C_MAP MAX Error on Loch Lomon?

Hi Guys

I've a Northstar Chartplotter with a C-MAP MAX chart in it covering The Firth of Clyde (which includes Loch Lomond) C-MAP Chart Ref: EW-M023.07.

Now, I was out last weekend crusing between the 3 islands, and was heading east between Inchmoan and Inchconnachan in what the chartplotter was telling me was between 14 and 20ft of water (as did my depthsounder).

I then ground to a halt on a gravel/sandbank around the following co-ordinate: 56 05'01.98" N 4 36'57.5" W.

Luckily we were going dead slow and after a bit of pushing with a pole, and shifting the weight around, we got back off the sandbank.

Now, my misses went balastic and said I should have looked where I was going. BUT I DID!

On my chartplotter it showed no obstructions on the level of detail/zoom I had; BUT......when I zoomed out, to an area that covered just about the 3 islands, the shallow zone showed up (as a green caution/obstruction zone).

So, after playing around, I've found that (on my system) if you are zoomed out covering a large range, then the obstruction is shown, however, if you then zoom in, then the area disappears (and thus you could run aground like I did).

So, if you have a C-MAP MAX chart I'd be very interested if this obstruction disappearing issue happens with you. So could you please ceck this and let me know.

I intend to contact C-MAP (now Jeppesen) to log the issue, but it would help if other have the problem.

And it does ask the question as to whether there are other areas on the Loch mapped/displayed incorrectly!

Cheers
Kenny

hi kenny, sounds like the same place we ground to a halt on last year, i never use the chart plotter, but use the map of loch lomond with all the depths on, (got it from the scottish library in edinburgh, online) so was entirely my fault, although i had been across the same place before, but this time the water was very low, so what im saying is although i saw the depth dissapearing i didnt act quick enough, but taught me a lesson to be more aware no matter what charts or maps say ,and to take more notice of water levels, oh yes i also had everyone onboard telling me i should have been watching where i was going, as if they could do the job better!!

Kenny,

Any pics or maps you could mark the spot on for us non map users ? I am supposed to be anchoring in there this Saturday night with Dreamcatcher and keen not to hit the same area.

Chris

Have a look here for the offending sandbank.

http://maps.google.com/maps?f=q&q=56.083980,-4.616028%20%28Glasgow%20G63,%20UK%29

Cheers

I think I got it on google earth, just sticks out a little from Inchmoan almost just before the point of Inch connachan justs out if you were heading east before the big bay on the left ?


Wish I could copy and past the google earth image.

Sorry for my garble just trying to work out if I have the right bit.


Chris

Hi guys


Here is a screen grab from Google Earth. Note: The Sandbank is not visible when on the water; satellite photo's are great at showing what's below.

yep thats the one we found one sunny day, i know lots of people who have been caught out on it, so dont feel too bad if you do!, this is mainly all sand so if you do ground should'nt hurt too much,!!