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Old 20-01-2022, 07:09   #1
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Madcap anti-anchor angel mooring idea?

Hi,


This is a daft idea I had:


When I anchor with my little 1250 kg Etap 22 I use all rope (with a short leader chain) and my little anchor angel (chum, or whatever) of a few kgs of lead that hangs at around half scope on a 'control line' is great for reducing the swinging circle in the ditch-crawling creeks and shallow areas where I love to sail. And it gives a catenary on the rope to reduce snubbing. I love it.


I am pondering the idea of an all rope swinging mooring (large single anchor block)


Although the area is soft mud and the anchor block will be sunk below the mud so I don't see chafe of the rope on the seabed being a problem (and this has been seen by existing practice in the area) I was looking at the 'eco' type setups designed to protect protected seabeds like reefs etc, where floating rope kept the rode off of the sea bed.


Well, then I thought of the opposite of my anchor angel (anti-angel), where I fix an always submerged float along the rode at a length less than the lowest water depth) which would both keep the rode off of the seabed, and provide an inverted catenary to reduce snubbing.
Is this idea crazy?


I'm looking for drawbacks and negative comments - go on - hit me

One thing I thought of is that the float would reduce the weight of the anchor block but it wouldnt be a huge float, so would be negligable as the block is v. heavy.


Cheers
Leigh
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Old 20-01-2022, 07:33   #2
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Re: Madcap anti-anchor angel mooring idea?

The weight mid-way along the anchor rode is called a 'Kellet'. With the kellet, the force you're countering is gravity. With a float, the force you're countering is buoyancy.

What is the weight of the kellet?

How much force is required to straighten the anchor rode with the kellet as compared to the float?

Also....What is the problem you're trying to solve here?
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Old 20-01-2022, 08:05   #3
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Re: Madcap anti-anchor angel mooring idea?

Quote:
Originally Posted by Shrew View Post
The weight mid-way along the anchor rode is called a 'Kellet'. With the kellet, the force you're countering is gravity. With a float, the force you're countering is buoyancy.

What is the weight of the kellet?

How much force is required to straighten the anchor rode with the kellet as compared to the float?

Also....What is the problem you're trying to solve here?
I've heard them called anchor sentinel, angle, chum, buddy, rider, is kellet the proper name?

The kellet is lead so the effective density giving the force down is 11.3 -1 = 10.3 kg / litre (g / cm^3)

With a float it would only be 1 kg/litre upwards (ignoring float plastic weight)

So the float needs to be ten times the volume to give the same force (in the opposite direction, but its a symmetrical problem)

So for the same force as with my roughly 15kg (? from memory its about the size of 1 and a half litre tetrapacks of milk ) kellet, I would need a float of 150 litres

Thats a float of diameter 66 cm - a two foot float!
Bigger than I had envizaged


Is that right? I whizzed through that and am prone to errors

There is no real problem - it was just an idea, although it would be to reduce swinging circle mainly (I am close to a mud bank) and also to reduce snubbing


EDIT - the idea of using a float is so that the anchor rode is kept off the sea bed - mostly
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Old 20-01-2022, 08:38   #4
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Re: Madcap anti-anchor angel mooring idea?

Ok, further searching led me to believe my kellet is probably only around 10 kg


so thats equivalent to a 44 cm (1.5 foot) diameter float
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Old 20-01-2022, 09:50   #5
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Re: Madcap anti-anchor angel mooring idea?

[QUOTE=Malagueta;3558248]I've heard them called anchor sentinel, angle, chum, buddy, rider, is kellet the proper name?/QUOTE]

Kellet.

The others are all brand names of kellets.

---

You need chain. It will scrub every time the tide changes. I like rope OK, but moorings even wear out chain.

There are moorings that do not use chain, but they float the rode, to keep it off the bottom. You don't need catenary (low rode angle) on a mooring the correct size (big mushroom or concrete block). A big anchor, not so much.
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Old 20-01-2022, 10:08   #6
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Re: Madcap anti-anchor angel mooring idea?

