add a date_updated column to the database. Currently there is a date_add column, but the date gets changed when the marker information is updated. I want to be able to show both the date added, and the date updated. Then reset the date_add columns to an appropriate date."


Yes I was disappointed when the newly added "update date" feature seemed to overwrite any original "marks changed date". It is important to retain that history. I hope none of this info has been lost.

It probably has been lost. And that's why I want to fix this. Thought I had it earlier today, but we still need to get some MySQL date handling stuff right.

packo wrote: I'm a big fan of computerised coordinate conversions as I am sure this will greatly reduce the error rate. I hope the user will still be able to see both (or all three) formats in the Dive-Site listing pages.


It will be stored as D.D for efficiency mapping it. But it will still be displayed in all three formats in the site listings. It's just that I will be able to input stuff in D.D or D M.M. Then I want the D M.M to be generated out of the database for the pop-up boxes in the maps, rather than it being in a short description text field I have to manually update.

packo wrote: "all dive sites within 15km of the midpoint between the Sorrento & Queenscliff boat ramps and less than 45m deep (or whatever you think a suitable 21% O2 OC limit is) list".


I'm not planning to ever implement stuff like that. That's way beyond what I need to have for people to be able to find out information about dive sites. But you could always do the positioning part of that sort of thing in a crude way when looking at the dive map of the sites. Plus now, using the KML file, you can get the information into other systems, e.g. Google Earth, and do that sort of thing there. In time I'll look into how to transfer more information than the site position into the KML file.

I've added a 'source' field to the database and populated it from information given in the short description. Next step will be to make it easy to edit that field and then remove the information from the short description. I plan to add something like (verified) or (unverified) where appropriate to the source field.

I used 50 metres in the nearest neighbours code to detect possible duplicate sites. But I can change it to whatever I like at will. I'm very mindful that there can be valid reasons for having sites very close to each other, for example like Packo's example at Castle Rock.

The current work in progress is to finish implementing the source field. To fix the date_add and date_modified issue.

Then change the contents of the pop-up box shown on the maps page.

Then work on putting legends in the database and using them from there.

Then I want to get back to improving the information, pictures and video for dive sites, getting people to help verify sites, and adding new ones.

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:37 am

G'day,

I've made some progress. The dates added and last updated are now working and being shown. Maybe it would now be useful to have a page where the last 10 or 20 sites added are shown. Interested?

I've rearranged how the core information is shown on for each site and on the GPS Marks page.

I can now input and edit marks using both decimal degrees (DD) and degrees and decimal minutes (DDM). Yippee!

The source information is now being stored in a more usable way in the database.

I've now added Golden Arch (Cuttle Arch) using the info from AB. See https://www.scubadoctor.com.au/melbourn ... olden-Arch . Thanks AB.

My system still puts Deep Pinnacles as the closest site to Castle Rock - 250 m, bearing 287°, WNW

Deep Pinnacles is also the closest site to Golden Arch - 137 m, bearing 95°, E.

Best regards, Lloyd Borrett.


P.S.
Plan is to now look at improving the information in the popup boxes when you click on a marker when viewing the maps.
And how to put more information about a site into the KML file.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:38 am

G'day,

The changes to the popup box when looking at the dive maps are done. Now there are just some 300 markers to update by removing the redundant information from the short description.

So now nearly all of the changes to the system proposed in the 1st post of this topic have been done. Hoping to have the legends part done later this week.

Best regards, Lloyd Borrett.

P.S. I'm starting to actually like what can now be done with this system. It's now a LOT more useful than the early version. Such is evolution.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:40 am

AB wrote: we have lots of sites others don't know about!)


Feel free to pass them on AB.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:40 am

G'day,

The lat and long in both DDM and DD formats are now going into the KML file.

Plus the Source information and a 'Read More' link are there as well, if we have them.

This makes the KML file a lot more useful, especially when looking at it in Google Earth.

I've thought about putting the dive type, access type and short description into the KML file as well, but I think that might make it a bit klunky.

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:41 am

G'day,

310 manual edits later, I've finally finished removing the redundant location DDM coordinates, datum and source information from the short descriptions.

In the back end, I've made changes so that the system reminds me about any missing long descriptions, source attributions or urls as I work through the list.

I've also updated the KML file to have the the dive type and access type information, plus have the icons used on the website dive maps for each dive type.

