Rocna and sticky mud.

[vyv_cox]

I always viewed the Morgan's Cloud condemnation of Rocna resetting with some scepticism. Partly because ever since we bought our Rocna we have been in predominantly sandy seabeds in Greece. Now, having moved from the Aegean to the Ionian we are seeing some differences.

Yesterday we anchored in a shallow muddy bay to ride out a southerly force 7. This morning the Rocna came up with huge clods of sticky mud attached that needed manual labour to remove. Interestingly it did not extend to the roll bar but was strongly adhered to the flukes.

We called in at Astakos, another muddy place, anchoring stern-to for shopping and lunch. On hauling the Rocna the flukes were again carrying big clods of mud, not extending back to the hoop. We motored to a nearby anchorage without removing the mud and anchored, but dragged at less than 2000 rpm astern. I cleared the mud by hand again and we anchored successfully.

So I can at least understand the Morgan's Cloud concern but so far cannot blame the hoop. It seems that any concave anchor might behave in the same way, hoop or not.

 

[Clancy Moped]

We had a similar experience in Patmos, again, sticky mud.

 

[Mistroma]

Interesting. A friend has have several instances of dragging in the Ionian. I think Amel supply a Rocna as standard and his has worked well since buying 6 or 7 years ago. The problem only emerged this year and he thought it might be excessive weed growth. He switched to a backup anchor which dragged once in mud but seems to be a one-off.

He switched to stainless chain this year, same size as the original chain. No other changes to anchor, connecting shackles etc., but different gypsy. He calibrated his chain counter and also has marks on chain.

Really odd as he has cruised the Ionian several times. No change to scope, anchor or shackles, just a swap to stainless chain.

I think he dragged in Corfu, Sivota (Mourtos) and Vlycho. Very odd.

 

[Bouba]

We bring up the seabed with our Rocna also....this doesn’t bother us but if you don’t clean it right away it dries to a form of concrete that can’t be removed. It hasn’t affected our anchoring efficacy but in the Med only the wind can change direction not a regular tide...so resetting hasn’t been an issue. However I don’t know if resetting on the sea bed has any relationship to raising the anchor with mud attached...and in fact the ability to lift mud (like a spade should) could be a sign of it’s holding and resetting strength

 

[Minerva]

I have a Knox anchor (same idea as Rona) and anchor most nights we're aboard on the Scottish West coast - frequently very well ventilated, tidal and often muddy.

Our anchor frequently brings up a large daud of mud with it - it's a sign of how well buried it's been. It's never affected the anchor resetting or causing us to drag. No issues at all.

 

[sarabande]

Has anyone done any work on the difference in mud collecting between a galvanised anchor and a stainless one of the same profile ?

I wonder whether the smooth surface of stainless allows mud to slide more easily than the rough surface of a galvanised one. It may be intuitively correct, but...

 

[thinwater]

I have experienced re-set problems with a Manson Supreme in sticky mud. Rare, requiring just the right combination of bottom characteristics, but it is a real thing. Clean it off and it sticks within a few feet.

 

[Minchsailor]

I'm with @Minerva on this one. Sailing in the same waters my Rocna (20kg for a Rustler 36) usually sets so well in thick mud that it is a struggle to break it out.

 

[Boathook]

I've used my rocna in mud (Newtown, Poole, Helford) quite a bit and it seems to set well. Sometimes it comes up covered in mud that requires manual removal and other times the mud can be seen to slide off. The anchor flukes always seem to have mud on them and sometimes it takes a while to get the anchor up as it is so well bedded in.
I always have to put a water hose on one end of the hoop to blow out the trapped mud.

 

[dunedin]

Anchored a lot on mud with a Rocna without issue. To remove the mud left on the anchor we tend to reverse briskly with the anchor just slightly below the surface before slowing and bringing anchor on board.

 

[RivalRedwing]

Par for the course on the East Coast, Pyefleet Creek being one notorious spot according to the deck crew.

Never presented us with a dragging problem (using a Rocna)

 

[srm]

West and north Scotland has many anchorages with sticky smelly mud. We regularly brought up big bottom samples on our 25kg Rocna that needs attacking with the boat hook and deck wash hose to clear. I don't know if the anchor breaks out and resets with a turn of the tide or change of wind direction, but suspect that given the volume and nature of the samples that the anchor buries deeply and stays that way until we break it out. It was not unusual in mud to heave the bow down with the windlass then wait for a few minutes before the anchor lets go of the bottom.

 

[vyv_cox]

I think many of us have experience of anchoring in mud. My point is that MC have downgraded the Rocna from their approved list because it failed to reset when it had sticky mud balls on it. Is this different from any other anchor?

