Small butt connectors. I used the same bi-color light in our boat
, each has a switch for white-off-red. Your main switch (circuit breaker?) can be left on and each controlled by its own switch. Unless you have a bunch of glue heat shrink connectors in that size, just use regular. (Dk Blue, if I recall
correctly.) If you want the water
tightness of a glued heat-shrink then use liquid tape or some caulk in the ends but if you have THAT much water
in your light you have other problems...
crimper in most tool kits works good for these, but a good pair is worth it if you need to do other more critical connectors. Maybe it is a chance to start that tool box of quality tools you'll eventually need...