Mooring Rode Cut, Help remedying

[Wannabes00n]

Hello,

About two weeks back a boat partner of mine received an alarming call from the Coast Guard at 9:30pm. Our J24 was adrift and had just floated by their dock. Fortunately at first light she was found fairly safe high and dry on sand/mud/shell not far from the Coast Guard Station. no readily discernable damage was found except pride of course. Without much ado we were able to pull her off at the following high tide.

We are trying to dissect how she came to be adrift. The boat lives in the municipal mooring field about a 1/4 mile W from the CG dock here in Charleston. We had a 24 lb anchor on the bottom which I thought was more than enough for this relatively light boat. 12 feet of chain from the anchor to shackle and then 30-40 feet of rode from the shackle to another shackle attached to a mooring ball. Max depth is probably 16 feet on a big tide but again pretty light boat. A 10 painter from the mooring ball secured the boat to the bottom. The boat was found with ball still attached and shackle still on ball. No anchor line in sight.

You can see the boat well from a bridge and often times I would see the boat "sailed" over the mooring meaning the line must be up under the keel. My thoughts are the probably excessive growth on the bottom sliced the rode. Perhaps a passing boater could have somehow sliced the rode between ball and the chain on a low tide.

Any thoughts on this? Any thoughts on how to prevent the boat from "sailing" up over a mooring while being a ideally good neighbor in a public mooring field? I dont believe someone intentionally cut us but this is possible.

Thanks for your expertise,

Richard

[Captn_Black]

Originally Posted by Wannabes00n

Any thoughts on this? Any thoughts on how to prevent the boat from "sailing" up over a mooring while being a ideally good neighbor in a public mooring field? I dont believe someone intentionally cut us but this is possible.

A line cut with a knife will have a clean edge (though if it is three strand the cut area may not all be the same length, as the line would have begun to unravel before the last strand was cut, so one would be longer, but still with a clean edge) a chafed line will be more ragged. If you have room you could set a stern anchor so that she is always facing the prevailing wind or swell, which ever is more practical/comfortable/safe. With a little practice you can adjust it so that she will swing within the normal range of the wind, but not have enough slack to drift over her own lines. This depends on if there is room for you to do so without impeding your neighbours ofc. With two stern anchors you can balance her even further.

I have a fair bit of experience doing so myself as I've anchored in some pretty bad areas, with shifting winds that would put me beam on to the swell. I was on a mooring and used two anchors off the stern to allow me to swing to face any seaward wind, and would stop me going beam on to swell if the wind came from elsewhere.

[Boatguy30]

Seems like you were very short on scope. Also, I hadn't heard that area refered to as the "municipal mooring field" would be nice if some type of inexpensive but decently regulated field was there.

You need around a 400 lb or more mushroom anchor on a boat that size to be complaint with a New England mooring field

[Captn_Black]

Oh wait... Your mooring bouy was attached to an anchor?? I assumed you were on an actual mooring as well.
Yes, boatguy is right, in 16 feet (did you include freeboard height?) you do not have enough scope. For chain and rode you want at least 5:1 - 80 feet.
"About" is not good enough, you need to know the maximum depth plus likely wave height plus height of your prow, then times that by 5. 24lb anchor is maybe just about ok for your boat, but the size makes no difference if it doesn't have a good angle to hold the ground at, which is why you need enough scope.

[wingless]

An all chain rode will not suffer from an accidental or intentional cut.

[Charlie]

I think that you should investigate what is needed for an adequate mooring ball. A 24lb anchor is probably fine for a 4000lb boat but your use of the anchor to hold a mooring was not the correct use of the anchor. The mooring needs to be secured with a weight because of the lack of scope. Appropriate size anchor but incorrect use.

[Captn_Black]

Originally Posted by Charlie

I think that you should investigate what is needed for an adequate mooring ball. A 24lb anchor is probably fine for a 4000lb boat but your use of the anchor to hold a mooring was not the correct use of the anchor. The mooring needs to be secured with a weight because of the lack of scope. Appropriate size anchor but incorrect use.

