When you say “shielded”, are you referring to the braided metallic covering that was used on military engines? I can’t see using that stuff on outboards. For one thing, it is stiff. For another thing, it is troublesome for leakage through to the shield. We saw a lot of it back in “The Day” on military surplus engines, and usually replaced it with unshielded wire because of the leakage problem.
BTW, the purpose of the shield was to prevent RFI, or Radio Frequency Interference, which was vital in military communications. For civilian use, it was replaced with carbon core wire, found in cars even today.
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