Marine anode with current tester

A sacrificial marine anode with a water proof encased current tester to alert an operator of proper connectivity, current status of the cathodic protection system for an associated marine structure, and status of current tester power supply is disclosed.

CROSS-REFERENCES TO RELATED APPLICATIONS

REFERENCE TO A MICRO-FICHE APPENDIX

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally related to a supplemental cathodic protection system for submersed metal portions of marine structures to mitigate corrosion thereto and to prolong the life of existing anodes installed on the structures.

2. Description of the Related Art

BRIEF SUMMARY OF THE INVENTION

Corrosion is an electrochemical process accompanied by the flow of electrical current. Corrosion occurs when the following elements are present: an electrolyte or medium which conducts current by ion flow, such as water; an anode or metal which corrodes to protect another metal, such as a propeller shaft, rudder, or hull on a boat; a cathode or metal which is protected by another metal, such as bronze and stainless steel fittings on a boat; and a metallic pathway or medium which conducts current by electron flow, such as the hull, bonding systems, electrical systems on a boat.

Galvanic corrosion is the most common form of corrosion that attacks the integrity of boating structures and marine equipment. Galvanic corrosion develops when different types of metals are electrically common by submersion into water. For example, if a boat equipped with a steel rudder that is bonded to a bronze or stainless steel fitting is placed into water, the steel rudder will corrode. The steel rudder becomes the anode, while more noble metals such as bronze or stainless steel become cathodes. The water acts as the electrolyte. The metallic path is the metallic hull of the boat or the boat's bonding system.

Cathodic protection is the process of reversing the corrosion current to stop the damaging corrosion process. One type of cathodic protection known as galvanic cathodic protection is achieved by placing a type of metal into the water with the boat and connecting it to the boat's metallic parts. Metals such as aluminum or zinc are less noble than the other boat metals and therefore act as anodes when connected to the metal parts of the boat.

Zinc anodes have been long used for mitigating corrosion on metal marine structures. These devices typically consist of a bare ingot of zinc mounted to the hull, propeller shaft or rudder, or similar metallic elements of a boat. These anodes are designed to provide protection from galvanic corrosion on the boat. Additionally, bare zinc anodes attached to a long wire that comprises a clamp at the unattached end have been used to supplement the mounted zinc anode systems.

Anodes of the art do not provide replaceable anode elements or protective casings to house the anode during use. Likewise, anodes in the art do not provide current monitoring circuitry to ensure proper deployment or attachment to provide adequate protective cathodic current flow protection to the metal marine structures.

It is therefore desirable to provide an improved apparatus for supplemental cathodic protection of submerged metal portions of marine structures to mitigate corrosion thereto which provides a combined anode and current tester.

It is an object of the present invention to provide an improved anode and current tester which indicates when the anode has been deployed correctly and a connection to the submerged metal portions of a marine structure is made in a satisfactory manner.

It is a further objective of the present invention to provide an improved anode and current tester which indicates when protective cathodic protection current is flowing.

It is still a further objective of the present invention to provide an improved anode and current tester which is easily installed and used by a lay operator.

It is yet a further objective of the present invention to provide an improved anode and current tester apparatus which does not damage surfaces that come in contact with the apparatus.

Yet another object of the present invention is to provide an improved anode and current tester apparatus which will prolong the life of existing anodes installed on marine structures.

The apparatus of the present invention consists of a replaceable anode element and a current tester element. The anode element comprises a cylindrical anode element consisting of a marine grade alloy selected from the group consisting of aluminum, magnesium, zinc, or the like.

The replaceable anode is housed inside a slotted plastic casing. The slotting provides contact between the anode and an electrolyte, such as seawater. The casing protects the anode and the metal marine structure from damage resulting from their contact due to wave action, or damage resulting from the anode contacting others surfaces, namely dropping the anode onto a surface such as a boat deck.

The current tester is housed inside a water proof enclosure. It comprises different colored light emitting diode (LED) lamps or other similar light sources to serve as self check mechanism for proper connection and adequate flow of cathodic protection current. By depressing a switch on the current tester, the operator is alerted as to whether or not the anode has been deployed correctly and attached to the metal marine structure in a satisfactory manner to register a resultant flow of protective cathodic protection current.

