Yamaha wiring harness

[Craig Winnerman]

While redoing my gauges in my 1997 S150TXRW, I noticed the wires the stock wiring harness are not tinned, but just plain stranded copper. They are also all 18 awg. I have read that all wiring for marine applications should be at least 16 awg and always tinned. Why does the Yamaha harness not use tinned wire and under gauged?

[boats.net]

No need for large gauge wire on sensor or signal wires. Yamaha has never used tinned wire.

[Craig Winnerman]

No need more for large gauge wire on sensor or signal wires. Yamaha has never used tinned wire.

Why does yamaha choose not to use tinned wire? When splicing into my harness there was corrosion on the copper strands, not much, but was blackish in color on the outer strands. Any marine rated wire is always tinned such as Ancor, etc.