Originally Posted by transmitterdan
Practical Sailor did some tests with tinned and untinned wire in marine environments. They found no significant difference in connection reliability
. Tinned wire will look better longer but it does not improve the conductivity over plain copper.
I'm not completely up on the spec for "marine" wire, but I do know from experience that some plastic insulation
seems more flexible yet more impermeable to water
than others, and that some wire wicks moisture in more than others.
With regards to tinning, most of us have seen old untinned stranded copper wire from boats, cars, trailers, etc where there was darkening and corrosion
up under the jacket, up to a few inches away from the stripped end.
So it's my expectation that the ideal "marine" wire would be tinned, fine stranded, and with a flexible, tight jacket. Maybe the type of strand and twist determines the conductor cross-section for a given AWG size?
If you're a professional, you pretty much have to be installing official "marine" wire (eg ANCOR) to reassure the customer, but I'm sure that less expensive yet suitable wire could be found if you search in other channels - eg automotive.