Well, if he is just using a bouy as a marker so that he doesn't have to take his anchor with him sailing, I don't see a problem - aside from the short scope and other issues. But he should be connecting directly to the rode when in use, not to the bouy. Not sure which is the case for OP, but yes, from his wording it sounds like he is using it as a mooring, so incorrectly.

[Montanan]

Recommend substantial sized chain rode from a proper weight and size ground tackle device to the mooring ball and then the use of two independent rope rodes in the form of a bridle from the mooring to the boats hard points. A 24 pound anchor would be suitable if the vessel was lying at anchor with substantial rode length to avail a reasonable ratio say 5 to 1 or more, but for a vertical rode deployment to a mooring ball one needs a much stouter ground tackle as the force is vertical not towards the horizontal which tug pulls the anchor deep into the ocean bottom.

The use of two rope rodes reduces the possibility of one rode being overwhelmed as to load and also provides for redundancy if one chafes through. Make one somewhat longer than the first so as to have the first take up a load before the second joins in the action.

References:

https://www.westmarine.com/WestAdvis...manent-Mooring

Mushroom anchors: A weight of 5–10 times boat length is a good rule of thumb, as a bare minimum. The heavier the better, as long as you don’t have to move it.

Cast iron pyramid [Dor-Mor] anchor: Its smaller size, concentrated weight and pyramid shape allows it to embed itself more rapidly, and its holding power (at a scope of 3:1) is up to about ten times its weight.

Mooring Chain
Chapman’s recommends two sections of galvanized chain: a heavier, primary chain and a lighter, secondary chain. The primary (ground) chain lies on the bottom. Its length should be 1 1/2 times maximum water depth. The secondary (riding) chain, is connected to the ground chain with a galvanized shackle or swivel. It's usually half the diameter of the ground chain and equal in length to maximum water depth. The heavier chain is not used for the entire run so that the mooring buoy does not have to support an excessive amount of weight. The chain should be as large as practical; make the riding chain at least double the size of the chain used on your anchor rode.

[Captn_Black]

The method used here in the less civilised world is as follows - Make a mould out of wood, a 55gallon barrel, a wheelie bin, etc (all of these are suitable sized for your ship), create a rebar frame inside, the rebar only needs to be lashed together with wire, no welding needed, a section of rebar shape like an omega should be at the top, with the U shaped part protruding from the mould. Pour the concrete. Normal concrete will set in seawater, but there are mixes that do it better, search online (even the Romans had a mox for this purpose). Ideally you want to do this a low tide, on the beach. After a few days to cure it is possible to get a power boat over the mold, and sling it under the centre of gravity, then use the rising tide to take the mooring block out to the desired location.
That is the cheapest way, but obviously the are potential problems with safety, local authorities etc. But the method can be adapted to work anywhere, though as you start needing things like cranes and planning permits, it gets more expensive. Anyway, I have seen it done that way, and knew an old sailor that did it only with his ship, but that requires I decent tidal range. If you have soft sand or mud in your area, you may be able to get away with a small mould, if you give the mooring a few weeks to sink into the sand before use.

Edit - the weight of concrete in seawater is less than on land -
Featured snippet from the web -
So a cube of concrete 1 foot on each side weighs 150lbs on dry land. We say that this concrete block displaces 1 cubic foot of water. The same volume of sea water weighs 64 pounds, which is the upward buoyant force that is applied to this concrete block when it sits on the bottom of the ocean.

[Wannabes00n]

Many Many thanks for all the thoughtful replies. Capt Black pegged it, we "anchored" a mooring ball and then tied off the boat to the mooring ball so we did not have to take anchor everytime we sail. As most everyone pointed out this not an ideal setup and likely our scope was too short but I am not drawing a direct link to how that affects the boat "sailing/riding" up over the mooring line if wind/tide are separate directions which is top of my theories how boat became adrift.

