Always use a snubber or your boat could end up like...

[DockDoc]

After only 3 years, and 4000 nautical miles under my belt I still say I am a very novice sailor.
Can someone explain to me how the chain became detached? I have a 20 foor bridle, and 300 feet all chain rode, but in the end there is 1 inch line attached to a mount inside the chain locker.

I did watch the video, I use adblocker and skipped ahead so it's less painful, but the description that the ferry waves kept rocking the bow and that caused clutch failure in a repetitive cycle to pay out ALL of the chain (how deep was this anchorage?) seems to defy logic. Why did the tie at the end not stop it?
Is it possible the chain came off the gypsy and the line chafed thru?
I am suspicious the friends are telling 1/2 the story so as not to impact any claim against insurance or just trying to be nice and not lay blame on their buddies.

Not just rhetorical questions, really looking for some input.

In defense of these folks I have to appreciate them posting this. Even if they do make a bit of money off this, (CPM =0.004 x 0.55 per 1000 views) I think.

To learn from one's own mistakes is smart, but to learn from other's mistakes is genius.

[Idlegreg]

Originally Posted by Mike OReilly

Fascinating discussion. This brings to mind the day shapes usage thread of some time ago, where again there seems to be a New World/Old World divide in common practice. Here too I am left wondering if the differing practices produce different outcomes.

I don’t have any sense that UK boats perform less well at anchor than us over in the colonies. But if this really is such a clear delineation of practice, then outcome data could be interesting.

I should note that where I cruise, 20 knots is normal winds. But it’s true that this does not produce ‘bar-hard’ rode on my relatively heavy full-keel boat. I use 3/8” chain (~10mm). Have not bothered to note exactly what windspeed is required, but probably over 25 … maybe 30.

Mike

Yes Outcome data would be very interesting having discovered this difference of the average skippers technique though I am not sure how you eliminate the almost infinite number of variables in boat, anchoring rig, weather, bottom material etc. etc. Still it might be relevant if it turned out that UK boats were dragging into danger more often than our Snubbing cousins over the pond.

20 knots is not unusual here and in many other places I have sailed but I would say the wind is often less during the main sailing season, especially at night and most anchorages provide quite a bit of shelter so that a true 20 Knots hitting the boat is not so common even in stormy weather. I also get the impression you spend long periods living at anchor and while I have been in that situation it has been when exploring along a coast and if stormy weather is developing I will have arranged my route to bring me into more heavily sheltered waters in advance of the bad weather - you may not have that choice or you like the wild exposed places enough to stay out there whatever the weather. I am not sure where you are but I am sure there are places where a more conservative approach to anchoring than my normal methods would be wise. I guess I started into this because there seemed to be a universal daily use of a Snubber which I doubt is required for many coastal cruising boats who enjoy predominantly fine weather and good shelter.

[wingssail]

Originally Posted by Auspicious

I generally consider average European sailors to be more capable, better trained, and more careful than average Americans. To eschew snubbers runs counter to that belief (an opinion) on my part. I may have to reconsider.

I consider that to be a bit of a slap in the face but I guess I deserve it being as I reject the mandatory "must use a snubber and must belay the rode other than by the gypsy" rules. As I said, I'm an ignorant American didn't know those rules, never followed them and still don't. I have and still will, decide for myself when I need to use a snubber and how or when to belay my anchor rode. We may not be better trained or as capable, but some of us are of an independent lot (not followers or sheep). My approach to anchoring has worked for a great many years without problems. I have snubbers aboard, use them when appropriate, and belay my anchor a variety of ways. I will concede that after following this thread I'll be a bit more protective of my windlass (after all it is old and has seen a lot of miles). And I will still avoid bad anchorages. I'll sail 100 extra miles to find a bullet proof anchorage, and if gets too rough, or becomes a lee shore, I'll set sail and leave, day or night (and have, many times)

AND, I have not found any generalizations such as you seem to be making to be true. I've found excellent and capable sailors from many countries, North and South America, NZ, OZ South Africa, and the Caribbean, among other places. (If you want to learn about sailing, watch a Kiwi.) Of course, also Europe (does that still include UK?) If there is any generalization that might apply, I've found that sailors from the EU (France excepted) tend to be a bit more conservative, (should I say stuffy?) than ones from some other places. Americans? We're not a homogeneous group.

Rules? Australia has a few. Boarding and officialdom? In over 50 years of boating, a lot of it in the US, as well as many other places around the world, I've never been boarded while underway or at anchor other than during check in inspections. Once the US Coast Guard came along side while we were sailing and queried me regarding my "San Francisco" homeport which was still on the side of my boat after two years in Seattle. I lied about how long I'd been there and they went away. Anyhow, I hear a lot about EU rules, but a lot of countries have them.

Taxes? Americans are NOT taxed from state to state as they move their boats until they exceed a given length of time in a new state.

