1920 rowboat motor coil wiring

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  • August 31, 2026 at 7:19 pm #327576
    Gregory Geurts
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      US Member

      Does anyone have a wiring diagram for a rowboat motor coil.  We have two broken wires exiting the coil but only see the one good nub we can reattach to.  (Right side in the pic).  Dremmeled around the potting a bit but can’t find a circuit connection point on the left.  Any suggestions?

      JGG13

      August 31, 2026 at 10:06 pm #327594
      Tubs
      Participant

        I don’t know if these pictures will be of any help. While occasionally one of these coils is still good, its probably about 100 to 1 that yours isn’t.

        RBM-coil

        I did this diagram before taking that coil apart. This is where I “believe” the wires go.

        RBM-coil-B

        A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

        August 31, 2026 at 10:50 pm #327599
        JOSEPH BRINCAT
        Participant

          US MEMBER PAY BY CHECK

          My understanding is that both coils are built the same, each have a primary and secondary winding. There are two coils on the same armature in order to gain the necessary high voltage output.  Magneto technology back in that era required that unusual arrangement. This I recall from a discussion with the guy that knows of such things … Mr T2

          Joe B

          August 31, 2026 at 11:17 pm #327600
          Tubs
          Participant

            That seem to be the case from what I found. The primary wiring harness was confusing to me but I struggle with electronics.

            A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

            September 1, 2026 at 8:44 pm #327679
            Gregory Geurts
            Participant

              US Member

              Thanks guys.  We will continue with the potting surgery and see if we can find the missing lead.  Else we will look at converting the coils.  May lead to more questions.  As always, appreciate the help!

              JGG13

              September 1, 2026 at 10:26 pm #327681
              JOSEPH BRINCAT
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                US MEMBER PAY BY CHECK

                I think that the RBM coil arrangement is analogous to the twin coil set-up on these Eisemann model 72 magnetos. There are two individual coils stuck together, mounted on a single armature. If you were to separate the two coils you find the ends of the two secondary windings connected together. The pictured coil is from a Muncey Neptune twin

                Joe B

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