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POWER UP WITH OUTBOARD GENERATOR - Transom Electrical Connection for Outboard Starter / Generator.
 

For those of you who ramp launch your boat seasonally wouldn't it be nice to quickly connect the outboard to the boat battery with the cable staying outside the cockpit?  To this end I mounted a trailer connector on Panache's transom for the outboard power connection.  I've enjoyed this convenience ever since 1981.  Its also nice to have an uncluttered cockpit.

There are marine connectors designed for this purpose but they are bulky and ridiculously expensive.  And rightly so if you consider the following operational requirements; water proof, electrical isolation, equipped with a weather proof cap and a strain relief to support the two cables (inside and out).  All very necessary.  I found the equivalent (almost) in the form of a four pin automotive trailer connector at far less cost.  The requirements under the back bumper of a vehicle are not that different from the marine environment.

• The metal case of the transom connector is aluminum so no corrosion.

• The mounting flanges are robust and seal the connector securely to the transom. 

• The spring loaded cap includes a single tooth ratchet to lock the transom and outboard portions together.  Piece of mind while under way!

• The transom portion lacks a water tight cap but I solved this with an annual dribble of ATF on the pins to protect them from corroding.  Electrical connection has never had a problem to date. 

• The transom portion is water tight after a generous application of Sikaflex over the cable entry and around the barrel.

• The outboard portion is water tight with a generous application of Sikaflex over the cable entry and around the barrel.

• The electrical pins are made of brass.  They are big enough to receive the wire and handle the current demands of the outboard starter.  The six amps of charging current from the generator is minimal in comparison.

• The connector assembly is polarized so you always plug it in correctly. 

TRANSOM CONNECTOR - Its ~12' from the transom connector to the boat battery resting in the aft end of the starboard settee.  To ensure maximum power to the starter I installed 2 red (positive) and 2 black (negative) wires each terminated to their own pin in the transom connector.  Red to the top pins and black to the bottom pins.  At the battery end, the red wires were brought together in a crimped and soldered 2 hole lug, bolted to the primary buss bars.  Similarly for the black wires.

The pins in the transom mounted portion are set in a Bakelite barrel that is locked to the housing with a tiny set screw.  To water proof this I coated the barrel with Sikaflex, then slid it back into the connector housing.  Then I tightened the set screw to lock it in place and let the Sikaflex cure.  This will likely be impossible to undo if maintenance is required so my solution is to buy another connector since they are relatively inexpensive. 

OUTBOARD CONNECTOR - Its only 2' to the outboard when fully down on the bracket so no need to double up cables here.  However, to ensure maximum power to the outboard starter I split the bare wire in 2 bundles, pushing a bundle into each pin.  Two adjacent upper pins conduct the positive power and the two adjacent lower pins conduct the negative power.  Then coated it all with Sikaflex for insulation and to prevent movement.

IMPORTANT - Make ABSOLUTELY certain you have the correct continuity through the transom and the outboard connectors.  If you cross wires on any of them you will have a very dangerous electrical short to the battery.  So before you connect to the battery, use an ohmmeter to confirm continuity.  Positive to positive and negative to negative with NO shorts between.  Then plug in the outboard connector and measure continuity end to end with NO shorts between.  Connect the transom cable to the battery and confirm the correct polarity at the end of the outboard cable.  If the voltmeter shows positive on the red wire it is safe to connect it to the outboard.  Finally it is safe to operate the outboard. 

INSTALLATION CONSIDERATIONS

1. Always support the power cables (especially heavy ones) for their full length.  Use a cable tray, conduit, etc.  The last thing you want is a bundle of heavy loose wires swinging with the motion of the hull.  This wears the insulation away, strains the connector and ultimately invites an electrical short or wire breakage.  Any of these is a recipe for disaster, considering that these cables are connected directly to the primary buss bars and then to the battery. 

2. While it is best to mount power cables high up in the hull, away from water or loose stuff stored down low, on an SJ23 there is an unobstructed path along the starboard hull to the battery in the settee.  This is the route used for the power cable on Panache.

3. To eliminate swinging cables leaving the transom connector I secured the unsupported cable with a tie wrap to the plywood bulkhead at the aft end of the cockpit well.

4. Leave at least a foot of slack in the wires to deal with a future calamity.  Its always nice to extract the transom connector out of the hull to service it.  The slack can be left coiled on the bottom of the hull.  Failing that, more wire can be mechanically spliced to the end or a length spliced in the middle.  See table below and don't ask!  Remember to use sealed heat shrink or vulcanizing tape wrapped tight over the crimped splice.  Follow that with two wraps of electrical tape over the splice.  It must be air tight and water proof to prevent corrosion.  (cont'd below table).

5. Spray the connector pins annually with fogging oil or dribble ATF on the pins to prevent corrosion.  This is the trick that converts a connector from dry use to wet use so it can operate on the water. 

6. See Tech Tip E01 for connection to battery.

7. See Tech Tip D13 for electrical connection under outboard cowling.

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