We cruisers, especially those who have ventured beyond our home regions, are a world community, and, while many of us have our own approaches and habits, largely a heterogeneous one.

[Auspicious]

It has been a rough week here at Chez Auspicious and I apologize if I have been prickly. I still type fast.

Originally Posted by Dockhead

Who is dismissing scientific analysis? Where did you get that from anything which has been posted?

The ABYC numbers are based, to my understanding on static analysis. That's why there is a big safety margin - to attempt to account for dynamics. I can check with the past technical VP there who is a friend and nearby. The upshot is that snatch loads are a big deal and snubbers absorb that much better than expecting catenary to do so.

See Alain's analysis.

Originally Posted by Dockhead

All that has been said is that some people, and rather many people in this part of the world, do without snubbers, at least larger boats, in calm weather. That's a fact which doesn't contradict any scientific analysis.

People do lots of silly things. Among them leaving all kinds of things on deck that increases windage. Jugs, dinghies, poorly packed sails, full enclosures, on and on.

Sorry. Still prickly.

I've been in my cockpit enjoying a cocktail and watched the windlass on a neighboring boat make a beautiful parabola as it launched from the foredeck due to a snatch load. Who sized the bolts on your chain stopper? Are you depending on whoever picked the bolt hole sizes?

We all get surprised by weather. It takes two minutes to rig a snubber and three minutes to recover. Is this not a good use of time?

Originally Posted by Dockhead

There are yobs everywhere

True

Originally Posted by Idlegreg

However (and ignoring the fact that engineers are always learning new truths) a calculation is only relevant if all the correct inputs are used including the often vague question as to what compromises the user is happy to make.

Scientists generally learn new truths. Engineers build things based on those truths. *grin* I absolutely agree with you about the input conditions and compromises (this field is called 'system engineering'). It also includes communications which many engineers are poor at. Helping the user ask the right questions is important.

Remember that building codes including ABS, DnV, Lloyds, etc are based on engineering calculations. Good engineers build requirements so that handbook engineers don't step on landmines.

I was inside Hurst Castle and as I said only for a few hours waiting for friends.

Originally Posted by wingssail

I consider that to be a bit of a slap in the face but I guess I deserve it being as I reject the mandatory "must use a snubber and must belay the rode other than by the gypsy" rules.

The issues are shear strength of the bolts that hold down your windlass, your chain stopper, and the worm gear on the windlass drive train. You have to worry about cold work hardening as well.

[Dockhead]

Originally Posted by Auspicious

. . . People do lots of silly things. Among them leaving all kinds of things on deck that increases windage. Jugs, dinghies, poorly packed sails, full enclosures, on and on.

Sorry. Still prickly.

I've been in my cockpit enjoying a cocktail and watched the windlass on a neighboring boat make a beautiful parabola as it launched from the foredeck due to a snatch load. Who sized the bolts on your chain stopper? Are you depending on whoever picked the bolt hole sizes?

We all get surprised by weather. It takes two minutes to rig a snubber and three minutes to recover. Is this not a good use of time?

With respect, I think you are following a kind of party line, without really thinking about the objective facts of the situation.


You never answered the question: You've got an anchor chain out which can absorb 894daN of force, about a ton, before the catenary is out of it. You're anchored in good holding, good shelter, and the forecast is 10 knots, gusts of 15. At 15 knots of wind, you can expect realistic force of 70daN. If you take the ABYC design standard, 208daN. If it exceeds the forecast a bit and blows up to 20 knots, it's 123daN (ABYC 370daN).



If the forecast is totally wrong, and a squall blows through with 30 knots of wind, you might see 277daN (ABYC 832). And your chain will absorb 894daN before the catenary is out and you will start to feel snatch loads, so even so, still no problem.



And if some freak weather blows up and the chain goes bar tight and you do feel a snatch load, will the sky fall? Will you instantly sink or rip the bow roller off? No, you go on deck and rig the snubber. But it doesn't happen. Not even once a year of going naked.



So do you seriously want to say that with a forecast of 10 knots, gusts of 15, it is somehow stupid not to rig the snubber?



Methinks you are suffering from some extremely over-rigorous thinking here. You laugh at saving two minutes rigging the snubber, but I can mix a bitchin martini in two minutes. What's the better use of time? My God, life itself is doled out in two minute dribs and drabs and every one of them is precious. Every one of those martinis is too.

[Idlegreg]

Originally Posted by Dockhead

And if some freak weather blows up and the chain goes bar tight and you do feel a snatch load, will the sky fall? Will you instantly sink or rip the bow roller off? No, you go on deck and rig the snubber. But it doesn't happen. Not even once a year of going naked.



So do you seriously want to say that with a forecast of 10 knots, gusts of 15, it is somehow stupid not to rig the snubber?



.

I think I go with this approach.

