Helping Blind Men See (a VIC only post!)

3 months 3 weeks ago - 2 months 2 weeks ago #303607 by packo
packo created the topic: Helping Blind Men See (a VIC only post!)
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I hope any non-Victorian divers might "click out" now to save us VIC folk some embarrassment. Didn't expect to be "banging on" again so soon, but recent events have forced my hand - and I have now had enough! Briefly the facts are:-

1 ) I have a long festering issue with my local dive shop located in Rye at the southern end of Port Phillip Bay.
2 ) The shop publishes unsafe timing advice for diving anywhere between 5km and 20km inside of the Heads.
3 ) The shop failed to investigate the issue and ignored a large set of evidence against their advice. They also ignore the view of the shipping authorities with a "what would they know!" attitude.
4 ) The Diving Industry of Victoria Association (DIVA), is a representative organisation of dive shops, dive course providers and the like. It claims to be "the diving community voice on issues affecting the Victorian dive industry and the Victorian diving environment."
5 ) DIVA has recently (19/10/17) declined a request I made for it to investigate the above issue. (I have previously claimed my LDS was a DIVA member because the DIVA president told me so. It appears I may have misheard, and in fact the business is not a DIVA member. Apologies for my previous misinformation.)
6 ) DIVA appears to have made its decision without examining any evidence. Rather it seems a quick "whip around" of some of its members has concluded that I am simply a "serial pest" they would rather do without.
7 ) DIVA proposes to take no action nor make any comment against the LDS's unsafe web published advice.
8 ) Unfortunately I have been too close to a number of drownings and near drownings to allow dangerous advice to remain in place without continuing the fight. Sadly without DIVA's support or "investigation".
9 ) Particularly following the DIVA decision, I feel no longer able to pursue the issue with Marine Safety Victoria. For the good of all divers and dive businesses, I don't want the embarrassment of a government body being confronted with the fact that some recreational diving businesses appear to have only "Neanderthal level knowledge" of tidal streams within the Bay.

********* A MAJOR DISAPPOINTMENT **********
The most disappointing aspect of this affair is that both the shop and DIVA have chosen to not view the fairly definitive live streaming video available for the Sorrento channel area. So little extra effort would be required to examine this convenient (and independent) source of evidence, yet neither the dive shop, nor the service centre, nor DIVA appear to have done so.

When my LDS claims it is "slack water" near Sorrento and recommends diving there (at Rip slack + 2 hours), the current has already built up to near the maximum rate in the reverse direction. This is the source of danger in their advice and why I am fighting to have that advice amended. Depending on the exact location, currents of between 0.6 and 2 knots may exist at the dive times they claim as "slack water".

********* WATCHING GRASS GROW **********
I do concede watching the video for the 30-40 minutes needed to confirm a switch in tide from flood to ebb or vice versa is a little like watching grass grow. To speed things up and allow for a more accurate timing of the change, I have recently installed a temporary "spar buoy" near the edge of the Sorrento channel and just within view of the webcam.

This buoy does not have the usual spherical float. The only reserve buoyancy is in the hollow spar itself. Therefore it presents a very low cross-section to wind and wave forces. There is a much larger cross-section at -2.5m down to allow it to easily "feel" the tidal stream.

The buoy and mooring are very light in weight and so respond relatively quickly as the weak reverse current grows just after slack water. Currents as low as 0.03knots (about one metre per minute) are easily and quickly detected. The mooring arrangement also allows a reasonably large movement of around 10m between the ebb and flood stream positions. At slack water the striped above water section stands around 0.5m out of the water. Here is a pic:-

NOTE: The very low reserve buoyancy means the spar buoy is dragged under underwater for most of the time and only surfaces for roughly 40 minutes either side of slack water. The small "tag" at the top is designed to point into any prevailing current. However this tag is often hard to see with the webcam as I probably stationed the buoy a little too far away.

********* "GRASS ROOTS" DIVERS TO THE RESCUE? **********
I am now appealing for some volunteers among ordinary dive-oz readers to do a bit of armchair "citizen science" and then convey the facts about tides in this area to both the dive shop and DIVA. You don't have to be a Victorian, or even a scuba diver or snorkeler. Kayakers, SUP folk, swimmers or anyone else who's safety depends in some way on a reasonable understanding of tides in the Bay could participate.

============= SOME GROUND RULES ===============
The webcam belongs to the local boat club and is intended primarily for their use to monitor moored vessels and its own maintenance operations. It is only available for use by the general public either through the good graces of the boat club, or because some public funding went into installing it. Please be sensible.

Please do not request control of the camera on strong north wind days if it appears to be focused on just one or a small group of boats. The nervous boat owners often like to check how their boats are riding.

If you request control of the camera at anytime within 40 minutes either side of Rip slack, but then see the coordinates are exactly on the spar buoy area, then please do not move the camera - others may be intently watching the grass grow, or perhaps taking screenshots.

