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Model 208-2 - Installation and Operating Instructions

Installing Zinc Anode Plates

  1. The anode plates(s) should be installed on the bottom of the hull, preferably between the transom and one third of the vessel length forward of the transom. The actual location will vary from boat to boat due to individual characteristics of the underwater hull and the interior arrangement of machinery and living space. The anode location is almost always a compromise between the ideal and what is possible. The ideal is for the anodes to be in the area of the highest concentration of metals to be protected. What is possible is generally determined by the accessibility on the inside of the hull for locating the necessary thru-hull penetrations.
  2. Each anode plate should be mounted on two insulated studs. Follow the detailed instructions supplied with the bolts.
  3. No anode should be located closer than twelve inches to the reference assembly.
  4. If an anode plate is mounted in an exposed location, where it possibly will catch or be damaged by debris in the water, a fairing block should be installed in front of it.
  5. Anode plates should never be painted.
  6. Zinc sacrificial anodes must be made of a very high quality alloy. Only zinc anodes that meet or exceed U.S. Navy military specification A18001J should be used. Ask your factory authorized Electro-Guard dealer if you don't know where to acquire anodes that meet the above specification. Using zinc anodes of inferior quality may result in inadequate protection.
  7. The table below shows zinc plate sizes and number relative to the boat size. All plates indicated are one-half inch thick.
    Boat Length Single Screw Twin Screw
    up to 34' 4" x 6" - 1 ea. 3" x 12" - 1 ea.
    35' to 39' 3" x 12" - 1 ea. 6" x 12" - 1 ea.
    40' to 45' 6" x 12" - 1 ea. 6" x 12" - 2 ea.
    46' to 55' 6" x 12" - 2 ea. 6" x 12" - 3 ea.
    Following the above table will provide enough zinc in ninety percent of the cases. If in doubt, put on more than called for in the table. Painting the underwater metal fittings will help reduce the electrical current drain on the anodes and, therefore, extend the life of the anodes. One inch thick anode plates will last almost twice as long.
  8. REMOVE ALL ZINCS WHICH ARE AFFIXED TO OR CONNECTED TO ANY BONDED UNDERWATER FITTINGS.CAUTION: Do Not Remove zincs that are on unbonded fittings or are installed in machinery inside the boat.

Installing the Reference Assembly:

  1. Install as close as is practical to, but not touching, a protected fitting.
  2. Never paint the reference electrode.
  3. Keep at least twelve inches away from the nearest anode.
  4. Follow the detailed instructions that are attached to the reference assembly.
  5. The alloy of the Electro-Guard reference plate is critical. Replace only with an appropriate Electro-Guard reference plate. Do not try to substitute as this may lead to failure of the system to operate correctly.

Installing the Controller:

  1. This unit may be flush mounted by making a cutout of sufficient dimensions to allow for the internal components. If flush mounted, the box should be installed on the reverse side of the panel to protect the electronic components. The unit may also be box mounted.
  2. To flush mount, make a cutout in the panel that is 2 7/8" x 5 1/4".
  3. On smaller vessels which do not have walk-in size engine spaces, it is preferable to locate the controller near the helm or in some other suitable location in the main cabin.
  4. The controller should be mounted in a high visibility location. It should not be located behind a door, inside a cupboard, or anywhere else where it will be hidden from view.
  5. Do not locate the controller where it may get wet or be exposed to weather.
  6. Do not locate the controller closer than 25" to any magnetic compass or auto pilot compass.
  7. Before mounting the controller box, drill a hole through the side, back or bottom to allow for controller cable entry.

