anchoring in 120kn gusts - which anchor will hold that??

[Simi 60]

Originally Posted by Mike Banks

You need a chain and nylon rode or snubber having at least a tensile strength equal to the entire laden weight of your vessel if you wish to be secure during storm conditions in open water with good bottom holding--and even heavier ground tackle would be better. ..

Yeah, cant see that being even possible for us.
60 ft and weigh 65 to 70,000 kg
What size rope and chain would we need for that?

13mm which we use has a working load of 1700kg
22mm grade L chain has a working load of 5000 kg

[daletournier]

Originally Posted by Simi 60

Yeah, cant see that being even possible for us.
60 ft and weigh 65 to 70,000 kg
What size rope and chain would we need for that?

That's actually a very good point.

What type and size anchor do you have? I assume you have quite abit of windage as well?

[Simi 60]

Originally Posted by daletournier

That's actually a very good point.

What type and size anchor do you have? I assume you have quite abit of windage as well?

150lb Manson Supreme.
I would have liked larger but we sent pictures, dimensions and weight of vessel to Manson NZ telling them we are full time cruisers in Cyclone prone waters and asking to be sized for an "Armageddon Anchor" and was assured that 150 was it, even when I said I was happy to buy bigger they insisted that it wasn't needed.

[daletournier]

Originally Posted by Simi 60

150lb Manson Supreme.
I would have liked larger but we sent pictures, dimensions and weight of vessel to Manson NZ telling them we are full time cruisers in Cyclone prone waters and asking to be sized for an "Armageddon Anchor" and was assured that 150 was it, even when I said I was happy to buy bigger they insisted that it wasn't needed.

That's interesting. Your anchor is approximately twice the weight of mine yet you weigh four times what I do and probably alot more windage.

In no way am I questioning Manson's recommendation.

[Matt Johnson]

Originally Posted by daletournier

That's interesting. Your anchor is approximately twice the weight of mine yet you weigh four times what I do and probably alot more windage.

In no way am I questioning Manson's recommendation.

An aircraft carrier is about 10,000 times the weight of my boat, but its anchor is only 550 times

Matt

[daletournier]

Originally Posted by funjohnson

An aircraft carrier is about 10,000 times the weight of my boat, but its anchor is only 550 times

Matt

I get it. My point is why is it accepted to go one size bigger than recommended? What's this based on? Why not two sizes bigger? Or why not just follow the manufacturer's recommendations?

[Breaking Waves]

Originally Posted by Simi 60

60 ft and weigh 65 to 70,000 kg
What size rope and chain would we need for that?

Not saying it is the right solution. But JFYI there is readily available commercial size rope which would do it - like 30mm EVERSTEEL-X is right at 70k kgs.

[a64pilot]

Originally Posted by daletournier

I get it. My point is why is it accepted to go one size bigger than recommended? What's this based on? Why not two sizes bigger? Or why not just follow the manufacturer's recommendations?

I went a two sizes bigger than Rocna’s recommendation based on their chart.
I did it initially to have an Armageddon anchor, didn’t mean to use it full time, but then decided why not?
I have a 33 kg and a 40 kg Rocna on my bow, no problem, no hobby horsing etc.
I’d never do this if I considered myself a fast boat of course, I’d have an aluminum anchor then.
Downsides are of course more money, more weight on the bow, larger windlass needed, and supposedly people make fun of you, but no one has even noticed.

I was at first concerned that maybe it would be harder to get it to set, harder to break it out / retrieve it, but none of that has proved to be true.
I don’t know why manufacturers say don’t go bigger then recommended, I see no downside beyond the obvious that it’s bigger and heavier and needs bigger and better gear.

I assume that’s it, people will put an oversized anchor on too small a chain / rode and too small of a windlass and complain that it doesn’t work as well?
Most people have the windlass the boat manufacturer put on the boat, and it’s often marginal.

Everything is a system, rigging, sails, motor etc. the whole system has to support each component.
You wouldn’t take out your 40HP motor and stick in an 80 and run the same transmission, prop and shaft would you?

[daletournier]

Originally Posted by a64pilot

I went a two sizes bigger than Rocna’s recommendation based on their chart.
I did it initially to have an Armageddon anchor, didn’t mean to use it full time, but then decided why not?
I have a 33 kg and a 40 kg Rocna on my bow, no problem, no hobby horsing etc.
I’d never do this if I considered myself a fast boat of course, I’d have an aluminum anchor then.
Downsides are of course more money, more weight on the bow, larger windlass needed, and supposedly people make fun of you, but no one has even noticed.

I was at first concerned that maybe it would be harder to get it to set, harder to break it out / retrieve it, but none of that has proved to be true.
I don’t know why manufacturers say don’t go bigger then recommended, I see no downside beyond the obvious that it’s bigger and heavier and needs bigger and better gear.

I assume that’s it, people will put an oversized anchor on too small a chain / rode and too small of a windlass and complain that it doesn’t work as well?
Most people have the windlass the boat manufacturer put on the boat, and it’s often marginal.