One option would be to float something in the water to create a drag of sorts so tide will more likely prevail in conflicting conditions. This creates more opportunity of some entanglement though.

Second thought is have 10 ft of chain or so from ball to shackle to rode to shackle to anoth 10/12 ft chain to anchor/mooring. This way the ball has counterweight as well. ideally enough to keep line vertical as possible in water column but not sink ball. Concerns there are chain rubbing up against hull and keel. Could go all chain but now we are exceeding the hulls value!

Stern anchor(s) are notable mention but due to transience of place I hate to foul someone else by taking up so much room for such a small boat. No one else has a stern anchor

The boat never appeared to have dragged and there was no sign of the rode connecting ball to chain. Impossible to know if we were intentionally cut or accidentally cut or cut ourselves. We found the boat with painter tied to ball and shackle still attached to ball. Another mistake we made was we doubled the rode but only tied it off once, creating a loop between ball shackle and anchor chain shackle. While I am confident in the figure 8 follow through with double stoppers and half hitched and pinned tags it is possible knot came undone.

I really appreciate the specifics on appropriate weight for this size boat. Hull weight, according to specs is 3,100#. Plan is to improvise a counter weight of concrete along the lines of Capt Black's thoughts. Capt Black sounds like my kind of Sailor!

Boatguy mentioned not knowing this was the municipal mooring field. I likely overstated by calling it the municipal mooring field. There are some moorings here placed and serviced by the Charleston City Marina. It is also a fairly common anchoring spot for cruisers transiting the area. Not much shore access unfortunately. As far as I am aware there is only enforcement on those mooring balls owned and maintained by Marina. While my boat might appear somewhat derelict there are others that have not moved in years.

Many thanks again to all. Everyone's recs are thoughtfully considered, relevant and helpful.

[dennismenace111]

We had a rash of anchor rodes come apart from mysterious reasons near my nome...after some enterprising lads spent a few nights on their boat secretly...they were dropped by a buddy and thus had no dighy floating nearby to give away that they were on board, we found a guy cutting anchor rodes because he wanted more room to swing. 3 or 4 boats went up against a seaall and suffered damage cause this bone head wanted more space. The City Marine patrol took care of him.

[Cpt Mark]

Lot's of potential failure points in the arrangement. A 24lb anchor. What kind of 24 lb anchor and how was it set?

[rmhutch59]

To stop the sailing you might try a bridle and increasing the windage as far aft as possible.

[Captn_Black]

Some people use a weighted old car tire or other reasonably heavy object off the stern to control the ship in light winds when the tide changes, though not tried that solution myself, I prefer a stern anchor. The way to avoid your stern anchor getting in the way of other ships while you're not there is to secure it to your "mooring" when you go out, use a non-floating line to avoid problems for yourself and others.

And thanks, being on a budget means I have to be inventive But I much I have learned such from observing the locals where I go. Though solutions for you will be even cheaper as you have a small ship.

I reckon that about a 15-25 gallon bucket of concrete would make a suitable mooring for you, if you take the time to allow it to sink into the sand. That should be fairly manageable without specialist equipment, could be suspended from your bowsprit and dropped into position. Though I wash my hands of any consequences :P It's up to you to decide if and how you can do it safely.

Remember that things are lighter in water (weight in air minus the weight of seawater they displace), so you want to use a heavy aggregate for your concrete, like granite gravel or something.

[Captn_Black]

Additionally, if you are worried that the ground is too firm for the concrete to fully sink in, or that it may pop out, you could try sticking some lengths of rebar through the bucket and protruding out at right angles to act as flukes and prevent it rolling if it does pop out.
Anyway, if you use this or a mushroom mooring, remember to use enough scope, as you don't want to be pulling on it vertically, even after it has set.