Connecting System Components to Controller:

  1. Route a green #14 AWG wire from the #1 Stud on the reference assembly to the controller. Connect this wire to the terminal marked "G" on the controller circuit board.
  2. Route a white #14 AWG wire from the #2 Stud on the reference assembly to the controller. Connect this wire to the terminal marked "W" on the controller circuit board.
  3. Route a yellow #14 AWG wire from a major fitting in the bonding system (such as a strut, shaft log or rudder log) to the controller. Connect this wire to the "Y" terminal on the controller circuit board. The yellow hookup wire should be a separate connection directly to a major fitting that is already in the general bonding system. The connection should be made at a different location than that of the general bonding system connection. This connection assures that the potential meter (colored display) will indicate the true solution potential of a major underwater fitting, which in turn represents the protection level of all the bonded fittings.
  4. Route a yellow #14 AWG wire with one black stripe (or tape marked with one black band) from the port propeller shaft sense brush to the terminal marked "P" on the controller circuit board.
  5. Route a yellow #14 AWG wire with two black stripes (or tape marked with two black bands) from the starboard propeller shaft sense brush to the terminal marked "S" on the controller circuit board.
  6. Route red #12 AWG wire from the bonding system trunk line to the controller terminal marked "R" on the circuit board.
  7. Route a red #12 AWG wire from the shaft wiper or slip ring contact that will input current into the shaft/propeller assembly to the controller terminal marked "R" on the circuit board.
  8. Route a brown #12 AWG wire from the anode(s) to the controller terminal marked "B" on the circuit board.
  9. Use marine grade DC primary wire to connect the system components to the controller. The wire color code should be followed. Wire of the correct colors is available at most marine hardware stores. The most common reason for new system malfunction is incorrect connection of hookup wiring. If the color code is followed, it is impossible to connect the system wiring incorrectly. The code is as follows: Brown (B) -- zinc anodes, Red (R) -- bonding system and propeller shaft current wiper(s), Yellow(Y) -- a major fitting in the bonding system, Yellow w/one black stripe or one black band (PS) -- port propeller/shaft sense brush, Yellow w/two black stripes or two black bands (S) -- starboard propeller/shaft sense brush, White(W) -- the # 2 stud of the reference cell assembly, Green(G) -- the #1 stud of the reference cell assembly.

Bonding the Boat and Connecting to the Barrier Strip:

  1. A heavy gauge trunk line should be installed near the centerline of the boat. It should start at the most forward thru-hull fitting and end near or on the transom. For boats up to 40' long, a AWG 12 solid, plastic insulated copper wire should be sufficient. The trunk line on larger boats should use AWG 10 or larger wire.
  2. Splice, solder and seal branch wires to connect all exposed underwater fittings. It is desirable to make the bonding to the major fittings redundant. For instance, a branch wire may be connected from the trunk line to a rudder log, from the log to two strut bolts, from the strut bolts to two shaft log bolts and from the shaft log back to the trunk line. Branch wires should be AWG 12. All underwater fittings that are to be protected together must be electrically bonded.
  3. Any existing bond wires which are will be used should be inspected for corrosion and/or poor connections.
  4. The propulsion engines should be included in the bonding system. The point of connection should be at the engine negative terminal or its buss as defined by the American Boat and Yacht Council's DC electrical wiring standards.
  5. A coiled, flexible wire should be connected between the main bonding trunk wire and any item that moves, such as the rudders, shaft wipers and engines. Marine DC primary wire is the recommended type for this purpose.
  6. Each propeller shaft should have a shaft wiper assembly installed. The proper location is forward of the shaft seal. Use an Electro-Guard model SB-6B for shaft sizes up to 1 1/4" diameter. Use a model HD-SB for 1 3/8" & 1 1/2" diameter shafts. Propeller shafts 1 3/4" & larger should use propeller shaft slip ring contacts to provide reliable protection. Shaft wipers should be connected directly to the terminal barrier bond connection. The connecting wire should be a minimum of AWG 12.
  7. Any iron, steel or aluminum underwater fittings or structures should be electrically isolated from this bonding system and protected separately. These metals are not adequately protected at the same electrical potential that the copper alloys, stainless steel and lead are protected.
  8. The bonding system should be connected directly by one or more AWG 12 or larger wires to the controller barrier strip.
  9. Allow time for the meters to stabilize after the boat is put into the water, or following final connection when an installation is made with the boat in the water.