DETAILED DESCRIPTION OF THE INVENTION

The present invention combines a marine anode housed within an anode casing which allows anode contact with an electrolyte when the casing is submerged within the electrolyte. The anode is disposed in noncontact association with a metal structure to be protected by a wire of suitably coated and insulated materials. Circuitry housed in a water proof casing is connected in series with the anode and metal structure by attachment to the wire. This circuitry has a self-contained direct current power source, and provides the operator with switched testing of current strength, proper connectivity of the marine anode, and flow of cathodic protection current. Once an anode has been corrosively consumed, it is easily replaced within the anode casing by a new anode of like material.

As shown inFIG. 1, a preferred embodiment of the present invention100comprises a 1.5 inch diameter by 12 inch or 24 inch long slotted or otherwise perforated, cylindrical anode casing10housing a detached 1.2 inch diameter by 12 inch or 24 inch long replaceable anode element20. The anode element is made from a marine grade alloy material selected from the group consisting of aluminum, magnesium, zinc, or the like. The slotted casing10has a plurality of slotted openings16, or similar access, along the casing wall to allow free flow of electrolyte through the casing slots or openings and provide electrolytic contact with the housed anode element20. The slotted casing10is further defined by one open, threaded end to receive a threaded cap40for easy anode access and replacement. The other end of the slotted casing10is closed by a permanent cap30. The anode casing10, and the caps30and40are made from durable grade polyvinylchloride, or similar materials, suitable for withstanding moderate external impact and the internal forces of the metal anode in turbulent electrolytic environments. The anode casing10with caps30and40thus provides protection from the anode impacting decking surfaces or boat sidewalls while in use.

The anode assembly of a preferred embodiment of the present invention,FIGS. 1 and 2, is supplied with a ⅛ inch diameter vinyl coated, stainless steel/insulated copper wire in two lengths. One wire length50which connects the anode element20to the current tester72is approximately twenty-five feet in length. The second wire length90connects the current tester72to a stainless steel connector60for connection to a metal marine structure bonding or cathodic protection system. The stainless steel connector60for a preferred embodiment of the present invention is an alligator type clamp. The second wire length can be tailored for the operator's convenience, but it typically ranges from approximately eighteen to twenty-four inches.

The threaded cap40on one end of the slotted or otherwise perforated anode casing10provides access for the attachment of the vinyl coated, stainless steel/insulated copper wire50to one end of the anode element20through an opening in the threaded cap end.

When an anode is corrosively consumed or otherwise ceases to provide adequate cathodic protection, it is easily replaced by another anode of like material by insertion into the slotted or otherwise perforated anode casing10. This process requires only the opening of the anode casing10at the threaded cap40end of the anode casing10by removal of the threaded cap40. The threaded end cap is positioned a distance along the copper wire50through the opening in the cap end. The consumed anode is detached from the vinyl coated, stainless steel/insulated copper wire50, which is in turn connected to one end of the new or replacement anode element20. One end of the new or replacement anode element20is attached to the copper wire50. The replacement anode element20with copper wire50attached is then inserted into the anode casing10along the casing's longitudinal axis. The threaded cap40is re-secured to the anode casing10and the apparatus of the present invention is ready to be reapplied to the marine structure to provide supplemental cathodic protection.

As further depicted inFIGS. 1 and 3, the current tester70of the present invention is installed in series with the anode assembly near the clamp end of the wire. The current tester70is housed inside a 1 inch diameter by 4 inch length of transparent vinyl tubing72with two plastic, water proof end caps74and76. It is critical to the proper function of the present invention that the sides of the vinyl tubing72provide sufficient compression pliability to allow an operator to depress the switch78of the current tester circuitry by squeezing the tubing72from the exterior of the tubing walls. This external activation of the switch78allows the operator to confirm the adequacy of the current tester circuitry power supply, connectivity of the anode and current tester, and current flow to the intended structure(s). The preferred embodiment of the present invention uses an internal, direct current battery pack306depicted generally inFIG. 3, as its power supply. One end cap74provides water proof access from the length of vinyl coated, stainless steel/insulated copper wire50which is attached to one end of the anode element20. The other end cap76provides water proof access from the length of vinyl coated, stainless steel/insulated copper wire50which is attached to one end of the anode element by an alligator type clamp60with insulated handles. The current tester70is thus made water proof when enclosed within the capped, vinyl tubing housing.

