This 8.2 tons instrument with a 6 meter tube for depths up to 250 meters has different peculiarities:

• Self-recover system of the barrel, in order to avoid barrel’s bend and possibility to use Vessels without DP system!
• The tilting of the Vibrocorer takes place through the action of two hydraulic cylinders. This makes easier the launch and recover of the equipment.
• Telemetry and remote control that includes:
  • real time penetration monitor and interruption in case of target reached;
  • inclinometer;
  • altimeter.

• Possibility for the Clients to check the performance in real time from their office.
• Extraction thrust of 200 KN. If that’s not enough, the quick release tube clamp frees the vibrocorer and leaves only the barrel on the seabed.
• 4 retractable stabilizers, independently hydraulically controlled and equipped with transducer, to always know the instantaneous position of each support foot in relation to the structure. The automatic leveling function is given by an inclinometer connected to the dedicated software.
• Jumbo Vibrocorer is fitting with TRT equipment!

The New Handling System has been utilized in a sampling survey in the Adriatic Sea managed by C.N.R. (Italian National Research Council) – ISMAR Bologna.
Due to the interest and trust grant obtained by Party Chief Dr. Fabio Trincardi, the new handling system has been mounted on the Oceanographic Vessel R/V Urania, made up of 4 reticular modules 5 meters long each connected to the cradle.

It has permitted the execution of long cores up to 20 meters, optimizing launching time and recovery of the instrument. In fact the rotation of the lattice of 90°, then the corer from horizontal position to vertical and vice versa, has taken place with an average time of less than a minute.
To underline further the practicality of the execution, it has since been sufficient to utilize only one crane to manage the entire manoeuvre.
The utilization of this new system has thus demonstrated its efficacy and secure control of launching on the sea of very long sampling instruments and, especially, in operative conditions of maximum safety for operators.

Thanks:

Dr. Fabio Trincardi (Director of ISMAR – C.N.R.)

Captain Vincenzo Lubrano Lavadera (R/V Urania – So.Pro.Mar. S.p.A.)

The dredge operation has to be supported by an adequate winch, able to drag and support stress of up to 10.000 Kg.

It is recommended to apply a count-meter and a dynamometer to the winch, in order to verify the tension data on the wire on-line. Simultaneously this data can be sent to a program that will graph the trend.

G. Busatti, P. Colantoni, A. Magagnoli, M. Mengoli – Il dragaggio del fondo marino strumentazioni e metodologie – Rapporto Tecnico n. 14, IGM – CNR, Bologna, 1981.

For deep waters has been designed a special winch: Carma^® Winch. This instrument, connected to the main cable, located just above the trigger, will allow the penetration speed to be controlled. The configuration variations of the corer would remain more or less unchanged, given that the height of the free fall will be set to zero, as will the slack. The elasticity of the cable will not, however, be insignificant, but this problem can finally be solved. Usually, the cable snaps back once released, after it stretches out due to the weight it sustains, depending on the depth of the job at hand. With this new method, the problem is solved because the mass of the corer – which weighs on the main cable – gradually, declines: the speed of the backlash of the main cable will be less than the speed of penetration of the coring tube in the seabed, thus allowing a much better result to be obtained.

The method of controlled penetration speed can also be used in geotechnical or environmental studies, for example in the dating of undisturbed samples for determining the time-line of human affected events when dealing with environmental issues such as contamination and pollution.

The Carma^® Corer SW-104 is made up of five main elements: the Head, the Core Tube, the Nose with core catcher, the “water-containment” valve and the Liner.

The Core Tube is made up of a thin tube of stainless-steel ø 114.3 mm, 1.5 mm thick, long 2008 mm (maximum length), 1354 mm or 654 mm (minimum length). It supports a transparent liner (110 mm diameter, 3 mm thick) that contains the sediment core and bottom water sample by way of a lower barrier in the form of a duck closing device and an upper water-containment valve. The load-bearing lattice, one with the core tube, consists of the arming, closure and recovery mechanisms; in addition it supports the dead weight made up of masses from 17 Kg to 100 Kg.

