Anchor substitute

[oldbilbo]

Musing on Roberto's explanation, and without presuming a solution, I recall 'anchoring' in Oban Harbour while awaiting the return of our pair of runners in the Scottish Islands Peaks Race. Now that bottom is notoriously foul, and many boats had snarled-up their 'ooks in the past. I scrounged a section of discarded heavy fishing net 2-3 metres square and - by reeving a rope through several parts of the net edges - made a sort of pouch. This I filled with boulders from the beach and lowered the bag o' stones onto the seabed, on a doubled rope. It did the job.

When time came to leave, we just released one part of the doubled rope and pulled it through, leaving the bag o' stones down there.

While there may be a shortage of suitable and convenient boulders up these African rivers, there may be other artifacts which could be pressed into service..... like retired diesel engine blocks, or big steel truck wheels.

And here's another good reason for buoying your anchor....

 

[RichardS]

When time came to leave, we just released one part of the doubled rope and pulled it through, leaving the bag o' stones down there.

And here's another good reason for buoying your anchor....

...... presumably because even if Oban Harbour wasn't a foul bottom before, it certainly is now.

Richard

 

[KellysEye]

>Sorry - But its why we carry 3 anchors and recommend everyone else do the same.

Agree that's what we had, all chain for the main anchor and chain and rope for the other two, 180 feet for the main anchor and 150 for the other two.

 

[vyv_cox]

I have come late to this thread sorry, but at least can relate from experience, with a not very original response. We were anchored at San Antonio, Ibitha a few years ago. Wind was very light, F3 maximum. We heard a bang and realised we were drifting downwind pretty quickly. Hauled the chain in (which was doing absolutely nothing to hold the boat) and found the swivel had broken, presumably due to stress-corrosion cracking, hence the bang. We reanchored using the Fortress but needed the assistance of a diver to find the Delta in thick weed.

Lessons learned:
1. This incident was what started me on destructive testing and analysis of swivels. I still use one but it's a good one.
2. Chain does not function as a substitute for an anchor
3. Ever since I have had a float on 1 metre of line attached to the crown of the anchor, so I can find it in weed.
4. We now have a Rocna but the Delta is stowed below, just in case.

 

[tudorsailor]

Having read about swivels/shackle breaking, I got a WIchard extra strong shackle (High Resistance Stainless Steel). However I also made soft shackle with 7mm dyneema who's breaking strain is probably equal to the shackle. So in the unlikely event of the shackle failing or the pin working loose, the soft shackle might prevent my losing my Rocna!
TudorSailor

 

[Neeves]

It will be interesting to learn how the soft shackle stands up to constant burying in the seabed. Dyneema has good abrasion resistance but I'm not aware of anyone using it repetitively in the harsh application of an anchor shackle.

Rather than the very expensive shackle you have bought you will find that a Crosby 209A (not the 209 series but the 209A series) will be cheaper and much stronger. The 209A are classified as Grade B and are typically 30% stronger than Van Beest's Green Pin and decent stainless shackles. You can obtain them from Tecni in the UK.

For extra security of any shackle - mouse and use Loctite.

Jonathan