Installing a helix (corkscrew) mooring.

[Popeye2]

I have a helix (corkscrew) mooring. 120 cm long. The sailboat is 5000 kg.
Can that mooring be screwed in by hand? Its to go in mud which has good holding power, so i guess a bit firm.
A tank essential? Can a dingy help in any way?

[GordMay]

Probably not.
The difficulty in putting in the mooring is installing the helix.
It can sometimes be done by a single diver with support from a boat on the surface*. Be sure that you have an experienced diver who is use to working in zero visibility that will result from the hard work of installing the helix.
Use a large pipe wrench and/or turning bar to gain leverage.
Place the pipe wrench around anchor shaft and begin screwing mooring anchor into the soil. A turning bar will provide more leverage as resistance builds.
Screw the mooring anchor into the soil until the forged eye is at or just below the soil surface. It is very important that only the forged eye is visible above ground. This indicates that the anchor has been fully installed.

*According to Helix Mooring Systems Inc.”
“Some of the Round Shaft (single helice) anchors can be installed by hand with a turning bar.
However, Square Shaft anchors are installed using a hydraulic torque motor. They can be installed from a surface barge using hydraulic drive tools, or by a diver using an underwater torque motor supported by a surface vessel.”

[billknny]

That description of how to install a mooring "by hand" assumes that you have someplace to brace your feet against to push. Not very likely on the bottom of the bay... even a really long lever doesn't help if you can't push against something.

Remember, even if you have a full scuba outfit, you weigh nothing underwater, so can't stand and brace yourself. The harder you try to turn the helix, the more YOU spin around it.

The short answer to the OP question is: "Do not plan on a hand installation."

[GordMay]

See also “Mooring Buoy Planning Guide”
➥ http://www.anaspides.net/documents/s...s/moorbuoy.pdf

[mvmojo]

In the USVI they would install hurricane mooring by putting in three helix moorings at 120 degrees apart all connected by chain to a large weight (engine block, concrete block, etc.) in the center and then a mooring chain up to the ball. The weight acted as a buffer against shock loading. To install the helix moorings, two divers would put a 8-10' bar through the mooring hook and "walk" around to screw it in. Of course, the bottom was all sand so no visibility issues, etc. But, two men wearing tanks with weights and just booties (no fins) could walk around in a circle to screw them in.

[Scubaseas]

What mvmojo and GordMay said about helix but if it's deep mud a mushroom mooring may work better. You can get a helix in mud with two divers and a 10' bar but it's a pain due to low visibility and requires good "communication" between the divers. If it's soft mud one diver can do it with a 10' bar but if it's that easy to put in it'll come out easy too.

[Capt. Ray]

They are properly installed by SCUBA divers with a support boat. A radial strut anchor is attached to the screwed piling and a hydraulic motor on top. The support boat provides the hydraulic pressure which turns in the helix screw.

[AndyEss]

In any installation of any screw, something has to resist the torque needed to advance the screw into the substrate.
The harder the substrate, the better the screw will hold. The harder the substrate, the more resistance you will need to counteract the torque needed to advance the screw.
Helix anchors in many ways are exactly the same as wood screws. The only difference is that sand and clay bottom soils act differently in terms of short term shear due to soil permeability.
In general, a hard clay bottom will give excellent holding - if you can actually generate and resist the torque needed to advance the screw anchor. Soft mud and loose sand, which will allow easy installation, will also have poor holding capacity.

[Popeye2]

Thanks.

[fatherchronica]

I worked 1 season on a salmon boat in Naknek, Alaska a long time ago. I watched several crews screw pretty long helix screw moorings into the river bottom at low tide when it was mud mostly. Being a citizen of the most advanced country in the solar system I have no idea how long 120 cms is, but maybe longer than than the temporary ones I saw installed. Almost everyday that I was in the river I saw boats whisked away on the ebb usually. I don't know if the screws came out, were faulty or the rodes were attached poorly. I was surprised how many crews operated full of alcohol and/or drugs. I do have an idea how long 100 mms is and how long a silly little mm longer is though. I want to add that when the tide was going either way the boats moored looked like you could have skied behind them.

[captstu]

How desperate is the water?

I put in many in 12’ with 2 dinghies, 20 feet of the largest pipe that will fit in the screw and some patience.

1 fit a float like an old life jacket to a pipe firmly attached to the top of the eye.
2 attach a float to the pipe soo so it floats just below the waterline to keep the screw upright
3 attach a t to the top of the pipe
4 drop the assembly in the water until the tip bites
5 put something thru the t and turn by hand as far as you can easily
6 put a pipe thru the t and each dingy grab an end facing opposite directions
7 slowly run both dinghies
8 by the other dinghy operator a beer

[Aeolus6]

Helix Mooring Systems have been used with good success in the aquaculture industry where a 5 knot tidal current in the Bay of Fundy generates a 5 ton drag on a submerged 100' hemispherical net. The helical screw anchors were installed by two divers using an hydraulic motor driven from the surface. For a load of 10,000 lbs, two 5' helical screws were joined together and buried 10' into the bottom up to the forged eye in a three anchor pattern. The key to success with this system is a well designed custom installation that accommodates bottom conditions.

[datapete568b]

Has anybody considered using a jet pump? Most dock builders jet poles
into the bottom with water pressure from a pump . water pressure clears
the sand and mud creates a hole , the helix falls into the hole, nature does the rest (or you can use the jet) to fill in the hole. Works great. (not in coral)

Pete

[Empty Pockets]

I put one in out in Abaco, after everyone told me it was impossible. Hard bottom. I used a length of PVC pipe enough for the water depth. Drilled one end for a 1/2” bolt through the eye of the helix, and the other end big enough for a hickory shovel handle. Two anchors on a run-about to keep it in place over the spot. The limestone bottom was hard, and my hands were blistered and bloody. I would imagine mud would be much easier. It’s definitely doable.

[Jim Cate]

Originally Posted by datapete568b

Has anybody considered using a jet pump? Most dock builders jet poles
into the bottom with water pressure from a pump . water pressure clears
the sand and mud creates a hole , the helix falls into the hole, nature does the rest (or you can use the jet) to fill in the hole. Works great. (not in coral)

Pete

Pete, I reckon there is a big difference between the "holding power" of such a jetted hole compared to screwing into mud that has been settling for eons. Backfilling the hole is unlikely to even really fill it in, let alone compact the fill to the consistency of the original mud.

I've done the piling setting using a jet to create the hole, but there we use the jet inside the pipe piling... and then fill the pipe with concrete. Kinda different!

I think for moorings, if ya don't screw it in, you are likely to get screwed later!

Jim