The camera URL is:-
Sorrento Sailing and Couta Boat Club Webcam

If you are on a tight data plan then monitor your usage. You need only briefly reconnect to the URL every 3-4 minutes to build up a series of "snapshots" of the scene. The camera can be PANNED, TILTED, and ZOOMED. It can be operated from smart-phones but it can be awkward to do so. A tablet, laptop or desktop computer is best. The camera aiming and zoom readings are displayed in a small panel in the bottom right part of the screen.

The major controls are:
Taking control: Button in square at bottom right.
Camera PAN control: Blue slider below video picture. "Left" is more negative.
Camera TILT control: Blue slider to right of video picture. "Down" is more negative.
Camera ZOOM control: Green slider further to right. "Up" is a higher Zoom magnification but a smaller zoom number.

Best "spar buoy" aiming & zoom numbers are:-
PAN: -17.25, TILT: -2.25, ZOOM: 1.6
Update 12/11/17: Sadly a boat with high topsides has recently occupied a mooring close inshore of the spar buoy and mostly obscured it. Suggested plan is to now monitor the movement of a yellow 5kt limit buoy and a porthand Sorrento Channel marker visible as a red pile with red rectangular top-mark. The position reversal of this buoy is only a slight movement and will be a little slower than the spar buoy due to its heavier weight. Suitable camera coordinates to view this are now:-
PAN: -13.25, TILT: -2.25, ZOOM: 2.03

Update 21/11/17: The special spar-buoy has now been recovered (see 3rd post), and so is no longer available for observation. There are plenty of other buoys/boats in the area whose positions will reverse with the tide. However waves, windage, and different underwater profiles will mean quite a spread of times. Many are suitable to make the main point that tide stream reversal at Sorrento is not 2 hours after slack at the Heads, and anyone who says it is has just reduced the safety of many water sports in this area.

This should give good coverage of the spar buoy area with the ebb tide position being near the left side of the frame and the flood tide position somewhat to the right of centre. These exact numbers do seem to allow accurate re-positioning of the camera after another user moves it. (They get a 60 second "countdown".)


BoM RIP Predictions (Note added 6/12/17: If anyone also downloaded the 2018 RIP predictions from this BoM site, then note that the BoM tide guys just informed me it had some missing maximum stream rates, and was not fixed until 24/11/17. If your copy predates that, it might be best to re-download the now repaired 2018 RIP pdf file.)

or the October & November "Packo Prediction pages" available at:-
October Packo Predictions
November Packo Predictions

Best viewing conditions are in good sunlight at a morning or afternoon slack. Sun glare can be a problem around 1pm (AEST).

Note: Even in calm weather you might see the buoy swap sides a little before the BOM times and particularly so for ebb slacks. This is an issue still being investigated and is due either to the BOM times being a little too late, or that on the Lonsdale side of the Heads the current reversal is a bit later than on the Pt Nepean side. The delay between Pt Nepean slack and Sorrento slack has been observed at around 6-9 minutes but will vary. The delay between Pt Nepean and Lonsdale bight BOM slacks is sometimes a little longer, meaning frequently the buoy switches over ahead of BOM Rip slack.

Weather may also affect timing somewhat. These shifts can be up to +/-30mins. However apart from catching you out, they are not so relevant here as the aim is to determine whether the scubadoctor's website claim of a 2 hour delay for slack water at Sorrento is valid.

********* FEEDBACK *********
Readers who manage to capture good clear spar buoy "swap overs" with accurate time records for when the buoy begins its journey to the other position might like to record the details of your observation including:
Date, Time, BoM Rip slack prediction, and whether flood or ebb slack.

If you think your "science" was well done with a definitive result, you may wish to send a brief email to the addresses below. These cannot be copied by "cut and paste", and will have to be copied by hand.

Even if you don't have the time for the full show, just a glance to see the buoy somewhere in the slack window, followed 2 hours later when the current has dragged it down into Davey Jone's locker is productive. This might still be a useful observation to feed back to the folks above.

Dive-oz members may also want to post their observations here. (Or give me a "You're a serial pest" blast - I'm happy to argue the case out with anyone!).

Remember it is really all about small incremental safety improvements because at the end of the day they all add up, and may just save a life! The correct information may also prevent the incidence of risky or abandoned dives at these "well inside sites".

In the long run it benefits no-one to allow crappy and unsafe information to stand. Bruised egos do heal - and often more quickly than they really should!

For the next little while I'll be somewhere off the QLD coast with a non-existent or patchy internet connection at best. I'll try to monitor this thread, and reply if needed, but there can be no guarantees on this.

Note that I will be removing both the spar buoy (and parts of this post) sometime in the second half of November, or when the scubadoctor advice is amended, should that occur earlier.

Last Edit: 2 months 2 weeks ago by packo.

