Regret to Inform Have Lost my Boat off Honduras...

[Rakuflames]

"
Originally Posted by Jim Cate
Well, since the discussion was relative to range marks, it does not matter if the datum registration is correct or not. One follows the range as observed by eyeball, not by what is on chart or VDU. Actually, once withing sight of the range markers no chart of any sort is required to get through a pass. Once through the pass, the chart again becomes useful and datum errors important if further piloting is needed.

Cheers,

Jim
Thought I repost it for people who don't get ranges....."


I don't think there is anyone here that doesn't get ranges. The question was NOT "What is a range marker?"

The question was whether those range markers were plotted accurately on the paper chart or not.

There is nothing in that question that implies lack of understanding of range markers. And by the way, the channel I have used more than any other has range markers. As it happens, those are accurate on both the paper chart and my chartplotter (although my question has nothing to do with chart plotters).

[boatman61]

Originally Posted by s/v Jedi

Almost all charts are electronic and the paper charts are just print outs of those electronic charts. It's only some 3rd world stuff that is still in paper source.

****... did not realise that Cook was that advanced...
or are you saying the all the data is now copied and stored on disc..

[psneeld]

Originally Posted by CarinaPDX

The excellent Startron recommended earlier dissolves algae, thus keeping things liquid and flowing. It is the use of biocide that is the problem: put it in your tank and the algae will all die and sink to the bottom, forming a nasty sludge (which is also corrosive). Simply put: don't use biocide.

On the range issue, ranges are often relocated in order to indicate the current channel. ALL charts, paper or electronic, must only be used for locating the range. The range itself must be trusted, even if it has been moved since the chart production.

Greg

Good post on the range issue...

[Rakuflames]

Originally Posted by psneeld

Good post on the range issue...

Well, that's the whole point of them. Still doesn't answer my question, though. it sounded as if there were people who were extremaly familiar with the channel in question, and i thought they would know whether those particular range markers were accurate on the chart or not (think about it -- that question does imply knowledge that they may be moved).

Channel markers may be moved also. That's why we have floating nuns and cans -- so they can be moved. Anyone who thinks channels are static and unchanging needs to take a basic navigation course.

[CarinaPDX]

I should add that it is not just ranges that may have been altered; navigation buoys are often moved to indicate the current channel. Going into a harbor by relying on the buoy locations on the chart or plotter is a mistake: the actual locations must always be verified, visually or with radar. Again, one of those times where naive reliance on charts and plotters can end in sorrow.

Off to a wedding...

Greg

[CarinaPDX]

Raku - we're on the same page here :-)

Gone

Greg

[psneeld]

Originally Posted by CarinaPDX

I should add that it is not just ranges that may have been altered; navigation buoys are often moved to indicate the current channel. Going into a harbor by relying on the buoy locations on the chart or plotter is a mistake: the actual locations must always be verified, visually or with radar. Again, one of those times where naive reliance on charts and plotters can end in sorrow.

Off to a wedding...

Greg

You have the opposite to worry about too...the buoy could be off station from where it's supposed to be.

Some mariners have a pretty good feel for which channels are going to move or not and which possibility is higher...buoy off station or buoy intentionally moved.

LNMs help that problem in the US...but you still need to ascertain which is correct or use your best judgment and guess. Sometimes that's a pretty serious guess...

[Paul Elliott]

Originally Posted by Rakuflames

Yes, I know you can't use GPS to interpret your paper charts.

I use the paper charts to interpret the GPS. When in doubt I go back to the paper chart.

So what I was really asking was if the PAPER chart has the range markers accurately placed. If it does, no problems. If the paper chart is wrong then it's going to be a lot trickier for a newer sailor.

Raku, you asked what "off-datum" meant. I explained that for you.

As for the range marks being accurately drawn on the charts, other than the lat/lon possibly being inaccurate, they are likely shown correctly relative to the channel, landmarks, etc. But I suppose they could be wrong, it depends on the chart. Local knowledge might be helpful. I certainly don't know.

But the whole point of range marks is to get you through a channel or pass. One would hope that the actual physical marks were appropriately placed.

[Rakuflames]

Originally Posted by CarinaPDX

I should add that it is not just ranges that may have been altered; navigation buoys are often moved to indicate the current channel. Going into a harbor by relying on the buoy locations on the chart or plotter is a mistake: the actual locations must always be verified, visually or with radar. Again, one of those times where naive reliance on charts and plotters can end in sorrow.

Off to a wedding...

Greg

Oh ship! you mean you have to LOOK AROUND?

WHO KNEW???????

[Rakuflames]

Originally Posted by Paul Elliott

Raku, you asked what "off-datum" meant. I explained that for you.

As for the range marks being accurately drawn on the charts, other than the lat/lon possibly being inaccurate, they are likely shown correctly relative to the channel, landmarks, etc. But I suppose they could be wrong, it depends on the chart. Local knowledge might be helpful. I certainly don't know.

But the whole point of range marks is to get you through a channel or pass. One would hope that the actual physical marks were appropriately placed.

But see, the question was -- are the range marker sets for THAT CHANNEL reflected accurately on the paper chart? Everything else is ... I don't know what it is.

[Wrong]

Whenever approaching landfall and channels I am topsides well out looking for markers and or lights. Forget the electronic and paper charts - unless things don't look right. Then I heave to and start double checking my waypoints. Stop. Look for other vessels and landmarks to confirm my approach is correct. Proceed only when sure my navigation is right. Binoculars help, but are difficult to use on a bouncy boat. Proceed cautiously constantly looking for markers...

[boatman61]

Originally Posted by Rakuflames

But see, the question was -- are the range marker sets for THAT CHANNEL reflected accurately on the paper chart? Everything else is ... I don't know what it is.

I don't know about the States... but in the UK there are updates of changes to Nav Marks published for Admiralty charts.. it is then up to the vendor of charts (Chandler) to update the info on any charts he may have in stock from earlier editions... or... you and me to keep our charts updated... You can also find update info in monthly magazines like 'Practical Boatowner' and 'Yachting Monthly'... so if you have a 1 year old chart and hit a nav mark that was moved 3 ago the fault is yours.. not the Publishers... it is down to you to keep your charts up to date.
All the relevant updates can also be accessed online.
Regarding Range Marks... they are usually on prominent buildings or other permanent fixtures etc and channels are dredged/blasted to keep them accurate...
But... someone else may know better

[NZGrant]

Well as a coastal sailing fella who wants to go offshore in the future I would like to thank both the OP and those that have upset him with their responses.

To the OP you had the balls to come on and tell us your side of the story which is great as we can all learn from it however did you really not expect to take a hammering from some on here?

To those that have upset the OP thank you also as people like myself don't want or need the PC ******** where no one is ever to blame for the situations they find themselves in. Most of the time it is our own fault and having already had the options brought to our attention like this is a great way to learn. Train hard and fight easy.

There have been lessons to learn here which hopefully might save someone else's life or boat or maybe both. For myself maybe a small genset and a method of filtering dewatering independant of the engine fuel lines run off the genset perhaps.

[boatman61]

Sorry.. my bad...
That should have read... "nav mark moved 3 months ago"

[Sailmonkey]

Originally Posted by Rakuflames

But see, the question was -- are the range marker sets for THAT CHANNEL reflected accurately on the paper chart? Everything else is ... I don't know what it is.

The reef cut isn't even shown on the charts for the area. The cruising guide makes mention of them with a hand sketch and an photo of the ranges, along with a position offshore to begin your approach.

However Xcalak is on the chart and the high range is visible for quite a distance. I wouldn't call this a channel, it's just a gap in the reef.