Dragging whilst on anchor

[MapisM]

Are talking the same end ?

Well, I think we are.
As I said previously, also in my experience the chain size/weight matters (aside from, very obviously, its length) - no disagreement on that.
What I disagree with is the idea that the overall ground tackle sizing only depends on windage, because in my experience the load peaks (which are what really matters for sizing of any equipment) happen with snatch load, which is mostly mass rather than windage driven.
In other words, a ballasted steel boat weighing 4 times another vessel with exactly the same windage needs a much more substantial ground tackle, imho - that's all I meant.

 

[MapisM]

It's like the debate last year on why snorkelling over your anchor was a bad habit to have.

I must have missed that debate, why should that be a bad habit?
Mind, I'm used to snorkel around the boat because it's a pleasure, to start with - looking at the anchor is just incidental.
I can see why you wouldn't want to do that in cold water with awful visibility, but I'd rather not go boating at all, in those conditions...

 

[Blue Sunray]

Blimey why is it that any thread on any forum about anchors always has to get nasty. If you and Elecglitch bother to read what I actually wrote, I never said or suggested that because a chain weighs 325kg it requires a force of 325kgf to pull it. As I said, I have on many occasions over nearly 30yrs of boating snorkelled out in high winds to observe how my anchor and chain is behaving and as I said I have yet to witness the final part of the chan lifting off the seabed such that the pull on the anchor is anything but horizontal. You can take it or leave it but I believe that because of that and because there is a certain coefficient of friction between the chain and the seabed, that part of the chain on the sea bed provides resistance to being pulled which is in addition to the resistance provided by the anchor

If you take your argument to its logical extension, why do you guys bother with chain at all? Why not connect your anchor to your windlass with wire rope which has a similar breaking strain but which is much lighter and can be stored more easily?

You are quite correct that I didn't read what you wrote (which was of course quite correct) but then again I wasn't replying to, or criticising, you, so do try not to get your underwear knotted unnecessarily.

 

[jrudge]

On your other point, there is no discernible friction of chain on a seabed unless it is caught round something. Again simple to find it if that is tosh by trying it with the other end of a chain with no anchor attached.

I was in Ibiza in Ibiza over summer. There was a bouy floating. It wasn't mine, but I was curious what was underneath it. Chain. Only Chain in a big pile.

Boat came along. Restaurant rib put him on the bouy. As we left I stopped next to him and told him he was connected to .... nothing. He didn't seem bothered. There again nor did the person who went right over the Santa Ponca reef in a 50 odd foot princess - I assume he averted disaster by literally millimetres.

 

[BartW]

On your other point, there is no discernible friction of chain on a seabed unless it is caught round something. Again simple to find it if that is tosh by trying it with the other end of a chain with no anchor attached.

when I need to explain to guests why I drop so much chain when anchoring overnight (5 or more times scope)
I'll asc them to imagine to drop a long and heavy chain on a lawn and try to pull that, compared to pulling a thin cable or a rope,
than they usually understand and appreciate the difference in friction.

when I do my morning swim, and look at the anchor, in many occasions the ancher is still in its drop postion, similar to the picture from MapisM.
when there has been a strong wind during the night, at worse, I can see traces from the chain that has been moving left and right, and ancher digging deeper in the sea bottom.

during our 8 season ownership x 7 weeks summer holiday's,
on average we stay 1 night of 3 on ancher, and my experience is the same as posters above;
a heavy and long chain is the best guaranty for a non dragging anchor
I have 150m 12mm chain on a 55ton boat, the old fashion anchor is >80kg
the extra length is usefull in marina's or anchorages, where you ancher stern to quay or stern to shore,
on a normal anchorage we never dropped >100m iirc, but very often +60m

 

[petem]

I was in Ibiza in Ibiza over summer. There was a bouy floating. It wasn't mine, but I was curious what was underneath it. Chain. Only Chain in a big pile.

Boat came along. Restaurant rib put him on the bouy. As we left I stopped next to him and told him he was connected to .... nothing. He didn't seem bothered. There again nor did the person who went right over the Santa Ponca reef in a 50 odd foot princess - I assume he averted disaster by literally millimetres.

Restaurants with buoys in Ibiza? Where was that Jeremy?

 

[jrudge]

Outside the Blue Marlin - south coast