Using your new anchor with kinetic rope

[Training Wheels]

Originally Posted by Mike OReilly

Have things changed? If so, I bet it has more to do with the fact that everyone now has a windlass.

No, not everyone.

[Mike OReilly]

Originally Posted by Training Wheels

No, not everyone.

Obviously I was exaggerating to make the point. Far more cruising-level boats now have windlasses. In part this is because average boat size has increased.

I'm still curious about this "kinetic rope." It was described earlier as a kind of bungee cord. So, I can see where it might work. But my questions are:

- Is it needed? Nylon is already chosen as rode or snubber for its elastic capabilities. Do we need more shock absorption?

- Will it produce too much bounce? Some have suggested we might produce a sling-shot effect, sending the boat bouncing all over the anchor, and creating even bigger shock loads.

- How durable is this kinetic rope? Any bungee cord I've worked with scores pretty low in this category.

- Cost?

Finally, weight savings is the reason suggested for this stuff. But is this needed? Aside from certain specific cases (very light boats, catamarans, etc.) saving a few 10s of kg in rode weight doesn't really make a lot of difference to most cruising-level boats.

[rslifkin]

If it allowed use of a more abrasion resistant rode instead of nylon, that might allow use of less chain in some applications. But a nylon snubber would likely work fine for that purpose as well. In most cases, I wouldn't think to do that for overall weight savings, but on boats that are particularly weight sensitive it might allow use of a bigger anchor.

[Muaddib1116]

From watching a few youtube videos after searching for kinetic rope, they seem to be almost entirely used to pull stuck vehicles out of mud or ditches. The operation usually has the towing vehicle accelerate with some slack on the rope, then it pulls and stretches, building up tension, and jerks the stuck vehicle out.

This seems to be exactly the opposite of what you would want with your anchor, especially given the weight differences between your boat and your anchor. Since there's very little weight to the rope, and a lot of stretch, your boat will start moving, build up momentum, load the rope, and then yank the anchor out of the bottom.

Maybe I'm wrong, but this is the only way I see this working.

As far as Izi Kalvo and his Viking anchors, I'm curious if you have any comparison test videos against other popular brands. What type of testing have you done? Your size/displacement ratings for your anchors are pretty staggering, especially compared to Mantus or Rocna's size charts.

Viking 5:
Anchor Weight - 3.4 kg (7.5 lbs)
Boat Weight - Up To 5000 kg (11023 lbs)
Max Boat Length - 7.5 m (24.6 ft)
Max Boat Length for Violent Storm - 6 m (19.7 ft)

Viking 7:
Anchor Weight - 5.2 kg (11.5 lbs)
Boat Weight - Up To 8000 kg (17637 lbs)
Max Boat Length - 11 m (36.1 ft)
Max Boat Length for Violent Storm - 8 m (26.2 ft)

Viking 10:
Anchor Weight - 9.5 kg (21 lbs)
Boat Weight - Up To 11000 kg (24251 lbs)
Max Boat Length - 15 m (49.2 ft)
Max Boat Length for Violent Storm - 10 m (32.8 ft)

Viking 15:
Anchor Weight - 12.6 kg (27.8 lbs)
Boat Weight - Up To 15000 kg (33069 lbs)
Max Boat Length - 18 m (59.1 ft)
Max Boat Length for Violent Storm - 13 m (42.7 ft)

Viking 20:
Anchor Weight - 21.4 kg (47.2 lbs)
Boat Weight - Up To 30000 kg (66139 lbs)
Max Boat Length - 1 m (68.9 ft)
Max Boat Length for Violent Storm - 15 m (49.2 ft)

Viking 25:
Anchor Weight - 27.3 kg (60.2 lbs)
Boat Weight - Up To 40000 kg (88185 lbs)
Max Boat Length - 21 m (68.9 ft)
Max Boat Length for Violent Storm - 15 m (49.2 ft)

Honestly, not being an anchor expert, these numbers almost seem arbitrarily determined and way out of line with pretty much every other anchor manufacturer I've looked at. I mean, you're recommending that you can use a 60lb anchor for a 44ton 70ft boat? Is there anything to back this up?

[Montanan]

Originally Posted by Muaddib1116

From watching a few youtube videos after searching for kinetic rope, they seem to be almost entirely used to pull stuck vehicles out of mud or ditches. The operation usually has the towing vehicle accelerate with some slack on the rope, then it pulls and stretches, building up tension, and jerks the stuck vehicle out.

This seems to be exactly the opposite of what you would want with your anchor, especially given the weight differences between your boat and your anchor. Since there's very little weight to the rope, and a lot of stretch, your boat will start moving, build up momentum, load the rope, and then yank the anchor out of the bottom.

Maybe I'm wrong, but this is the only way I see this working.