The unique qualifying aspects of the new instrument are the following:

• Maximum reduction of disturbance of the core, in particular on top;
• Recovery ratio of the penetration close to 100%;
• Absence of water percolation from the top of the core towards the bottom;
• Bottom closure mechanism that allows the undisturbed vertical extraction of the core sample;
• Easily changeable mass;
• Large core diameter of 104 mm (surface area of 85 cm2) that permits detailed sub-sampling and restores an undisturbed nucleus;
• Instrument made up of anti-oxidant material to avoid contamination;
• Maximum adaptability to diverse operating conditions.

The best technique is that using gravity speed controlled/reduced by a winch.
The gravity corer SW-104 is equipped with an aluminium service tri-pod: a variable-tilt carrier can hold the corer in a vertical position or at different angles to optimise on-board operations on the corer itself or on the recovered sample.

The Carma^® Corer SW-104 has obtained the registering of a design patent.
Title: “Apparecchiatura di carotaggio per la campionatura di fondali fangosi e sabbiosi”
Holder: Consiglio Nazionale delle Ricerche
Inventor: Angelo Magagnoli & Maurizio Mengoli

• Head: consisting of a cylindrical iron weight (variable), providing the necessary momentum for the instrument to penetrate.
• Steering fins: a hydrodynamic structure designed to maintain the vertical position of the device during free fall.
• Barrel: composed of stainless-steel 5m-long elements of elevated mechanical strength that can be joined to make up a 10, 15 or more metre barrel.
• Liner: is in PVC with a 100 mm external diameter, 3 mm thickness, and is placed inside the barrel to be filled with sediment during core penetration.
• Nose, cutter and core catcher: the lowermost part of the barrel is reinforced by a core nose which ends with a cutter, designed to facilitate core penetration, and includes a catcher, designed to hold the sediment inside the liner when the core is pulled out of the seafloor.
• Connecting sleeves: designed to rapidly and efficiently join barrel elements by using circular straps instead of using bolts or screws.

The Piston is the most important component of the corer, because it allows for the attainment of long and high-quality core samples from the seabed, characterized by alternating mud and sand layers on which we can perform the study of sedimentary basins from a geological, environmental or paleoclimatic point of view, as well as other relative studies (neotectonic evolution, gravity instability and submarine landslide). These studies are of great importance to off-shore activities, as well as to the control and the limitation of exploitation of the continental platform.

The “active piston” is powered by an automatic mechanism situated at the base of the core barrel. It is able to create a strong suction on the sediment necessary to overcome the friction around the inside walls and facilitate the entrance of the core into the liner.
The piston contains a sphere interception valve controlled by a spring that opens and closes the hydraulic communication between the chambers, until the end of the penetration.

The central cylinder is equipped with some extractable pin valves that in case of a strong depression existing between the piston and the core, or in case of exceeding limits, are activated autonomously during the working phase. In fact, one or more pins can be taken out of their location to restore the right hydraulic pressure in order to avoid the breakage of the core and the liner’s implosion.

The configuration of the Piston Corer CP-20 is variable in weight (from 650 to 2150 Kg) and length (up to 30 metres), in order to choose the right setting for the physical and mechanical characteristics of the soil to be penetrated.

The best technique is the new controlled penetration speed. Depending from the water depth, the new method, called “Angel Descent“, can be used in two different ways: in deep water the Carma® Winch permit the sampling following the patented methodology. In shallow water, up to 30m, is not needful the new winch.

Alternatively has been reached so far very good results using the traditional technique of the free-fall, activated by a mechanical release system applied on the main wire and hooked to the eyebolt’s corer. It consists of a trigger, a counter-weight and a wire-releaser of a determined length depending on the height of the chosen fall.

An accessory instrument essential to the reconstruction of events during the coring is made up of a loaded cell on the snatch block and it provides a digital output for on-line acquisition of the main wire’s strength data.
This data produces a dynamometric graph, which points out the significant events during the coring phase: the corer’s descent, the release, the seabed impact, the penetration, the extraction and the recovery.

