Select to expand quoteYara said..D3 said..Datawiz said..
So there I was motorsailing down the shipping channel (Port Phillip Bay), not a soul around. It's blowing 10-15kn about 30deg off the starboard bow.
I'm running the route on the autopilot that I set up quite a while ago on the Raymarine C80 Chart Plotter at the helm. I have waypoints set about 50 metres off each channel marker. The Raymarine runs Navionics charts updated about 4 years ago.
I've run this route more than 20 times before, and I'm on the leg from Channel Marker No 14 to the next waypoint at No 12, a distance of approx 1.2nm.
Since Nos 14, 12 & 10 form a straight line, I decide by using 'Advance Waypoint' to skip the No 12 waypoint and go to the No 10 waypoint.
This will give me time for a bit of a break down below from the cold and wet cockpit before I have to come up and set the next waypoint on the Raymarine when we get to No 10
Down below, I have my iPad running iNavx with Navionics charts (updated about 2 months ago) on the table in front of me.
Besides the chart, iNavx displays my track, COG, SOG, depth, true & apparent wind speed & direction, AIS, etc, so I've got a reasonable handle on what's happening.
The wind is now more like 15-18 knots.
I'm looking at the screen and seeing I'm on track with nothing near me when... BANG!!
The whole boat shudders and iPad and coffee flies off the table, other stuff ends up on the floor and I fly up to cockpit in less than a second head full of "what the hell's happening ????!!!!".
What the hell happened was I'd just driven head first into Channel Marker No 12 at 5.5 knots!
After the flurry of establishing I've not been holed so not in danger of sinking then getting the boat under control, getting the headsail down manually because the furler is smashed, I try to understand what happened.
It took a while, but it comes down to this - the Navionics chart on the iPad does NOT show the No 12 Channel Marker, the version on the Raymarine C80 Chart Plotter DOES show the No 12 Channel Marker!
I also have the Navionics iPad app, and it DOESN'T show No 12 either.
I also have iSailor on the iPad and it DOES show No 12.
I often skip waypoints and have never had a problem before, but what happened this time was, being close hauled like I was, the boat can tend to have some weather helm and apparently the autopilot was not able to keep the boat on track, so I have accumulated enough leeway to end up colliding with No 12 - but not enough to trigger an "off course" alarm on the autopilot.
Obviously, if No 12 had been showing on the iPad, I would have seen it approaching and taken appropriate action.
As far as damage is concerned, headsail furler, pulpit and bow roller are severely damaged, but I consider myself very lucky - it could have been a lot worse.
Naturally, this episode raises some questions including the integrity of charts other than the hard copy originals.
Typical Channel Marker - I think the one I hit was even bigger!
Navionics Chart on IPad iNavx.
iSailor on iPad Chart
And yes...I do know about the warnings and disclaimers on these navigation apps.
So...any thoughts?
regards,
Allan
Question, actually two, to get a bit more context.
1- Was the planned route exactly the same on both bits of gear?
2- What was your level of zoom? It would be useful to know what scale is required to show that a boat can actually be 50 metres off track
D3, as I explained earlier, if the autopilot is sailing to a waypoint, it is not sailing on a defined track, only to a defined destination. Mind you, Datawiz being a data-wiz, maybe he has a U-beaut fancy autopilot which actually controls to a track, rather than just correcting the course to the waypoint.
He said he was on track and did not get an off track alarm.
So I'm wondering what the tolerances are. You plan your track, the boat sails to the waypoint but you should be able to have a way to check how far of your planned safe route you are.
Select to expand quoteYara said..
So would it have been better to set a compass course using this technique rather than waypoints?
That is the way we should do it and calculating for set and drift is not that difficult but does take a bit of time.
Therein lies the problem if single or short handing in close quarters. You have that many things to be thinking and taking care of that it is easy to miss something.
Datawiz mentioned that he had done this particular passage about 100 times so "familiarity breeding contempt" may have been a factor.
I'm always on edge in Port Phillip. Its so easy to get bored and so many little things to run into. Some fixed and some moving. Last week there was a lone swimmer between 1/2 mile out between Brighton and Sandy.
The biggest fear is that I might flatten some dude fishing in a tinny. They are often a very long way out and just a spec in an expanse of water easy to miss if the sun is wrong.
A
Can't even rely on paper charts.
A mate of mine was looking for a ship wreck, this was before GPS etc, and was having a lot of trouble finding it.
Resorting back to basics he used a sexton to establish the headlands around the area and he eventually worked out that the charts, based on Captain Cook's, put the whole of the east coast of North Island of New Zealand 3/4 of a nautical mile to the west.
Once that was factored in he found the wreck on the first dive, made a lot of money too.
Select to expand quoteAndrew68 said..
I'm always on edge in Port Phillip. Its so easy to get bored and so many little things to run into. Some fixed and some moving. Last week there was a lone swimmer between 1/2 mile out between Brighton and Sandy.
The biggest fear is that I might flatten some dude fishing in a tinny. They are often a very long way out and just a spec in an expanse of water easy to miss if the sun is wrong.