Everything is a system, rigging, sails, motor etc. the whole system has to support each component.
You wouldn’t take out your 40HP motor and stick in an 80 and run the same transmission, prop and shaft would you?

Yep, your right, no downside other than cost and the cost is irrelevant when the wind is blowing hard.

[Breaking Waves]

Originally Posted by s/v Jedi

- 300’ 1-1/4” Octoplaid nylon secondary rode with chain leader
- 3x 130’ 1-1/4” Octoplaid nylon with chain leader to create another big rode, or use for lines into the mangroves.

- 4x 16-ton cargo lift straps with eyes both ends for wrapping around trees, mangroves, posts etc.
- 4x sand screws to drive into the ground when nothing else to tie onto

I've only tied into mangroves a few times so I can't really comment on optimal set up for that - but I have tied into higher latitudes hundreds of times and (IMHO) the optimal set-up looks a bit different than that - just for the record here are some quick thoughts.

1. Floating line is preferred (over nylon). It is much less likely to get around a prop - yes that should not happen but you are maneuvering (usually prop in reverse) with a rope in the water and it does (with nylon). When you pull it back on board it does not come back all covered in mud and kelp. And it does not absorb a ton of extra water weight.

UHMW is the lux solution. It does create a small termination and winching challenge because of slipperiness - there are ofc good solutions to those challenges (learn the tugboat hitch and splicing). It is also pretty damn expensive.

My personal preferred option is poly-olefin (like https://www.samsonrope.com/mooring/rp-12-ultra-blue). It has a good price/value point. does not create any termination/winching challenges. Is nice to handle and durable.

Polypro is probably the most commonly used - cheap and available at every fishing chandlery in 220m or 440m coils. I might comment that the commercial fishing stuff is vastly better in quality that the crappy yellow prolypro sold in recreational marine.

This changes a bit when you are in territory with BIG pieces of ice floating around. You don't want floating line to trap big ice. So in some circumstances where that is a possibility you may want to use sinking line - polyester is preferred but nylon is fine in that case. You need some experience and seamanship to judge these cases. It is not super common.

2. Lengths - longer than you might expect, for three reasons. It is nice to dinghy the lines in from some distance out, so you are not too close to the hard edges while you are starting the tie out in case stroing gusts come in. And you want to be able to reach the strongest best-located tie points, and they are usually not as conveniently located as on a manmade dock. And third - you sometimes want to take the line out around the shore object and back to the boat (easiest release in the morning) or tie a really big loop.

In Patagonia, where the coves are typically really ideally set up - I would say 1 x 220m piece and 2 x 100m pieces and 2 x 50m pieces. Would be a basic working inventory. Beyond Patagonia (further south and in the north like Greenland and labrador) things are a bit commonly less idea than in Patagonia and you might need 2 x 200m and 2 x 100m.

3. Systems/storage - if you are using this stuff every day, as you would in Patagonia, you need a way to run them in and out quickly and tangle-free, and a way to stow them while sailing but still have quick access when you get to harbor. There were two general solution - the bigger full time chile boats tended to go with spools, while the smaller and transiting boats tended to go with line bags.

We used line bags, and the shape is critical. They should NOT be duffle shaped (eg short and wide) - that shape will often tangle the line when it runs out. They should instead be tall and narrow - which can take a line stuffed in and it will run back out smoothly. Strong mesh is the preferred material - allow the line to dry. Webbing carrying straps and wire-rimmed mouths (hole open the mouth so you can stuff with both hands) are nice to have.

4. Connecting around trees and rocks, etc - the first trick/tip is you want the connection point to be easily accessed (like from the dinghy). You don't want to have to be scrambling ashore as you are releasing the boat. So the connections nedd to be longish, out over the water preferably.

Chain is heavy and a pain in the ass to move around if you are scrambling up rock faces or across bogs.

I started off with all sorts of options - chain/wire/webbing strops/etc and basically ended up with three approaches. The simpliest, if the tie was around a nice smooth large tree, was just to take a bit loop of the shoreline and tie a bowline well out over the water (sometimes just loop it and bring it all the way back to the boat but teh large bowline loop most often). If the object was more knarly I used old dyneema cored sheets - which are strong and quite chafe and cut resistant, and 'free' - as the loop around the object - sometimes doubled if it was particularly knarly. And finally if there was no choice except use an object I thought might cut textile I would use pieces of chain - but this was really rare - happened more frequently when tieing to old abandoned whaling and commercial docks that to 'natural' ties.

There are some eco considerations when tieing to trees - you don't want to tear them up/kill them with your shore tie. So chain and especially wire are not really on. You want to tie to bigger ones - I did find with mangroves bigger than my thigh could hold the boat in a cat 1 without pulling up/out. And it's best to spread the loading as much as you can.

[Mike Banks]

My vessel was a multi so not having that three or four tons of lead rushing back against the anchor meant I could get away with lighter ground tackle. My vessel only weighed about seven tons fully fuelled and watered with all stores and crew aboard.