A new instrument purchased by Carmacoring for a deep study of the coring dynamics is the accelerometer. Fixed at the corer head, records the acceleration every 2 milliseconds, up to a maximum depth of 3000 metres. See the picture where is possible detect the free-fall and the penetration phase.

Graph Accelerometer

• A. Magagnoli: “CP-20” Carotiere a pistone per carote di sedimento lunghe fino a venti metri. Technical Report n.83, CNR – ISMAR – Sez. Geologia Marina, Bologna, November 2003. (“CP-20 Piston corer for sediment cores up to twenty metres long).

• A.Magagnoli: Sistema Universale per il brandeggio di carotiere lungo venti metri. Technical Report n. 85, CNR – ISMAR – Sez. Geologia Marina, Bologna, December 2003.

Registered patent as utility model related to the Corer
Registered patent as design patent regarding the Active Piston
Holder: Research National Council – Rome, Italy
Inventor: Angelo Magagnoli – Bologna, Italy

• Head: consisting of a cylindrical galvanized iron mass with a variable weight of 200 to 800 Kg which provides the momentum necessary for the instrument to penetrate into the sedimentary layers.
• Barrel: in galvanized iron with a 105 mm external diameter and a variable length of 2 to 6 metres. A longer dimension is achievable by using a proper connecting sleeve. Inside the barrel a liner in PVC meets the right housing, with a 90 mm external diameter (84 internal), implemented to hold the sample.
• Nose, including cutter and catcher: the lowermost part of the barrel is reinforced by a core nose which ends with a stainless-steel cutter. A device with 4 spades of triangular shape locks the nose needed to keep the sample during the corer’s recovery. The closure of the spades is controlled by the liner at the start of the extraction of the seabed.

The most common techniques are two:

• Gravity: lowering the corer at the maximum speed permitted by the winch until it impacts with the seafloor.
• Free-fall: activated by a mechanical release system applied on the main wire and hooked to the eyebolt’s corer. It consists of a trigger, a counter-weight and a wire-releaser of a determined length depending on the height of the chosen fall.

 “Angel Descent” method can be used in deep and shallow water.

A loaded cell on the snatch block, an accessory instrument essential to the reconstruction of events during the coring, provides a digital output for on-line acquisition of the main wire’s strength data.

This data produces a tensiometric graph, which points out the significant events during the coring phase: the corer’s descent, the release, the seabed impact, the penetration, the extraction and the recovery.

A new instrument purchased by Carmacoring for a deep study of the coring dynamics is the accelerometer. Fixed at the corer head, records the acceleration every 2 milliseconds, up to a maximum depth of 3000 meters.

G. Busatti, A. Magagnoli, M. Mengoli: Carotiere a gravità 1.2 T. Rapporto Tecnico n. 13, C.N.R. – Istituto di Geologia Marina, Bologna, 1980.

The Box Corer is made up of a rectangular basement in galvanized iron tapered on the higher portion.
When the Box Corer touches the seabed, a tubular column in the square section descends and a trigger device releases the shovel which will recover the sample.

The column can house up to 5 rectangular weights of 14 Kg each, in order to obtain the correct weight and thrust on the box.
The box, stainless-steel plated, has been positioned on the lower part and has a removable side with a bayonet coupling to directly observe the lithological characteristics of the sample without causing any disturbance.

Let the Box Corer down armed until it impacts with the floor. Afterwards the release of the column takes place and then the penetration of the box into the sediment. The wire of the winch has to be reeled in slowly in order to obtain the correct rotation of the shovel and the closure of the box.

N. 5 modular rectangular masses in lead, 14 Kg each.
Total weight: 80 Kg
Dimension of box: 170×170 mm; height: 250 mm; volume: 7.2 litres

Another kind of grab is the Shipek model, which collects the sample in a semi-cylindrical box, kept open until impact with the seabed. At the moment of impact, a pre-loaded spring triggers a rotation of the box which house the enclosed sample undisturbed until it surfaces.

Volume of the scoop: 3 litres