A
I've found out the hard way that if you see another vessel and its below the horizon
IT"S BLOODY CLOSE !!!!
Select to expand quotenswsailor said..
he eventually worked out that the charts, based on Captain Cook's, put the whole of the east coast of North Island of New Zealand 3/4 of a nautical mile to the west.
That is a hell of a compliment to Cook's navigation and charting capabilities isn't it??
He had only just been to Tahiti to observe the angle of the transit of Venus in front of the Sun from which the mathmeticians could greatly improve the calculation of longitude for ships at sea.
So, for Cook's determination of longitude to be only 1,500 yards out from actual is pretty damned amazing for the time.
You got balls of steel, big as an elephants, mate, for this admission! Thank you!
After all the comments - whatever they were - few conclusions must be drawn.
Sailing, navigating is inherently a dangerous pastime or occupation no matter what.
Nothing, l mean nothing whatsoever is able to replace the human touch and even human touch is sometimes far from reliable no matter how careful or experienced one might be.
Relying on electronic navigation only, is foolish and dangerous.
Using multiple electronic nav aids simultaneously is at best confusing especially if they are not using the same charts and operating systems.
Vector charts like navionics should only be used as guides and not trusted for navigating because, beside being complicated to operate while handling a boat, the data discrepancies shown at different zoom levels.
Raster charts, paper or electronic, - like Memory Map - do not have this inherent shortcomings and are simpler and more reliable nav aids!
Having low excess on one's insurance makes any mishap more bearable.
If we would be more honest to ourselves we would not forget the dozens of mishaps and near misses we had and face the reckoning with more honesty and humility.
Fair winds!
Gutsy effort Datawiz. It's a nice reminder not to get complacent.
I guess there is always a risk of running into something singlehanded sailing. I was just lucky not to run into boat that did not have AIS. You just can't stay vigilant 24/7.
But your story will make me add some more visual checks when sailing in channels.
Select to expand quotesirgallivant said..
Vector charts like navionics should only be used as guides and not trusted for navigating because, beside being complicated to operate while handling a boat, the data discrepancies shown at different zoom levels.
Raster charts, paper or electronic, - like Memory Map - do not have this inherent shortcomings and are simpler and more reliable nav aids!
Even raster charts and OZ hydrographic charts sometimes lie. They were 800 meters out in longitude in the eastern Louisiades. C-Map was actually more accurate. And buoyage can change faster than the chart corrections, particularly in places like the Sandy Straits and Moreton Bay with their shifting sand banks.
Navionics in Gladstone harbor is very confusing, it has not caught up since the gas terminals were built and the new channels dredged. It is just another place that needs your attention all the time. Aus 245 on Memory Map is up to date, but you don't have time to be peering at a computer as you traverse the port.
Yep, you are - unfortunately - dead right Phoenix.
This is the reason why even concerning the AHO raster charts l used conditional not an absolute!
It is a gamble, really, and you can only try to minimise the odds, chances of an accident or incident.
Good seamanship and a disciplined mind helps, thou.
More so when sailing alone.
Allan: another compliment for publicly fessing up. Who amongst us has not taken himself below for respite, in spite of knowing he should be eyeballing at all times? Me for one. And I did almost flatten a couple of blokes in a tinny once, very very bad of me. Luckily my old Compass plods along so slowly I had time to react to their shouts and steer away
Andrew - I saw that mad swimmer off Brighton and called it into the Coast Guard to put out a Securite, which they did. Their boat couldn't find him, which I assume means he made it to shore in the meantime. If he'd been run down it would have been on the news.
Cheers, Graeme
For charts, always be sure the Zone Of Confidence to assist with avoiding embarrassment
Yes, thanks for pointing the Navionics omission of #12. I notice on the chart that the channel narrows between #10 and #14 and the structure that used to be at the tip of the sandbank at the south east entrance to the Pinace has been removed by the Waterway's team of workers. They are a funny bunch with a few stories to tell.
I fish to the north and had no idea that Navionics left #12 off the chart!
I was drifting fro flatty off quarantine and glanced a big yellow beacon as I was cooking a meal. Lesson learned and in a wooden boat i would not fare well in a direct collision! I noticed on my last trip from Melbourne in July after dark that #21 was in total darkness, no green flash..... it was spooky to see it glide by about 20 meters away. Probably been repaired by now?? Another near miss and one to look out for in Port Phillip. If I hadn't been watching i would have hit Chinamans hat dead on in the early hours on my way to the Geelong Wooden Boat festival. I had my way point to clear the mark by 50 or so meters. As I approached i saw the light to starboard and thought i was ok. Then i see shadow looming in the misty darkness directly in front of me!!! Holly **** I lifted the pilot piston off the tiller and swung her to port. As it was I missed by a good distance as its hard to tell in the dark but if i was below making a cuppa that would have been it for sure! The trap was set as there is a pile 50 meters south east of the Chinamans Hut structure and it was this that was lit and marked on navionics as i had read the chart.