Well--to survive a cyclone in open water, assuming all other criteria for survival are met and the anchor is massive and of good design, your vessel needs two inch chain, about 50 mm link diameter and storing it will require a large heavily reinforced anchor locker because you will need about a hundred feet of it at least, if you are also using nylon to give some elasticity--and I recommend twice that length of chain for normal purposes in normal conditions, but you could get away with lighter chain in normal conditions too..

The diameter of the nylon rode for attachment to 50 mm chain would be about 70 mm--preferably multi-stranded plait I would also use a kellet of about seventy-five pounds weight, soft shackled to the chain a metre or two before the nylon rode connection, using a lighter chain tether or dyneema--and more weight than that in the kellet if I had an anchor davit with which to handle it.

Never anchor out in storms by choice. Even light ships, with their massive permanent anchoring systems, have been known to be sunk at their moorings when huge cyclone-driven surges forced them underwater.

You can put out too much chain in deep water. The waves will be smaller out there, but you may have to abandon your anchor when it is over.

In water up to fifty feet or so you can safely put out the lot if you have swing room. If you drop all your chain into deep water you may be hard pressed to retrieve it. My windlass would dead-lift one hundred and thirty feet of 12 mm chain plus the 60 pounds anchor, but that was about it. Overheating a motor, or drifting between bouts of lifting to allow things to cool off or charge to build up as the engine revs in idle is not great seamanship. Choice of anchorage and tide is important--and when a storm is forecast even more so. Get to shelter.

Of course you can get away with far less than this tackle for normal usage--but being out in a hurricane is not normal usage. For that you need extreme tackle. Much better to seek shelter in a creek where one can anchor fore and aft with long ropes, and breast ropes to trees ashore, where you can get away with one inch chain and two inch diameter nylon.

On my trimaran I had 130 metres of 12 mm chain and two hundred metres of 20 mm diameter nylon rode, and I used a kellet weighing about thirty pounds or so--if forget exactly, but not less than that. It may have been more--but you need it to be about half of the weight of your anchor, and that for my vessel was sixty pounds for her main bower anchor and thirty pounds for her auxiliary anchor.

[StuM]

Originally Posted by Breaking Waves

...

My personal preferred option is poly-olefin (like https://www.samsonrope.com/mooring/rp-12-ultra-blue). It has a good price/value point. does not create any termination/winching challenges. Is nice to handle and durable.

Polypro is probably the most commonly used - cheap and available at every fishing chandlery in 220m or 440m coils.
...

Generally, an excellent post.

But I do wish manufacturers would use accurate names. It would prevent this sort of confusion.

Polyolefin is not a specific rope material, it is a generic term for a number of different polymers.

Both polypropylene (polypro) and polyethelene are polyolefins.

When Samson call their Ultra Blue a "polyolefin" and a "bi-polymer" rope, all it tells us is that it is some blend of two out of some eight possible polyolefins, all of which have different characteristics.

To quote Grog:
https://www.animatedknots.com/rope-materials
"Polyolefin:
A chemical group which includes both polypropylene and polyethylene. When describing rope, polyolefin may refer to a mixture or to either one of these fibers."

Or:
Polyolefin Fibers
"Polyolefin fibers are synthetic fibers in which the fiber forming substance is a synthetic polymer composed of at least 85% by weight of polyethylene, polypropylene or any other polyolefin.
Most polyolefin fibers are made from polypropylene (PP) or polyethylene (PE). The later is the most widely used polyolefin."

[Delfin]

Originally Posted by s/v Jedi

No those waves don’t create shock loading. If you closely observe the video, you can see that. There is a cycling load curve of course but that is well within range of keeping the anchor in the seabed. The energy is absorbed first by the bow splitting the wave, then the bow rising all dampening the wave impact.

You contradict yourself. Shock loading is defined as a sudden increase in force. So when you say that there is a "cycling load curve", you're just saying the force increases suddenly, which the bow responds to by raising.

So yes, in high winds, waves increase and this increases the shock loading on the vessel, which is diminished by using a correctly sized elastic snub line.

Really wondering why there is an argument about basic physics....

[valhalla360]

Originally Posted by s/v Jedi

First, the reason why: in sustained hurricane force winds, the rode is taut at all times and there is no shock loading. Also, an all chain rode provides shock absorbers not by elasticity but by it’s weight being lifted off the seabed.

That assume no yawing and the wind is sustained.

My take on the OP's situation is it's not a hurricane but high latitude sailing and storms roll in and out fairly regularly with winds building and falling off plus land features may impact winds making the direction and force variable.

Rode will always have additional elasticity (up to breaking point). Once a chain is bar tight, for practical purposes, there will be no elasticity. One catch is 10-20ft of snubber likely isn't enough in hurricane force winds.

To the OP's original idea that holding strength can be calculated accurately...30% would be a starting point for variability in fairly well controlled situations. Add in more realistic variability in anchoring conditions and 50-70% variations from projected holding are very realistic.

[Ibetitsthisway]

This is all about Finding the gear That will 100% surely hold 120kn Wind Without carrying an anchor That weights as much as the boat itself



If some one has a better approach than me... Please Tell.



"there is no way of knowing" is no Option.




To me my approach looks satisfying and jedi and some others seem to have Real life proof of this.