Originally Posted by
RGMN
Never tin the wire prior to crimping in the contact. This guarantees you will not get a gas tight crimp. And get poor electrical contact as well. If you feel you need to solder the wire to "seal" them do it after crimping, not before. Or just use
blocked wire and not worry about it.
Marine cables/wires are typically tinned in order to prevent corrosion. Lead is a very ductile metal (more than copper) that crimping will easily mold. See
here for West Marine advisor on electrical cables. Notice that the label "Marine grade cable" applies to tinned cables.