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3 months 2 weeks ago - 3 months 1 day ago #303620 by packo
packo replied the topic: Helping Blind Men See (a VIC only post!)
Hello again,
Well back from a nice QLD cruise around the Whitsunday Island group. No diving, but some very pleasant snorkelling. However cyclone Debbie did make a bit of a mess of some parts of the fringing reefs in Bufferfly Bay. Areas protected from the north east seem to have been spared.

I skippered a 34 foot bareboat sailing catamaran around this extensive island cruising ground. Luckily we had excellent weather with plenty of warm sunshine, good afternoon sailing breezes, mirror smooth evening anchorages, just a few thunderstorms but hardly any rain, and of course a great crew.

The bareboat charter limits don't let you go out to the GBR of course, but we really appreciated its just over the horizon presence giving us no swell at all for the 10 days. Came back to a rather cool and wind blown Rye :(

Yesterday managed to escape Rye and my LDS battles by cycling to the next bayside village eastward in some glorious warm sunshine. Called in at the dive shop there. In a wonderful surprise found a younger style dive shop owner who knew his tide flows. We had a good chat on the topic and it was quite uplifting after all the crap I have been through.

Forum rules say no overt advertising but let's just say my warm sunny afternoon cycle was pleasant in the extreme, but I needed to drink a lot of water, and even a few swigs of my sport drink.

There is now perhaps a small chance DIVA may rethink its ruling that it saw no safety issue in the matters I raised about the Rye LDS website advice.

Be that as it may, I really need some grass roots support soon on observations of my "spar-buoy" movements as the tide reverses at Sorrento. It has been in the water a few months now and is slowly loosing its small reserve buoyancy as various marine critters take up residence. I will be pulling it out in about a fortnight so would appreciate it if some readers can feed back their observations to DIVA and the dive shop.

I know it is sort of "cheating" but I'll put up my own observations done at this morning's flood slack. I used slightly different camera settings than recommended in the previous post, but then compensated for this by using the highest camera resolution. It gives a slightly wider field of view:-

For planning the best times to observe buoy "swap overs", here is a extract of some "Packo predictions" for slack water at the Heads for the next 10 days. See other posts for the full details but the coloured boxes should help you sort out which columns of the table are useful for planning "spar buoy" observations. Note sun glare around 1pm can be a problem.

Update 12/11/17: See previous post for the red note regarding the boat now obscuring some parts of the "spar buoy" area. Sigh! :(
Last Edit: 3 months 1 day ago by packo.

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3 months 4 days ago - 3 months 1 day ago #303642 by packo
packo replied the topic: Helping Blind Men See (a VIC only post!)
Hello all, a final wrap-up:

Update 21/11/2017: Pulled my spar-buoy out today after a 2 month plus deployment. It gave me plenty of good results despite being partly obscured from the webcam in the last week as some of the vacant Sorrento moorings were reoccupied. It grew quite some weed. Here is a cleaned up view after recovery:-

I got one or two photo mosaics in the last days by trying to work around the boat. The second sequence shows a weather shift and how these can be anticipated in advance by using the VRCA Pt Richards "Tidal Surge" plots.

Had a meeting with various top knobs at the VRCA in October and extracted some promises of "we'll see what we can do" about a number of small defects that make their plots difficult to use for weather corrections to slack water. We will have to wait and see, but I doubt anything much will happen in time for the summer holidays.:(

and (oh dear, just saw typo in 2nd text line in the following image. It should read: 10:40 + 5 mins = 10:45am )

Most of the aim for "spar-buoy" was to firm up some numbers and timing of my own "packo predictions" for the Rip. Another aim was to hope the idiots in my local dive shop might also take a look at the live video off Sorrento and see that their slack timing nonsense for this area was dangerous and needs to be removed.

To anyone viewing the video it is bleedingly obvious that current reversal at Sorrento occurs within minutes of it happening at the Rip and all this "dark ages diver folklore" about delays of 2 & 3 hours at Sorrento & Rosebud is complete tosh. Why they cling to it so vehemently and reject bucket loads of contrary evidence is totally unknown. It appears some blind men don't actually want to see clearly.

Strangely they seem to have no interest whatsoever in consulting "the 3rd umpire". At first neither did DIVA. However another Peninsula dive shop a little east of Rye has come onto the scene and supported me. This may result in a DIVA rethink. It will likely be a long slow process as DIVA seems to have more than a few "Myth Men" in its ranks.

Even if they do switch around to eventually declare the LDS advice I have complained about as "not safe", neither of the Rye businesses are DIVA members, so they could still possibly ignore any new finding DIVA might make. On the positive side the dive shop owner is on record as saying "If DIVA wants to investigate the claims of this serial pest further, then I’d certainly be interested in the outcome."

Well he was never very interested in "investigations and outcomes" over the last 2 years (neither mine, nor doing his own, nor PoMC's views), but if DIVA does perform a back-flip, I will make certain he is aware of it and remind him of his "being interested" claim!

Last Edit: 3 months 1 day ago by packo. Reason: typo notification

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