Now I'm working on adding, enhancing or updating the long descriptions for plenty of dive sites. If you have any contributions you could make towards this, they would be most gratefully received.

Thinking of adding a web page to do conversions between DD, DDM and DMDS coordinate formats.

I've found some sites I could add, but their marks are using AUS66 for the datum. Haven't found a useful tool to convert AUS66 to WGS84. Not keen to have to write one. Might have to fire up my GPS unit and use that to do the conversions.

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:42 am

G'day,

I've been adding some dive sites, plus updating the information for a few shore dive sites using details provided by Michael Mallis. More shore dive updates still to do.

I've also created a page to show the 10 most recent Melbourne dive sites added, see
https://www.scubadoctor.com.au/recent-dive-sites.htm

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:42 am

G'day,

Just restored access to the dive information sheets from the Maritime Archaeolgy Unit of Victoria Archaelogical Survey, where we have them. They used to be part of the various wreck dive site descriptions, but at some point most went missing.

Have also made some changes to the KML file to make it more standards compliant. Its now a fully valid KML 2.2 feed. Not that this means much to most of you, but it makes me feel better. :-)

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:43 am

G'day,

The code to have legends being managed and stored in the database and using them from there is done.

Some sites have been updated to use this method. Plenty more still to update.

So hopefully all of the changes I felt were needed to the database and code are now done. My focus can now stay on updating, enhancing or adding information and dive sites.

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:44 am

G'day,

Quite a few of the dive sites lie within the boundaries of the six areas that make up the Port Phillip Heads Marine National Park.

See http://parkweb.vic.gov.au/__data/assets ... ds-MNP.pdf

Would be nice if I could flag those sites as such.

I guess it could be done by importing the KML file into Google Earth. Then somehow adding the various park boundaries into Google Earth, and reading off which sites are within the boundaries. Then I could work through the list and update the site information.

Update: Maybe this file is all we need.
https://services.land.vic.gov.au/datavi ... _parks.kml

Anyone interested in giving that a go?
Update: It's done! Simpler than I thought it would be. So even I could handle it.

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:44 am

G'day,

On Friday (Australia Day) I came up with the MySQL statement to get the sites of a particular legend type. Then I created a new page to show the sites flagged as 'Ideal for Snorkelling'. See https://www.scubadoctor.com.au/melbourn ... -sites.htm

On Saturday I went around Port Phillip, down the Back Beaches, and into Westernport adding or updating the site and legend details for shore dives.

Now the snorkelling community can benefit from the information as well.

Using this same technique, I could now list scallop and/or cray dive sites as well. But right now there aren't enough of them for it to be very useful.

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:46 am

packo wrote: Issue #1: Identifying an updated version of the KML file.


Done. Sorry, I should have done it that way in the first place. I actually have a code snippet to do it and forgot to use it.

packo wrote: Issue #2: Depth info?

Any plans for this?


No. I've put assigning a single number to depth and putting into the KML file info in the too hard basket. What should the number be?

There are dive sites where the max depth is deep (e.g. beyond 40 metres), but there is also plenty for people to see at shallower depths (e.g. less than 30 or even 18 metres).

I try to convey this via the depth range in the short description, and more completely in the long description. I believe assigning a single depth value can often be more misleading than helpful.

packo wrote: Issue #3: Unique site ID number?


I looked at the KML standard to see if there was some other field I could use to get such an ID number into the file, but I can't see a way.

I don't really want to change the placemark name I'm already using. But a compromise might be to add a three or four digit ID based on the database record ID in front of the placemark name. I'll think about it.

packo wrote: ******* SOME NEEDED COORDINATE "FIX-UPS" - please don't ignore! *******


In order to make change to dive site marks:
Give me the site name.
Give me the lat and lon that the mark should be.
Give me why it needs to change.
Give me the new source and/or who has verified the mark.

With this information I can make changes. Without those details it's not going to happen anytime soon.

Best regards, Lloyd Borrett.



User avatar
lloyd_borrett
Site Admin
Posts: 175
Joined: Thu, 11 May 2006 5:44 pm
Location: Rye, Victoria, Australia
Contact:

Re: Melbourne Dive Maps Database

Postby lloyd_borrett » Sun, 18 Mar 2018 7:51 am

G'day,

The above posts are my side of the conversation that happened in the Dive-Oz topic The Scuba Doctor dive maps
See http://diveoz.com.au/index.php/forum/ha ... -maps.html
(If it's still there.)