[QUOTE=thinwater;3558325]
Quote:
Originally Posted by Malagueta View Post
I've heard them called anchor sentinel, angle, chum, buddy, rider, is kellet the proper name?/QUOTE]

Kellet.

The others are all brand names of kellets.

---

You need chain. It will scrub every time the tide changes. I like rope OK, but moorings even wear out chain.

There are moorings that do not use chain, but they float the rode, to keep it off the bottom. You don't need catenary (low rode angle) on a mooring the correct size (big mushroom or concrete block). A big anchor, not so much.



Thanks
'Kellet' it is then


I already have the rope protected with firehose (with my plan I can move the hose out of the way to inspect the rope at low water) and so perhaps my float should be at low water depth and only large enough to keep the rope off of the bottom.


Prob'ly my 'inverted kellet float' idea will only work in reducing swinging circle and snubbing when its lighter conditions anyway?
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Old 20-01-2022, 10:46   #7
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Re: Madcap anti-anchor angel mooring idea?

Quote:
Originally Posted by Malagueta View Post
Prob'ly my 'inverted kellet float' idea will only work in reducing swinging circle and snubbing when its lighter conditions anyway?
This is also true of the actual kellet. In stronger conditions, the anchor or mooring rode will be straightened anyway. This means that your swing circle will not be reduced during stronger conditions. If you are close to a mud bank, you should ensure that your swing circle keeps you off the bank when the rode is straightened, regardless of the setup you choose.

As for the efficacy of an "inverted kellet," it may reduce snubbing to the same extent as a traditional kellet, but it will reduce your anchor's holding power more than you realize. A traditional kellet is thought to improve holding power of an anchor by adjusting the angle at which the rode pulls on the anchor. A weighted kellet causes the rode near the anchor to pull closer to horizontal, which causes an anchor to dig into the seabed more effectively. Of course, once the rode is straightened that effect is lost, so kellets are unlikely to help with holding power in strong conditions. However, with your "inverted kellet," the angle of the rode near the anchor will be closer to vertical. This will have a similar effect to shortening the scope of your anchor. In strong conditions, the rode will straighten and you will have the same angle as a normal rode, but in moderate conditions I expect your holding power will be reduced.

Now maybe none of that matters with a big concrete block for an anchor, but it's worth thinking about.

If I were you, I would ditch the kellet entirely. If you use a nice stretchy nylon rope for your rode, you should have plenty of cushion against snubbing. You can also add an extra stretchy bridle if needed. And if you use a line that floats, you should be able to keep the rope off the seabed. However, you will have to be vigilant about chafe. If the rope catches on your big concrete block, or a piece of debris, or just slides against a small part of the seabed, you could have a problem. If it were me, I would keep a chain leader, but that does impact the seabed.
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Old 20-01-2022, 15:40   #8
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Re: Madcap anti-anchor angel mooring idea?

Public yacht moorings in Queensland are exactly that - a buried anchor (screw-type rather than concrete block or mushroom) with a massive rope vertically up to a mid-water float (generally at least 3m below water level so it cannot be fouled by passing boats), then another massive rope to a surface float that provides for tide range, and a pennant attached to a swivel below the surface float. They’re made this way to protect the seabed and corals, while maintaining a relatively small turning circle. No chain at all.

This document describes a wide range of mooring designs: https://gcwa.qld.gov.au/wp-content/u...cture-2014.pdf
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Old 20-01-2022, 17:01   #9
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Re: Madcap anti-anchor angel mooring idea?

Nothing wrong with your suggestion. Deepwater Oilfield mooring systems use mid-water buoys of hundreds of tons buoyancy. Very effective at keeping the mooring off seabed.
Every situation is different though, just think through every wind/current, weight/angle scenario.
Worst case is the conditions 'straighten' the mooring line and sink the mid-water buoy further. You. then have a straight 'snatch load' pull to the block.
The major advantage to me is that ALL the forces are significantly dampened by the mid-water buoy. The chafe (angle) maybe improved, or not. The load will be reduced from using a kellett - as I said think it through.
One point to consider is if the mid-water buoy is not a solid fixed volume, but a 'soft' buoy (think fender), the buoyancy will be reduced as the depth increases. (Boyles Law). Plan around a 10% reduction in volume/buoyancy for each meter water depth, (if the solid buoy floods it becomes a kellett!).