As far as Izi Kalvo and his Viking anchors, I'm curious if you have any comparison test videos against other popular brands. What type of testing have you done? Your size/displacement ratings for your anchors are pretty staggering, especially compared to Mantus or Rocna's size charts.


Honestly, not being an anchor expert, these numbers almost seem arbitrarily determined and way out of line with pretty much every other anchor manufacturer I've looked at. I mean, you're recommending that you can use a 60lb anchor for a 44ton 70ft boat? Is there anything to back this up?

Your correct as to the physics of kinetic energy and its loading. As you have indicated the kinetic rope will absorb the kinetic energy of a moving object as it works to deaccelerates the object. It converts motion into a stored linear force. Very much like a gear transforms speed to torque.

One nevers wants your vessel to move when it as on anchor. A moving object induces momentum which energy then has to become resisted to stop its further movement. That movement could be across the ground, or vertically as will be induced by the force of displacement associated with waves [including wakes].

A boat will be faced with windage force which is an exponential factor with the velocity of the wind, it will also be faced with displacement forces associated with waves. The force of the wind tends to be less volatile, steadier in load applied to the rode and the object the rode is attached. That load force changes when the wind speed changes and a gust results in exponential increase in loading.

Wave action is displacement action and is function of the size and periodicity of the waves and the weight of a boat's displacement of the water. When a boat rises and falls due to waves it has a momentum that is induced and resisted. As a wave rises the boat, it increases the displacement load by the kinetic energy transfer into the boat which can be very, very high, far beyond the weight of the boat.

One benefits from having some stretch in your rode to smooth the loading spreading the peak loading over a short period of time, example, half the periodicity of the waves. It is the peak loading that tends to jerk the anchor from its set and once jerked from its set foundation it has to reestablish a setting else it just drags along with little to almost no resistance.

The weights / sizing specifications recommendations you listed for the exemplary anchor due seem light, at least that is my gut sense.

Of keen issue is whether the boat at anchor is being subject to significant wave action which wave action can induce dramatic peak loading. A calm anchorage is tremendously less challenging than an anchorage exposed to swells, waves or wakes.

An anchorage which is subject to stiff currents is also a exposure that induces dramatically greater loads on an anchor. Water having far more density than air, it can put a great deal more load onto boat, especially a non-streamlined hull. Then there are the instances wherein the rode itself becomes entangled with debris or flotsam and the resistance against a current stream of such entanglements can very easily overwhelm even the biggest and most secure anchors / moorings; if the anchor or mooring does not drag then the pull on the rode caused by entanglements of debris on the rode can simply pull the boat under water. This happens when anchored in a river or tidal basin that is flooding or ebbing. Nightmare.

Windage loads will increase exponentially with wind velocity, hence an anchor that could hold in modest winds can be exponentially downsized in its holding capacity. But the anchor needs to have exponentially greater holding capacity as the windage increases.

Note that one has to look at the total and peak loading characteristics of the at anchor vessel, which includes loads due to windage, current flow [including entanglements on the rode or mooring buoy], and kinetic energy loads associated with both across the ground motion [momentum] and the vertical loading and periodic displacement peakings. Many factors, and it is the worst case scenario when they all peak and cross simultaneously.

As to anchors, clearly there are design attributes and size attributes. Sizing up is a grand thing to do as it aids very significantly. Due note that anchors are a bit like boats displacement, there is a cubic factor involved in sizing and in weight.

The only time an anchor can be considered too big is when one is trying to lift it and or when one is not at anchor and you are just transporting it on board your vessel, [while transiting] because the large and heavy anchor requires space aboard and displaces water to float it.

When an anchor is actually being used it can never be too big, it is only too big when it is not set in the surface below the water.

[slug]

Originally Posted by Izikalvo

As for the kinetic rope, no, I did not try it, that it also why i asked for old-timers opinions here, so far as you can see most are against it, still gathering information.

The idea of losing weight without compromising performance is very appealing to me, I believe that in 10 years from now we will see self-drilling anchors with no chain at all, act as a mooring just below the bow of your boat, but, again, time will tell.

Elastic anchor rode acts as a shock absorber

This reduces the chance of breaking the anchor out of the bottom in extreme conditions

[Muaddib1116]

I think there's an optimum amount, and that amount is far less than kinetic rope offers. You want some stretch to prevent snapping the anchor line taught due to a sudden extreme gust of wind, and yanking the anchor loose. But you also don't want so much that it allows the boat to build up a lot of momentum and then yanks the anchor out. I think you guys need to go watch some videos of these ropes in use. They are primarily used for pulling large vehicles out of stuck situations by similarly sized or smaller vehicles. I can only imagine how quickly you will slingshot your anchor off the bottom if it's your boat that's doing the pulling.

[rslifkin]

The length of the kinetic section of the rode can always be shortened to get less total stretch.

