Anchoring technique - new props please

[kashurst]

As title suggests we had a bit of a disaster two weeks ago. Anchored dragged whilst I was ashore. SWMBO didnt get engines started soon enough and we ended up bobbing up and down against a harbour wall but shallow rocks mangled the props. On the positive side the fenders were out!
So after a bit of thought as to what went wrong I suspect my anchoring technique is could be improved and swmbos engine starting practiced. Also we often find ourselves anchored over seagrass that can be tricky to get a grip in

Usually I drop the anchor whilst slowly moving backwards for 4 to 5 times the depth. Anchor is a big delta on 12mm chain. Sometimes its very apparent thattheanchor has caught as the boat moves backwards and then jerks forwards momentarily, other times the boat just stops and after 5 mins watching a transit I usually decide we are OK. This time we were OK for three hours before it let go. No big wave, or sudden gusts the boat just went sliding.
Considering buying a rocna anchor as we anchor a lot (but not overnight) do these reset readily ?
Doing this on an ipad sorry for rubbish typing

 

[oGaryo]

have you thought about setting up a GPS fence around the boat when you go ashore and have the gizmo that does it txt you if it goes outside the fence? can be done for <£50 obviously won't fix the root cause of the anchor slipping but may alert you in time to do something about it yourself rather than rely on the crew to react in time, even if it's to give them a call and talk them through starting the engines

 

[jrudge]

have you thought about setting up a GPS fence around the boat when you go ashore and have the gizmo that does it txt you if it goes outside the fence? can be done for <£50 obviously won't fix the root cause of the anchor slipping but may alert you in time to do something about it yourself rather than rely on the crew to react in time, even if it's to give them a call and talk them through starting the engines

As described your technique sounds fine.

As an aside bear in mind that the damage is probably covered by your insurance - striking an underwater object.

 

[Deleted User YDKXO]

This sounds very similar to what happened to me a couple of weeks ago. We were Med moored stern to against a concrete quay with about 4x depth of anchor out and we'd been there about 15hrs including a restful night. SWMBO and I were sitting in the saloon drinking coffee when we heard the bathing platform bang against the quay wall. Very fortunately we were on board as we'd only just returned from a shopping trip and I was immediately able to start the engines and move away. Also very fortunately, although the seabed shallowed against the quay, we didn't clatter the props on the rocks.
We have a 40kg Delta and a load of chain and it had never dragged before. We also have a practiced technique when stern to mooring against a quay of dropping the anchor and about 2 x depth of chain and then snubbing the anchor by reversing on both engines for several seconds before letting out more chain and backing up to the quay so on this occasion I was pretty sure the anchor was well set which begged the question as to why we'd clouted the quay. The only conclusion I could come to was that several charter boats had moored after us the previous evening and none of them had much of a clue what to do; in fact I had to help one of them to moor up their boat. I was fairly sure that at least some of their chains had crossed others including possibly ours and I did see one boat near us in the morning having great difficulty lifting their anchor so its possible that they snagged our chain whilst trying to raise theirs and that caused our anchor to break out. Could this have happened to you?
I drew several lessons from all this. Firstly to keep an eye on anyone trying to lay their anchor chain near ours and to pay special attention when they try to raise it. Secondly, although we had tied some crossed lines at the stern to the quay as well as the usual stern lines, they had loosened overnight and I hadn't bothered to tighten them in the morning which allowed the stern to move around quite a lot in the wind. Its possible that by keeping all lines tight, it would have stopped the stern moving so much and avoided the bathing platform clouting the quay. Lastly to put out some large ball fenders at the stern which, even if the anchor chain slackened, would have stopped the bathing platform hitting the quay. Stupidly, because our RIB overhangs the bathing platform, I had assumed it would act as a fender but it didn't.
I'n your case, I wouldn't bother with changing the Delta for a Rocna. Firstly, if you search the internet, including this forum, there's plenty of info about Rocna moving their production to China which resulted in a reduction in quality. Secondly, the Rocna shank is deeper than the Delta one so if your bow roller is closed, you might have a problem stowing it. Thirdly, IMHO the Delta is a good anchor and is as good as any other anchor out there

 

[Elessar]