It's for good reason that many mooring buoys are hard and have a rope running through the centre (with a stopper knot on top) and a securing eye. The length is made up so the buoy is on surface at the highest tide. The stopper knot pulls the buoy down under load but the buoy slides down the rope should someone need to lift the eye to connect.
I personally try and lengthen my pennant to the buoy so the buoy can get pulled underwater when the boat moves away (called a watching buoy as it breaks surface and 'watches' the boat). It makes for a nice steady pull with no shock, exactly what you are trying to achieve with the only difference being you have 2 buoys (one subsea and a marker buoy on rope end), and the 'commercial' mooring systems use one buoy for cost and ease of installation.
In my view your idea is a better system.

Best
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Old 21-01-2022, 04:49   #10
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Re: Madcap anti-anchor angel mooring idea?

You must also consider others in your mooring field.

Is the swinging circle you're creating going to mean you'll intersect with others' swinging circles?

Also, will your mid-level kellet (yes, it is actually called a kellet) mean that it would be possible for somone with a deeper draft to accidently snag your pennant?

Generally, same-sized boats with similar drafts are grouped together on lighter buoys in shallower water in mooring fields, but that's not always the case.

Just a couple of other items to consider...
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Old 21-01-2022, 05:29   #11
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Re: Madcap anti-anchor angel mooring idea?

OP, you refer to anchoring and then to mooring, so not sure if you're thinking of long term or just short term. Certainly there are times when keeping nylon rode off the bottom is critical. The example mentioned about protecting coral in Aussieland is a great example.

When I was in the Persian Gulf I quickly learned to do all my anchoring with polyprop line. The bottom was a minefield of sharp limestone outcroppings and a tangled mess of nylon anchor lines and fishing lines everywhere. This was obviously just short term anchoring, but it solved a problem.
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Old 21-01-2022, 06:26   #12
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Re: Madcap anti-anchor angel mooring idea?

I join with Shrew, Thinwater, and LittleWing77 in affirming the nomenclature kellet.

I've spent not a few hours looking at the etymology of the word. It shows up for perhaps the first time in the early 20th century.

A 1918 issue of The Rudder has: The “kellet” is much used by fishermen for increasing the holding power of the single anchor.

When I last looked Oxford English Dictionary and the other usual authorities of English etymology mention kellet not at all. Or if mentioned, noted as 'origin unknown'.

Digging further reveals two possible origins, both of which end in about the same place.

The first suggests that kellet was a borrowing (but the borrower remains unidentified) from Newfoundland/Labrador dialect killick, an anchor with wooden crooks acting as flukes bound to a dense rock for mass. Use of killick in Newfoundland and Labrador for a fisher's anchor is attested as recently as 1971.

The second origin story also points to killick, but without a North American origin (and also without any explanation of how or who distorted killick to kellet. This second origin story notes that killick was the accepted naval nomenclature for an anchor symbol on naval uniforms.

OED and others record killick, killock, and variants in modern English in 1630 - 1643 for the same thing: a dense rock to which is bound wooden crooks, claws, or fluke to improve the performance of the rock as drag embedment anchor.

One of the scholars researching Newfoundland and Labrador dialects linked killick to Scottish Gaelic aka Erse kellagh (and variants including cillick, kellick) which Smyth in The Sailor's Word-book (1867) glossed as a stone in a wooden anchor.

You'll of course note that a few things are left unclear, including:

1. if a killick was on a naval ship, was it an improvised anchor or a light anchor, not heavy enough to be a ship's bower but adequate for a ship's boat, and therefore also adequate as a kellet to be run down the ship's anchor cable to increase the capacity of the anchor+cable system to absorb energy?