 

[Roberto]

This is mine on one occasion several years ago, the original block of mud was about double that, the time to get the camera and come back to the bow to take the picture about one half had fallen. Even then, the remaining lump extended as a single mass well beyond the hoop, which was like agglomerated with mud. Quite sticky mud, as it can be seen on the chain links.
Note the twisted connector after a few 180° turns, I got rid of it.
Like others, never had any problems with 180° turns, in whatever bottom, if Panope or MC have had different experiences the only plausible explanation I find is they anchor in a different way from mine.

 

[sailaboutvic]

We now using a Manson in the Netherlands, it roo comes up with clumps of mud and need to be cleared, some time going in astern while leaving the anchor dangling in the water does the job .
So far we had no problem with it reset .

 

[Bouba]

This is mine on one occasion several years ago, the original block of mud was about double that, the time to get the camera and come back to the bow to take the picture about one half had fallen. Even then, the remaining lump extended as a single mass well beyond the hoop, which was like agglomerated with mud. Quite sticky mud, as it can be seen on the chain links.
Note the twisted connector after a few 180° turns, I got rid of it.
Like others, never had any problems with 180° turns, in whatever bottom, if Panope or MC have had different experiences the only plausible explanation I find is they anchor in a different way from mine.

View attachment 143694

Yes.... I also want to know what the connection is between the anchor being dragged at sea bottom level and lifting it vertically

 

[Mistroma]

Yes.... I also want to know what the connection is between the anchor being dragged at sea bottom level and lifting it vertically

I think people are indicating that the Rocna holds well when it digs into mud and a straight pull simply causes it to try to dig in further. However, it comes to the surface with a large lump of mud when it's broken out and brought to the surface. That means it will have a similar lump of mud attached if there's a large change in wind direction and it it then lies on the sea bed. The large lump of mud attached to the anchor effectively changes the shape and prevents it digging in easily. The "mud ball" encased anchor is reduced to being a fairly light lump of metal and mud being dragged around. A large concrete block will hold but a mud covered anchor is simply not heavy enough to remain in one place.

At least that's what I've picked up from comments about the Rocna bringing up a lump of mud. I'd be interested to hear any different explanations.

 

[Bouba]

I think people are indicating that the Rocna holds well when it digs into mud and a straight pull simply causes it to try to dig in further. However, it comes to the surface with a large lump of mud when it's broken out and brought to the surface. That means it will have a similar lump of mud attached if there's a large change in wind direction and it it then lies on the sea bed. The large lump of mud attached to the anchor effectively changes the shape and prevents it digging in easily. The "mud ball" encased anchor is reduced to being a fairly light lump of metal and mud being dragged around. A large concrete block will hold but a mud covered anchor is simply not heavy enough to remain in one place.

At least that's what I've picked up from comments about the Rocna bringing up a lump of mud. I'd be interested to hear any different explanations.

Yes, I agree. Lifting the Rocna means it’s at the correct angle to scoop the mud and then be winched up to the boat. On the sea bed with the correct scope the angle is different and it buries....if the direction changes it reburies...has anyone got definitive proof that mud clumping stops this happening?

 

[srm]

Does the anchor actually break out and drag on the surface with a 180 degree change of pull direction, in which case a mud ball will have a detrimental effect. Or, does it remain buried and possibly change its orientation within the mud. Much will depend on the physical properties of the bottom sediment but I suspect the latter from my experience. However, I have not made any direct observations so it would be interesting to see evidence of the anchor's behaviour in real life situations.

 

[Mistroma]

Does the anchor actually break out and drag on the surface with a 180 degree change of pull direction, in which case a mud ball will have a detrimental effect. Or, does it remain buried and possibly change its orientation within the mud. Much will depend on the physical properties of the bottom sediment but I suspect the latter from my experience. However, I have not made any direct observations so it would be interesting to see evidence of the anchor's behaviour in real life situations.

It seems reasonable to assume that a slow change in direction would usually allow the anchor to just realign whilst staying buried. It is also reasonable that a large sudden change in direction would break it out in a similar manner to it being lifted. I can easily see it failing to dig in again as easily if a large lump of mud remains at that point.

All guesswork of course and no evidence to confirm this is what's happening in real life. Only evidence so far comes from the picture in post #14.

I have just remembered that I recently watched a guy trying to clear mud from a Rocna in Vlycho. I wasn't close enough to see the hoop but he reversed a lot before giving up and resorting to a boat hook. Lot of raising, lowering and poking to break off lumps. I had completely forgotten about that until my wife reminded me. She had noticed it first and pointed it out. We wondered if our Bruce would be as bad but it came up with a small lumps on the tip of each side claw.