More night sailing - echosounding your passage

[Sgeir]

'Twas on a dark and errm, fairly decent night, JohnBuch and I were sailing from Largs towards the north end of Arran when we noticed some flashing yellow lights in the distance. Well, fish farms don't move quickly so we ruled that out, as did we also the possibility of a mobile mini-cab office.

Turned out it was a submarine, apparently doing its speed trials off the "measured miles" in Arran. Can't remember whether we radioed them first, or t'other way about, but, despite being under sail at the time (nuclear gives way to sail), they were quite keen that we keep well clear. Being wimps, we agreed and, changing plans, headed north for the West Kyle.

Getting there was fine, but there was no moon and probably cloudy as I recall, and the breaking waves on the shoreline were more to be heard than seen. We were tacking into wind and, with an occasional check on the charts, found that setting the echosounder alarm to (as I recall) a 10m depth worked perfectly for tacking our way up the Kyle. Fortunately we didn't experience any false readings.

Great fun, and a good night's sail. Can't remember where we ended up though...

 

[fireball]

[ QUOTE ]
setting the echosounder alarm to (as I recall) a 10m depth worked perfectly

[/ QUOTE ] Our East Coast friends would have a quiet sail at that setting! /forums/images/graemlins/laugh.gif

 

[phatcat1]

Oh, how I long for 10m depth! Does it really exist, or is it just a myth told by old sailors

 

[fireball]

It's ok - I think he missed the "c" ... /forums/images/graemlins/laugh.gif

 

[Sgeir]

I know - seems dangerously shallow to me!

;-)

 

[Koeketiene]

I think it's a myth.

At one time last summer the echosounder showed 21m below the keel - and we promptly ran aground.

Two summers ago I have a vague recollection of 10 metres plus below the keel in the Solent. But I think that was alcohol induced - must have missed a decimal point somewhere.

 

[Csail]

10m is loads (30'ish) how big is your keel???

 

[shmoo]

10m !

The first time I entered the Deben I dutifully called up John White the HM on the phone for last minute pilotage tips and got the usual "go a bit this side of the red and a bit that side of the green and you will be fine"

When we were in and tied to one of John's moorings he passed by and asked if all went well and I explained that I was a bit worried at only having half a metre under the keel at one point and he breezily asked "how much water do you need?"

 

[Phoenix of Hamble]

Hee Hee... well spotted....

It is true that most East coast sailors complain that their depth sounder display is strangely offset to the right, and all the left of the screen isn't working.... in fact, mine did once prove that it didn't function by showing a vertical line, a bit like this, "1", just to left of the normal depth display once. /forums/images/graemlins/wink.gif

SWMBO was so freaked out by the depths when we first moved to the East Coast, that I changed the depth sounder offest by 1m, so that when it read 1m we were pretty much about to hit the bottom.... it took me over a year to own up... /forums/images/graemlins/grin.gif

 

[Sgeir]

[ QUOTE ]
10m is loads (30'ish) how big is your keel???

[/ QUOTE ]Don't you think that rather depends on the nearness of the shore and the steepness of the ground? Our keel is 1.7m.

 

[shmoo]

Mine seems less worried by absolute depth, more by changes. Last year crossing the western Channel towards Cornwall I was summoned on deck from my slumbers to explain why we were losing depth to discover it had gone from 90m to 80m in about 30 minutes.

 

[bilbobaggins]

[ QUOTE ]
Don't you think that rather depends on the nearness of the shore and the steepness of the ground?

[/ QUOTE ]

Er, I think it also has something to do with the *nature* of the ground beneath the keel.....

After all, East Coast ooze is a great deal friendlier to a 'blond moment' at the helm than Arran granite! In some places, like around Portishead, it's OK to stand on in until you can see the seagulls' knees. After all, it's only the density of the ooze you're sailing in thereabouts that changes.

In other modes of sailing, such as closing the north coast of Spain after a week at sea - when one had been sailing in 4000 metres of briny and the echo sounder begins to read *anything* again - peeps take to peering closely at the thing and wittering on about tidal heights diagrams when still 50 miles out from the hard sticky-up stuff......

That's one of the benefits of sailing other peeps' boats - you can be objective about hazard avoidance, leaving poor bluddy owners to twitch and witter to their hearts' content!

/forums/images/graemlins/grin.gif

 

[Sgeir]

Don\'t try this at home

I should point out, just in case anyone is tempted to try it, csail's words were in jest. For the record, IMHO, going less than 10m, under sail, in the dark, in the West Kyle is likely to smack your boat on to the rocks - a 10m depth can mean a couple of boat lengths or not much more.

 

[hornblower]

I have navigated along the 10m contour in the Solent in fog more than once - you just have to beware the buoys - they are on the same contour but they are a friendly sight in a peasouper just dont bounce off them.

 

[silver-fox]

[ QUOTE ]
[ QUOTE ]
10m is loads (30'ish) how big is your keel???

[/ QUOTE ]Don't you think that rather depends on the nearness of the shore and the steepness of the ground? Our keel is 1.7m.

[/ QUOTE ]

East coast sailors can be so bold because its mud glorious mud all the way - not a rock in sight! Bit different round Arran!