2. do kellagh/killick relate to keel? Was a killick a ballast stone, a dense stone of the sort used for ballast and carried in the bilges above the keelson and so named after the keel and also suitable for use in a wooden anchor, including an improvised one?

3. was kellet formed by an entrepreneur who was marketing just another version of an anchor sentinel, an anchor chum, an anchor angel etc? Or was kellet just a version of killlick by variation through use in the population of fishers and boaters?
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Old 21-01-2022, 08:06   #13
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Re: Madcap anti-anchor angel mooring idea?

Thanks all! :Thumbsup:

This is for my mooring (I use a kellet for anchoring. I used to use a Chum but now I use a kellet. Always)

The last mooring broke at the bottom shackle connecting the bottom chain to the concrete block, which is now lost under the mud. Probable cause corrosion together with shackle sliding along the metal bar out of the concrete block which was too much of an arc rather than an eye. This was in 2 years. A couple of years before that the bottom shackle undid and she went walkabout as well! I didnt put the shackle on, but it was my responsibility, always learning! I'm amazed how quick the corrosion is here.

The new block will be put in the same place so no fouling of other boats - that's why I am close to the bank, I was last in, but not the end of the world as I have a draft of 70 cm with the keel up (ETAP 22 wont go over like this). I dont hit the bank and always float. just. Its muddy but not up to your elbows soft.

This time I am going to try a no metal solution, that has been used around here before where all the upper rodes are rope - 3-strand nylon. Its a shallow sheltered small bay in the Estuary.

Here is my solution, its all made now, baring some details, waiting for the workboat to put the mooring in.

The idea is to replace a 'make it big so it can rust away' design brief with a 'make it lighter and inspect regularly' approach.

The idea is that at low tide I can pull round the lower rope loop through the plastic tube embedded in the concrete block so as I can inspect all the rope and replace as necessary. The swivel will be always accessible to keep it freed up too. The three loops in the centre of the diagram will be simply joined by a loop to loop (I think that's a stop hitch?) to allow easy undoing. The fire hose is shorter than it appears in the sketch so that it can slide to one end of the rope and the centre part of the rope is visible. The fire-hose is whipped and sewn through the rope at either end (to be cut when needed to inspect rope) to stop it moving.

I'm not sure whether or not to put a floatation buoy or not. I actually think now that given the position and the smallness of my boat (22' 1.25 tonne) its not worth trying mainly because given the lack of water, it will be a navigation hazard to other boats as I obviously cant position it always 3m or so under the water

The concrete block has poly fibres mixed in to increase the tensile strength and I got some pultruded sand coated GRP rebar from a friend in my lab doing Civil Eng research. The steel cross bar is 10 cm diam and is the only bit of metal except the swivel and thimble in the eye splice connected to it. The block is 1 by 1 by 0.3 m and will be buried. We dont have hurricanes.

I'm sure I am being completely daft, but I want to try something different.
I also like to experiment, in a safe way of course
If it doesnt work I will see that and will go back to chain.


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Old 21-01-2022, 10:20   #14
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Re: Madcap anti-anchor angel mooring idea?

The river marina I am in at the moment uses all poly rope moorings without any metal in the system except for a swivel. The concrete blocks have a plastic tube loop moulded into the concrete through which an endless rope is spliced. There is a swivel between the endless rope and a single line tail rope with a large spliced eye with a buoy threaded onto the tail rope under the spliced eye.

The system works well and chafe has not been a problem. The moorings were converted to this system from the old ones with metal fittings in 2011 because corrosion in the metal fittings had proved to be excessive.
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Old 21-01-2022, 10:23   #15
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Re: Madcap anti-anchor angel mooring idea?

Sounds a bit like what I am doing


My figure disappeared from my above post, prob me in an edit.


Maybe I should put the swivel where the loop joins the upper rope too - but not sure how practical that is now. I couldstill inspect it at low tide, but it would also lay in the mud at low tide



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