[slug]

Originally Posted by Muaddib1116

I think there's an optimum amount, and that amount is far less than kinetic rope offers. You want some stretch to prevent snapping the anchor line taught due to a sudden extreme gust of wind, and yanking the anchor loose. But you also don't want so much that it allows the boat to build up a lot of momentum and then yanks the anchor out. I think you guys need to go watch some videos of these ropes in use. They are primarily used for pulling large vehicles out of stuck situations by similarly sized or smaller vehicles. I can only imagine how quickly you will slingshot your anchor off the bottom if it's your boat that's doing the pulling.

Your best defense is to monitor the weather forecast

If things are looking bad seek shelter or prepare for the worst

Any who is constantly preparing for the worst is dumber than your thumb after you whack it with a hammer

[Muaddib1116]

Originally Posted by rslifkin

The length of the kinetic section of the rode can always be shortened to get less total stretch.

If that's the case, why bother, just use a long enough nylon strand snubber to get your stretch.

But that's not what the OP was suggesting. He was suggesting a 10m chain and the rest being kinetic rode. I would think, regardless of whether you have 10m of chain and then 10m of kinetic rope, or if you are in deeper waters 10m of chain and 20 or 30 meters of kinetic rope that it's probably not a good idea. I think you want your rode stretch to be controllable to the situation and the amount of rode you have out, so a long snubber bridle that you can adjust the length of makes more sense to me.

I think that part of his goal, especially given his claims about his anchors, is to be some sort of revolutionizing force in the anchoring world, bucking tradition and bringing in an era of ultralight anchors and rodes. I don't know enough to say this is impossible, and maybe in a decade we'll all be laughing at how heavy the anchors and chain we used to carry were, but I think that in general anchors and rodes have been getting heavier and heavier with a lot of success.

[rslifkin]

Originally Posted by slug

Your best defense is to monitor the weather forecast

If things are looking bad seek shelter or prepare for the worst

Any who is constantly preparing for the worst is dumber than your thumb after you whack it with a hammer

That depends on where you boat. In some areas, short, severe bursts of weather can pop up without much warning on a day with an otherwise good forecast.

[Dockhead]

Originally Posted by Muaddib1116

I think there's an optimum amount, and that amount is far less than kinetic rope offers. You want some stretch to prevent snapping the anchor line taught due to a sudden extreme gust of wind, and yanking the anchor loose. But you also don't want so much that it allows the boat to build up a lot of momentum and then yanks the anchor out. I think you guys need to go watch some videos of these ropes in use. They are primarily used for pulling large vehicles out of stuck situations by similarly sized or smaller vehicles. I can only imagine how quickly you will slingshot your anchor off the bottom if it's your boat that's doing the pulling.

Indeed!


Not only this, but stretch in a rode also makes it vulnerable to chafe and heat buildup. Has anyone seen a specification for any of this "kinetic rope"? I am quite sure that it is not rated for constant stretching 24/7. Even straight nylon rode is vulnerable to chafe and premature breakage; see https://www.petersmith.net.nz/boat-a...right-rode.pdf


As you and others have said, shock absorption in a rode is desirable but needs to be the right amount, not enough to let forces build up and snatch the anchor out, as kinetic rope is specifically designed to do.



I think the most reliable rodes do not rely on the main rode at all for elasticity; a parallel snubber fulfills this function, while chain provides the full strength link between anchor and boat.


Kinetic rope as an anchor rode is a spectacularly bad idea, for all the reasons stated.

[Dockhead]

Originally Posted by Muaddib1116

. . . but I think that in general anchors and rodes have been getting heavier and heavier with a lot of success.

Yes. The state of the art is the heaviest anchor one can possibly handle, and all chain rode, with a separate nylon snubber.



Tomorrow something different might be invented, but I haven't seen it yet, personally.

[slug]

Originally Posted by rslifkin

That depends on where you boat. In some areas, short, severe bursts of weather can pop up without much warning on a day with an otherwise good forecast.

I’m very familiar with katabatic winds

Folks who choose to anchor in the katabatic jets are dumber than your thumb after you whack it with s hammer

[Dockhead]

Originally Posted by slug

I’m very familiar with katabatic winds

Folks who choose to anchor in the katabatic jets are dumber than your thumb after you whack it with s hammer

You keep saying that, but there is often no choice. Anywhere where there is high ground above the shore, may be subject to katabatic winds, which is nothing other than a thermal inversion. I've experienced it in the Adriatic, and I've experienced it in Greenland.



Unexpected strong conditions go with the territory in many places. If it's not katabatic winds, it is a land-type of thermal thunderstorm line. It is a really good idea to anchor in a way which will withstand a greater force, than the predicted or ordinary weather. That means -- the heaviest and best anchor which you can handle, the choice of all experienced and knowledgeable cruisers.