Holding bottom (not!)

[Mike k]

Had final fling in the Mersey yesterday for 5 weeks as Marina lock now closed for repairs.

Went to a new mark and ok tide was 9.6 m and flowing strongly but deployed anchor to hear a long grumbling noise which seemed to be coming from the windlass motor which i had stopped activating- but it was actually the anchor dragging along a hard bottom with the noise apparrently reverbrating through the chain. Eventually I had to deploy 50m of chain before it held- my anchor is a lewmar delta.
i am told the river bottom at that point is limestone and depth was only 30feet at the flood- is there any views on suitability of anchor and would be interested on any views /experiences of similar situations.

thanks

 

[Searush]

Limestone could well be a flat rock bed. Nothing will grip that. Tides are big at the moment & the Mersey flows fast, especially on the ebb as there has been a lot of rain & it all has to get out after the flood. 30' depth = 30m minimum chain required anyway so 50m is not unreasonable given the strong tides.

Remember that rumbling sound well, it needs to pull you out of a deep sleep with a gallon of adrenaline flowing!

Stick to anchoring on mud, clay or sand bottoms if you can. Stones, shale & shingle are other iffy ones, some types will take an anchor, some won't.