This year's release of the excellent and highly recommended Antares Charts includes one of the Cuan narrows which confirms what some of us have suspected for some time: the Admiralty chart is significantly wrong, despite release only a year or so ago of a correction chart-let for this area. (E.g. the HO shows a depth of over 10m NE of the Cleit Rock: Antares' 5.4m is much more believable.)
The problem when coming through Cuan is of course guessing the position of the underwater rock (Claymore's Rock? ) between the Cleit and the Seil shore, so there is a tendency to hold too close in to the Cleit beacon thus getting swept through worryingly shallow water. In absence of a beacon on the hidden rock (which would be a great benefit to us all) I have taken the Antares position which I read as: 56 deg 15.863 N 5 deg 37.409 W and placed a "danger" way point there on my plotter chart. Hopefully this may make things a bit easier - I'll report back.
DaveS wrote:This year's release of the excellent and highly recommended Antares Charts includes one of the Cuan narrows which confirms what some of us have suspected for some time: the Admiralty chart is significantly wrong, despite release only a year or so ago of a correction chart-let for this area. (E.g. the HO shows a depth of over 10m NE of the Cleit Rock: Antares' 5.4m is much more believable.)
My 1980s CCC Sketch Chart Number Six shows 2.5m midway between the north end of Torsa and the nearest bit of Seil. How does that compare?
Never attribute to malice that which is adequately explained by stupidity - Hanlon's Razor But don't rule out malice - First Corollary to Hanlon's Razor
DaveS wrote:This year's release of the excellent and highly recommended Antares Charts includes one of the Cuan narrows which confirms what some of us have suspected for some time: the Admiralty chart is significantly wrong, despite release only a year or so ago of a correction chart-let for this area. (E.g. the HO shows a depth of over 10m NE of the Cleit Rock: Antares' 5.4m is much more believable.)
The problem when coming through Cuan is of course guessing the position of the underwater rock (Claymore's Rock? ) between the Cleit and the Seil shore, so there is a tendency to hold too close in to the Cleit beacon thus getting swept through worryingly shallow water. In absence of a beacon on the hidden rock (which would be a great benefit to us all) I have taken the Antares position which I read as: 56 deg 15.863 N 5 deg 37.409 W and placed a "danger" way point there on my plotter chart. Hopefully this may make things a bit easier - I'll report back.
Dave have you considered relaying this information to the HO, they might be appreciative of it and make amendments to future publications.
C_W
My old CMap CDs put a lump at 56N 15.8658' 005W 37.3958' so it looks as if it's been there some time...
Must remember to check the plotters I actually use when next aboard...
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DaveS wrote:
The problem when coming through Cuan is of course guessing the position of the underwater rock (Claymore's Rock? ) between the Cleit and the Seil shore, so there is a tendency to hold too close in to the Cleit beacon thus getting swept through worryingly shallow water. In absence of a beacon on the hidden rock (which would be a great benefit to us all) I have taken the Antares position which I read as: 56 deg 15.863 N 5 deg 37.409 W and placed a "danger" way point there on my plotter chart. Hopefully this may make things a bit easier - I'll report back.
It's been a while but my recollection was that even aiming the boat determinedly at the Cleit Rock beacon it's pretty well impossible to hit anything because the tide is so strong that it sweeps you clear. Thus 'aim at the beacon' becomes a helm instruction and keeps you clear of the much more problematic underwater rock off the N shore.
DaveS wrote:This year's release of the excellent and highly recommended Antares Charts includes one of the Cuan narrows which confirms what some of us have suspected for some time: the Admiralty chart is significantly wrong, despite release only a year or so ago of a correction chart-let for this area. (E.g. the HO shows a depth of over 10m NE of the Cleit Rock: Antares' 5.4m is much more believable.)
My 1980s CCC Sketch Chart Number Six shows 2.5m midway between the north end of Torsa and the nearest bit of Seil. How does that compare?
The Antares survey stops a bit to the SW of that so can't say.
Silkie wrote:The UKHO are always appreciative of Dave's corrections but I suspect Mr Antares might not be quite so thrilled.
Antares send information to the HO directly. The recent chart correction moving the position of the wreck in the Doirlinn, Tobermory was credited to Antares.
Incidentally, the latest edition of the chart for Loch Tarbert, Jura still shows the leading lines in the wrong place...
Update: Antares have produced an updated version of their 2012 Cuan chart. "Claymore's Rock" is now shown at 56 deg 15.862 min N 5 deg 37.407 min W i.e. slightly closer to the Cleit and with a depth of 0.3m rather than 1m. The revised depth sounds more likely given that this rock has been photographed at an exceptionally low tide.
Green Boat wrote:
It's been a while but my recollection was that even aiming the boat determinedly at the Cleit Rock beacon it's pretty well impossible to hit anything because the tide is so strong that it sweeps you clear. Thus 'aim at the beacon' becomes a helm instruction and keeps you clear of the much more problematic underwater rock off the N shore.
erm . . . this might sort of perhaps work OK going East-West, though I have not had any difficulty getting into shallower water than intended by passing close to the beacon on occasion . . .
but definitely not advice I'd recommend anyone to follow if transiting West to East, when the tide will almost certainly carry you onto the Cleit if you do this.
The worst hazard I ever encountered in Cuan Sound were bunch of cowboys in ribs who were, I believe, ferrying teenagers to some sort of outward bound style camp on a nearby island. They took great delight in buzzing me (and other boats) very close and at very high speed - in my case resulting in a 720 degree turn as we approach the Cleit Rock from the west, which is character building stuff.
Never attribute to malice that which is adequately explained by stupidity - Hanlon's Razor But don't rule out malice - First Corollary to Hanlon's Razor
) between the Cleit and the Seil shore, so there is a tendency to hold too close in to the Cleit beacon thus getting swept through worryingly shallow water. In absence of a beacon on the hidden rock (which would be a great benefit to us all) I have taken the Antares position which I read as: 56 deg 15.863 N 5 deg 37.409 W and placed a "danger" way point there on my plotter chart. Hopefully this may make things a bit easier - I'll report back.