Copying them here has been my feeble attempt at preserving the information.

Unfortunately, it's not really possible to copy in the contributions to the discussion made by others.

Best regards, Lloyd Borrett.



DAE avatar
packo
Forum Moderator
Posts: 40
Joined: Thu, 22 Mar 2018 8:34 am

Re: Melbourne Dive Maps Database

Postby packo » Thu, 22 Mar 2018 2:01 pm

Firstly a big thanks to Lloyd for resurrecting the Scuba Doctor Forums in response to the demise of the dive-Oz website & forums. That site continued for an amazing 19+ years but was sadly brought down due to serious health issues in the administrator's family circle.

I wish Lloyd's forum adventure well and acknowledge it is a brave thing to do it the face of the social media onslaught of the past dozen years. Perhaps this week's scandal about the extent and power of those who "data mine" Facebook posts and use them for fairly dark and devious purposes, may see some divers "unfriend" that platform and wind up here!

I am also grateful for Lloyd's tolerance of some of my "blasts" that are often directed at the Scuba Doctor businesses and what I see as bad information on this website!

However I plead again for him to read the material carefully and with a cool head in a belief that eventually the penny will drop and things will be put right. Perhaps in this new forum amongst his own customers I might find some who are more prepared to listen and test my claims, or at least argue them out!

The "Scuba Doctor Dive Sites" project is a fantastic initiative and is creating a great diver resource. However like all big projects it does have some wrinkles that need to be ironed out. I am just trying to play my part in this process but my input is frequently ignored.

I see this project as so worthwhile that I'll usually point out corrections a number of times before I eventually give up. I know Lloyd is often busy doing other things. If you as a forum member or reader disagree, then please speak up so we can toss around the evidence to get the best outcome. If you should happen to agree with a correction, then it is also worth speaking up to get that change to happen a little faster.

The following is basically a port of my last dive-Oz post regarding the "Scuba Doctor Dive Sites" project. No changes have been observed yet (22/03/2018). (note in dive-Oz I used olive green to quote things and haven't changed over to the phpBB way yet.)

Lloyd wrote:
"packo wrote: Issue #1: Identifying an updated version of the KML file."
Answer:
"Done . ."
Thanks Lloyd thats a good fix and makes it very clear with both date & file size for us to go on.

Lloyd wrote:
"packo wrote: Issue #2: Depth info? Any plans for this?"
Answer:
"No. I've put assigning a single number to depth and putting into the KML file info in the too hard basket. What should the number be? . . . . . I try to convey this via the depth range in the short description,
. . . I believe assigning a single depth value can often be more misleading than helpful."


?? I only had in mind adding your depth (range) text line to the CDATA[..] block in the KML file. For example:

Code: Select all

<description><![CDATA[Dive Type: Wall Dive<br />
Access Type: Boat access<br />
Depth: 15m to 40m<br />
Lat: -38 17.654 (-38.294233)<br />
. . .


Lloyd wrote:
"packo wrote: Issue #3: Unique site ID number?"
Answer:
"I looked at the KML standard to see if there was some other field I could use to get such an ID number into the file, but I can't see a way. . . . But a compromise might be to add a three or four digit ID based on the database record ID in front of the placemark name. I'll think about it."

Please do. That sounds like a very clever compromise, something like:- "dive#123-the-abyss"

However I worry that the database record ID might not be "fixed enough" where records are added ahead of it. I think that however you assign the numbers in the first instance, (maybe by record ID), it then needs to be incorporated into the record itself so it can never change. If a record is deleted for some reason, its id number must die with it and never be reused.

Not sure if your record id order is alphabetical (with insertions of new sites appropriately), or whether the record id is maintained in record creation order (with new sites appended). It doesn't really matter which as the number isn't meant to mean anything other than a unique "shorthand" for each particular site.

Lloyd wrote:
"In order to make change to dive site marks:
Give me the site name.
Give me the lat and lon that the mark should be.
Give me why it needs to change.
Give me the new source and/or who has verified the mark."

and then:
"With this information I can make changes. Without those details it's not going to happen anytime soon."

Gee you're a hard man to deal with at times! I shouldn't have to sleuth around to find where things have gone wrong but just put up a case that they have!

