Using your new anchor with kinetic rope

[Izikalvo]

We are playing with a new idea since anchors becoming lighter, would you consider using a new-gen light anchor with 10-meter chain and the rest of the rode be a kinetic Nylon rope that can be stretched?

We estimate that this kind of setup will dismiss the usage of a windlass with boats up to 40ft.

what do you think?

[a64pilot]

No.
I have no idea what kinetic rope is, but a combo chain / three strand nylon rode is very stretchy, but is not as desirable as all chain, often due to the chafing issue. If your never near coral and rock, then I see no problem with it, but I am sometimes in rock.
I try to avoid coral if at all possible.

[Pete7]

Originally Posted by a64pilot

No. I have no idea what kinetic rope is, .

Think of a big bungee, used in off road recovery to extract bogged in vehicles, by driving the towing forward builds up energy in the rope plus forward movement of the tow vehicle increases the available pulling force, or something like that.

Not sure if I would want that for an anchor rope if sailing around the anchorage. Strong wind gust sends you off to one side and stretches the rope, wind drops and you go flying back across the other way. It might even be possible to sail over the anchor to windward in the lull.

I'll stand on the shore and watch if someone wants to demonstrate it.

Originally Posted by Izikalvo

We estimate that this kind of setup will dismiss the usage of a windlass with boats up to 40ft. what do you think?

Now normally I can pull up the 40m of 8mm chain and 10kg of Rocna by hand. That is so long as it isn't windy or there is a couple of knots of current/tide running. Then you need the windlass and this on a 31ft yacht. We don't all sail in the flat calm tide free waters of the Med. 40 feet you say, sorry you will need a windlass to lift even your smaller anchors in strong wind and tide conditions.

I would be happy to test your theory and you did ask for volunteers a while back to test your anchor, but mine still hasn't arrived despite volunteering

[Dockhead]

Originally Posted by Izikalvo

We are playing with a new idea since anchors becoming lighter, would you consider using a new-gen light anchor with 10-meter chain and the rest of the rode be a kinetic Nylon rope that can be stretched?

We estimate that this kind of setup will dismiss the usage of a windlass with boats up to 40ft.

what do you think?

Well first of all, you say "since anchors are getting lighter" -- where in the world do you get this? Over my approximately 40 years of cruising, anchors have on the contrary been constantly getting heavier and heavier. This tendency has been reinforced by the evolving scholarship which emphasizes the importance of anchor weight to the exclusion of chain weight (c.f. Dashew; Peter Smith).



Second, a lot of work has been done on the optimal rode material. Problems with nylon rodes have been well known for at least 20 years; see: https://www.petersmith.net.nz/boat-a...right-rode.pdf


90% or more of experienced cruisers use chain rodes, for different reasons including the value of catenary, and resistance to chafe. The only experienced cruisers I have ever known who use rope as a primary rode, are those on very light multihulls, and those on very small monos.



If you're going to use rope rode for some reason, use polyester, which loses less strength when wet and which is vastly more chafe resistant when loaded.

[Slainte1]

Yes your idea is fine. People talk about catenary with all chain rode but in a blow the chain is pulled straight with the corresponding snatch loads. Better to use sufficient chain to prevent chafe only and nylon rode for the rest

[groundtackle]

Izzy, yup you are on the right track but use low stretch high tech abrasion resistant with snubbers to control the tugs when required.
The plan for my little 30' Mega is a titanium and carbon fiber Excel with an underdeck drum winch that I can operate on my phone, from my bunk.
I'll post pics.
Chris

[thinwater]

New generation anchors offer greater holding that past designs. Of course that means you can use a lighter anchor and have the same security we had in the past with a less effective design. Obviously.

At the same time, the conventional (forum and internet) wisdom is that we should get even bigger anchors for more security. I'm not going to argue against that too strongly; my last boat came with an undersized Delta and I replaced it with a NG anchor 10 pounds heavier. But even by old advice, the original anchor was too small.

Rope vs. Chain? That's been flogged to death. I would say ask locally. There ARE experienced cruisers from areas where coral and rock are rare that use rope without trouble. I used rope on my home Chesapeake Bay for many years, with vary a nick or any measurable chafe.

One of the main reason for all chain on many boats is that, with a windlass, chain is simply easier to handle. Windlasses are more common than they used to be.

Nylon vs. Polyester? This is an interesting one. The feeling seems to vary regionally. If you use polyester without a snubber and don't have much out (less than 100 feet) it has little stretch and the ride is a jackhammer. Looser polyester weaves advertise more stretch, but they don't mention that this looser weave reduces the chafe resistance to LESS than 3-strand nylon. Stretch increases with looser weave. Chafe increases with looser weave. In fact, nylon webbing (tight weave) will outwear Amsteel (loose weave) in side-to-side abrasion testing under load on rock by 2-4 times. Strange but true--try it.

Nylon can stretch too much. Yup, I've done testing that shows that past a certain point, to much stretch increases yawing, which increases rode tension and decreases anchor stability. Like too soft spring on a car.

Rope stretch varies with diameter. No one said you couldn't go up a size. Then you get better chafe resistance (stronger and less pressure/area, and as a result, better than some polyester lines) and moderate stretch.