  1. The controller is fully automatic and is preset at the factory for optimum operation on the average boat. If all instructions have been followed, the "Protection Level" meter will read somewhere in the green "SAFE" zone when the boat is in seawater.
  2. The Anode Current meter should read between 20 and 900 milliamps (mA). Continuous current readings near or over 900 mA should be reason to contact your dealer for a checkup to find the reason. The larger the boat and the more exposed underwater metal, the greater the expected milliampere reading. Anode current may change considerably from time to time as the controller adjusts for varying tidal conditions, temperature, salinity and adjacent boats causing problems. Underway it will vary from readings at the dock. Any radical change in either meter from the normal as determined over a period of time should be cause for checking your system to determine the reason or have your Electro- Guard dealer check the system for you.
  3. On some boats prone to caustic alkali attack to the wood adjacent to thru-hull fittings (as evidenced by the buildup of a whitish powdery or crystalline chemical, sodium hydroxide, and subsequent deterioration of the wood) which is caused by over protection, it may be necessary to have your dealer reduce the automatic protection level to compensate for this unusual condition in your boat's hull. Any hydroxide buildup should be treated with white, distilled vinegar and your dealer should be contacted.
  4. The green "SAFE" zone on the Protection Level meter affords ample protection for brass, bronze, Monel, copper, stainless, and lead. However, base metals such as iron, steel and aluminum do not have adequate protection in this zone. This system should not be used to protect iron and its alloys or aluminum.
  5. The propeller shaft protection level selector switch allows individual, isolated readings of the each shaft and propeller. Since the rubbing contact of the propeller shaft contact is tenuous and not as reliable as a fixed bonding contact, a protection level sensing contact is installed on each shaft and connected to the switch. The switch is normally in the center position. In this position the potential meter indicates the protection level of all the boat's underwater fittings that are connected into the general bonding system. The switch lever can be moved momentarily into a position to either side of the center position. When the lever is in either of these momentary positions, the protection level indicated is an isolated reading of the port or starboard (whichever is selected) shaft and propeller only. The shaft readings should be the same as the reading for the general bonding system (center position of switch). A shaft protection level reading that varies significantly from the general bonding system reading indicates that the propeller shaft contacts require cleaning and/or adjustment. Neither a higher nor a lower protection level reading for a propeller shaft is acceptable.
  6. When the boat is moved into brackish or fresh water areas, the protection level meter will indicate in the low or under zone and the anode current meter will show zero current. This is normal behavior for the system because there are insufficient ions in fresh water to conduct the electrical current necessary to operate the system.
  7. The Electro-Guard system does not protect engines, machinery or any other metal parts inside the boat.

Trouble Shooting:

Should the meters display readings that indicate system malfunction the following diagnosis of the readings and trouble shooting procedures should assist in determining the source of the problem.

  1. The Protection Level meter needle indicates in the "HIGH" or "OVER" zone and the Anode Current meter is at zero. Zinc anode(s) may be shorted directly to the bonding system or one or more anode has been installed directly on an underwater fitting. Or there may be a problem with electrical continuity between the ac shoreline ground and the boat's bonding system.
  2. The Protection Level meter needle indicates at the left end of the "OVER" zone and the anode current meter is at zero -- both meters are reading at their zero points. The controller may not be connected to the reference cells or the bonding system.
  3. The Protection Level meter indicates in the "LOW" or "UNDER" zone and the anode current meter is indicating an abnormally low or zero current. The system's zinc anode(s) is either too small or completely gone; the anode(s) is consumed or has fallen off the insulated mounting studs. Also, a poor or broken electrical connection between the anode and the controller will have this same result, as will an anode that has been cast from a contaminated zinc alloy and has passivated. Only zinc anodes that meet the U.S. Navy military specification A180001J should be used with this system.
  4. The Protection Level meter indicates out of the "SAFE" zone and the anode current meter indicates somewhere between 150 and 900 milliamps. Either the meter reference wire is disconnected or the meter bond (sense) wire is disconnected or connected to a thru-hull fitting that is not in the general bonding system.

model 208-2

Model 208-2 schematic


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