Black Panther 1,686 Posted May 24 Share Posted May 24 Reminds me of this photo Quote Link to post Share on other sites
ex Elly 221 Posted May 24 Share Posted May 24 So you won't be joining the ICA? 😅 1 Quote Link to post Share on other sites
Black Panther 1,686 Posted May 25 Author Share Posted May 25 Unlikely Quote Link to post Share on other sites
Jon 391 Posted May 27 Share Posted May 27 An Outbound 46 hit Navutu reef in the Lau a couple of nights ago ’Thursdays Child” Quote Link to post Share on other sites
aardvarkash10 1,057 Posted May 27 Share Posted May 27 6 minutes ago, Jon said: An Outbound 46 hit Navutu reef in the Lau a couple of nights ago ’Thursdays Child” Serious question; how does this happen in a time of precision GPS and boat/course management systems? Quote Link to post Share on other sites
Jon 391 Posted May 27 Share Posted May 27 Plotting a course from Minerva to Savusavu Put in a few waypoints to go up between the islands in the Lau However you then need to zoom in and follow the route as many things don’t show at low zoom 1 Quote Link to post Share on other sites
Jon 391 Posted May 27 Share Posted May 27 GPS aided groundings are more common than you’d like to think All speculation on my part at this point 1 Quote Link to post Share on other sites
Psyche 718 Posted May 27 Share Posted May 27 1 hour ago, Jon said: GPS aided groundings are more common than you’d like to think even best crews do it at the highest level! https://panbo.com/lessons-of-vestas-volvo-wreck-but-what-about-the-c-map-grounding-alarm-similar/ Quote Link to post Share on other sites
Black Panther 1,686 Posted May 27 Author Share Posted May 27 I've never used way points, always seemed weird to me. Quote Link to post Share on other sites
Island Time 1,284 Posted May 27 Share Posted May 27 IF That was the cause, it is very poor passage planning - and that looks somewhat likely. Situational awareness! Never relay on one source of navigational data! Confirm your position with multiple sources, and ALWAYS do a high zoom fly through of your passage plan. Contrary to BP's position, waypoints are a highly useful navigational aid - one inserted into this route, several miles off the reef, to either side, while planning the passage would have avoided the issue. So would boundaries with alarms (easy to put around any danger points), exactly as you would on a paper chart. Radar guard zones with alarms set at a few miles would likely have seen the breakers. Poor SOP's look to have caused the loss of this vessel.... A warning to us all. Take care out there! 1 1 Quote Link to post Share on other sites
Island Time 1,284 Posted May 27 Share Posted May 27 14 hours ago, Jon said: GPS aided groundings are more common than you’d like to think All speculation on my part at this point John, is that Navionics? It shows up a pretty high zoom on CMAP; Quote Link to post Share on other sites
Jon 391 Posted May 28 Share Posted May 28 Yes Navionics, if you look at the two images Vanuatu Vatu is only visible in one also all systems have there risks, it has a declutter mode effectively that drops stuff as you zoom out, I always create a route not to follow directly but to use as a reference line so I can zoom in and out and still know we are heading in the correct general direction I guess this is so it can be run on mobile devices I’m assuming I like it as I run an iPad in the cockpit and encourage all crew to use it while in watch, when I first sailed offshore navigation was a dark art that was guarded by one or two aboard and was done in secrecy way down below at a hidden table, not quite but I like all crew to be situationally aware at all times, even my 3 year old grandson can use an iPad. He FaceTimes us every few days when he gets up The key to all systems is knowing there limitations 1 Quote Link to post Share on other sites
Island Time 1,284 Posted May 29 Share Posted May 29 5 hours ago, Jon said: Yes Navionics, if you look at the two images Vanuatu Vatu is only visible in one also all systems have there risks, it has a declutter mode effectively that drops stuff as you zoom out, I always create a route not to follow directly but to use as a reference line so I can zoom in and out and still know we are heading in the correct general direction I guess this is so it can be run on mobile devices I’m assuming I like it as I run an iPad in the cockpit and encourage all crew to use it while in watch, when I first sailed offshore navigation was a dark art that was guarded by one or two aboard and was done in secrecy way down below at a hidden table, not quite but I like all crew to be situationally aware at all times, even my 3 year old grandson can use an iPad. He FaceTimes us every few days when he gets up The key to all systems is knowing there limitations Totally agree. understanding your tools and their limitations is an important part of being a Skipper. Quote Link to post Share on other sites
Island Time 1,284 Posted May 29 Share Posted May 29 This would be a rough basis for that passage. The red bits are boundaries - alarms go if we try to cross one. You don't have to follow exactly, but no boundaries nearby or crossed, you are good to go. Takes 5-10 mins to setup.. Its easier to do the thinking and planning while at anchor, once you've decided where you want to go. Then if stuff is going wrong, one of the primary tasks is already done... Passage planning, including boundaries and clearing marks etc, are all part of the RYA yachtmaster course, and should be 2nd nature to any skipper. 2 1 Quote Link to post Share on other sites
Addem 120 Posted May 29 Share Posted May 29 I worry about low zoom gps losing important detail. My practice when embarking on a new or unfamiliar passage is to get out the paper chart. List the hazards and major way points expected and then transfer to the GPS. I then cross them off as I pass them. For a night passage, an old seadog showed me the benefit of also making a light list. Has proved worth while at least once. 2 2 Quote Link to post Share on other sites
Island Time 1,284 Posted May 29 Share Posted May 29 OK, here is another example - this is the same waypoint - just different chart scales... This is zoomed in, this next one zoomed out to next scale So, the waypoint has not moved! But the position of the reef moved about 2nm! The SAME issue is on the PAPER CHARTS at different scales. Interestingly, in this case the larger chart is the correct one. Not the 1st time I've seen that. Where there is little shipping, the charts are not fully reliable. You must have 3 data points to have a safe position. A modern digital radar would see the breakers, and can give you an overlay to show you which chart is right.... Depths and hand bearing compass could also work, as could a satellite image. This is why everything should have a clearance in your plotting - I usually use 5nm, especially at night, and especially around sunken reefs. Be careful out there! 1 Quote Link to post Share on other sites
darkside 63 Posted May 29 Share Posted May 29 Yep the west coast of the Red Sea jumped about a mile east/west on Cmap at different zooms. They may have fixed that now as it was a while ago. Vavau used to move about a quarter mile. Quote Link to post Share on other sites
Black Panther 1,686 Posted May 30 Author Share Posted May 30 The good old days of paper charts. Notes 1 this island is 1.5 nm west of charted position 2 this rock is 4 nm west of the charted position. 3 this rock was observed in 1889 but hasn't been seen since 4 this chart needs to be moved 8nm east. Interesting most of the corrections were east/west. A guy with a sextant could determine north/south reasonably accurately but east/west not so much. 1 1 Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.