As title suggests we had a bit of a disaster two weeks ago. Anchored dragged whilst I was ashore. SWMBO didnt get engines started soon enough and we ended up bobbing up and down against a harbour wall but shallow rocks mangled the props. On the positive side the fenders were out!
So after a bit of thought as to what went wrong I suspect my anchoring technique is could be improved and swmbos engine starting practiced. Also we often find ourselves anchored over seagrass that can be tricky to get a grip in

Usually I drop the anchor whilst slowly moving backwards for 4 to 5 times the depth. Anchor is a big delta on 12mm chain. Sometimes its very apparent thattheanchor has caught as the boat moves backwards and then jerks forwards momentarily, other times the boat just stops and after 5 mins watching a transit I usually decide we are OK. This time we were OK for three hours before it let go. No big wave, or sudden gusts the boat just went sliding.
Considering buying a rocna anchor as we anchor a lot (but not overnight) do these reset readily ?
Doing this on an ipad sorry for rubbish typing

what do you call a "big" delta. Sealine are awful for under speccing anchors. I just did major GRP surgery to go from a 10 to 16kg delta, but now it feels rock solid.

Also 4-5 times depth if shallow is a bit skinny, and did you allow the metre from the water to you bow roller?

 

[henryf]

Slightly tongue in cheek but I wonder if the Sea horses who live in the Sea Grass lifted up your anchor ?

Did the boat swing round at any point? If so it is possible that the anchor was dislodged at that point with a pull at right angles to the shank. You would hope that if properly dug in the weight of chain should have taken out the bulk of any pull.

A final thought and please forgive that it is an obvious one I assume the tide hadn't risen to the point where you no longer had 4 times your depth out. Also do you mark or measure the chain to ensure you are laying the scope you think you are.

Henry

 

[benjenbav]

As title suggests we had a bit of a disaster two weeks ago. Anchored dragged whilst I was ashore. SWMBO didnt get engines started soon enough and we ended up bobbing up and down against a harbour wall but shallow rocks mangled the props. On the positive side the fenders were out!
So after a bit of thought as to what went wrong I suspect my anchoring technique is could be improved and swmbos engine starting practiced. Also we often find ourselves anchored over seagrass that can be tricky to get a grip in

Usually I drop the anchor whilst slowly moving backwards for 4 to 5 times the depth. Anchor is a big delta on 12mm chain. Sometimes its very apparent thattheanchor has caught as the boat moves backwards and then jerks forwards momentarily, other times the boat just stops and after 5 mins watching a transit I usually decide we are OK. This time we were OK for three hours before it let go. No big wave, or sudden gusts the boat just went sliding.
Considering buying a rocna anchor as we anchor a lot (but not overnight) do these reset readily ?
Doing this on an ipad sorry for rubbish typing

Sorry to hear about this. A rotten thing to happen. Gary mentions a gps fence which I think you can set up with something like Boatwarden, which is a free app on Iphone. No idea how good it is or whether, in practice, it would just allow you to get back to the quay in time to see your boat being smashed against the rocks.

Sadly, I don't think Dragqueen, despite the excellent name is an app which is quite up to setting a remote fence.

 

[macnorton]

Next time you think you may have this problem use two anchors (on the same chain) about the sea depth apart.

 

[DAKA]

Also we often find ourselves anchored over seagrass that can be tricky to get a grip in

Usually I drop the anchor whilst slowly moving backwards for 4 to 5 times the depth. Anchor is a big delta on 12mm chain. Sometimes its very apparent thattheanchor has caught as the boat moves backwards and then jerks forwards momentarily, other times the boat just stops and after 5 mins watching a transit I usually decide we are OK. This time we were OK for three hours before it let go. No big wave, or sudden gusts the boat just went sliding.
Considering buying a rocna anchor as we anchor a lot (but not overnight) do these reset readily ?
Doing this on an ipad sorry for rubbish typing

We had the same issue a couple of weeks ago in newton creek (spring but not much current)

Same technique as you describe (which caused the problem).

dropped the anchor and motored astern to dig it in.

BUT at this time of year the weed is very thick and dying off.

in motoring astern i tangled up a ball of weed the size of a beer barrel.

my anchor just rolled itself across more dead weed.

I had to haul it up and clear the weed before dropping again.
HM said it happens in a regular basis when the weed is dying.

