Dragging a Delta.

[gljnr1983]

I find that the faster you are going when you set a delta the harder it is to get out of the sediment as i had to power out of some soft stuff a couple weeks ago,the soft stuff must have been mega deep tho.

 

[Hoolie]

Fluid dynamics says the drag from a concave surface is considerably higher than a convex one.
Soft mud is not an entirely fluid media, but its close. Combined with the larger blade area of the new generation anchors, the resistance of the blade area is concpsiderably higher than the older generation anchors in soft media.

But they'll still drag, albeit at a more modest rate! Better to anchor elsewhere ... ...

 

[LadyInBed]

I have dragged a 10kg Delta at Shipstal and in South Deep so I use my large Danforth in those locations. The Delta doesn't seem to like the soft black mud.
I have now upgraded the 10kg Delta to a 16kg Delta, I have yet to try it on the soft black mud.

 

[noelex]

But they'll still drag, albeit at a more modest rate! Better to anchor elsewhere ... ...

If the drag exceeds the force you will stay put. At least that's the hope
The point about about the holding or substrate is important however.
A good holding can make a big difference.

 

[ithet]

Last summer I had difficulty setting my plough (copy) upstream at Shipstall - it would not hold on the very soft "ooze". Finally managed to anchor between the moorings but it was still probably just acting as a mud weight. I have actually replaced with a Delta this year as got fed up with pinched fingers!.

 

[arto]

Delta anchors never drag.

I think you'll find it was just the chain stretching.

More seriously: I've had a Delta drag twice. Once with far too little scope (computational error) and the other after anchoring somewhere in Fishguard outer harbour in a bit of a blow. Since it was around 3am at the time after crossing from Dunmore East, I suspect tiredness and user error may have played a part.

 

[Channel Sailor]

A couple of years ago I replaced a rusting 25lb Sowester Plough anchor (CQR copy) with a 10kg Delta. ......."

Just wondering if the 25lb plough and the 10kg Delta are the correct size for the boat in the first place. Anyway, I too reckon that a Delta does "plough", but if correctly sized for the boat and the conditions (wind and tide) is is being used in, then the expected drag can often be handled so as to not cause a problem. I'll guess that many purchasers buy the anchor size "recommended". But I seem to recall the max conditions for that "recommendation" is F5 or 6 in a sheltered bay! Just checked on the Lewmar web site and cannot see the basis for the recommendation stated anywhere.

My requirement for anchoring is for it to hold in a F7 in a bay (when there is a F8 out at sea), or F5 plus a strong tide running. This requirement is based on experiences when cruising in the English Channel, because I find that shelter in a nearby bay at anchor can be far safer than battling a tide or entrance in foul weather to windward to find buoy or being 6th out on a pontoon. With a suitable anchor, shallow draft, and a rock hopping chart it is surprising where safe havens can be found in the most dreadful weather.

In very soft bottoms, fairly shallow, and no swinging around risk, I too would use a Fortress, maybe even adjusted to increase the blade angle (not that i have ever done that myself).

As an experiment, on a windy night, try laying out two anchors of different types off the bow on either side (easier for multihull owners), and see which one the boat is straining to in the morning.

 

[grumpy_o_g]

While not ruling out the possibility that some of the issues reported were due to the condition of the bottom, we dragged in a well known anchorage and dragged past several other annchored boats that did not seem to have any problems. I just get the impression that the delta can be a bit tempramental - particularly in heavy mud.

It's not a cheap solution but a large light Fortress is excellent in soft mud, mostly because you tend to go for a size bigger as it's so light I suspect. Makes an excellent Kedge with just a few metres of chain and it's easy enough to simply take it forwards and chuck it over the bow unless you're on Maltese Falcon.

 

[DJE]

My thoughts afterwards were to lay two anchors next time or to think about a bigger main anchor. The kedge is a 7.5kg Bruce so it could be interesting to see how that performs. The boat is only 29 foot so the anchor sizes are as recomended - but as somebody said the recomendation may well be based on reasonably sheltered conditions. Also I think the bottom might be ploughed up by frequent anchoring - but other boats were holding as we dragged.
Looking at the anchorage from the adjacent high ground I think there might be room in our old favourite spot as we don't mind touching the bottom at low water. I'll have to do some experiments next time I'm there. Might even try tandem anchors!

 

[RichardS]

A few years ago I tried to anchor alongside a German boat in very soft mud but the Delta kept dragging. Two guys from the German boat dinghied over and asked if I wanted some help so the three of us tried another half dozen times before we got the Delta to hold in reverse.

I asked what the Germans were using and they said a Bugel with a hoop and it always bit first time so I bought an anchor with a "hoop".

I've never dragged with the "hoop" anchor. Although I've been to similar soft mud anchorages, I've never been back to the same spot so not a conclusive test.

Richard

 

[doug748]

Aye, give that Bruce a try.

Let it lie on a shortish scope for ten minutes and then let more out.

 

[noelex]

I think there are two different types of soft mud anchorages which does complicate the discussion.
There are anchorages where there is uniform soft mud and no matter how deep the anchor sets the substraite is still very soft. The second type has soft mud, but if the anchor penetrates deep enough there is a harder base that will provide good holding.
It is offen difficult to tell the difference, the anchors behaviour while setting and the mud that it brings up when raised give some clue, but by then it often too late.
Some anchors do very well with one or the other type of mud, but if crusing different areas you really need an anchor that will cope with all conditions, particularly for a larger yacht where the anchor weight makes it impractical to change. This versatility is one of the main attractions of the new generation anchors.