However for everybody elses sake, in order to avoid the "it's not going to happen anytime soon" scenario, I'll do your "pro forma" approach, but the "why it needs to change" is long winded in some cases because its complicated. Here we go:-

***************** DIVE SITE ENTRIES REQUIRING REVIEW *********************
*********
The site name: LONSDALE WALL (The word "SHALLOW" needs to be restored.)
The lat and lon that the mark should be: Same as present (-38 17.153, 144 37.839)
Why it needs to change: A couple of months back I grizzled about the Lonsdale Wall mark because:-
a) The google coords (-38.292033 144.630550) were in deep 50m water about 75m (too far) from the nearest part of the Wall.
b) The conversion to minutes in the short description was ok for Latitude (17.522 S), but was bad for the Longitude at (36.744) instead of 37.833 E (which put the site near Point Lonsdale's main street).

Lloyd fixed up the issue of bad coordinate conversions by "computerising everything" but then wrote:

"I've updated the Lonsdale Wall location with a mark from a better source. (It's what was the Lonsdale Wall Shallow mark.) Not sure how that other location got in there."
and then later wrote:
"The mark for Lonsdale Wall, -38 17.153, 144 37.839, is what is/was used by the dive charter operators."

This is where things went wrong! Yes ONE charter operator did have a site he named "Lonsdale Wall Shallow" but it was well north of the "corner point" where the wall "splits" into a shallow section (13m-22m wall) which continues north, and a deeper section (22m to 50m+ wall) which turns and heads east.

From Lloyd Borrett's personal web pages, we get:

Code: Select all

(http://www.borrett.id.au/divelog/divesite.php?id=42)
Lonsdale Wall Shallow    Port Phillip Bay, VIC
Country:      Rating:   Max. Depth: Difficulty:
Australia     4 star    25 m        Advanced Open Water
. . . .   
Latitude:     Longitude:                 Datum:
38° 17.153′ S 144° 37.839′ E Google Map  WGS84
2 dives at this location:
77 | 159

. . . which is where your new coordinates came from. However checking your first dive at this location in 2007 from:-

Code: Select all

(http://www.borrett.id.au/divelog/index.php?id=77)
77    10-02-2007 22 m  39 min   Lonsdale Wall Shallow    Port Phillip Bay, VIC

in the divelog comment section we get these words from Lloyd:-
"I've been told by everyone that the Lonsdale Wall is a special place to dive. Well if what I saw today at Lonsdale Wall Shallow, and only going down to 22m is any indication, then I definitely want to get back and do the real thing".

Which is my point exactly! While "Lonsdale Wall Shallow" (at -38 17.153 144 37.839) might be a nice dive, it isn't the "real thing".

You blew away "the real thing" entry when you dumped the "Lonsdale Wall" entry (-38 17.552 144 37.833) instead of just shifting its coords 75m or so towards the Wall (as per my Survey Map). That deletion desperately needs to be reversed before any more of the diving season disappears.

Therefore a new and separate "LONSDALE WALL" entry has to be (re)created with coords of say: -38 17.495 144 37.795 (or -38.29158 144.62992), but this should wait until the changes here are completed as per next line.

The new source and/or who has verified the mark: n/a - coords don't need to be changed, just "SHALLOW" added to the name and the "Read more link" deleted or its text adjusted.

Following so far?
The confusion may have been compounded by the old BSAC Sites List, which did have "Lonsdale Wall" at the 75m off point, but also its own (different) "Lonsdale Wall Shallow" which was at -38.292033/144.630550 or 38 17.479 S 144 37.788 E.

Note this second "Lonsdale Wall Shallow" mark is just a tad north and a tad west of the mark I am suggesting, ie. a little further "inland" from the lip of the wall, and in shallowish ~12m water. (Hence the name "shallow" even though the BSAC details list it as a 12m to 50m Wall.)

It seems possible another outfit had these two marks, this "other" Lonsdale Wall Shallow, and then "Lonsdale Wall (Deep)". That outfit may have "sounded for the Wall lip" by steaming between the "Shallow" and "Deep" marks. (ok its just a theory to try and make sense of it all - but supports the case for a unique id number!)