We stayed for lunch but stayed overnight in the marina because I lost confidence.

as I decided we were just staying for lunch the second time I just dropped the anchor in and didnt motor back.

when I lifted the anchor it was covered in black silt, it had dug in perfectly.

Perhaps for over nighting the correct technique is to let the anchor settle through the weed to the sand/silt (say 1/2 hour) then start the engine and power back to check it is dug in .

Another issue is going astern can turn the anchor backwards due to the water flow so you end up dropping it upside down.

I try to let it hit the bottom before I go astern.

 

[Bandit]

I find you or a tuned in shmbo need to be on the bow when you lay an anchor put out length of chain required and reverse on one engine until chain stops dragging (chain shakes and you feel vibration) when the anchor bites the chain should go bar tight and solid no shaking and the bow starts to dip under strain then ok.

I find it difficult to judge whether anchor has bitten from fly or saloon helm as you have no feel.

I believe you are insured for this it's negligence or accidental damage.

When the boat is lifted for prop repair/change if props well mangled insist they draw the shafts for inspection in a lathe.

While you are about it with shafts out change the cutless bearings a minimal cost as most of the work is in removing and refitting shafts & props.

 

[blueglass]

.

Another issue is going astern can turn the anchor backwards due to the water flow so you end up dropping it upside down.

I try to let it hit the bottom before I go astern.

+1 IMHO essential to have the anchor firmly on the bottom before going astern. Personally go for a min of 5x depth and can't sleep until I can remain on station with one engine on tickover astern and anchor chain bar tight with no vibration/rumbling.

 

[cryan]

When your motoring astern are you sure your moving in the same direction as the wind/tide? If you were to set your anchor against the direction of natural drift then when you cut your engines you may swing round and pull the anchor out?
Probably better to just drift astern whilst paying out your rode so as the anchor gets a chance to properly dig in and set. Also motoring astern to fast could cause the anchor to just skip along the bottom as opposed to slowly burrow itself in?

 

[longjohnsilver]

I find you or a tuned in shmbo need to be on the bow when you lay an anchor put out length of chain required and reverse on one engine until chain stops dragging (chain shakes and you feel vibration) when the anchor bites the chain should go bar tight and solid no shaking and the bow starts to dip under strain then ok.

I find it difficult to judge whether anchor has bitten from fly or saloon helm as you have no feel.

I believe you are insured for this it's negligence or accidental damage.

When the boat is lifted for prop repair/change if props well mangled insist they draw the shafts for inspection in a lathe.

While you are about it with shafts out change the cutlessc

I've just come back from Dartmouth where I saw a local sail boat simply drop his anchor and a bit of rope and then go ashore. Unsurprisingly I saw Dart Nav have to move the boat at least twice during the week, once after I spent 10 minutes in my dinghy keeping off another anchored boat. And my observation of his anchoring technique was after he had been moved for the third time!

 

[blueglass]

Probably better to just drift astern whilst paying out your rode so as the anchor gets a chance to properly dig in and set. Also motoring astern to fast could cause the anchor to just skip along the bottom as opposed to slowly burrow itself in?

unless there's a very strong tide or wind (both in same direction)simply drifting astern just isn't enough IMHO. In the non tidal med we see UK charterers and flotilla boats making this mistake all the time. As soon as any wind comes up they are dragging all over the place and wondering why.
I agree powering astern too fast is counter productive. For us, engines on tickover are about right.

 

[Lozzer]

I have spent all summer dragging the anchor in all different scenarios.

I have dragged the anchor despite having set it nicely then laid out 100m of 12mm chain. Things have been that bad that I have dragged in less than 10 knots of wind and no tide or current (Med based).

I have been skippering yachts for 30 years so have a bit of an idea. But I am baffled

I skipper an 85' motor yacht and its quite embarrassing dragging the anchor so often.

One of my winter jobs is to check out replacing our existing setup. We have a pair of Deltas which I think are on the light side. In fact they are so light I can pull the anchor up by hand whilst leaning over the bow!!!

People rave about Manson so will be checking these out.

I'm wondering if the fact that I usually have stabilisers on has any impact. Usually we sit at totally different angle to all other boats. Makes life so interesting...