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The Cruising Yacht Club of Australia has just released its inquiry into the deaths of two sailors (including owner-skipper Andrew Short) in a catastrophic grounding during the Flinders Islet race last October. It may not seem to have much to do with a C&C 27, but the inquiry is a crucial exposure of the hazards of relying on GPS chart plotters for safe navigation. I've posted at greater length on my cruising blog (www.sweetwatercruising.com) about the inquiry, but the main takeaway points are that this maxi managed to run smack into Flinders Islet in the night despite having two GPS chart plotters. The owner-skipper was navigating almost exclusively by plotter, and as the inquiry outlined, GPS is prone to position degradation linked to the particular configuration of the satellite constellation. A the time of the grounding, there was an estimated degradation of at least 100 meters. The inquiry his critical of the growing trend of sailors relying exclusively on chart plotters, which can have other problems related to internal software. An eye-opener of an inquiry. I'm skeptical of how much play it will get in the boating media, as it highlights operational problems with a particular brand, and the manufacturer declined to cooperate with the inquiry.Doug Hunter
Diva
C&C 27 Mk1
Midland Bay Sailing Club
www.sweetwatercruising.com
Doug Hunter
Diva
C&C 27 Mk1
Midland Bay Sailing Club
www.douglashunter.ca
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Doug,
Good message. I have some particularly gory photos of a boat that went aground on Nekker Island a few years back when the skipper was sailing waypoint to waypoint by GPS and autopilot. Even when the plotter/GPS is right, the underlying chart can be wrong. I'm a big fan of chart plotters because I sail single handed, but I don't trust them any more than my DR skills. Nothing beats a set of eyes looking forward.
Mike M
SV Wind Horse
#375
Galveston, Tx
Mike M
SV Wind Horse
#375
Galveston, Tx
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Maybe a decade ago when CHS started digitizing charts for GPS nav, they declined to digitize 2239, which was an important chart that covered southeastern Georgian Bay. It turned out it was so inaccurate that the Hope Island lighthouse (and thus Hope Island) was out of position by something like 1,000 feet. So they waited and brought out a whole new replacement chart, 2241. That was an eye-opener. CHS had to do a lot of work to get some charted areas up to snuff for GPS.
When I was at the Toronto boat show in January, I was chatting with a guy who makes third-party charts with shaded elevation and other topo info. We were talking about nav charts in Georgian Bay, and I mentioned that in many areas with "blue" depths, there's been no actual surveying, that these areas often have been guesstimated by CHS looking at aerial photos. He was stunned. Those of us who go looking for private anchorages know that "blue paint" navigation can yield you spots with 10 feet or more of depth...or a bunch of rocks nobody's ever written down.
Doug Hunter
Diva
C&C 27 Mk1
Midland Bay Sailing Club
www.sweetwatercruising.com
Doug Hunter
Diva
C&C 27 Mk1
Midland Bay Sailing Club
www.douglashunter.ca
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I sailed many of the beautiful bays surrounding Boothbay Harbour in Maine at high tide. On another day I sailed those waters at low tide.
I was shocked to see the rocks and shoals that I had luckily sailed over that were not marked on the charts.
Only 70 days to go to Launch.
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A big concern with chart plotters going forward is that a lot of newbie boaters have been lured into a false sense of security/accuracy by the GPS in their car, which magically fixes them right to a particular road. Those units employ some clever software filtering to locate the car on the road, and the same can't be expected on a marine chart with a boat. When I first started using GPS a decade or so ago, I saw my plotted position wander up on dry land while running Georgian Bay's small craft route. Fixes are much better now with the US military having removed signal degrade for civilian users and the advent of WAAS. But plotters can still make mistakes, in refresh rates, in displaying all data layers (like rocks and soundings). They're a great tool, and they've done infinitely more good than harm, but their limitations and foibles need to be heeded.Doug Hunter
Diva
C&C 27 Mk1
Midland Bay Sailing Club
www.sweetwatercruising.com
Doug Hunter
Diva
C&C 27 Mk1
Midland Bay Sailing Club
www.douglashunter.ca
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Disaster rooted in equipment that allows people to venture outside their capability envelope is a recurrent problem in a lot of activities these days, not just in sailing. It was argued that Michel Trudeau, Pierre's youngest was where he was - in the path of an avalanche - because the superb quality of his and his friends' back-country gear allowed their ambition to exceed their negligible experience. Mountain-climbing suffered an explosion of deaths with the introduction of lightweight equipment (the Matterhorn region tumbled from relative safety to a death a day during one climbing season as it was invaded by the inexperienced).
That said, the Flinders Islet Inquiry is an important contribution, as it highlights an aspect of GPS behaviour that isn't really well understood. I sorta-kinda knew how GPS position information could be degraded, but the error presumed from this incident, around 500 meters, is _ten_ times what I assumed to be the worst-case scenario. Moreover, the usual over-reliance-on-GPS warning/nag is couched in terms of power failure; this was worse, because everything seemed to be working fine.
There are a lot of lessons there for everyone, racers and cruisers - everything from the misleading tendencies of miracle equipment to the way that seemingly minor decisions about safety equipment can have life-threatening consequences. A worthy read. Thanks Doug, for bringing it to our attention.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
Last edited by (2010-03-01 06:33:56)
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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I seem to be in full maritime disaster mode this week. My op-ed piece on the sinking of the school tall ship Concordia and the investigation complications caused by its Barbadian "flag of convenience" ran on Tuesday in the National Post. You can read it online here. http://www.nationalpost.com/todays-paper/story.html?id=2629596&p=1
I consider it a happy coincidence that the day after my piece ran, Transport Canada said it would be launching its own investigation.Doug Hunter
Diva
C&C 27 Mk1
Midland Bay Sailing Club
www.sweetwatercruising.com
Doug Hunter
Diva
C&C 27 Mk1
Midland Bay Sailing Club
www.douglashunter.ca
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I have been preaching dual navigation for years after being scared big time while racing. The electronic devices are very good to a limit, and only really should be used as a quick reference and not as an exclusive source.
I have updated all my charts and checked them against others who do the same thing so that I feel somewhat comfortable. Besides, a three position fix really tells you where you are.
'IRIS'
1975 C&C 27 Mk lll
Hull # 453
Kittery Point, Maine
'IRIS'
1975 C&C 27 Mk lll
Hull # 453
Kittery Point, Maine
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THe National Post report was most informative.
It is apparent the registration of vessels under a flag of convenience is designed to protect owners/operators of these vessels.
The sinking of ships and the death of passangers/crew are significant events that demand full public investigation and reports.
The offiical investigations should provide vital information to protect persons and property on the seas of the world.
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It's always been clearto me, and this ongoing string of object lessons does nothing to dissuade me: learn paper chart navigation and manual positioning before electronic positioning/chartplotting, be prepared to use both when pleasurecraft cruising, and learn from a "school" that integrates the two with consistent terminology.
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1974 Mark II C&C 27
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1974 Mark II C&C 27
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Kittery Point is a beautiful place.
and David Mazury provides excellent counsel.
Whenever I sail unfamiliar waters I personally add the EXTRA precaution of "checking with the locals." These are the sailors who know the location of specific danger positions in the area.
Happy getting the boats ready for launch. Only 53 days to go at BYC, Ottawa
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