Engine Harness Upgrade

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By David Miller; Manager, Panel Department, Seaward Products and Gerard Douglas; Chief Engineer, Catalina Yachts and C27

Many Catalina owners have read or heard about the harness upgrades available from Seaward Products as retrofit kits. Some of the published information is misleading, and most of it is incomplete. Seaward is the OEM supplier of panels and harnesses to Catalina Yachts, and has been authorized by them to provide owners with replacement parts and technical information. We are writing this article to clear up any misconceptions about the harness upgrade.

Please see this important message board topic: CRITICAL UPGRADES::: http://c34.org/bbs/index.php/topic,4546.0.html

Ammeters & Shunts are discussed in this MB topic::: http://c34.org/bbs/index.php/topic,6032.0.html

A Bit of History on the Harness

Catalina Yachts has for years used a 10 or 15 foot extension harness with molded rubber plugs to connect the inboard engine to the engine control panel in many models. Charging current from the alternator went through the charging wire up the harness to the ammeter in the panel, and then back down the harness to the battery. A slight variation to this system began in the 1988 model year, with the substitution of a voltmeter for the ammeter in the panel. In the revised system, the charging wire still went up the harness to the panel, and the length of the charging circuit remained the same. With the introduction of the 1993 models, there were numerous changes in the harness and panel system, so many in fact that a new style panel carries a label identifying it as a "Type "A" High Efficiency Panel". One feature of this new system is a change in the routing of the charging circuit from the alternator direct to the battery, significantly shortening the length of the charging wire. Another change is the use of terminal strip connectors in place of the original rubber plugs in the harness. Since it's introduction, the new system has proven to be much more efficient at charging the batteries, while requiring less maintenance.

Applicability of the Upgrade

Replacement Harness Diagram

No boats manufactured prior to the 1993 model year came from the factory with the high efficiency panel. Therefore, all 1992 and earlier models would benefit from the installation of the retrofit kit. If you bought your boat used, and need to know if an upgrade has been installed by a previous owner, remove the engine control panel and inspect the harness connector behind it. If it is not a 12 post termstrip, you do not have the upgrade and should consider installing a kit. Note: some owners have removed the rubber plugs from the harness and reattached the wires using butt connectors. While this may be better than the original plugs, it fails to have the maintenance free reliability of the termstrips.

Shortcomings of the Original System

This charging system design began evolving in the 1970's when there were few 12 volt appliances in use. Today, owners have a plethora of appliances such as TVs, VCRs, Loran, navigation electronics and refrigeration units, all of which impose higher loads on the batteries, with corrspondingly higher charging system loads to keep the batteries charged. To meet the demands of these new systems, some owners have installed high output alternators and/or aftermarket regulators like the Spa Creek Auto Mac, which significantly increase charging current, in some cases beyond that which the charging circuit is designed to handle.

One problem with the original wiring is corrosion, which is inevitable given time and the marine environment. When corrosion forms on electrical terminals it adds resistance to the circuit. This generates heat in the connection and reduces the amount of energy available to charge the battery or run the appliance. Corrosion on the terminals of a harness plug it is not readily seen, nor easy to correct. Most harness connectors are wrapped with black electrical tape to keep them from coming apart, making them difficult to inspect or repair, and giving owners the false sense that corrosion can't happen here.

Another drawback to the original system is the extreme length of the wires in the charging circuit. An ammeter is a device that measures the flow of electrical current and must be connected in series with the charging wire between the alternator and the battery. This requires the wire to run all the way from the engine to the panel and back again, a considerable distance when the meter is located well away from the engine. In the case of a C-34 the round trip can be over 30 feet! It takes energy to force electrical current through a wire, and the longer the wire, the more energy it takes. Energy wasted in forcing current through unnecessarily long wires robs the system of some of it's efficiency. A voltmeter, however, is wired in parallel. It can be located anywhere in the system, not necessarily in the charging wire itself, which allows the wire to be shorter and more directIn 1988 the ammeter was replaced by a voltmeter because the ammeter could give misleading readings under some conditions. Since Catalina boats have a battery selector switch in the charging circuit, there exists the possibility of someone turning the switch to the off position while the engine is running. Although this would cause the diodes in the alternator to burn out and stop all charging of the batteries, the pointer on the ammeter would stay in the center of the dial; the same position which also indicates fully charged batteries and correct operation of the charging system. Under these circumstances the operator would be unaware of any charging problem until the batteries went flat. A voltmeter, however, will indicate continually decreasing voltage under the same circumstances. Though the ammeter was replaced in 1988, the length of the wires in the charging path remained the same, and the charging system still suffered from resistive losses associated with long wires.

At its worst, the combination of high resistance caused by corrosion in the harness plugs and a high charging current caused by flattened batteries or high output aftermarket charging accessories can generate heat in the plugs. If continued for an extended period of time this can lead to melting of the insulation around the plugs. Further use of plugs with damaged insulation can result in electrical short circuits and total system failure.

It is important to note that the problems with the original harness are related to lack of maintenance and improper use. If the plug connections are kept clean and charging currents kept to within designed limits, the original harness will cause no trouble. Owners of boats with few 12 volt appliances or aftermarket charging system accessories may wish to continue using the original harness plugs, but they must impose a rigid, documented routine for cleaning, inspecting and tightening the harness plugs. The frequency of this inspection depends on the boating environment, with saltwater use requiring more frequent attention.

