Just a follow-up. I get sort of irrated at the people who post pretty profound questions, a lot of knowledgable TF folks devote some time and energy to the problem to produce thoughtful suggestions, and the OP is never heard from again.
Back to my situation. I was surprised to find that, this inspection round, the boat entrance connections are good - no charring, no corrosion. Likewise the boat end plugs on the SP cables. My 30 amp SP cables connect to a 50 X 30 (2) Y.
Both the Y side and the SP cable side connectors (actually, the white plastic "plate" that fills the connector center) are not charred but discolored brown - looks like heat damage and the precursor to real charring - but only at the White conductor position (using the NEMA reference drawings). The male tang had black surface corrosion - not into the "meat" of the tang.
There was slight moisture present within the plug housing - couldn't tell if it was condensation or water intrusion ( I have the Marinco "sealing collar" installed on both SP cxable to Y connections). Interesting that the ground tang on both showed slight and localized verdigris - may be because the cables went voyaging this summer and were stowed on deck while underway - but with the female/male ends mechanically connected to hopefully avoid saltwater exposure.
Dried out the plugs, used a brass bristled brush to brighten the "White" tang and an old time points file to get into the female side. Final cleaned and applied Boeshield.
Going forward - for now I'll save my $ and be more watchful of connector condition. Although the Y to SP connections are under partial cover and are suspended and supported with the conductors/connections in the vertical, I will rig a rain shield to divert any rain running down the conductor - similar in concept to the old time dock line "rat guards" - and see what happens.
The long term plan will, I think, have a conversion to Hubbel components if not Smartplug.
As always, I sincerily appreciate the thoughtful input and advice from the TF crowd.