After all the whole thing is pretty safe compared to the years I spent cycling to work in London.

[Idlegreg]

Originally Posted by Auspicious

It has been a rough week here at Chez Auspicious and I apologize if I have been prickly. I still type fast.

Better Prickly and communicate what you think than silent :-)

I've been in my cockpit enjoying a cocktail and watched the windlass on a neighboring boat make a beautiful parabola as it launched from the foredeck due to a snatch load. Who sized the bolts on your chain stopper? Are you depending on whoever picked the bolt hole sizes?

I suspect some of this whole debate relates to inadequate deck gear on many boats.

Remember that building codes including ABS, DnV, Lloyds, etc are based on engineering calculations. Good engineers build requirements so that handbook engineers don't step on landmines.

But the whole point is I don't want to be a "Handbook Engineer" at least not all the time. I want to make my own choices in real time - with expert help where possible - and then stand or fall on my own cunning/stupidity. That often means assessing the situation on the day and deciding how many belts and how many braces will make me feel safe.

When I think back to the Couple whose story led to this thread it's true they lost their boat but at least they were out there sailing the World and they are still alive to tell the tale. Whatever criticism we may have for their decisions it is best we don't do too much to encourage those others we see sitting in port year after year constantly improving their already tank like steel boat until their health fails and the dreams go with it. We must all choose the balance that suits our character and then go sailing.

[Delfin]

Originally Posted by Dockhead

With respect, I think you are following a kind of party line, without really thinking about the objective facts of the situation.


You never answered the question: You've got an anchor chain out which can absorb 894daN of force, about a ton, before the catenary is out of it. You're anchored in good holding, good shelter, and the forecast is 10 knots, gusts of 15. At 15 knots of wind, you can expect realistic force of 70daN. If you take the ABYC design standard, 208daN. If it exceeds the forecast a bit and blows up to 20 knots, it's 123daN (ABYC 370daN).



If the forecast is totally wrong, and a squall blows through with 30 knots of wind, you might see 277daN (ABYC 832). And your chain will absorb 894daN before the catenary is out and you will start to feel snatch loads, so even so, still no problem.



And if some freak weather blows up and the chain goes bar tight and you do feel a snatch load, will the sky fall? Will you instantly sink or rip the bow roller off? No, you go on deck and rig the snubber. But it doesn't happen. Not even once a year of going naked.



So do you seriously want to say that with a forecast of 10 knots, gusts of 15, it is somehow stupid not to rig the snubber?



Methinks you are suffering from some extremely over-rigorous thinking here. You laugh at saving two minutes rigging the snubber, but I can mix a bitchin martini in two minutes. What's the better use of time? My God, life itself is doled out in two minute dribs and drabs and every one of them is precious. Every one of those martinis is too.

Stupid doesn't perhaps apply, but lacking prudence might. This summer we anchored in Kindergarten Bay in SE Alaska with zero wind, and zero wind forecast and by 10 pm had 60 knots. S**t happens, if not often, but taking 60 seconds to attach a snub line doesn't seem too onerous. Plus, the snub line, even in calm conditions, quiets the chain, which is the other reason we always use one.

[Mr B]

My boat when I boat it came with all the Bells and Whistles except a Windlass,
The chain and anchor, A Danforth was easily pulled up by hand,

It was the first time I had ever seen a snubber, A rope with a rubber section and the rope wrapped around it, A hole in each end the rope went thru, It cant slip on the line,
No Idea on how it worked,
I wasnt even sure what it did, But I have one,

This thread finally informed me what a snubber was, I have one of those,
Do I use it, Nope, 100 metres of chain does the same thing, It takes the shock out of the anchor line,

Why dont big ships use snubbers, I can give you an example,
In the early 70's I worked in the shipyard at Brisbane,
Im an Engineering Blacksmith, I worked under steam Hammers, Big ones,
The ship yard lost the D shackle for a ships anchor and I had to make a new one for the ship,
It was 6 inches in Diametre, Stood six feet tall and weighed 8 tons,
Thats just one shackle to hold the anchor on the chain,
Plus the massive chain it was connected too,
The catenary action of that weight would remove any need for a snubber, But then again, How would they put a snubber on a chain and anchor that size,

[Simi 60]

Originally Posted by Delfin

Stupid doesn't perhaps apply, but lacking prudence might. This summer we anchored in Kindergarten Bay in SE Alaska with zero wind, and zero wind forecast and by 10 pm had 60 knots. S**t happens, if not often, but taking 60 seconds to attach a snub line doesn't seem too onerous. Plus, the snub line, even in calm conditions, quiets the chain, which is the other reason we always use one.