Sooooo, having perhaps lead divers astray for the last 2 months, they might be glad to, in your own words:- "definitely want to get back and do the real thing"! In the pro forma this change looks like:-

***********
The site name: Lonsdale Wall (New or resurrected entry needed)
The lat and lon that the mark should be: around 38 17.495 S 144 37.795 E
Why it needs to change: See previous entry reasons.
The new source and/or who has verified the mark: Packo GPS/PoMC Survey Map:-
Image

Forget the "packo's dropoff" indicator as I'm not sure of its accuracy. It is the result of my attempt to translate the horizontal sextant angles I used when I first dived here (mid 1970s), back into today's GPS numbers. Navigation by horizontal angle measurement with a sextant (note its not "shooting the sun", but more like surveying with a theodolite), actually gave better accuracy than today's GPS, but was a real bitch in a small boat and very tedious. No way I'd go back!

***********
The site name: The Pinnacles (Cape Woolamai PI)
The lat and lon that the mark should be: 38 34.363 S 145 20.232 E
Why it needs to change: Original coords 500m too far offshore, maybe first pair of decimal minute digits in latitude accidentally swapped.
The new source and/or who has verified the mark: clustered alternatives as follows-

Code: Select all

38 34.358 145 20.238  (-38.572633, 145.337300) [DK PINACL - one Lloyd "rejected"]
38 34.364 145 20.232  [from a 2005 getunder dive club list]
38 34.353 145 20.250  [latrobe valley scuba club guy in old dive-oz post]
38 34.340 145 20.257  [as above, different guy - also given in 14yr old dive-oz post and then claimed "good" by someone diving them]
38 34.363 145 20.236 (145 20.226 +15m East allowance) [VSAG source]
38 34.348 145 20.355  [Used by diver who DIDN'T FIND THEM - note error in Lng (20.355 possibly a typo from 20.255, which put them 150m too far East). However note Latitude is consistent with the other marks and not the ScubaDoc Lat of 38 34.638 S. Surely this is enough evidence to update the ScubaDoc mark?]


***********
The site name: William Salthouse
The lat and lon that the mark should be: 38 16.335 S 144 42.395 E
Why it needs to change: Existing coords are protected zone centre. Wreck 100m NE.
The new source and/or who has verified the mark: Packo GPS, Getunder list, PoMC doco, Charts

***********
The site name: Lonsdale Arches
The lat and lon that the mark should be: 38 17.994 S 144 36.744 E
Why it needs to change: PoMC(CDP) Dive Site Map, DVG site List, AB map, VSAG List all suggest
Lonsdale Arches site is approx 150m east of Twin Bommies site. However SD list has it 80m WSW.
The new source and/or who has verified the mark: Old VSAG & BSAC List, Packo GPS,
Electronic Chart Image:-
Image

***********
The site name: Lonsdale Bommies
The lat and lon that the mark should be: 38 17.965 S 144 36.497 E
Why it needs to change:I think different groups may each have their own "Lonsdale Bommies" marks scattered over this general area.

The point is the existing given coords are what most people call "Lonsdale Arches" (I think). LADS & Chart data suggest a sizeable "outlier reef" centred around 17.96, 36.50 with more reef further north is the area most call "Lonsdale Bommies".

The "Lonsdale Bommies" I dive are at the SW edge of this patch at 38 17.965 144 36.497. There are a few more bommies a little further SW including one with a small swim-through at 38 17.975 144 36.488. Others may have better spots but the existing coords do need to change to avoid a "duplicate site" with Lonsdale Arches.
The new source and/or who has verified the mark: Packo GPS, Electronic chart above.

***********
The site name: Isa (wreck)
The lat and lon that the mark should be: 38 14.270 S 144 41.286 E
Why it needs to change: I think old mark is AGD66 datum, despite it being claimed as WGS84.
The new source and/or who has verified the mark: I've compared the wreck location on both an ageing 1990s paper chart (to AGD66 datum), against a modern electronic chart (to WGS84 datum):-
Image
The wreck location measured from the old paper chart gives AGD66 coords that are very similar to the Scuba Doc numbers. When scaled appropriately and superimposed on each other the wreck is seen to be in about the same position on each chart. It is the same wreck:-
Image
The wreck coordinates in "WGS84 speak" are 38 14.270 S 144 41.286 E. While it might be tempting just to switch the entry datum to AGD66 and "buyer beware", I suggest they MUST be changed to the WGS84 equivalent (or use my numbers) to avoid divers transgressing into the rather serious military "no-go" zone just south of the wreck. (see the "blue cross" in the map above which is where this error may land you.)