The tester further comprises the necessary electronic circuitry used to detect cathodic protection current flow from the anode to the metal marine structure to be protected. Housed with the tester within the water proof assembly described above is the current supply for the electronic circuitry. The tester provides a manual switch78accessible from the housing exterior by operator applied pressure and a red LED signal80to check the current tester battery life,FIGS. 1 and 3. The tester further provides a green LED signal82to check if the proper connection is made to the metal marine structure to be protected and if a flow of cathodic protection current of 5 mA or greater is detected,FIGS. 1 and 3.

FIG. 2depicts use of an embodiment of the apparatus of the present invention to provide protection to the rear portion of a marine structure,200, having a stern drive unit234with propeller240. The wire portion50of at least one apparatus of the present invention is secured to the unsubmerged portion of the structure so that at least one housed anode portion10hangs three to four feet below the bottom of the submerged portion of the structure,200. In this fashion, the housed anode is within the electrolyte solution, but reamins above any mud or vegetation present in, and any sea floor or similar bottom surface below, the electrolyte.

As shown inFIG. 2, the current tester70is connected in series to the vessel's battery212at the negative post and the anode10by lengths of vinyl coated, stainless steel/insulated copper wire,90and50, respectively. An alligator type clamp connector60secures the length of wire from the tester70to the battery212. The marine vessel's stern drive unit234is grounded to the hull244and connected to the battery212by line256. The housed anode portion10is disposed in noncontact association with the metal elements of the marine structure200to be protected.

FIG. 3is an electrical schematic of a circuit suitable for performing the current testing functions of the present invention. In the following description ofFIG. 3, the component values and identification refer to one particularly preferred embodiment of the circuit and are not limiting to the present invention. As well understood by those in the art, the absolute magnitudes of the components and the particular types of components used in the circuit ofFIG. 3can be changed without adversely affecting the operation of the present invention as long as certain relationships and characteristics of the components are maintained.

FIG. 3shows the line from the anode50and the line from the structure to be protected90. The operator then applies pressure to the transparent portion of the current tester to depress the internal switch or push button78.

As the button78, a normally open push button switch, is pressed, current flows from the battery306into the test circuit. A voltage divider consisting of two resistors,308and309, divides voltage from the battery306to a pre-set reference voltage. The switch78also provides power to the lm324 type operational amplifiers,301-303. Three of the four operational amplifiers built into the lm324 type chip,301-303, are used in this embodiment of the present invention. The first,301, as a primary stage comparator across the shunt resistor307to detect current flow. Its output is fed into the second two switch stage operational amplifiers,302and303, amplifying the signal to determine its value relative the reference voltage. If the output value is below the reference voltage, one of the operational amplifiers302is switched to high, and the other303is low. If the output value is above the reference voltage, these operational amplifier switched values are reversed. This embodiment of a circuitry suitable for the present invention is wired such that if the output of the primary stage operational amplifier301is below the reference voltage, the red LED80is illuminated and the green LED is not illuminated. If the output of the primary stage operational amplifier301is above the reference voltage, the red LED80is not illuminated and the green LED is illuminated. The switching point or current detection threshold is determined by the values and placement of the voltage divider resistors,308and309, and the value of the shunt resistor307. A current limiting resistor310is in series with the LED's,80and82, to prolong battery306and LED life.

Prior to anode deployment, a red LED304glow indicates that the current tester power supply306is adequate but that no current is flowing through the anode10,FIGS. 2 and 3. After anode deployment, i.e.,FIG. 2, the operator again applies pressure to the transparent portion of the current tester to depress the internal switch or push button78. A green LED305glow indicates current flow through the anode10, signifying proper apparatus connection to the vessel200and operation of the anode circuitry. In the present circuitry, the green LED305lights up at about 5 mA. One or more LED's of different colors can be added to this circuitry (not shown), triggered by differing current levels to indicate the level of current output from the anode.

Accordingly, an improved marine anode with current tester has been disclosed.

A latitude of modification, change and substitution is intended in the foregoing disclosure, and in some instances some features of the invention will be employed without a corresponding use of other features. Therefore, it is appropriate that the appended claims be considered broadly and in a manner consistent with the spirit and scope of the invention disclosed herein.