I'm with you on this one being a repeat offender on the summer storm front.
Snubber takes less than a minute to put on and being a hook, drops off by itself on retrieval as it hits the bow roller, so don't even need anyone to go up front if needing a quick escape.
Rope and hook drags in the water but pressure wave keeps it off the paint and its still around 55ft back to the prop

[Delfin]

Originally Posted by Mr B

My boat when I boat it came with all the Bells and Whistles except a Windlass,
The chain and anchor, A Danforth was easily pulled up by hand,

It was the first time I had ever seen a snubber, A rope with a rubber section and the rope wrapped around it, A hole in each end the rope went thru, It cant slip on the line,
No Idea on how it worked,
I wasnt even sure what it did, But I have one,

This thread finally informed me what a snubber was, I have one of those,
Do I use it, Nope, 100 metres of chain does the same thing, It takes the shock out of the anchor line,

Why dont big ships use snubbers, I can give you an example,
In the early 70's I worked in the shipyard at Brisbane,
Im an Engineering Blacksmith, I worked under steam Hammers, Big ones,
The ship yard lost the D shackle for a ships anchor and I had to make a new one for the ship,
It was 6 inches in Diametre, Stood six feet tall and weighed 8 tons,
Thats just one shackle to hold the anchor on the chain,
Plus the massive chain it was connected too,
The catenary action of that weight would remove any need for a snubber, But then again, How would they put a snubber on a chain and anchor that size,

Your last sentence answers the question of why large ships don't use snubbers. Chain catenary works until it the chain is lifted completely and becomes bar tight. Then surge loads from waves are transmitted directly to whatever the chain is attached to. A snubber dissipates those forces over a distance, cutting them to a fraction of what they would have been without. If one argues that in a really big blow, the chain will end up being bar tight even with a snubber, that would be true as long as the snubber is too light for the conditions experienced. A thicker snub line under those conditions will still stretch, and still reduce the final load on the vessel.

[Jim Cate]

Originally Posted by Delfin

Your last sentence answers the question of why large ships don't use snubbers. Chain catenary works until it the chain is lifted completely and becomes bar tight. Then surge loads from waves are transmitted directly to whatever the chain is attached to. A snubber dissipates those forces over a distance, cutting them to a fraction of what they would have been without. If one argues that in a really big blow, the chain will end up being bar tight even with a snubber, that would be true as long as the snubber is too light for the conditions experienced. A thicker snub line under those conditions will still stretch, and still reduce the final load on the vessel.

Of course it is useful to realize that ships drag anchors too. And ever since one dragged ashore near Newcastle Australia some years ago, the many ships that anchor off that harbour waiting their turn to load are required to up anchor and go to sea when harsh weather threatens... not when it arrives.

These are huge ships, mostly colliers, and are anchored in around 150 feet depth or more, so plenty of catenary... but the harbour authority does not trust their anchors!

Jim

[Mike OReilly]

As someone who has a basic grasp of physics, I understand what Auspicious is driving at. Avoiding snatch loads is a good thing. I think of the rationale for snubbers in the same way I think of preventers on my boom. Sure, I can avoid the potentially devastating problem with skill, knowledge and good luck, most of the time. But sometimes shyte happens, and I’d rather have a preventer, or a snubber, already rigged when it does.

Idlegreg, I appreciate your kind and sensible comments on this. You are correct that I cruise in moderately challenging waters. And when I anchor, I almost never stay for less than a few days — often weeks or even months. So these factors definitely colour my perspective.

Auspicious wrote:

We all get surprised by weather. It takes two minutes to rig a snubber and three minutes to recover. Is this not a good use of time?

I guess this my basic anchoring premise; that things can change quickly and drastically, and given how easy it is to tie on a couple of stout snubbers, it seems like false economy not to do so. Much like it is false economy not to rig my preventers, or my running backs.

But I greatly respect some of the voices here, and I really am intrigued over the apparent regional differences taken to this whole snubber practice. Like I said, I would love to see actual regional data, but agree it hard to impossible to distill out all the other factors.

Interesting…

[a64pilot]

Ships don’t use snubbers other than the reason they can’t, but it’s also mass or really inertia, our small light weight boats will be tossed around rather easily, while the huge mass of a ship won’t move much in the waves you would expect to see in an anchorage.

There is something called the square cube ratio that explains a lot of why massive things don’t act like small things. Like why you don’t see fiberglass ships, and why you don’t usually see small steel boats etc.
And why there is even a realistic limit as to how large a sailing ship can be and still sail.

But you rig a snubber for when your in town and that unexpected 45 kt squall rolls through. Like I said earlier I don’t use one when we are in the ICW and we stop overnight and aren’t leaving the boat, I just use the chain stopper.

[sdj]

Originally Posted by a64pilot

But you rig a snubber for when your in town and that unexpected 45 kt squall rolls through. Like I said earlier I don’t use one when we are in the ICW and we stop overnight and aren’t leaving the boat, I just use the chain stopper.

Could you comment further on "in town" and exactly why this different to the ICW? thx