Hm, how much chain should i have, drifted 'nicely' last night

[simonfraser]

27ft mobo Aquador
No, i am not going to get into what is the best anchor discussion

I had 30m of 6mm chain down, that's all i have at the mo, had been thinking of sorting that last week

2:30 am: 5.5m high tide, anchored in 2m above low water, bow 1m above water
So max Anchor depth 8.5m, yep now doing the sums, that would be trouble in a blow

Major storm and wind, finished up dragging onto the mud at 2:30 am, luckily bow on, so managed to reverse her off and re-anchor in the dark with the spotlight that i had just fitted, premonition.......

Just checked the holding power of the current anchor in the mud at low tide, all the chain out, could not pull it loose in reverse

So how much chain would you get for the above scenario ?

 

[superheat6k]

For lunch 3 X depth is fine, but overnight I would like at least 5 X depth down, so allowing for some spare anchoring in up to 10m requires ~60m in the chain locker

 

[ChrisJBSC]

30 m of chain is plenty. But I would want it all on the sea bed: So add 30m of rope and you will do fine.

The drift could be due to other factors! Tide changed, so the chain dragged over the anchor and pulled it out. Anchor not in the mud, but on a bed of sea weed.

 

[sarabande]

30m of 6mm chain is pretty marginal in that depth, in strong wind (plus tidal stream and wind-induced current ?) for a mobo with a bit of windage and bouncing around.

Some issue with the anchor failing to engage fully with the seabed as the primary cause of the drift, since checking the anchor later was successful.


How did you drag bows on to the shallow mud from deeper water ? Wind ? Tide ?

 

[simonfraser]

'How did you drag bows on to the shallow mud from deeper water ? Wind ? Tide ?'

Sarah that's is odd eh ? Dragged her off 30 mins b4 high water, was in a narrow creek, so can only suppose she slid down the side with the wind and tide behind her.
The stern drawing more kept her stern into the tide ? Assuming the anchor had broken out by then.

If I'd had a shaft drive I'd still be there now, the OD was in the up position, spun in the air a few times, props seem ok, can see them over the stern.

 

[kashurst]

buy a Rocna - sticks in anything and resets itself in the unlikely event it came out.

 

[Richard10002]

For lunch 3 X depth is fine, but overnight I would like at least 5 X depth down, so allowing for some spare anchoring in up to 10m requires ~60m in the chain locker

+1

25.5m minimum, (3x depth)

42.5m ideal for overnight, (5x depth)

60m for stormy conditions, (7x depth).

So you only really have enough for fairly benign conditions, and it's no surprise that you dragged.

At least you have learned a lesson at no real cost. Why not do a few RYA courses. You'll get lots of info and advice over a very short space of time, and it would save you reinventing the wheel

 

[simonfraser]

yeh fair point, i knew the x depth rule, just did not think last night through on a 'new' boat.
the existing chain is obviously way too short for purpose, 20m, unless anchored in a milpond.

hindsight is a wonderful thing, was in a small creek, F1 overnight. possibility of thunderstorms .....
v high tide, this resulted in the marshes around the creek flooding so now exposed, then the thunderstorm arrived just at the top of tide

bad 'planning' on my part, have ordered a way longer chain

 

[powerskipper]

normally 4 x depth of water if all chain
6 x if rope and chain.

so if you depth finder is off set to below your running gear this can lead to thinking you are in shallower than you are.
if overnighting I would put out enough to hold in maximum depth expected and a bit more 4 maybe 5 m more. if worried and if room I would put out pretty much all chain I had within reason.

27ft mobo Aquador
No, i am not going to get into what is the best anchor discussion

I had 30m of 6mm chain down, that's all i have at the mo, had been thinking of sorting that last week

2:30 am: 5.5m high tide, anchored in 2m above low water, bow 1m above water
So max Anchor depth 8.5m, yep now doing the sums, that would be trouble in a blow

Major storm and wind, finished up dragging onto the mud at 2:30 am, luckily bow on, so managed to reverse her off and re-anchor in the dark with the spotlight that i had just fitted, premonition.......

Just checked the holding power of the current anchor in the mud at low tide, all the chain out, could not pull it loose in reverse

So how much chain would you get for the above scenario ?

 

[simonfraser]

tnx, interesting point is the size of the creek too, as you can see from the b4 pic, not a lot a of room to let out chain without wondering all over the sides and finish up on sloping mud.
thinking about the incident, there was something on the anchor when i pulled it up at 2:30 am, perhaps it was weed, but i had other things on my mind ! i finished up on the shore by the shed far left had side, past the buoy on the mud.
never had an anchor set fail on me b4, considering the wind i should have checked things more carefully during the blow.
yes i did know i would dry out .....

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