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