Benefits from the Upgrade Kit


A termstrip has screws that clamp onto the end of soldered wires, making a very solid connection that does not loosen with vibration like a friction fit connector. Soldered wire ends leave no place for corrosion to enter and attack the wires. Once a voltmeter has been mounted in the panel either when the boat was built or when a kit is installed, there is no need to run the charging current all the way up to the panel and then back down to the large (battery) post on the starter motor, which is only about 2 feet from the alternator in the first place. The wire coming out of the alternator can be cut off at the rubber harness connection and then attached directly to the starter motor post. This combination of improved connections on the harness and shorter wires in the charging circuit results in much better charging of the batteries by the alternator and provides easier starting of the engine.

Contents of the Upgrade Kits


The upgrade consists of 3 different items depending on your needs. Kit "A" is for 1970's through 1987 model boats, and contains a voltmeter, 2 termstrips, a charging terminal, step-by-step instructions and wiring diagrams (cost: $50). Kit "B" is for 1988 through 1992 boats that already have a voltmeter, and contains all the items mentioned above except the meter (cost: $20). A replacement harness (cost: $33.50) is available for use with either connector package, and is required under the following conditions:

  • When the original harness has been ruined by over current melting, a lightning strike or contact with a hot surface such as an exhaust manifold. When the owner wishes to move the control panel to a more accessible position, and the original harness will not reach that far.
  • When the original harness is too short to allow access to the rubber plugs behind the panel and must be replaced with a longer one in order to install the kit.

Selection of the Correct Upgrade Package

Determine whether you need Kit A or B by looking for an ammeter or a voltmeter on your engine panel. Determine whether you need a replacement harness. Remove the engine panel. If it comes out far enough so that the rubber plugs are about 8-10 inches from the opening, you should have enough room to work and can install a kit and use your existing harness. Determine whether you need to purchase any additional components by inspecting switches, lights and gauges for proper operation. Pay particular attention to starting switches on 1988 to 1992 model boats. Loose connections here can cause resistive heating and lead to melting of the non-corrosive nylon switch components.

Installation of an Upgrade Kit


All kits are complete and well documented and can be installed by anyone who feels comfortable working in tight places using tools such as wire cutters and soldering equipment. Installation steps are as follows.

Locate the lower set of harness plugs next to the engine and remove the black electrical tape. Cut all the wires on both sides of the plugs and discard the plugs. Remove the insulation from the end of the orange wire coming from the alternator and crimp on the provided terminal. Attach this orange wire to the large battery post on the starter motor to complete the charging circuit.

Remove the insulation from the ends of the remaining wires and tin the end of each with solder. To do this, melt a small glob of solder on the iron and bring it in contact with the wire end. As the wire heats up, it will wick the solder into the strands of the wire. Supply a bit more solder to the wire so the end is fully tinned, right up to the insulation. Don't overdo it, and try not to let the insulation get burned. This may take some practice, so try it a few times on some scrap wire until you get the hang of it. Insert the wire ends into one side of the engine term strip and tighten the clamping screws. If you are not installing a replacement harness, strip and tin the ends of the old harness and install them in the termstrip as you did before, matching the colors of the wires. If you are installing a replacement harness, lay the new one in the bilge area and tape one end to the end of the old harness. You will use the old harness to pull the new one up to the panel.

Go up to the cockpit and remove the engine panel from its mounting position to gain access to the upper set of harness plugs. If you're installing a type "A" kit on a boat built prior to 1987, the ammeter must be removed and replaced with the voltmeter provided in the kit. Cut all the wires on both sides of the plugs and discard the plugs. Install the panel termstrip and connect the panel and harness to it using the "strip and tin" procedure outlined above. Replace the panel. If you're installing a new harness, pull out the old one before connecting it to the termstrip and discard it. Strip and tin the ends of the new harness and install them in the termstrip, then replace the panel and return to the bilge. Strip and tin the new harness wire ends there and install them into the other side of the engine termstrip. Coil up any excess harness whether or not you've installed a new one.

Owners who are not very handy with tools have noted that this can take up to "half a Saturday" to complete, while dealers who have lots of wiring experience can perform the task in a couple of hours. Upon receiving the kit and reading the instructions thoroughly, the owner must decide whether to install the kit himself or have a dealer or boatyard do it for him.

Other Items that Seaward Provides Catalina Owners

Seaward can provide all the information about how to relocate engine panels on early boats from down in the cockpit risers to up in the coaming, including information on the new fiberglass panel enclosure being made by Catalina Yachts. Seaward's new Catalina engine control panels feature improved alarm systems with indicator lights for both high water temperature and low oil pressure. 1994 model Catalina AC-DC panels use circuit breakers instead of the fuses used in the past, and have more control circuits in both the AC and DC sections. Although Catalina has used a number of different vendors to supply its panels over the years, Seaward carries a large stock of replacement gauges, switches and other components regardless of the original panel manufacturer.

Some owners may remember seeing the Seaward name elsewhere on Catalina boats, since we are suppliers of stoves, cooktops, microwave ovens and water heaters. Seaward's customer service department has replacement parts available for these items as well.

Editor's Note: David Miller is ready to answer your questions on Catalina harness and electrical system upgrades (as of 2007). He can be reached at Seaward Products by calling (562)-699-7997