If part of the rode is chain, that reduces the length available for stretch.

You don't want less than ~ 50 feet of rope out. Put out just 10 feet of rope plus chain, and that the rope will be overworked.

Complicated. Chain is simpler but heavier. At the moment I'm playing with oversized nylon rope and liking it. Still light, and easy to handle.

No one answer. But I'd go with chain on a 40-foot boat, without question. It's just easier.

[rslifkin]

I agree with Thinwater's ideas. I'm re-doing my ground tackle setup this winter. I've got a planing hull powerboat, so while it'll carry plenty of weight up forward without an issue, weight hurts performance and increases fuel consumption (especially weight up forward on my hull).

So being in an area where rocky bottoms are mostly in shallow anchorages and there's no coral concerns, I decided to go for 75 feet of chain (5/16" G43) and then 300 feet of nylon behind that. I figure that should be enough chain to avoid chafing the nylon against the bottom in most cases. Windlass choice was driven partly based on picking a windlass that's known to handle a rope-chain splice cleanly without manual fiddling, making use of the mixed rode easy.

For rode size, the windlass is spec-ed to take 5/8". That should be strong enough, but I've had the thoughts of whether it might be too stretchy. I've got a test piece of 3/4" 8 plait sitting here for me to try when I get the windlass mounted before I order the new rode. If it works well enough in the gypsy, I might up-size the nylon to 3/4" for better chafe resistance, a bit less stretch, etc. But if I'm not 100% sure it'll work well (Maxwell claims this windlass can only handle 5/8" and nothing else), then I'll just stick with 5/8" and call it good. 99% of my anchoring is in pretty light weather anyway, so for the rare time the winds really pick up and I'm at anchor, I'll live with a little extra sailing (the boat does plenty of that anyway). Or I'll find other ways to steady the situation.

[groundtackle]

Thin, give me your shipping address and I'll send you your Aluminum Excel, whatever size you like. You need to play with this thing.
I'll trade it for a copy of your new book.
Chris
250.516.7888

[Montanan]

Kinetic energy ropes work to derive peak snatch loading. Which is exactly what you don't want to happen against your anchors as it can lead to pulling out.

The process is achieved by allowing a load to first accelerate and then to have the kinetic energy of the load to become stored into the elastic fiber of the rope as the load is slowed.

With a rode one does not want your vessel to accelerate, you want the boat to not move away from the anchor, to gain momentum so as to not build kinetic energy. You accomplish this by having minimal stretch. Minimal stretch allows for the peaking load applied by wave or wake action to be spread over a short period of time and a short distance of travel. You want just a bit of spring, not a lot of spring in your rode. Enough to level out what otherwise would be the peak loads of riding up over waves [and the tug of sudden harsh wind gusts].

The last thing you want is for your vessel to sling shot or sail about and thence have its motion needing to be halted when the rode pulls tight.

FYI. Inertia is an intrinsic characteristic of the object related to its mass. Inertia tells you how much force it will take to cause a particular acceleration o deacc on the object. Momentum is a function of an object's mass and velocity. Momentum is a measure of the kinetic energy of the object.

[slug]

Originally Posted by Izikalvo

We are playing with a new idea since anchors becoming lighter, would you consider using a new-gen light anchor with 10-meter chain and the rest of the rode be a kinetic Nylon rope that can be stretched?

We estimate that this kind of setup will dismiss the usage of a windlass with boats up to 40ft.

what do you think?

A lightweight anchor is about as useful as a lightweight steamroller

An all rope anchor rode is very tiresome to live with
Stinging jellyfish tentacles all over your crew , fishhooks in their hands , chafe , storage ...

A single hander will not be able to heave the rode in and drive the boat .....at two in the morning as the thunderstorm kicks in

[Mike OReilly]

Always love learning about new anchor stuff. Have never heard of "kinetic rope" before, but now that it's been explained, I understand. Certainly seems like a good idea in theory. Love to hear some real-world experience though.

How does it compare to nylon? Is it really desirable, or needed, to have more stretch? After all, most of us choose nylon to get the desired stretch. Is more needed? Is there a risk of over-acceleration, as some here suggest?

And what about durability. Someone compared this rope to a bungee cord. I've never found bungee cord to be very strong, and UV chews through it pretty fast. How durable is this stuff?

I am unaware that anchors are getting lighter. I don't even know what this means, other than as Thin explains it. But this is not about getting lighter, or heavier for that matter. It's about better design, and (from my perspective) maximizing the anchor to match your normal operating capacities.

[motion30]

I've been in a lot Of Anchorages and the boats with big anchors and all chain hold better

[Dockhead]

Originally Posted by slug

A lightweight anchor is about as useful as a lightweight steamroller . . .

Best phrase of the whole thread

[rslifkin]

I wouldn't necessarily say a lightweight anchor is useless. Think of a Fortress. But at the same time, some conditions require weight (such as sinking through a bed of weeds to get a good bite into the bottom underneath). So a heavier anchor makes a better general purpose anchor, even if the design were otherwise unchanged. But a lightweight and high surface area anchor can work very well for the conditions it's good at.