fireball
New member
This!!
It's absolutely crucial to forget the charted depths when looking at anchoring in an area of shifting sands. The whole main harbour has changed significantly in the last few years.
Anchoring East Head - Overnight
- Thread starter alnunn
- Start date
This!!
It's absolutely crucial to forget the charted depths when looking at anchoring in an area of shifting sands. The whole main harbour has changed significantly in the last few years.
alnunn
New member
Great - Well that all makes a lot more sense and takes worry off my mind!
So lets say I arrive at East Head tomorrow night at 8pm, looking at the tidal curve it reads approx 4m at that time. The tide will fall to 1.4m, therefore I can expect the tide to be 2.6m lower than the spot I find at 8pm. I approach my spot and the echo sounder reads 5m, take the 2.6m off for the tide drop, and a further 0.5m to allow for my draft. At low tide, I can expect to be (safely) in 1.9m of water? The next high tide reads 4.2m (Saturday morning) - that means I should be +0.2m higher than when I arrived at 8pm, so my scope needs to be 5 x 5.2m, Now I presume + or - 0.2m here or there does not matter too much so simply 5 x 5m should suffice - more important to make sure the hold is actually good than get hung up on whether you have an extra metre of chain out or not.
So I've left myself just 0.5m of water at low tide. As I swing on my 25m of chain, what is the chance I will come across some ground? Does this REALLY matter? If your bottom touches the ground a little?
So lets say I arrive at East Head tomorrow night at 8pm, looking at the tidal curve it reads approx 4m at that time. The tide will fall to 1.4m, therefore I can expect the tide to be 2.6m lower than the spot I find at 8pm. I approach my spot and the echo sounder reads 5m, take the 2.6m off for the tide drop, and a further 0.5m to allow for my draft. At low tide, I can expect to be (safely) in 1.9m of water? The next high tide reads 4.2m (Saturday morning) - that means I should be +0.2m higher than when I arrived at 8pm, so my scope needs to be 5 x 5.2m, Now I presume + or - 0.2m here or there does not matter too much so simply 5 x 5m should suffice - more important to make sure the hold is actually good than get hung up on whether you have an extra metre of chain out or not.
So I've left myself just 0.5m of water at low tide. As I swing on my 25m of chain, what is the chance I will come across some ground? Does this REALLY matter? If your bottom touches the ground a little?
Elessar
Well-known member
yep you got it. With 0.5m clearance at LW not much chance of touching in calm weather, though high pressure will reduce it a bit. You might swing in and touch gently, but am I bothered? No.
Talulah
Well-known member
You need to know though if the echo sounds zero reading is at the height of the transducer, the bottom of the keel, sea level etc and if a safety margin has already been included in that reading.
Zero on our boat means zero under the keel. Different people prefer different reference points.
Zero on our boat means zero under the keel. Different people prefer different reference points.
alnunn
New member
Thank you! I think I have it in my head that IF I got the calculations slightly wrong or moved a little unexpectedly that the world is going to come to an end. I think I just needed some re-assurance that touching the bottom is really not an issue (on sand/mud) - maybe not rocks 
alnunn
New member
I've done it! It has been relatively easy but a little bit of a worrying night. Will probably stay another night. BUT... I have a new problem... I am running out of cigarettes!
superheat6k
Well-known member
Nice one.
I don't smoke but SWMBO does. I keep a spare packet hidden away for that event - it isn't worth the grief, believe me !!!
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Elessar
Well-known member
excellent - hopefully you won't worry the next time!
alnunn
New member
Does the beach shop at west wittering beach have convenience stuff? Just wondering if I should take a wander round...
henryf
Well-known member
Inspired to visit Emsworth. Handy little mid river pontoon. Lovely run up in the sunshine. Slight breeze which I suspect will drop off later on. Not too scruffy at all. Yet to explore Emsworth.......
Henry
Henry