Although conversion from AGD66 into WGS84 does vary a bit depending on where you are in Oz, for Victoria a "good enough" correction is:- SUBTRACT 0.090mins from Latitude number (ie. move it Northward), and ADD 0.080mins to Longitude (ie. move it Eastward).

***********
The site name: Eliza Ramsden
The lat and lon that the mark should be: 38 17.632 S 144 40.455 E
Why it needs to change: Existing coords possibly mark the tip of the old thrusting bowsprit. Quite some time ago through corrosion and big swells the bowsprit was "bent backwards" (with some broken off?). It now points vertically upward in a strange way. The result is the old coords now mark deep water well forward of the bow. Anchoring there in a dirty ebb tide, divers may not find the wreck. The Longitude needs to be shifted East about 15-20m, with the Latitude moved a tad south.
The new source and/or who has verified the mark: PoMC detected the change in least depth in this notice to mariners:
"Mariners are advised that the wreck Eliza Ramsden and Goorangai have the following updated minimum clearance depths in the following locations:
Eliza Ramsden Minimum Depth 10.9m
38 17.632 S 144 40.451 E (WGS84)
Goorangi Minimum Depth 13.9m
38 17.404 S 144 40.985 E (WGS84)"


*********** OTHER FIX-UPS IN SOME "READ MORE ABOUT LINKS" **********
Site: THE PINNACLES (Cape Woolamai PI)
Bad Text: Descriptive text is about "DEEP PINNACLES" site off Point Lonsdale but coords and other details are for the Phillip Island Pinnacles.

Site: THE ABYSS
Bad Text: Text claims this is on the Lonsdale side of the shipping channel when it is on the Pt Nepean side.

********************************************************************
Phew! You make the "correction process" so long and hard. It is very tedious. Its fingers crossed for "4th time lucky for the Lonsdale Wall site". I'm on the verge of giving up checking things over!

If I report a traffic light fault to VIC ROADS, they don't expect me to supply the circuit diagram, show where the fault is, theorise how it might have occurred, and offer advice on repairs!

Maybe there should be some mechanism where a site someone has questioned could show that is under some cloud, and ask for feedback from those best able to help.

cheers,
packo

Update 3/4/2018: Lloyd has given me an undertaking to examine the above material sometime after Easter. Fingers crossed the corrections might then be made.

Update 26/10/2018: Sadly only "The Pinnacles" off Cape Woolamai at Phillip Island has had its GPS coordinates corrected. I tried one last time in the post "Comparing Dive Site Maps", but it seems Lloyd is unwilling to take my word on just about anything - well not without the usual long hard resistance struggle! I'll leave it alone for a good while and just hope others might step up to the plate to point out the necessary changes so the database becomes as good as it can be.

Update 19/04/2019: Well no support from other divers materialize but slowly and surely I seem to be getting somewhere! Among the issues raised above, the list of Scuba Doctor site "fix-ups" now includes:- "The Pinnacles - Cape Woolamai", "Lonsdale Wall", "Lonsdale Wall Shallow", the "William Salthouse" wreck, and "The Abyss". For the moment I shall leave the Lonsdale Arches & Lonsdale Bommies issues alone until I have had more survey time in those areas and better understand where the charter operators go. The Eliza Ramsden GPS tweak is quite minor and can be let go. Although the bad "Isa Wreck" position could potentially produce a bad outcome for those relying on Sdoc's mark, I suspect almost no one has an interest in that wreck!

Update 25/09/2020: Some more progress to report after some offline representations to Lloyd in early September: The old "Isa" wreck mark has been recognised as being to AGD66 datum and the numbers corrected to WGS84 datum. This also shifts the wreck site out of the no-go military zone. Other fix ups included moving the "Formosa" 02 minutes south to the ocean coast, fixing a minor typo to the J3 Swan Island sub location, and moving the "Mountain Maid" position to a mark from the Getunder club (but note Heritage Vic has it a little further NE at 38 14.279S, 144 42.459E). These and a few other changes were implemented in the 03 Sep 2020 kml file update. Thanks for that Lloyd.




Who is online

Users browsing this forum: No registered users and 0 guests